U.S. patent application number 15/668448 was filed with the patent office on 2017-11-16 for detection of geomagnetically-induced currents with power line-mounted devices.
The applicant listed for this patent is Smart Wires Inc.. Invention is credited to Frank Kreikebaum, Paul Phillipsen, Stuart E. Ross, Yuli Starodubtsev.
Application Number | 20170328935 15/668448 |
Document ID | / |
Family ID | 53774736 |
Filed Date | 2017-11-16 |
United States Patent
Application |
20170328935 |
Kind Code |
A1 |
Kreikebaum; Frank ; et
al. |
November 16, 2017 |
DETECTION OF GEOMAGNETICALLY-INDUCED CURRENTS WITH POWER
LINE-MOUNTED DEVICES
Abstract
A device for use in a power transmission system to sense GICs.
The device may be a part of a reactance-injecting device on a power
line, it may be a standalone device, or it may be a part of another
type of device. The device may include a sensor to sense magnetic
fields (e.g., a Hall effect sensor). The sensor may be positioned
in the air gap of a magnetic core formed concentrically around the
power line. The signal from the sensor may be converted to a
digital signal and separately processed to determine the magnitude
of the AC current and the magnitude of the DC (or quasi-DC)
current. If the output signal of another NC current sensor is
available, that output signal may be used to adjust/calibrate the
determined magnitude of the DC current. The sensor may communicate
with other devices in a network to provide GIC information.
Inventors: |
Kreikebaum; Frank; (Oakland,
CA) ; Phillipsen; Paul; (Shingle Springs, CA)
; Ross; Stuart E.; (Wilmington, NC) ;
Starodubtsev; Yuli; (Hampstead, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Smart Wires Inc. |
San Francisco |
CA |
US |
|
|
Family ID: |
53774736 |
Appl. No.: |
15/668448 |
Filed: |
August 3, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14940910 |
Nov 13, 2015 |
9753059 |
|
|
15668448 |
|
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|
14597377 |
Jan 15, 2015 |
9217762 |
|
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14940910 |
|
|
|
|
61937220 |
Feb 7, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01R 15/207 20130101;
G01R 21/08 20130101; G01R 19/0092 20130101; G01R 15/202
20130101 |
International
Class: |
G01R 19/00 20060101
G01R019/00; G01R 15/20 20060101 G01R015/20; G01R 15/20 20060101
G01R015/20; G01R 21/08 20060101 G01R021/08 |
Claims
1. A device for monitoring geomagnetically-induced currents in a
power transmission line, comprising: a magnetic core disposed about
a power transmission line, the core being configured to provide an
air gap therein, wherein with the exception of the air gap, the
magnetic core completely surrounds the power transmission line; a
magnetic sensor positioned in the air gap to sense magnetic fields
and produce an output signal representative of the magnetic fields;
and a signal processing unit that receives the output signal and
determines the magnitude of a geomagnetically-induced current in
the power transmission line therefrom; wherein the magnetic sensor
is electrically isolated from ground.
2. A device as claimed in claim 1, wherein the magnetic sensor is
electrically connected only to the signal processing unit.
3. A device as claimed in claim 1, further including an upper
housing and a lower housing that are configured for placement
around a power line and for attachment to each other to contain the
core, sensor, and signal processing unit therein.
4. A device as claimed in claim 1, wherein the core includes at
least two separate core portions.
5. A device as claimed in claim 1, wherein the core includes at
least three separate core portions.
6. A device as claimed in claim 5, wherein one of the three
separate core portions is configured to extend approximately 180
degrees around the power line.
7. A device as claimed in claim 5, wherein two of the three
separate core portions are each configured to extend approximately
90 degrees around the power line.
8. A device as claimed in claim 1, wherein the signal processing
unit processes signals at or near DC with a DC processing
portion.
9. A device as claimed in claim 8, wherein the DC processing
portion includes a low pass filter.
10. A device as claimed in claim 8, wherein the DC processing
portion includes a unit for determining the mean of the signals and
providing a DC component signal representative thereof.
11. A device as claimed in claim 1, wherein the signal processing
unit separately processes AC signals and signals at or near DC with
an AC processing portion and a DC processing portion,
respectively.
12. A device as claimed in claim 11, wherein the AC processing
portion includes a unit for determining the RMS value of the signal
and providing an AC component signal representative thereof.
13. A device as claimed in claim 11, wherein the AC processing
portion includes a high pass filter.
14. A device as claimed in claim 13, wherein the AC processing
portion includes a unit for determining the RMS value of the signal
and providing an AC component signal representative thereof.
15. A device as claimed in claim 14, wherein the AC processing
portion includes a ratio-determining unit that determines the ratio
of a reference signal to the AC component signal and produces a
ratio signal representative thereof.
16. A device as claimed in claim 15, wherein the reference signal
is determined externally by a different AC current monitor.
17. A device as claimed in claim 1, wherein the signal processing
unit separately processes AC signals and signals at or near DC with
an AC processing portion and a DC processing portion, respectively;
wherein the DC processing portion includes a unit for determining
the mean of the signals and providing a DC component signal
representative thereof; wherein the AC processing portion includes
a unit for determining the RMS value of the signal and providing an
AC component signal representative thereof; wherein the AC
processing portion includes a ratio-determining unit that
determines the ratio of a reference signal to the AC component
signal and produces a ratio signal representative thereof; and
wherein the signal processing unit includes a multiplier unit that
multiplies the DC component signal by the ratio signal.
18. A device as claimed in claim 1, wherein the signal processing
unit determines a DC component and an AC component; and wherein the
AC component is compared to a reference signal representative of an
external measurement of the AC current in the power line and, based
on the comparison, the DC component is adjusted in proportion
thereto.
19. A device as defined in claim 1, wherein the device includes a
transmitter and an antenna for communicating
geomagnetically-induced current information to an external
device.
20. A device as defined in claim 19, wherein the external device
includes a receiver for receiving information related to
geomagnetically-induced currents.
21. A device as defined in claim 1, wherein the device includes a
current transformer for drawing current off of the power line to
provide operating power to the device.
22. A device as defined in claim 1, wherein the magnetic sensor
includes a Hall effect sensor.
23. A device as defined in claim 22, wherein the output signal from
the sensor is an analog signal and the device includes an
analog-to-digital (ND) converter.
24. A device as defined in claim 23, wherein the analog signal is
provided from the sensor to the ND converter via a twisted pair of
wires.
25. A device as defined in claim 1, wherein the device includes an
injecting unit for injecting reactance into the power line.
26. A device as defined in claim 25, wherein the injecting unit
includes a coil placed relative to a power line in order to inject
the reactance therein.
27. A method of operating a power transmission system having a
power transmission line, comprising: placing a magnetic core onto
the power transmission line of the power transmission system, the
core being configured to provide an air gap therein, wherein with
the exception of the air gap, the magnetic core completely
surrounds the power transmission line; positioning a magnetic
sensor in the air gap to sense magnetic fields and produce an
output signal representative of the magnetic fields, wherein the
magnetic sensor is electrically isolated from ground; and receiving
the output signal and determining the magnitude of a
geomagnetically-induced current in the power transmission line
therefrom.
28. A method as defined in claim 27, further including sending a
communication based on the determining the magnitude step to a
first component of the power transmission system.
29. A method as defined in claim 28, wherein the first component of
the power transmission system is remotely located from the location
where the magnetic core and the magnetic sensor are located
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 14/940,910, entitled "DETECTION OF
GEOMAGNETICALLY-INDUCED CURRENTS WITH POWER LINE-MOUNTED DEVICES,"
filed Nov. 13, 2015, which is a continuation of U.S. patent
application Ser. No. 14/597,377 entitled "DETECTION OF
GEOMAGNETICALLY-INDUCED CURRENTS WITH POWER LINE-MOUNTED DEVICES,"
filed on Jan. 15, 2015, which claims priority to U.S. Provisional
Patent Application No. 61/937,220 that is entitled "DETECTION OF
GEOMAGNETICALLY-INDUCED CURRENTS WITH POWER LINE-MOUNTED DEVICES,"
filed on Feb. 7, 2014, the contents of each of which are
incorporated herein by reference in their entireties.
FIELD
[0002] The present invention generally relates to
geomagnetically-induced currents on power lines of a power
transmission system.
BACKGROUND
[0003] Power transmission systems are formed of a complex
interconnected system of generating plants, substations, and
transmission and distribution lines. A significant issue currently
plaguing power transmission systems may be characterized as
geomagnetically-induced currents (GICs), which are currents induced
in a power line due to time-varying magnetic fields external to the
Earth and resulting time-varying magnetic fields along the Earth's
surface. The time-varying magnetic fields external to the Earth
often result from solar activity and the activity of other
extra-terrestrial objects.
[0004] These GICs have been measured as high as 100 amps for a 20
minute duration. They are typically in a much lower frequency range
than the 50-60 Hz AC power that is conducted on power lines in
modern power transmission systems. These GICs typically have such
low frequency as to be quasi-DC currents. Unfortunately, modern
transmission systems do not handle DC currents well. For example,
high DC currents may cause undesirable resistive heating of
components such as transformer windings which can cause such
components to fail and result in a partial failure of the power
transmission system. Prior art systems for measuring GICs can be
bulky, expensive, and require major efforts to be installed. In
many cases, this is because the GIC sensor requires a break in the
power line in order to install same.
[0005] It is against this background that the techniques disclosed
herein have been developed.
SUMMARY
[0006] A first aspect of the present invention is embodied by a
device that monitors for a geomagnetically-induced current (or GIC)
on a power line (e.g., the first aspect also encompasses a method
or methods for monitoring for/identifying the existence of a GIC on
a power line). The described device is mounted on the power line
and will hereafter be referred to as a GIC monitor. The GIC monitor
includes a magnetic core, which in turn incorporates an air gap.
The magnetic core extends about at least part of a power line when
the GIC monitor is installed or mounted on the power line. A
magnetic sensor is positioned in the air gap of the magnetic core.
This magnetic sensor is configured to sense a magnetic field(s) and
produce an output signal that is representative of the magnetic
field(s) (e.g., representative of the strength of the magnetic
field). A signal processing unit is configured to identify or
determine the existence of a geomagnetically-induced current (or
GIC) using the output signal from the magnetic sensor.
[0007] A number of feature refinements and additional features are
applicable to the first aspect of the present invention. These
feature refinements and additional features may be used
individually or in any combination. The following discussion is
applicable to the first aspect, up to the start of the discussion
of a second aspect of the present invention.
[0008] The GIC monitor may include an upper housing and a lower
housing. The upper housing and lower housing may be at least
partially separable from one another, and in the installed position
or configuration may capture a power line between the upper and
lower housings. In one embodiment the upper and lower housings are
completely separable from one another, and when positioned to
capture a power line therebetween may be detachably connected in
any appropriate manner (e.g., using one or more threaded fasteners;
such that the upper and lower housings are then maintained in a
fixed position relative to one another).
[0009] The magnetic core of the GIC monitor may be of any
appropriate configuration, including where the magnetic core is a
multi-piece structure. One embodiment has the magnetic core
including at least two separate core portions or sections in
relation to proceeding about a power line (e.g., each core portion
or section may correspond with a different angular segment relative
to an axis along which the power line extends). Another embodiment
has the magnetic core including at least three separate core
portions or sections in relation to proceeding about a power line
(e.g., each core portion or section may correspond with a different
angular segment relative to an axis along which the power line
extends). In the case of a three-piece core configuration and when
the GIC monitor is mounted on a power line: 1) one of the core
portions may be configured to extend at least generally 180.degree.
about the power line; 2) another of the core portions may be
configured to extend slightly less than 90.degree. about the power
line; and 3) another of the core portions may be configured to
extend slightly less than 90.degree. about the power line. The air
gap for the magnetic core may be located between the pair of
slightly less than 90.degree. core portions.
[0010] The magnetic core may be characterized as including an upper
core section. The upper core section may extend at least generally
180.degree. about a power line in the installed configuration. A
one-piece configuration may be used for the upper core section. A
plurality of core segments disposed in end-to-end relation could
collectively define the upper core section.
[0011] The magnetic core may be characterized as including a lower
core assembly, which in one embodiment includes two lower core
sections that are spaced from one another to define the air gap in
which the magnetic sensor is disposed. A one-piece configuration
may be used for each such lower core section. A plurality of core
segments disposed in end-to-end relation could collectively and
separately define each lower core section. In any case, a first
face of a first of the lower core sections may abut a first face of
the noted upper core section, while a second face of this first
lower core section may interface with/define a boundary of the air
gap. A first face of a second of the lower core sections may abut a
second face of the noted upper core section, while a second face of
this second lower core section may interface with/define a boundary
of the air gap. The second faces of the first and second lower core
sections may be separated by the air gap and may at least generally
project toward one another.
[0012] The magnetic sensor used by the GIC monitor may be of any
appropriate type, including a Hall effect sensor. The Hall effect
sensor may output an analog signal. The GIC sensor may utilize an
analog-to-digital (ND) converter to convert the analog output
signal from the Hall effect sensor to a digital signal. For
instance, the analog output signal from the Hall effect sensor may
be provided to the ND converter (e.g., via a twisted pair of
wires).
[0013] The output signal from the magnetic sensor may be in the
form of a differential output signal. The output signal from the
magnetic sensor may be provided directly to the signal processing
unit. However, one or more devices may be disposed between the
magnetic sensor and the signal processing unit, for instance to
condition the output signal in any appropriate manner (e.g., to
improve upon the signal-to-noise ratio). One or more of such
devices could also be incorporated by the signal processing
unit.
[0014] The signal processing unit may be of any appropriate
configuration that is able to determine a GIC using an output
signal from the magnetic sensor. The signal processing unit may
include a DC processing portion or section to identify the
existence of a GIC on the power line using the output signal from
the magnetic sensor. Such a DC processing portion may utilize at
least one low pass filter of any appropriate type (e.g., to filter
out higher frequency signals, such as signals that are
representative of the AC current on the power line). The DC
processing portion may further utilize a unit for determining the
mean of the signal(s) that is representative of the DC or quasi-DC
current on the power line. Any such DC or quasi-DC current may be
equated with a GIC by the GIC monitor.
[0015] The signal processing unit of the GIC monitor may be
configured to calibrate the value of the GIC that was determined by
its DC processing portion. An AC processing portion or section may
be utilized by the signal processing unit for this calibration.
Generally, the AC processing portion obtains signals that are
representative of the AC current on the power line from two
separate sources, and uses a ratio of these signals to calibrate
the value of the GIC that was determined by the DC processing
portion.
[0016] The AC processing portion of the signal processing unit may
utilize at least one high pass filter of any appropriate type
(e.g., to reduce or filter out lower frequency signals, such as
signals that are representative of a DC or quasi-DC current on the
power line). The AC processing portion may further utilize a
root-mean-square or RMS detector for determining the magnitude of
the signal(s) that is representative of the AC current on the power
line. A signal that is representative of the AC current on the
power line may be input to the signal processing unit from another
source (e.g., from a current monitor of a reactance module that
also may incorporate the GIC monitor). The ratio of these two AC
signals may then be used to adjust the GIC that has been determined
by the DC processing portion.
[0017] The GIC monitor may include a transmitter and an antenna for
communicating GIC information to one or more external devices
(i.e., external to the GIC monitor). Any appropriate type of
transmitter and antenna may be utilized. Multiple transmitters,
multiple antennas, or both may be used by the GIC monitor. The GIC
monitor may be "self-powered" when mounted on the power line (e.g.,
using power from the power line on which the GIC monitor is
installed). In one embodiment the GIC monitor includes a current
transformer to provide operating power for the GIC monitor.
[0018] The GIC monitor may be in the form of a stand-alone unit
(i.e., separately mounted on a power line). Alternatively, the GIC
monitor may be incorporated by another line-mounted device, for
instance a reactance module. A transformer may be defined when such
a reactance module is mounted on a power line (e.g., a single turn
transformer). The primary or the secondary of this transformer may
be the power line itself. The other of the primary or the secondary
for this transformer may be one or more windings of a core for the
reactance module (e.g., a first winding wrapped around a first core
section of the reactance module, a second winding wrapped around a
second core section of the reactance module, or both for the case
when the first winding and second winding are electrically
connected). Such a reactance module may be configured to
selectively inject reactance into the corresponding power line (the
power line on which the reactance module is mounted). Such a
reactance module could be configured to selectively inject
inductance into the corresponding power line (e.g., to reduce the
current or power flow through the power line, or a
current-decreasing modal configuration for the reactance module).
Such a reactance module could be configured to inject capacitance
into the corresponding power line (e.g., to increase the current or
power flow through the power line, or a current-increasing modal
configuration for the reactance module).
[0019] A reactance module may include any appropriate switch
architecture for switching between two different modes of
operation. A reactance module may include one or more processors
disposed in any appropriate processing architecture to control
operation of any such switch architecture. In a first mode, a
reactance module may be configured to inject little or no reactance
into the corresponding power line (e.g., a bypass or monitoring
mode). In a second mode, a reactance module may be configured to
inject substantially more reactance into the corresponding power
line compared to the first mode (e.g., an injection mode).
[0020] A second aspect of the present invention is embodied by a
method of operating a power transmission system (e.g., the second
aspect also encompasses a power transmission system that is
configured to execute the method(s) described herein). A current on
a power line of the power transmission system is monitored by a
geomagnetically-induced current device or monitor (GIC monitor)
that is installed on the power line. An existence of a
geomagnetically-induced current or GIC on the power line is
identified by the GIC monitor (from the monitored current on the
power line). The GIC monitor sends a communication to another
component of the power transmission system in response to an
identification of a GIC by the GIC monitor.
[0021] A number of feature refinements and additional features are
applicable to the second aspect of the present invention. These
feature refinements and additional features may be used
individually or in any combination. The GIC monitor used by the
second aspect may be in accordance with the above-described first
aspect. A GIC communication in accordance with the second aspect
could embody information such as the magnitude of the identified
GIC, a time at which the GIC was identified (e.g., a time stamp),
the power line on which the GIC was identified, at least the
general location of the GIC, and the like. The GIC monitor may send
a GIC communication to any appropriate component of the power
transmission system, such as a utility-side control system (e.g.,
an energy management system; a supervisory control and data
acquisition system; a market management system).
[0022] Any feature of any other various aspects of the present
invention that is intended to be limited to a "singular" context or
the like will be clearly set forth herein by terms such as "only,"
"single," "limited to," or the like. Merely introducing a feature
in accordance with commonly accepted antecedent basis practice does
not limit the corresponding feature to the singular (e.g.,
indicating that the GIC monitor includes "an antenna" alone does
not mean that the GIC monitor includes only a single antenna).
Moreover, any failure to use phrases such as "at least one" also
does not limit the corresponding feature to the singular (e.g.,
indicating that the GIC monitor includes "an antenna" alone does
not mean that the GIC monitor includes only a single antenna). Use
of the phrase "at least generally" or the like in relation to a
particular feature encompasses the corresponding characteristic and
insubstantial variations thereof (e.g., indicating that a structure
is at least generally cylindrical encompasses this structure being
cylindrical). Finally, a reference of a feature in conjunction with
the phrase "in one embodiment" does not limit the use of the
feature to a single embodiment.
BRIEF DESCRIPTION OF THE FIGURES
[0023] FIG. 1 is a schematic of one embodiment of a power
transmission system having line-mounted reactance modules.
[0024] FIG. 2A is a perspective view of one end of an embodiment of
a line-mountable reactance module.
[0025] FIG. 2B is a perspective view of an opposite end of the
reactance module of FIG. 2A.
[0026] FIG. 3 is an exploded, perspective view of the reactance
module of FIGS. 2A/2B.
[0027] FIG. 4A is a perspective view of a lower core assembly
positioned within a lower housing section from the reactance module
of FIGS. 2A/2B.
[0028] FIG. 4B is an exploded, perspective view of the lower core
assembly and lower housing section from the reactance module of
FIGS. 2A/2B.
[0029] FIG. 4C is a cutaway view showing the lower core assembly
seated within the lower housing section, and taken perpendicularly
to the length dimension of the reactance module of FIGS. 2A/2B.
[0030] FIG. 4D is an enlarged, perspective view of the lower
housing section from the reactance module of FIGS. 2A/2B, and
illustrating the encapsulating sections for the lower core
assembly.
[0031] FIG. 4E is a perspective view of the interior of one of the
lower end caps that is attached to the lower housing section,
illustrating an antenna housing disposed therein.
[0032] FIG. 4F is an enlarged, perspective view of an insert for an
antenna disposed at one of the ends of the reactance module of
FIGS. 2A/2B.
[0033] FIG. 4G is an enlarged, perspective view of an internal
cavity for an antenna disposed at one of the ends of the reactance
module of FIGS. 2A/2B, illustrating an exciter or probe of the
antenna.
[0034] FIG. 4H is a perspective view of a variation of the lower
housing section from the reactance module of FIGS. 2A/2B, and which
incorporates installation hooks.
[0035] FIG. 5A is an exploded, perspective view of an upper core
assembly and upper housing section from the reactance module of
FIGS. 2A/2B.
[0036] FIG. 5B is a bottom view of the upper core assembly seated
within the upper housing section from the reactance module of FIGS.
2A/2B.
[0037] FIG. 5C is a cutaway view showing the upper core assembly
seated within the upper housing section, and taken perpendicularly
to the length dimension of the reactance module of FIGS. 2A/2B.
[0038] FIG. 5D is a perspective view of the interior of the upper
housing section from the reactance module of FIGS. 2A/2B, and
illustrating the encapsulating sections for the upper core
assembly.
[0039] FIG. 6A is a perspective view of the lower core assembly
from the reactance module of FIGS. 2A/2B.
[0040] FIG. 6B is a perspective view of the lower core section for
the lower core assembly from the reactance module of FIGS. 2A/2B,
illustrating spacers installed on faces of the individual lower
core segments that collectively define the lower core section.
[0041] FIG. 6C is a perspective view of the lower core section for
the lower core assembly from the reactance module of FIGS. 2A/2B,
illustrating the faces of the lower core segments that collectively
define the lower core section (before installing the noted
spacers).
[0042] FIG. 7A is a perspective view of the upper core assembly
from the reactance module of FIGS. 2A/2B.
[0043] FIG. 7B is a top perspective view of the upper core section
for the upper core assembly from the reactance module of FIGS.
2A/2B.
[0044] FIG. 7C is a bottom perspective view of the upper core
section for the upper core assembly from the reactance module of
FIGS. 2A/2B, illustrating spacers installed on faces of the
individual lower core segments that collectively define the lower
core section.
[0045] FIG. 7D is a bottom perspective view of the upper core
section for the upper core assembly from the reactance module of
FIGS. 2A/2B, illustrating the faces of the individual upper core
segments that collectively define the upper core section (before
installing the noted spacers).
[0046] FIG. 8A is one perspective view of the lower core assembly
and electronics from the reactance module of FIGS. 2A/2B.
[0047] FIG. 8B is another perspective view of the lower core
assembly and electronics from the reactance module of FIGS.
2A/2B.
[0048] FIG. 9 is one embodiment of a protocol for assembling the
reactance module of FIGS. 2A/2B.
[0049] FIG. 10 is an electrical block diagram for an embodiment of
the reactance module of FIGS. 2A/2B.
[0050] FIG. 11A is a schematic of an embodiment of a power supply
from the electrical block diagram of FIG. 10.
[0051] FIG. 11B is a schematic of an embodiment of a power supply
and a current monitor from the electrical block diagram of FIG.
10.
[0052] FIG. 12A is a schematic of an embodiment of a fault
protection system for the reactance module of FIGS. 2A/2B.
[0053] FIG. 12B is an embodiment of a fault current protocol that
may be used by the fault protection system of FIG. 12A to execute a
plurality of bypass sequences.
[0054] FIG. 12C is a flow chart illustrating one embodiment of a
first bypass sequence that may be executed by the fault protection
system of FIG. 12A.
[0055] FIG. 12D is a flow chart illustrating one embodiment of a
second bypass sequence that may be executed by the fault protection
system of FIG. 12A.
[0056] FIG. 12E is a flow chart illustrating one embodiment of a
third bypass sequence that may be executed by the fault protection
system of FIG. 12A.
[0057] FIG. 13A is a schematic of an embodiment of a power
transmission system with distributed control for multiple arrays of
reactance modules of the type presented in FIGS. 2A/2B.
[0058] FIG. 13B is a schematic of a reactance module or distributed
series reactor (DSR) array controller used to provide distributed
control for the power transmission system of FIG. 13A.
[0059] FIG. 13C is an electrical block diagram that may be utilized
by DSR array controllers from the power transmission system of FIG.
13A.
[0060] FIG. 13D is a diagram of a system condition/contingency data
structure that may be incorporated by DSR array controllers from
the power transmission system of FIG. 13A.
[0061] FIG. 13E is an embodiment of an operations protocol that may
be used by the power transmission system of FIG. 13A to control
operation of individual reactance modules.
[0062] FIG. 13F is an embodiment of a system
condition/contingency-based protocol that may be used by the power
transmission system of FIG. 13A to control operation of individual
reactance modules.
[0063] FIG. 13G is another embodiment of a system
condition/contingency-based protocol that may be used by the power
transmission system of FIG. 13A to control operation of individual
reactance modules.
[0064] FIG. 14 is a block diagram of one embodiment of a GIC
monitoring system.
[0065] FIGS. 15A and 15B are an exploded view and a non-exploded
view of components of a magnetic core for the GIC monitoring system
of FIG. 14.
[0066] FIG. 16 is a block diagram of an embodiment of a signal
processing unit for the GIC monitoring system of FIG. 14.
[0067] FIG. 17 is an exploded view illustrating how the GIC
monitoring system of FIG. 14 could be incorporated into the DSR of
FIG. 2A.
[0068] FIG. 18 is an exploded view illustrating how the GIC
monitoring system of FIG. 14 could be implemented in a standalone
device.
[0069] FIG. 19 is a schematic of a power transmission system that
includes a plurality of GIC sensors.
[0070] FIG. 20 is one embodiment of a GIC monitoring protocol that
may be used by the power transmission system of FIG. 19.
DETAILED DESCRIPTION
[0071] While the disclosure is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that it is not intended
to limit the disclosure to the particular form disclosed, but
rather, the disclosure is to cover all modifications, equivalents,
and alternatives falling within the scope as defined by the
claims.
[0072] One embodiment of a power transmission system is illustrated
in FIG. 1 as identified by reference numeral 10. The power
transmission system 10 includes a plurality of power lines 16
(three in the illustrated embodiment, for providing three-phase
power) that extend between an electric power source 12 and a load
22. Any appropriate number of electrical power sources 12 and loads
22 may be associated with the power transmission system 10. A
plurality of towers 14 of any appropriate size, shape, and/or
configuration may support the various power lines 16 at
appropriately spaced locations. The power lines 16 may be of any
appropriate type, for instance power transmission lines (larger
capacity) or distribution lines (lower capacity).
[0073] A plurality of distributed series reactors (DSRs) or
"reactance modules" are installed on each of the power lines 16 of
the power transmission system 10, and are identified by reference
numeral 24. Although hereafter these devices may be referred to as
"DSRs", it should be appreciated such a reference is actually to a
"reactance module." Any appropriate number of DSRs 24 may be
installed on a given power line 16 and using any appropriate
spacing. Each DSR 24 may be installed on a power line 16 at any
appropriate location, including in proximity to an insulator.
Generally, each DSR 24 (more generally each reactance module) may
be configured/operated to inject reactance (e.g., inductance,
capacitance) into the corresponding power line 16. That is, a given
DSR 24 (more generally a given reactance module) may be of a
configuration so as to be able to inject inductance into the power
line 16 on which it is mounted (e.g., the injected reactance may be
an inductive reactance or inductance, which may reduce the flow of
current through the power line 16 on which the DSR 24 is mounted).
A given DSR 24 (more generally a given reactance module) may also
be of a configuration so as to be able to inject capacitance into
the power line 16 on which it is mounted (e.g., the injected
reactance may be a capacitive reactance or capacitance, which may
increase the flow of current through the power line 16 on which the
DSR 24 is mounted).
[0074] FIGS. 2A, 2B, and 3 illustrate a representative
configuration for the DSRs 24 presented in FIG. 1, and which is
identified by reference numeral 30. Generally, the configuration of
the DSR or reactance module 30 presented herein is of the type that
provides for the injection of inductance into a power line 16 on
which it is mounted. However and as in the case of the DSR 24
discussed above, the DSR 30 could be configured so as to inject
capacitance into the power line 16 on which it is mounted (not
shown).
[0075] The DSR 30 of FIGS. 2A, 2B, and 3 is configured for
installation on a power line 16 without requiring a break in the
same. In this regard, a housing 40 of the DSR 30 includes a first
or lower housing section 80 and a second or upper housing section
120 that are detachably connected in any appropriate fashion. A
first or lower end cap 90 and a second or upper end cap 124 of the
housing 40 are positioned on one end 42 (e.g., a power end) of the
DSR 30, and another lower end cap 90 and upper end cap 124 are
positioned at the opposite end 44 (e.g., a control end) of the
housing 40. As will be discussed in more detail below, the DSR 30
uses a pair of cavity-backed slot antennas 100 (e.g., FIGS. 4E, 4F,
and 4G), one being positioned at least generally at each end 42, 44
of the DSR 30. As such, a slot 94 for the antenna 100 extends
through the wall thickness of the housing 40 at each of its ends
42, 44.
[0076] The housing 40 of the DSR 30 at least substantially encloses
a core assembly 50 (e.g., in the form of a single turn
transformer). Although the core assembly 50 (e.g., collectively
defined by core assemblies 130, 160) is illustrated as having a
round or circular outer perimeter, other shapes may be appropriate.
A first or lower core assembly 130 is disposed within the lower
housing section 80 (e.g., within a compartment 86), while a second
or upper core assembly 160 is disposed within the upper housing
section 120. The lower core assembly 130 includes a first or lower
winding 144, while the upper core assembly 160 includes a second or
upper winding 174. The windings 144, 174 may be electrically
interconnected in any appropriate manner. The lower core assembly
130 and the upper core assembly 160 are collectively disposed about
the power line 16 on which the DSR 30 is installed. When the core
assembly 50 is installed on a power line 16, it collectively
defines a single turn transformer, where the primary of this single
turn transformer is the power line 16, and where the secondary of
this single turn transformer is defined by the windings 144, 174
for the illustrated embodiment. However, the secondary of this
single turn transformer could be comprised of only the lower
winding 144 or only the upper winding 174. For example, the lower
core assembly 130 may include the lower winding 144, and the upper
core assembly 160 may not include the upper winding 174. Similarly,
the lower core assembly 130 may not include the lower winding 144,
and the upper core assembly 160 may include the upper winding 174.
As such, the primary of the noted single turn transformer is the
power line 16, and the secondary of this single turn transformer
may be the lower winding 144 by itself, may be the upper winding
174 by itself, or collectively may be the lower winding 144 and the
upper winding 174. Furthermore, while the power line 16 is
described herein as the primary winding and some combination of the
lower and upper windings 144, 174 are described herein as the
secondary winding, as that may be conventional when describing the
power line 16 when it is part of a single-turn transformer, for the
purposes of the device 202 to be described herein, one could refer
to the combination of the lower and upper windings 144, 174 as the
primary winding and the power line 16 as the secondary winding. In
each case, the function is the same.
[0077] The housing 40 of the DSR 30 also at least substantially
encloses electronics 200 for undertaking various operations of the
DSR 30. The electronics 200 are disposed within the lower housing
section 80, and are separated from the lower core assembly 130 by a
partition or barrier 82. This partition 82 may provide shielding
for the electronics 200, such as shielding against electromagnetic
interference. Any appropriate shielding material may be utilized
for the partition 82.
[0078] A pair of first or lower clamps 64 are associated with the
lower core assembly 130, and may be anchored relative to the lower
housing section 80 in any appropriate manner. A pair of second or
upper clamps 66 are associated with the upper core assembly 160,
and may be anchored relative to the upper housing section 120 in
any appropriate manner. Although the clamps 64, 66 could directly
engage the power line 16, in the illustrated embodiment a pair of
line guards 20 are mounted on the power line 16 at locations that
correspond with the position of each pair of clamps 64/66.
[0079] Additional views of the lower housing section 80 and lower
core assembly 130 are presented in FIGS. 4A-4G. FIG. 4A shows the
lower core assembly 130 being positioned within the lower housing
section 80, while FIG. 4B shows the lower core assembly 130 being
exploded away from the lower housing section 80. A barrier or
partition 82 is associated with the lower housing section 80, and
defines a lower or electronics compartment 84 and an upper or core
compartment 86 (e.g., FIG. 4C). In one embodiment, the electronics
compartment 84 is at least substantially waterproof. Moreover and
as noted, the electronics compartment 84 may be shielded from the
core assembly 50, for instance by the above-noted barrier or
partition 82. In any case, the electronics 200 are disposed within
the electronics compartment 84, while the lower core assembly 130
is disposed within the core compartment 86.
[0080] The lower core assembly 130 is retained by encapsulating
sections 150, 152 within the lower housing section 80 (e.g., FIGS.
4B, 4C, and 4D). In one embodiment, the encapsulating sections 150,
152 are each in the form of a silicone elastomer encapsulant such
as Sylgard.RTM. available from Dow Corning (the Sylgard.RTM. for
the encapsulating sections 150, 152 may be matched to the
dielectric and operational performance rating of the DSR 30). The
encapsulating section 152 is disposed between the lower core
assembly 130 and the partition 82 of the lower housing section 80.
The encapsulating section 150 is disposed between the lower core
assembly 130 and the power line 16. A first or lower power line
cavity 138 extends along the length of the lower core assembly 130
(within the encapsulating section 150) for receiving a lower
portion of the corresponding power line 16. FIG. 4D shows the
relative position of the encapsulating sections 150, 152, with the
lower core assembly 130 being removed to show this relative
position.
[0081] A pair of first or lower end caps 90 are disposed at each of
the two ends 42, 44 of the DSR 30, and are each detachably
connected in any appropriate manner to the lower housing section
80. Each lower end cap 90 includes an end wall 92. A slot 94
extends through the entire thickness of the end wall 92, may be of
any appropriate shape, and is part of the associated antenna 100.
The slot 94 may be characterized as having a "folded configuration"
to provide for a desired length. An antenna compartment 98 is
disposed within each lower end cap 90. An end plate 88 (FIG. 4F)
separates this antenna compartment 98 from the electronics
compartment 84. Generally, each antenna 100 utilizes an aperture
that extends through the housing 40 of the DSR 30, and this
aperture may be of any appropriate shape/size, and may be
incorporated in any appropriate manner (e.g., such an aperture
could actually project downwardly when the DSR 30 is installed on a
power line 16).
[0082] Other components of the antenna 100 are illustrated in FIGS.
4E, 4F, and 4G. Again, an antenna 100 is located at least generally
at the two ends 42, 44 of the DSR 30 in the illustrated embodiment,
with each antenna 100 being located within its corresponding
antenna compartment 98. Each antenna 100 includes an antenna
housing 102 of any appropriate size/shape and which may be formed
from any appropriate material or combination of materials. The
antenna housing 102 includes a back section 104, along with a
plurality of side sections 106 (four in the illustrated embodiment)
that extend to the back side of the end wall 92 of the
corresponding lower end cap 90. As such, the end wall 92 of the
corresponding lower end cap 90 may be characterized as defining an
end of the antenna housing 102 that is disposed opposite of the
back section 104.
[0083] An insert 110 (FIG. 4F) may be disposed within the antenna
housing 102. This insert 110 may be formed from any appropriate
material, for instance Teflon.RTM.. An insert 110 may not be
required in all instances. In any case, a projection 112 may be
formed on an end of the insert 110, and extends into the slot 94 on
the end wall 92 of its corresponding lower end cap 90. The antenna
housing 102 defines an internal cavity 108 having an exciter or
probe 114. The antenna 100 may be characterized as a slotted
antenna or as a cavity-backed slot antenna. Notably, neither
antenna 100 protrudes beyond an outer perimeter of the housing 40
for the DSR 30.
[0084] A variation of the DSR 30 is presented in FIG. 4H in the
form of a DSR 30'. Corresponding components of these two
embodiments are identified by the same reference numerals. Those
corresponding components that differ are further identified by a
"single prime" designation in FIG. 4H. Unless otherwise noted, the
DSR 30' includes the same features as the DSR 30.
[0085] One difference between the DSR 30 and the DSR 30' is that
there is a single antenna 100 in the case of the DSR 30' of FIG.
4H. This single antenna 100 may be disposed at an appropriate
location between the ends 42, 44 of the DSR 30 (e.g., within the
housing 40). In the illustrated embodiment, the antenna 100 is
disposed at least generally midway between the ends 42, 44 of the
DSR 30'. Relatedly, the end wall 92' of the two lower end caps 90'
need not include a slot 94. Instead, a similar slot would be
included on the bottom of the housing 40 to accommodate the antenna
100 for the DSR 30' (i.e., on the surface of the first housing
section 80 that projects in a downward direction when the DSR 30'
is installed on a power line 16).
[0086] Another difference between the DSR 30 and the DSR 30' of
FIG. 4H is that the DSR 30' includes a pair of installation hooks
96. One installation hook 96 may be disposed within the lower end
cap 90' at each of the ends 42, 44 of the DSR 30'. Each
installation hook 96 may be anchored in any appropriate manner
relative to the first housing section 80 of the DSR 30'. That is,
the installation hooks 96 will move collectively with the lower
housing section 80 during installation of the DSR 30' on a power
line 16. It should be appreciated that the installation hooks 96
could also be integrated into the structure of the DSR 30 in any
appropriate manner.
[0087] The installation hooks 96 facilitate installation of the DSR
30' on a power line 16. Generally, the first housing section 80 of
the DSR 30' may be suspended from a power line 16 by disposing each
of the installation hooks 96 on the power line 16 (the installation
hooks 96 engaging the power line 16 at locations that are spaced
along the length of the power line 16; the installation hooks 96
could be positioned directly on the power line 16, or on a
corresponding line guard 20). The second housing section 120 may
then be positioned over each of the power line 16 and the first
housing section 80. At this time, the second housing section 120
may be supported by the power line 16 and/or the first housing
section 80.
[0088] With the second housing section 120 being properly aligned
with the first housing section 80, a plurality of fasteners may be
used to secure the second housing section 120 to the first housing
section 80. As the second housing section 120 is being connected to
the first housing section 80, (e.g., as the various fasteners are
rotated), the first housing section 80 may be lifted upwardly in
the direction of the second housing section 120, which in turn will
lift the installation hooks 96 (again, fixed relative to the first
housing section 80) off of the power line 16. Ultimately, the
installation hooks 96 are received within the hollow interior of
the second or upper end caps 124 of the second housing section 120.
Once the second housing section 120 and the first housing section
80 are appropriately secured together, both installation hooks 96
will be maintained in spaced relation to the power line 16.
[0089] Additional views of the upper housing section 120 and upper
core assembly 160 are presented in FIGS. 5A-5D. FIG. 5A shows the
upper core assembly 160 being exploded away from the upper housing
section 120 (the upper core assembly 160 being received within a
core compartment 122 of the upper housing section 120), while FIG.
5B shows the upper core assembly 160 being positioned within the
upper housing section 120 (more specifically within the core
compartment 122). A pair of second or upper end caps 124 are
detachably connected to opposite ends of the upper housing section
120 and define corresponding portions of the two ends 42, 44 of the
DSR 30.
[0090] Referring now to FIG. 5C, the upper core assembly 160 is
retained by encapsulating sections 180, 182 within the upper
housing section 120. In one embodiment, the encapsulating sections
180, 182 are a silicone elastomer encapsulant such as the
above-noted Sylgard.RTM.. The encapsulating section 182 is disposed
between the upper core assembly 160 and the upper housing section
120. The encapsulating section 180 is disposed between the upper
core assembly 160 and the power line 16. A second or upper power
line cavity 168 extends along the length of the upper core assembly
160 (within the encapsulating section 180) for receiving an upper
portion of the corresponding power line 16. FIG. 5D shows the
relative position of the encapsulating sections 180, 182, with the
upper core assembly 160 being removed to show this relative
position.
[0091] FIGS. 6A-6C present various enlarged views pertaining to the
lower core assembly 130. The lower core assembly 130 includes a
first or lower core section 132 (FIG. 6B) having a pair of
oppositely disposed ends 136. A first or lower winding 144 (FIG.
6A) wraps around the lower core section 132 between its two ends
136.
[0092] The lower core section 132 of the lower core assembly 130 is
collectively defined by a plurality of first or lower core segments
140 that are disposed in end-to-end relation. Any appropriate
number of individual lower core segments 140 may be utilized (four
in the illustrated embodiment). Adjacent lower core segments 140
may be disposed in abutting relation, or adjacent lower core
segments 140 may be separated from one another by an appropriate
space (typically a small space, such as a space of no more than
about 1/8 inches). Each lower core segment 140 includes a pair of
faces 142 (FIGS. 6C and 4C) that extend along opposite sides of the
corresponding lower core segment 140 in its length dimension. The
faces 142 on each of the two sides of the lower core section 132
may be characterized as collectively defining a core section face
(i.e., the lower core section 132 may be characterized as having
two core section faces, with each of the core section faces being
defined by the faces 142 of the lower core segments 140 on a common
side of the lower core section 132). Each face 142 is in the form
of an at least substantially planar or flat surface. The faces 142
of the various lower core segments 140 are disposed in at least
substantially coplanar relation (e.g., the various faces 142 are at
least substantially disposed within a common reference plane). A
separate spacer 146 (e.g., FIGS. 6A, 6B, 4C) is appropriately
secured (e.g., bonded; adhesively attached) to each face 142 of
each lower core segment 140. A single spacer could collectively
extend over those faces 142 of the various lower core segments 142
that are on a common side of the lower core segments 142 (not
shown). In any case and in one embodiment, each spacer 146 is in
the form of tape or a dielectric film, for instance a polyamide
film (e.g., Kapton.RTM. tape available from DuPont Company).
Kapton.RTM. tape dimensions for each spacer 146 (as well as spacers
176 addressed below) may be specific to the magnetization and loss
performance ratings of the DSR 30.
[0093] The spacers 146 on a common side of the lower core section
132 may be characterized as collectively defining an interface 134.
Therefore, the lower core section 132 includes a pair of laterally
spaced interfaces 134 that each extend along the entire length of
the lower core section 132 (e.g., between its opposing ends 136).
One embodiment has each spacer 146 having a thickness within a
range of about 0.07 inches to about 0.13 inches, although other
thicknesses may be appropriate (e.g., to realize a desired amount
of reactance to be injected into the power line 16 by the core
assembly 50). Generally, the spacers 146 associated with the lower
core section 132 contribute to providing and maintaining a desired
and controlled physical and electric/magnetic spacing between the
lower core assembly 130 and the upper core assembly 160.
[0094] FIGS. 7A-7D present various enlarged views pertaining to the
upper core assembly 160. The upper core assembly 160 includes a
second or upper core section 162 (FIG. 7B) having a pair of
oppositely disposed ends 166. A second or upper winding 174 (FIG.
7A) wraps around the upper core section 162 between its two ends
166.
[0095] The upper core section 162 of the upper core assembly 160 is
collectively defined by a plurality of second or upper core
segments 170 that are disposed in end-to-end relation. Any
appropriate number of individual upper core segments 170 may be
utilized (four in the illustrated embodiment). Adjacent upper core
segments 170 may be disposed in abutting relation, or adjacent
upper core segments 170 may be separated from one another by an
appropriate space (e.g., in accordance with the discussion
presented above on the lower core section 132).
[0096] Each upper core segment 170 includes a pair of faces 172
(FIGS. 7D and 5C) that extend along opposite sides of the
corresponding upper core segment 170 in its length dimension. The
faces 172 on each of the two sides of the upper core section 162
may be characterized as collectively defining a core section face
(i.e., the upper core section 162 may be characterized as having
two core section faces, with each of the core section faces being
defined by the faces 172 of the upper core segments 170 on a common
side of the upper core section 162). Each face 172 is in the form
of an at least substantially planar or flat surface. The faces 172
of the various upper core segments 170 are disposed in at least
substantially coplanar relation (e.g., the various faces 172 are at
least substantially disposed within a common reference plane). A
separate spacer 176 (e.g., FIGS. 7A, 7B, 5C) is appropriately
secured (e.g., bonded; adhesively attached) to each face 172 of
each upper core segment 170. A single spacer could collectively
extend over those faces 172 of the various upper core segments 170
that are on a common side of the upper core segments 170. In any
case and in one embodiment, each spacer 176 is in the form of tape
or a dielectric film, for instance a polyamide film (e.g.,
Kapton.RTM. tape, noted above).
[0097] The spacers 176 on a common side of the upper core section
162 may be characterized as collectively defining an interface 164.
Therefore, the upper core section 162 includes a pair of laterally
spaced interfaces 164 that each extend along the entire length of
the upper core section 162 (e.g., between its opposing ends 166).
One embodiment has each spacer 176 having a thickness within a
range of about 0.07 inches to about 0.13 inches, although other
thicknesses may be appropriate (e.g., to realize a desired amount
of reactance to be injected into the power line 16 by the core
assembly 50). Generally, the spacers 176 associated with the upper
core section 162 contribute to providing and maintaining a desired
and controlled physical and electric/magnetic spacing between the
lower core assembly 130 and the upper core assembly 160.
[0098] When the upper core assembly 160 is properly aligned with
the lower core assembly 130, the interface 164 on one side of upper
core assembly 160 will engage the interface 134 on the
corresponding side of the lower core assembly 130. Similarly, the
interface 164 on the opposite side of upper core assembly 160 will
engage the interface 134 on the corresponding side of the lower
core assembly 130. Having each spacer 176 on the upper core
assembly 160 engage a corresponding spacer 146 on the lower core
assembly 130 maintains a desired physical and electric/magnetic
spacing between the upper core assembly 160 and the lower core
assembly 130 (e.g., a spacing within a range of about 0.14 inches
to about 0.26 inches at the corresponding interfaces 134/164,
although other spacings may be appropriate).
[0099] FIGS. 8A and 8B present additional views of the lower core
assembly 130 and the electronics 200. The electronics 200 includes
a printed circuit, control board, or controller 214, a second
electrical switch 206 (e.g., a contactor, bypass switch, or contact
relay), a first electrical switch 204 (e.g., an SCR), an MOV (metal
oxide varistor) 230, and a fault protection system 220 (again,
these components are located within the electronics compartment 84
of the lower housing section 80, and are isolated from the core
assembly 50 by the barrier or partition 82). A separate antenna
cable 62 is also located within the electronics compartment 84 and
extends from the controller 214 to each of the two antennas 100 for
the DSR 30. The first electrical switch 204 (e.g., SCR) and the
fault protection system 220 are utilized by the DSR 30 in fault
current or surge conditions encountered in the power line 16 on
which the DSR 30 is mounted. The MOV 230 is used by the DSR 30 for
lightning protection. The controller 214 controls operation of the
second electrical switch 206 (e.g., contactor), which in turn
establishes the mode of the core assembly 50. The core assembly 50
may be disposed in either of first or second modes. In the second
or injection mode, the core assembly 50 injects reactance into the
power line 16 on which the DSR 30 is mounted (inductance for the
illustrated configuration of the DSR 30, although the DSR 30 may be
configured to instead inject capacitance as noted above). In the
first or non-injection mode, the core assembly 50 injects little or
no reactance into the power line 16 on which the DSR 30 is
mounted.
[0100] One embodiment of a protocol for assembling the
above-described DSR 30 is presented in FIG. 9 and is identified by
reference 190. The protocol 190 is applicable to assembling the
lower core assembly 130 within the lower housing section 80, as
well as to assembling the upper core assembly 160 within the upper
housing section 120 (including simultaneously (e.g., using
different machine sets) or sequentially (e.g., using a common
machine set). Hereafter, the protocol 190 will be described with
regard to assembling the lower core assembly 130 within the lower
housing section 80.
[0101] The lower core section 132 may be assembled by disposing the
first core segments 140 in alignment (step 191). The ends of
adjacent first core segments 140 may be disposed in abutting
relation, or a small space may exist between each adjacent pair of
first core segments 140. In one embodiment, the various first core
segments 140 are positioned within an appropriate jig for purposes
of step 191 of the protocol 190.
[0102] The first winding 144 may be associated with the assembled
first core section 132 pursuant to step 192 of the protocol 190.
The first winding 144 may be created/defined "off the first core
section 132", and then separately positioned on the first core
section 132 (so as to extend between its ends 136) for purposes of
step 192. Another option would be to wind wire on the assembled
first core section 132 (around its ends 136) to create/define the
first winding 144 for purposes of step 192 of the protocol 190. In
any case, the first winding 144 may be attached to the first core
section 132 in any appropriate manner, for instance using an epoxy
(step 193). In one embodiment, the first winding 144 is separately
attached to each of the individual first core segments 140 that
collectively define the first core section 132.
[0103] Spacers 146 may be installed on the various faces 142 of the
first core segments 140 that collectively define the first core
section 132 (step 194). Steps 192-194 may be executed in any
appropriate order (e.g., step 194 could be executed prior to or
after step 192). In one embodiment, a separate spacer 146 is
provided for each face 142 of each first core segment 140. Any
appropriate adhesive and/or bonding technique may be used to attach
the spacers 146 to the corresponding first core segment 140 (more
specifically, to one of its faces 142).
[0104] The first core assembly 130 is positioned within the first
housing section 80 (step 195). The lower core assembly 130 is
magnetically held relative to the lower housing section 80 (step
196). An appropriate jig may be used for purposes of step 196. Step
196 may entail using one or more magnets to maintain the various
faces 142 (of the lower core segments 140 that collectively define
the lower core section 132) in at least substantially coplanar
relation (e.g., to dispose the faces 142 in a common reference
plane), to maintain a desired spacing between the lower core
assembly 130 and the interior of the lower housing section 80 in a
desired spaced relation (e.g., the partition 82), or both. In one
embodiment, each face 142 of each lower core segment 140 is
positioned against a flat or planar surface of a corresponding
magnet (e.g., a separate magnet may be provided for each lower core
segment 140). Thereafter, a potting material (e.g., Sylgard.RTM.)
is injected to encapsulate all but the upper surfaces of the
spacers 146 of the lower core assembly 130 within the lower housing
section 80 (step 197), and this potting material is allowed to cure
in any appropriate manner to define the encapsulating sections 150,
152 discussed above (step 198).
[0105] A representative electrical block diagram of the DSR 30 is
presented in FIG. 10. The DSR 30 may be characterized as including
a first device 202 (e.g., a transformer that includes the core
assembly 50 of the DSR 30), the above-noted first electrical switch
204 (e.g., an SCR), the above-noted second electrical switch 206
(e.g., a contact relay), a current transformer 208, a power supply
210, a current monitor 212, and the above-noted controller 214.
Again, the DSR 30 may be mounted on a power line 16 such that
reactance may be injected into the power line 16. The first device
202 may be in the form of (or part of) a reactance injecting
circuit, for instance a single turn transformer. The first device
202 may be disposable in each of first and second modes. For
example, switching the first device 202 from the first mode to the
second mode may increase the injected reactance being input to the
power line 16 when the DSR 30 is mounted on the power line 16. The
first device 202 may be operably connected to the controller 214
via the first electrical switch 204 (e.g., SCR) and/or the second
electrical switch 206 (e.g., a contact relay). In other words, the
first device 202 may be operably connected with the first
electrical switch 204, the second electrical switch 206, and/or the
controller 214.
[0106] In one embodiment, the first electrical switch 204 (e.g., an
SCR) may be a solid-state semiconductor device, for instance a
thyristor pair. The first electrical switch 204 may be operably
connected to the first device 202 and/or the controller 214. In
this regard, the first electrical switch 204 may be operable to
control the injection of reactance into the power line 16. For
example and when the first electrical switch 204 is closed, a
minimum level of reactance, corresponding to the first device 202
leakage reactance, is injected into power line 16. In another
example and when the first electrical switch 204 is open and the
second electrical switch 206 (e.g., a contact relay) is open,
reactance is injected into power line 16. As will be discussed in
more detail below, the first electrical switch 204 also may be
operable to pass an overcurrent.
[0107] The controller 214 may be any computerized device (e.g., a
microcontroller) that is operable to manage the operation of
multiple devices and/or communicate with multiple devices in order
to implement one or more control objectives. For example, the
controller 214 may be operable to switch the first device 202 from
the first mode to the second mode and/or communicate with any
device of the DSR 30. In this regard, the controller 214 may be
operably connected to the first electrical switch 204 (e.g., an
SCR), the second electrical switch 206 (e.g., a contact relay), the
first device 202, the current monitor 212, and/or the power supply
210. The controller 214 may switch the first device 202 from the
first mode to the second mode via the second electrical switch 206.
The first mode for the DSR 30 may be characterized as a bypass mode
and the second mode for the DSR 30 may be characterized as an
injection mode. When the second electrical switch 206 is closed
(i.e., is conducting), the first device 202 is in bypass mode
(e.g., the first device 202 is shorted) and little or no reactance
is injected into the power line 16 via the DSR 30. When the second
electrical switch 206 is open (such that the first device 202 is
not shorted) the first device 202 is in injection mode where
reactance is injected into the power line 16. At this time and if
the DSR 30 incorporates the first electrical switch 204, the first
electrical switch 204 should also be open (along with the second
electrical switch 206, and again such that the first device 202 is
not shorted) such that the first device 202 is in injection mode
where reactance is injected into the power line 16.
[0108] The controller 214 may switch the first device 202 from
bypass mode to injection mode when the current monitor 212
determines that a current of the power line 16 satisfies a
predetermined threshold. For example, the current monitor 212 may
be operable to measure the current on the power line 16 (at the DSR
30) and communicate the measured current to the controller 214. If
the measured current satisfies the predetermined threshold (e.g.,
if the current is greater than the threshold, or is equal to or
greater than the threshold, as the case may be), the controller 214
may switch the first device 202 from bypass mode to injection mode
by opening the second electrical switch 206 (e.g., contact relay)
such that reactance is injected into the power line 16. Similarly,
if the measured current thereafter no longer satisfies the
predetermined threshold (e.g., if the measured current drops below
the predetermined threshold), the controller 214 may switch the
first device 202 from injection mode back to bypass mode by closing
the second electrical switch 206 such that the first device 202 is
shorted and such that no substantial reactance is injected into the
power line 16. As such, the controller 214 may be operable to
switch the first device 202 between the bypass and injection
modes.
[0109] The current monitor 212 may measure the current on the power
line 16 via the current transformer 208. In this regard, the
current transformer 208 may be mounted on the power line 16 and may
be a separate component from the first device 202. In one
embodiment, the current transformer 208 may be operable to produce
a reduced current that is proportional to the current of the power
line 16 such that the current may be processed and/or measured by a
measuring device (e.g., the current monitor 212) and/or the current
may provide power to electronic components (e.g., the power supply
210). The power supply 210 may be operably connected with the
current transformer 208 and/or the controller 214. In this regard,
the power supply 210 may receive power from the current transformer
208 and provide power to the controller 214.
[0110] The DSR 30 may be mounted on the power line 16 such that an
injected reactance may be input to the power line 16. In one
embodiment, the injected reactance may be an inductive reactance
(e.g., inductance). For example, when inductance is injected into
the power line 16, the flow of current in the power line 16 may be
reduced and diverted to underutilized power lines in interconnected
and/or meshed power networks. In another embodiment, the injected
reactance may be a capacitive reactance (e.g., capacitance). For
example, when capacitance is injected into the power line 16, the
flow of current in the power line 16 may be increased and diverted
from power lines in interconnected and/or meshed power
networks.
[0111] FIG. 11A illustrates one embodiment that may be used as the
power supply 210 for the DSR 30 addressed above in relation to FIG.
10. The power supply 210 of FIG. 11A includes a bridgeless power
factor correction circuit or a bridgeless PFC 310 and a regulator
322. As discussed above, the power supply 210 may receive power
from the current transformer 208 (where the power line 16 is the
primary of the current transformer 208), and the current
transformer 208 may be operable to produce a reduced current that
is proportional to the current on the power line 16 such that the
current transformer 208 may provide power to the power supply 210.
In one embodiment, the current of the power line 16 may be
characterized as a first current and the reduced current provided
by the current transformer 208 may be characterized as a second
current. In this regard, the current transformer 208 receives the
first current and outputs the second current, the second current is
different than the first current, and the second current is
proportional to the first current.
[0112] The second current may be based at least on the number of
turns of a secondary winding (not illustrated) of the current
transformer 208. For example, the secondary winding of the current
transformer 208 may comprise 100 turns. In this example, the second
current would be 1/100 of the first current (i.e., the first
current is 100 times the second current). The current transformer
208 may be configured to provide any desired reduction of the
current on the power line 16.
[0113] The bridgeless PFC 310 includes the current transformer 208,
a first controllable switch 312, a second controllable switch 314,
a first rectifier 316, a second rectifier 318, and a capacitor 320.
The first rectifier 316 may be operably connected to the first
controllable switch 312 and the second rectifier 318 may be
operably connected to the second controllable switch 314. In this
regard, the operation of the first and second rectifiers 316, 318
may be dependent on the operation of the first and second
controllable switches 312, 314, respectively. For example, the
first and second rectifiers 316, 318 may output a current to the
capacitor 320 based on the state of the first and second
controllable switches 312, 314, respectively. The first and second
rectifiers 316, 318 may be any silicon-based semiconductor switch
(e.g., diodes). The first and second controllable switches 312, 314
may be any semiconductor transistors (e.g., MOSFETs). The first and
second controllable switches 312, 314 also may be operably
connected to the regulator 322. In this regard, the regulator 322
may be configured to switch each of the first and second
controllable switches 312, 314 between a conducting state and a
non-conducting state.
[0114] As discussed above in relation to FIG. 10, the power supply
210 may provide power to the controller 214 of the DSR 30. The
power supply 210 may be operable to output a regulated voltage
(e.g., a 24 VDC output) to the controller 214. When the regulated
voltage satisfies a predetermined threshold (e.g., if the regulated
voltage is greater than the threshold, or is equal to or greater
than the threshold), the regulator 322 may switch the first and
second controllable switches 312, 314 to the conducting state. In
one embodiment, the predetermined threshold may be within a range
from about 23.9V to about 24.1V. This predetermined threshold may
be a standard design power supply voltage for the system. When the
first and second controllable switches 312, 314 are in the
conducting state, the output current from the first and second
rectifiers 316, 318 may be shunted. For example, the second current
received from the current transformer 208 may flow through the
first and second controllable switches 312, 314 such that the power
supply 210 is shorted and no or very little current flows through
the first and second rectifiers 316, 318. As discussed above, the
capacitor 320 may receive current from the first and second
rectifiers 316, 318. As such, when the output current from the
first and second rectifiers 316, 318 is shunted, the capacitor 320
may begin to discharge.
[0115] When the regulated voltage no longer satisfies the
predetermined threshold (e.g., if the regulated voltage drops below
the predetermined threshold), the regulator 322 switches the first
and second controllable switches 312, 314 to the non-conducting
state. When the first and second controllable switches 312, 314 are
in the non-conducting state, the second current from the current
transformer 208 may flow through the first and second rectifiers
316, 318. As such, the capacitor 320 may receive the output current
from the first and second rectifiers 316, 318 and may begin to
charge. In turn, the output voltage of the power supply 210 is
regulated. In one embodiment, the regulator 322 may have an
operating frequency substantially higher than the current frequency
on the power line 16.
[0116] As discussed above in relation to FIG. 10, the current
monitor 212 may be operable to measure the current on the power
line 16 (at the DSR 30) and communicate the measured current to the
controller 214. One embodiment that may be used as the current
monitor 212 is illustrated in FIG. 11B. The current monitor 212 of
FIG. 11B may be operably connected to the current transformer 208,
and furthermore may be configured to measure the second current
from the current transformer 208. The current transformer 208 may
be operable to output the second current to the power supply 210
through the current monitor 212. In this regard, the controller 214
may be configured to switch the current transformer 208 from a
first state to a second state. The first state may include the
current transformer 208 outputting the second current to the power
supply 210. When the current transformer 208 is in the first state,
the power supply 210 outputs the regulated voltage. The second
state may include a measurement of the second current via the
current monitor 212. When the current transformer 208 is in the
second state, the first and second controllable switches 312, 314
are in the conducting state and the power supply 210 is shorted
such that the second current flows through the first and second
controllable switches 312, 314. Shunting the power supply 210
operation while the current transformer 208 is in the second state
may remove any contribution of high-frequency switching noise, or
other non-linearity associated with the power supply 210 operation
from the measurement of the second current. As a result, the
quality and signal-to-noise ratio of the current monitor 212 may be
increased.
[0117] As illustrated in FIG. 11B, the controller 214 may include a
logical summing device 332. The logical summing device 332 may be
any simple logic element or programmable logic device such as a
programmable logic array and a field-programmable gate array, to
name a few. The logical summing device 332 may be configured to
output a control signal. When the control signal is active, the
current transformer 208 is in the second state and the first and
second controllable switches 312, 314 are in the conducting state.
This is true even if the regulated voltage no longer satisfies the
predetermined threshold. In other words, when the power supply 210
is in normal operation, and the regulated voltage no longer
satisfies the predetermined threshold, the first and second
controllable switches 312, 314 are switched to the non-conducting
state. However, if the control signal from the logical summing
device 332 is active, the first and second controllable switches
312, 314 remain in the conducting state, resulting in the absence
of influence of control pulses from the regulator 322 on the
measurement of the second current. In this regard, the control
signal from the logical summing device 332 may facilitate the
measurement of the second current via the current monitor 212. When
the current monitor 212 measures the second current, the second
current may have a signal-to-noise ratio of at least about 48
dB.
[0118] The current monitor 212 may include an instrumental current
transformer 342, a burden resistor 344, a differential amplifier
346, a comparator 348, and/or an analog-to-digital converter 349.
The instrumental current transformer 342 may be operably connected
to the current transformer 208 and configured to reduce the second
current from the current transformer 208 to a third current. This
third current may be less than the second current and proportional
to the second current. This third current may be less than the
first current (i.e., the current of the power line 16), and is
proportional to the first current. The burden resistor 344 may be
operably connected to the output of the instrumental current
transformer 342 such that a voltage develops on the burden resistor
344. The voltage on the burden resistor 344 is proportional to the
third current, and thus to the first and second currents. The
differential amplifier 346 may be operably connected to the burden
resistor 344 and may be configured to convert and/or amplify the
voltage on the burden resistor 344. The analog-to-digital converter
349 may be operably connected to the differential amplifier 346 and
the controller 214. As such, the differential amplifier 346 may
send the analog-to-digital converter 349 an analog signal
representative of the voltage on the burden resistor 344. In turn,
the analog-to-digital converter 349 may be configured to convert
the analog signal from the differential amplifier 346 into a
digital signal from which the controller 214 can determine the
current on the power line 16. As will be discussed in more detail
below, the comparator 348 may be operably connected to the
differential amplifier 346 and the controller 214, and may be
configured to send an interrupt signal to the controller 214.
[0119] FIG. 12A illustrates one embodiment for the above-noted
fault protection system 220 of the DSR 30. The fault protection
system 220 includes the power supply 210 (FIGS. 10 and 11A), the
current monitor 212 (FIGS. 10 and 11B), a voltage detection circuit
356, the first device 202 (e.g., a transformer that uses the core
assembly 50) addressed above (FIG. 10), and the first electrical
switch 204 (e.g., an SCR; FIG. 10). The fault protection system 220
may include a plurality of different bypass sequences that are
separately executable. The plurality of different bypass sequences
may be executed to activate the first electrical switch 204 to
short the first device 202. As discussed above, the first
electrical switch 204 may be operable to pass an overcurrent. When
the first electrical switch 204 is activated, the first electrical
switch 204 may pass the overcurrent. In this regard, the plurality
of different bypass sequences may be separately executed to protect
the DSR 30 from overcurrent and/or fault conditions. The plurality
of different bypass sequences may include first, second, and third
bypass sequences.
[0120] The first bypass sequence may include the controller 214
activating the first electrical switch 204 (e.g., an SCR) to short
the first device 202 (e.g., a transformer that uses the core
assembly 50) based upon the controller 214 determining that an
output from the current monitor 212 satisfies a first predetermined
threshold (e.g., if the output is greater than the threshold, or is
equal to or greater than the threshold). For example and as
discussed above, the current monitor 212 may include/utilize one or
more of the differential amplifier 346, the analog-to-digital
converter 349, and the controller 214. As such, the output from the
differential amplifier 346 may be an analog signal (e.g., a voltage
signal) that gets sent to the analog-to-digital converter 349,
where it is converted and sent to the controller 214 which
determines if the analog signal satisfies the first predetermined
threshold. In this case, if the first predetermined threshold is
satisfied, the controller 214 may activate the first electrical
switch 204 to short the first device 202.
[0121] The second bypass sequence may include the comparator 348
sending a communication (e.g., an interrupt signal) to the
controller 214, indicating that the output from the current monitor
212 satisfies a second predetermined threshold. For example and as
discussed above, the comparator 348 may be operably connected with
the differential amplifier 346 and the controller 214. As such, the
output from the current monitor 212 may be the analog signal from
the differential amplifier 346. The comparator 348 may receive the
analog signal (e.g., a voltage signal) at its input, and determine
if the voltage signal satisfies the second predetermined threshold.
If the voltage signal satisfies the second predetermined threshold,
the comparator 348 may send the interrupt signal to the controller
214. In this case, the controller 214 may activate the first
electrical switch 204 (e.g., an SCR) to short the first device 202
(e.g., a transformer that uses the core assembly 50), in response
to receiving the interrupt signal from the comparator 348. In other
words, the interrupt signal may prompt the controller 214 to
activate the first electrical switch 204. In order to activate the
first electrical switch 204, the controller 214 may send a series
of electrical pulses to the first electrical switch 204 such that
the first electrical switch 204 begins conducting.
[0122] The output of the differential amplifier 346, i.e., the
analog signal, may be representative of the current on the power
line 16. For example, when the analog signal satisfies the first
predetermined threshold, this may indicate that the current on the
power line 16 is at least about 1100 Amps. In another example, when
the analog signal satisfies the second-predetermined threshold,
this may indicate that the current on the power line 16 is at least
about 1800 Amps. In other examples, the first and second
predetermined thresholds may be selected based on specific
applications of the fault protection system 220 of the DSR 30
relative to a given installation. The first and second
predetermined thresholds may be selected to be above expected
normal operating current limits on the power line 16. In other
words, the first and second predetermined thresholds may be any
value suitable to enable execution of the first and second bypass
sequences to protect the DSR 30 from overcurrent and/or fault
conditions.
[0123] The third bypass sequence may include the voltage detection
circuit 356 (e.g., a crowbar circuit) activating the first
electrical switch 204 (e.g., an SCR) to short the first device 202
when a detected voltage satisfies a third predetermined threshold.
The detected voltage may be a voltage of the first device 202. For
example and as discussed above, the first device 202 may be a
single turn transformer including windings 144, 174 on the core
assembly 50 (e.g., the secondary of a single turn transformer). As
such, the detected voltage may be a voltage present on the
secondary windings 144, 174 of the core assembly 50. In one
embodiment, the third predetermined threshold may be at least about
1800 volts. The third predetermined threshold may be selected based
on specific applications of the fault protection system 220 of the
DSR 30 relative to a given installation. The third predetermined
threshold may be selected based on the operational limits of the
electronic components within the fault protection system 220 of the
DSR 30 and/or the number of secondary windings 144, 174 of the core
assembly 50. In other words, the third predetermined threshold may
be any value suitable to enable execution of the third bypass
sequence to protect the DSR 30 from overcurrent and/or fault
conditions.
[0124] A secondary function of the fault protection system 220 may
include protection of the second electrical switch 206 addressed
above (e.g., a contact relay; FIG. 10). The second electrical
switch 206 may be operably connected to the controller 214 and the
first device 202. The controller 214 may be configured to switch
the second electrical switch 206 between an open position and a
closed position in order to switch the DSR 30 between bypass and
injection modes of operation as discussed above. During such a
change of position, the second electric switch 206 may be
vulnerable to damage from electric arc and/or excessive currents
through its contact surfaces. This damage may be minimized by
externally shunting the contacts of the second electrical switch
206 during any such change of position, where the duration of the
change of position may be within a range from about one millisecond
to about one second. The secondary function of the fault protection
system 220 may be activated by the controller 214 issuing a series
of electrical pulses to the first electric switch 204 during the
period when the second electric switch 206 is changing positions.
In turn, the first electrical switch 204 may enter a conducting
state, thereby shunting the contacts of the second electric switch
206.
[0125] For the same purpose, when the first electrical switch 204
is activated (e.g., when any of the first, second, or third bypass
sequences is executed), the second electrical switch 206 remains in
either the open position or the closed position. For example, if
the second electrical switch 206 is in the open position (e.g., the
DSR 30 is in injection mode) when the first electrical switch 204
(e.g., an SCR) is activated, the second electrical switch 206
remains in the open position during the execution of any of the
first, second, or third bypass sequences. In another example, if
the second electrical switch 206 is in the closed position (e.g.,
the DSR 30 is in bypass mode) when the first electrical switch 204
is activated, the second electrical switch 206 remains in the
closed position during the execution of any of the first, second,
or third bypass sequences.
[0126] The first bypass sequence may have a first response time,
the second bypass sequence may have a second response time, and the
third bypass sequence may have a third response time. The first
response time may be the amount of time it takes for the controller
214 to determine that the output from the current monitor 212
satisfies the first predetermined threshold. For example, the
analog-to-digital converter 349 may receive the output from the
current monitor 212 while the controller 214 is performing another
function, which may result in a first response time. In another
example, the controller 214 may process the output from the current
monitor 212 immediately upon receiving it, which may result in a
first response time that is different than the first response time
in the first example. The second response time may be the amount of
time it takes for the comparator 348 to determine that the output
from the differential amplifier 346 satisfies the second
predetermined threshold. The third response time may be the amount
of time it takes for the voltage detection circuit 356 to determine
that the detected voltage satisfies the third predetermined
threshold.
[0127] The first response time may be faster than the second
response time and the third response time, and the second response
time may be faster than the third response time. For example, the
controller 214 may determine that the output from the current
monitor 212 satisfies the first predetermined threshold before the
comparator 348 determines that the output from the differential
amplifier 346 satisfies the second predetermined threshold and
before the voltage detection circuit 356 determines that the
detected voltage satisfies the third predetermined threshold. As
another example, the comparator 348 may determine that the output
from the differential amplifier 346 satisfies the second
predetermined threshold before the voltage detection circuit 356
determines that the detected voltage satisfies the third
predetermined threshold. The second response time may be faster
than the first response time and the third response time. For
example, the comparator 348 may determine that the output from the
differential amplifier 346 satisfies the second predetermined
threshold before the controller 214 determines that the output from
the current monitor 212 satisfies the first predetermined threshold
and before the voltage detection circuit 356 determines that the
detected voltage satisfies the third predetermined threshold. The
third response time may be faster than the first response time and
the second response time. For example, the voltage detection
circuit 356 may determine that the detected voltage satisfies the
third predetermined threshold before either the controller 214 or
the comparator 348 determine that the output from the current
monitor 212 satisfies the first or the second predetermined
thresholds.
[0128] If the first bypass sequence is executed, the second and
third bypass sequences may not be executed. Similarly, the second
bypass sequence may be executed if the first bypass sequence is not
executed. The first bypass sequence may not be executed when the
output from the current monitor 212 is not processed by the
controller 214 and/or if the second response time is faster than
the first response time. The third bypass sequence may be executed
if the first and second bypass sequences are not executed and/or if
the third response time is faster than the first and second
response times.
[0129] One embodiment of a protocol for protecting the DSR 30 is
presented in FIG. 12B and is identified by reference numeral 360.
The protocol 360 generally includes the steps for detecting a fault
current and executing a plurality of different bypass sequences to
protect the DSR 30 from damage. As current flows through the power
line 16, the current transformer 208 produces a reduced current
that is proportional to the current of the power line 16 (step 361)
and the voltage detection circuit 356 monitors the voltage of the
first device 202 (step 362). The reduced current produced by the
current transformer 208 may be measured by the controller 214 (step
363) or the comparator 348 (step 366). Step 363 includes the
controller 214 determining if the reduced current satisfies the
first predetermined threshold (step 364). If the reduced current
does not satisfy the first predetermined threshold, step 363 is
repeated, i.e., the controller 214 continues measuring the reduced
current produced by the current transformer 208. If the reduced
current does satisfy the first predetermined threshold, the first
bypass sequence 371 (FIG. 12C) is executed (step 365).
[0130] In step 366 of the protocol 360 of FIG. 12B, the comparator
348 measures the reduced current produced by the current
transformer 208. Step 366 includes the comparator 348 determining
if the reduced current satisfies the second predetermined threshold
(step 367). If the reduced current does not satisfy the second
predetermined threshold, step 366 is repeated, i.e., the comparator
348 continues measuring the reduced current produced by the current
transformer 208. If the reduced current does satisfy the second
predetermined threshold, the second bypass sequence 380 (FIG. 12D)
is executed (step 368).
[0131] In step 362 of the protocol 360 of FIG. 12B, the voltage
detection circuit 356 monitors the voltage of the first device 202.
Step 362 includes the voltage detection circuit 356 determining if
the voltage of the first device 202 satisfies the third
predetermined threshold (step 369). If the voltage does not satisfy
the third predetermined threshold, step 362 is repeated, i.e., the
voltage detection circuit 356 continues to monitor the voltage of
the first device 202. If the voltage does satisfy the third
predetermined threshold, the third bypass sequence 390 (FIG. 12E)
is executed (step 370).
[0132] With reference now to FIG. 12C, one embodiment of the first
bypass sequence 371 is presented.
[0133] The first bypass sequence 371 may include the steps of
monitoring the current of the power line 16 (step 372), assessing
whether the line current on the power line 16 satisfies the first
predetermined threshold (step 373), and shorting the first device
202 in response to identification of satisfaction of the first
predetermined threshold (step 375). Step 373 may include the step
of measuring the current via the analog-to-digital converter 349
(step 374). Step 375 may include the step of activating the first
electrical switch 204 (step 376). Step 376 may include the step of
sending a series of electrical pulses to the first electrical
switch 204 such that the first electrical switch 204 begins
conducting (step 377).
[0134] FIG. 12D illustrates one embodiment of the second bypass
sequence 380. The second bypass sequence 380 may include the steps
of monitoring the current of the power line 16 (step 381),
assessing whether the line current on the power line 16 satisfies
the second predetermined threshold (step 382), sending an interrupt
signal to the controller 214 in response to identification of
satisfaction of the second predetermined threshold (step 384), and
shorting the first device in response to identification of
satisfaction of the second predetermined threshold (step 385). Step
382 may include the step of measuring the voltage input to the
comparator 348 (step 383). Step 385 may include the step of
activating the first electrical switch 204 (step 386). Step 376 may
include the step of sending a series of electrical pulses to the
first electrical switch 204 such that the first electrical switch
204 begins conducting (step 387).
[0135] With reference now to FIG. 12E, one embodiment of the third
bypass sequence 390 is presented. The third bypass sequence 390 may
include the steps of monitoring the voltage of the first device 202
(step 391), assessing whether the voltage satisfies the third
predetermined threshold (step 392), and shorting the first device
202 in response to identification of satisfaction of the third
predetermined threshold (step 394). Step 392 may include the step
of measuring the voltage of the first device 202 via the voltage
detection circuit 356 (step 393). Step 394 may include the step of
activating the first electrical switch 204 (step 395). Step 395 may
include the step of outputting the voltage of the first device 202
to the input of the first electrical switch 204 via the voltage
detection circuit 356 (step 396). In one embodiment, the second
bypass sequence 380 (FIG. 12D) is executed when the first bypass
sequence 371 (FIG. 12C) is not executed. The first bypass sequence
371 (FIG. 12C) may not be executed when the current from the power
line 16 is not measured by the analog-to-digital converter 349. In
one embodiment, the third bypass sequence 390 is executed if
neither the first bypass sequence 371 (FIG. 12C) nor the second
bypass sequence 380 (FIG. 12D) are executed.
[0136] FIG. 13A illustrates one embodiment of a power transmission
system 400, or more generally a distributed control architecture
for use by such a power transmission system. The power transmission
system 400 includes at least one power line 16 (three shown in the
illustrated embodiment). One or more power lines 16 may be
supported by a plurality of towers 14 that are spaced along the
length of the power line(s) 16. As in the case of FIG. 1, the power
transmission system 400 of FIG. 13A may include one or more
electrical power sources 12 (not shown) and one or more electrical
loads 22 (not shown).
[0137] A plurality of DSRs 30 are installed on a given power line
16--multiple power lines 16 each may have multiple DSRs 30
installed thereon. One or more DSR array controllers 440 may be
mounted on each power line 16 that incorporates DSRs 30.
Alternatively, a given DSR array controller 440 could be mounted on
a tower 14. In any case, each DSR array controller 440 may be
associated with a dedicated power line section 18 of the power line
16. A given power line section 18 could have a single DSR array
controller 440, or a given power line section 18 could have a
primary DSR array controller 400, along with one or more backup DSR
array controllers 440.
[0138] Any number of DSR array controllers 440 may be associated
with a given power line 16. A given power line 16 may be defined by
one or more power line sections 18 of the same length, by one or
more power line sections 18 of different lengths, or both (e.g., a
power line section 18 is not limited to a portion of a given power
line 16 that spans between adjacent towers 14 as shown in FIG. 13A;
a given power line 16 may be divided up in any appropriate manner
into multiple power line sections 18, each of which may have one or
more DSR array controllers 440 that are dedicated to such a power
line section 18).
[0139] One or more DSRs 30 are mounted on each power line section
18 of a given power line 16. Any appropriate number of DSRs 30 may
be mounted on each power line section 18. The various DSRs 30 that
are mounted on a given power line section 18 define what may be
referred to as a DSR array 410. Each DSR array 410 may have one or
more DSR array controllers 440 that are dedicated to such a DSR
array 410 (e.g., multiple controllers 440 may be used for any given
DSR array 410 to provide redundancy). In one embodiment, a given
DSR array controller 440 is only associated with one DSR array 410.
As such, one or more DSR array controllers 440 and each DSR 30 of
their dedicated DSR array 410 may be associated with the same power
line section 18. It should be appreciated that DSRs 30 need not be
placed along the entire length of a given power line 16 (although
such could be the case), and as such there may be a gap between one
or more adjacent pairs of power line sections 18 that each have an
associated DSR array 410.
[0140] Each DSR 30 in a given DSR array 410 only communicates
(directly or indirectly) with one or more DSR array controllers 440
that are assigned to the DSR array 410 (e.g., the primary DSR array
controller 440 for the DSR array 410 and any redundant or backup
DSR array controllers). A given DSR array controller 440 could
communicate directly with each DSR 30 in its associated DSR array
410. Another option would be to utilize a relay-type communication
architecture, where a DSR array controller 440 could communicate
with the adjacent-most DSR 30 on each side of the DSR array
controller 440, and where the DSRs 30 could then relay this
communication throughout the remainder of the DSR array 410 on the
same side of the DSR array controller 440 (e.g., DSRs 30 in a given
DSR array 410 could relay a communication, from DSR 30-to-DSR 30,
toward and/or away from the associated DSR array controller
440).
[0141] DSR array controllers 440 associated with multiple DSR
arrays 410 communicate with a common DSR server 420 of the power
transmission system 400. Each of these DSR array controllers 440
could communicate directly with this DSR server 420. Alternatively,
the DSR server 420 could directly communicate with one or more DSR
array controllers 440, and these DSR array controllers 440 could
then relay the communication to one or more other DSR array
controllers 440 in the power transmission system 400. It should
also be appreciated that the power transmission system 400 could
incorporate one or more backup DSR servers (not shown), for
instance to accommodate a given DSR server 420 going "off-line" for
any reason. In any case, the DSR server 420 in turn communicates
with what may be characterized a utility-side control system 430.
Representative forms of the utility-side control system 430 include
without limitation an energy management system (EMS), a supervisory
control and data acquisition system (SCADA system), or market
management system (MMS).
[0142] The power transmission system 400 could utilize any
appropriate number of DSR servers 420. A single DSR server 420
could communicate with a given utility-side control system 430.
Another option would be to have multiple DSR servers 420 that each
communicate with a common utility-side control system 430. The
power transmission system 400 could also utilize any appropriate
number of utility-side control systems 430, where each utility-side
control system 430 communicates with one or more DSR servers
420.
[0143] A given DSR server 420 may be characterized as providing an
interface between a utility-side control system 430 and a plurality
of DSR array controllers 440 for multiple DSR arrays 410. A DSR
server 420 may receive a communication from a utility-side control
system 430. This communication may be in any appropriate form and
of any appropriate type. For instance, this communication could be
in the form of a system objective, a command, a request for
information, or the like (e.g., to change the inductance on one or
more power lines 16 by a stated amount; to limit the current on one
or more power lines 16 to a stated amount; to limit the power flow
on one or more power lines 16 to a stated amount; to set a
temperature limit for one or more power lines 16).
[0144] The DSR array controllers 440 may send information on their
corresponding power line section 18 to a DSR server 420. The DSR
server 420 in this case may consolidate this information and
transmit the same to the utility-side control system 430 on any
appropriate basis (e.g., using a push-type communication
architecture; using a pull-type communication architecture; using a
push/pull type communication architecture). The DSR server 420 may
also store information received from the various DSR array
controllers 440, including information from the DSR array
controllers 440 that has been consolidated by the DSR server 420
and at some point in time transmitted to an utility-side control
system 430.
[0145] Each DSR array controller 440 may be characterized as a
"bridge" between a DSR server 420 (and ultimately a utility-side
control system 430) and its corresponding DSR array 410. For
instance, one communication scheme may be used for communications
between a DSR array controller 410 and the DSRs 30 of its DSR array
410, and another communication scheme may be used for
communications between this same DSR array controller 410 and the
DSR server 420. In this case, a DSR array controller 410 may
require two different interfaces--one interface/communication
module for communicating with the DSRs 30 of its DSR array 410, and
another interface/communication module for communicating with a DSR
server 420.
[0146] As noted, FIG. 13A may be characterized as a distributed
control architecture for a power transmission system (or as a power
transmission system with a distributed control architecture). In
this regard, consider the case where the utility-side control
system 430 sends a communication to a DSR server 420. The DSR
server 420 may repackage/translate/reformat this communication, but
in any case sends a corresponding communication to one or more DSR
array controllers 440. Each such DSR array controller 440 that
receives such a communication makes a determination as to the modal
configuration for each DSR 30 in its corresponding DSR array 410
(i.e., determines whether a given DSR 30 should be in a first or
bypass mode, or whether this DSR 30 should be in a second or
injection mode, and this may be undertaken for each DSR 30 in its
corresponding DSR array 410). Notably, the communication that is
received by the DSR array controller 440 does not itself indicate
as to what the modal configuration should be for each DSR 30 in the
DSR array 410 for the recipient DSR array controller 440. As such,
each DSR array controller 440 must have sufficient intelligence so
as to be able to be able to make this determination on its own.
[0147] FIG. 13B presents a representative configuration for a DSR
array controller 440 that may be utilized by the power transmission
system 400 of FIG. 13A. The DSR array controller 440 includes a
housing 442. Preferably, the housing 442 allows the DSR array
controller 440 to be mounted on a power line 16 without having to
break the power line 16 (e.g., by using detachably connectable
housing sections at least generally of the type discussed above in
relation to the DSR 30). Moreover, preferably the housing 442 is
configured to reduce the potential for Corona discharges.
[0148] The DSR array controller 440 includes a current transformer
444 that is disposed within the housing 442 and that derives power
from the power line 16 to power electrical components of the DSR
array controller 440. Various sensors may be utilized by the DSR
array controller 440, such as a fault current sensor 446 and a
temperature sensor 448. Moreover, the DSR array controller 440
utilizes a processing unit 454 (e.g., defined by one or more
processors of any appropriate type, and utilizing any appropriate
processing architecture).
[0149] FIG. 13C presents a functional schematic that may be
implemented by a DSR array controller 440. The DSR array controller
440 includes the above-noted processing unit 454. Memory 452 (e.g.,
any appropriate computer readable storage medium) may be
operatively interconnected with the processing unit 454. The memory
452 may be of any appropriate type or types, and may utilize any
appropriate data storage architecture(s). One or more sensors 456
(e.g. the above-noted fault current sensor 446; the above-noted
temperature sensor 448) may also be operatively interconnected with
the processing unit 454.
[0150] One or more antennas 450 may be utilized by the DSR array
controller 440 for communicating with the DSRs 30 in its
corresponding DSR array 410. Any appropriate type of antenna 450
may be utilized by the DSR array controller 440, including a
cavity-backed slot antenna of the type utilized by the DSRs 30.
Multiple antennas 450 could also be used to communicate with the
DSRs 30 in its corresponding DSR array 410, including where two
antennas 450 are incorporated by the DSR array controller 440 in
the same manner as discussed above with regard to the DSRs 30
(e.g., an antenna 450 may be provided on each end of the DSR array
controller 440). As noted, the DSR array controller 440 may use one
communication scheme (e.g., a first communication scheme) for
communicating with the DSRs 30 of its DSR array 410.
[0151] The DSR array controller 440 also communicates with the
utility-side control system 430 through the DSR server 420 in the
embodiment of FIG. 13A. In this regard, the DSR array controller
440 may include a communications module 466 of any appropriate type
and an interface 460. If the communications module 466 provides for
wireless communications with the DSR server 420, the DSR array
controller 440 may require one or more antennas of any appropriate
type. For example, the communications module may be at least one of
an Ethernet adapter, a cellular modem, and a satellite modem, to
name a few. In another example, the interface 460 may be part of
the processing unit 454 and may include at least one of a SPI bus,
UART, and a 12C serial bus, to name a few. In any case, the DSR
array controller 440 may use another communication scheme (e.g., a
second communication scheme) for communicating with the DSR server
420. In one embodiment, the DSR array controller 440 uses different
communication schemes for communications with the DSR array 410 and
the DSR server 420. It could be appreciated that a dedicated
antenna(s) may be required for communications with the DSRs 30 of
the corresponding DSR array 410, and that a dedicated antenna(s)
may be required for communications with the DSR server 420.
However, it may be possible that a common antenna(s) may be used to
communicate with both the DSRs 30 of the corresponding DSR array
410 and with the DSR server 420.
[0152] The DSR array controller 440 may also incorporate a power
supply 458 of any appropriate type, and that is operatively
interconnected with the above-noted current transformer 444 (FIG.
13B). The power supply 458 may receive a current flow from the
current transformer 444, and may provide power to one or more of
the processing unit 454, the memory 452, the antenna(s) 450, one or
more antennas associated with the communication module 466 (for
communicating with the DSR server 420), one or more sensors 456, or
any combination thereof.
[0153] FIG. 13D presents one embodiment of a first data structure
480 (e.g., a lookup table) that may be stored/reside in the memory
452 of a given DSR array controller 440. The first data structure
480 may utilize any appropriate data storage architecture.
Generally, for each of a plurality of system contingencies or
conditions 482, the first data structure 480 includes a
corresponding model configuration for at least one control
objective for each DSR 30 associated with the DSR array controller
440. Again, there are two "modal configurations" for the DSRs 30.
One modal configuration (e.g., a first modal configuration or first
mode) for each DSR 30 is where the DSR is disposed in a
non-injection or bypass mode (e.g., where little or no reactance is
being injected into the corresponding power line 16 by the DSR 30,
or more specifically into the corresponding power line section 18
on which the DSR 30 is mounted). The other modal configuration
(e.g., a second modal configuration or second mode) for each DSR 30
is where it is configured to inject reactance into the
corresponding power line 16 (e.g., an injection mode). The amount
of reactance injected by a given DSR 30 when in its second modal
configuration (or when in its second mode) is substantially greater
than the amount of reactance, if any, that is injected by a given
DSR 30 when in its first modal configuration (or when in its first
mode).
[0154] The first data structure 480 includes a modal configuration
for two different control objectives for each DSR 30 that is
associated with the DSR array controller 440 (three representative
DSRs 30 being shown for purposes of the first data structure 480 of
FIG. 13D; each DSR 30 within the corresponding DSR array 410 would
of course be included in the first data structure 480). The first
data structure 480 presents both a power factor control modal
configuration 484 (one control objective) and a low-frequency
oscillation control modal configuration 486 (a different control
objective) for each DSR 30 associated with the DSR array controller
440, and for each system condition or contingency 482. Any number
of control objectives may be stored in the first data structure
480, including a single control objective or any appropriate number
of multiple control objectives.
[0155] The system conditions or contingencies that are loaded into
the first data structure 480 may represent at least some or all of
the permutations for a power transmission system in relation to
each power source utilized by the power transmission system
(whether on line or off line), the load level presently imposed on
the system, the operating status of the transmission lines forming
the interconnected grid, the operating status of the transformers
and substation equipment supporting the operation of the
transmission lines forming the interconnected grid, or any
combination of the above that combine to create a normal, abnormal
or emergency operating condition for the grid. The same system
conditions or contingencies may be loaded into the memory 452 of
one or more DSR array controller 440. In one embodiment, a set of
DSR array controllers 440 will have the same system conditions or
contingencies loaded into their corresponding memory 452. However,
each DSR array controller 440 will have its own modal configuration
for each of its DSRs 30, and for each control objective. It should
be appreciated that the first data structure 480 for each DSR array
controller 440 may be updated without having to dismount the DSR
array controller 440 from its corresponding power line 16 (e.g.,
using the built-in communication capabilities of the DSR array
controllers 440)
[0156] One embodiment of an operations protocol for the power
transmission system 400 of FIG. 13A is presented in FIG. 13E and is
identified by reference numeral 500. The utility-side control
system 430 sends an operations objective communication to the DSR
server 420 (step 502). This operations objective communication may
be of any appropriate type. The DSR server 420 may translate this
communication from the utility-side control system 430 into an
appropriate DSR format (step 504). In any case, the DSR server 420
sends a corresponding communication to the relevant DSR array
controllers 440 (step 506). Each of the DSR array controllers 440
will independently determine the modal configuration for the DSRs
30 in its corresponding DSR array 410 based upon receipt of this
communication (step 508). The communication associated with step
506 does not itself indicate the modal configurations that are
determined by step 508. Thereafter, the DSR array controllers 440
may send a modal communication to one or more of the DSRs 30 in its
corresponding DSR array 410 (step 510), and the DSRs 30 may be
operated in accordance with any modal communication that has been
received (step 514). It should be appreciated that the protocol 500
could be configured such that a modal communication is sent by a
given DSR array controller 440 to each of its corresponding DSRs 30
(step 510), or a given DSR array controller 440 could be configured
to send a modal communication (step 510) only to those associated
DSRs 30 that have been determined to be in need of a modal change
in accordance with step 508.
[0157] The operations protocol 500 of FIG. 13E may include what may
be characterized as an optional "temperature override" feature. In
this regard, step 512 of the protocol 500 is directed to
determining if an excessive temperature condition exists on any
given power line section 18 (e.g., determining whether an operating
temperature meets or exceeds a predetermined temperature threshold,
and which may be undertaken in any appropriate manner). Each power
line section 18 may be monitored for the existence of an excessive
temperature condition. This monitoring may be undertaken by the DSR
array controller(s) 440 and/or the DSRs 30 for such a power line
section 18. In any case and in the event that such an excessive
temperature condition has been determined to exist, the protocol
500 may be configured to execute step 516. Step 516 is directed to
configuring one or more of the DSRs 30 on the subject power line
section 18 (with an excessive temperature condition) to inject
inductance into this power line section 18. Injecting inductance
into a given power line section 18 that is experiencing an
excessive temperature condition should reduce the current flow
through such a power line section 18, which in turn should reduce
its operating temperature. It should be appreciated that steps 512
and 516 on the noted temperature override feature may be
implemented at any appropriate location within the protocol 500.
Moreover, it should be appreciated that the temperature override
logic could be incorporated by the DSR array controllers 440 (which
would then send an appropriate communication to the DSRs 30 of
their corresponding DSR array 410, such that step 516 would be
executed by the individual DSRs 30 upon receiving such a
communication from their corresponding DSR array controller(s)
440), that the temperature override logic could be incorporated by
the individual DSRs 30 of each DSR array 410 (e.g., such that each
individual DSR 30 could independently determine when step 516
should be executed), or both.
[0158] One embodiment of an operations protocol for addressing
system conditions or contingencies is illustrated in FIG. 13F and
is identified by reference numeral 520. Step 522 of the protocol
520 is directed to sending or transmitting a system condition or
system contingency communication to one or more DSR array
controllers 440 of the power transmission system 400. This system
condition/contingency communication may come directly from the
utility-side control system 430 or through the DSR server 420. In
any case, one or more DSR array controllers 440 may receive the
system condition/contingency communication (step 524). Each DSR
array controller 440 will then retrieve the modal configuration
information from the first data structure 480 for all DSRs 30 in
its corresponding DSR array 410 (step 526). That is, each DSR array
controller 440 will locate the system condition/contingency within
its first data structure 480, and will then retrieve the associated
modal configuration for each DSR 30 in its DSR array 410 for the
associated control objective. Each DSR array controller 440 may
then send a modal communication to each DSR 30 in its corresponding
DSR array 410 (step 528) to specify whether a given DSR 30 should
be in its first or bypass mode, or whether this DSR 30 should be in
its second or injection mode. The controller 54 of a DSR 30 that
receives such a modal communication from its corresponding DSR
array controller 440 will then dispose the DSR 30 in the
communicated mode pursuant to step 532 (either by switching the
mode of the DSR 30, or maintaining the DSR 30 in its then current
mode). It should be appreciated that the protocol 520 could be
configured such that a modal communication is sent by a given DSR
array controller 440 to each of its corresponding DSRs 30 (step
528), or a given DSR array controller 440 could be configured to
send a modal communication (step 528) only to those associated DSRs
30 that have been determined to be in need of a modal change based
upon step 526.
[0159] The operations protocol 520 of FIG. 13F may include what may
be characterized as an optional "temperature override" feature. In
this regard, step 530 of the protocol 520 is directed to
determining if an excessive temperature condition exists on any
given power line section 18 (e.g., determining whether an operating
temperature meets or exceeds a predetermined temperature threshold,
and which may be undertaken in any appropriate manner). Each power
line section 18 may be monitored for the existence of an excessive
temperature condition. This monitoring may be undertaken by the DSR
array controller(s) 440 and/or the DSRs 30 for such a power line
section 18. In any case and in the event that such an excessive
temperature condition has been determined to exist, the protocol
520 may be configured to execute step 534. Step 534 is directed to
configuring one or more of the DSRs 30 on the subject power line
section 18 (with an excessive temperature condition) to inject
inductance into this power line section 18. Injecting inductance
into a given power line section 18 that is experiencing an
excessive temperature condition should reduce the current flow
through such a power line section 18, which in turn should reduce
its operating temperature (assuming of course that current flow can
be diverted to one or more other power lines 16/power line sections
18). It should be appreciated that steps 530 and 534 on the noted
temperature override feature may be implemented at any appropriate
location within the protocol 520. Moreover, it should be
appreciated that the temperature override logic could be
incorporated by the DSR array controllers 440 (which would then
send an appropriate communication to the DSRs 30 of their
corresponding DSR array 410, such that step 534 would be executed
by the individual DSRs 30 upon receiving such a communication from
their corresponding DSR array controller(s) 440), that the
temperature override logic could be incorporated by the individual
DSRs 30 of each DSR array 410 (e.g., such that each individual DSR
30 could independently determine when step 534 should be executed),
or both.
[0160] The operations protocol 520 of FIG. 13F assumes that the
various DSR array controllers 440 are able to receive system
condition/contingency communications from the utility-side control
system 430 and/or the DSR server 420. That may not always be the
case, and is accommodated by the operations protocol that is set
forth in FIG. 13G and that is identified by reference numeral 540.
Step 542 of the protocol 540 is directed to assessing receipt of
system condition/contingency communications. In the event a
predetermined number of DSR array controllers 440 are not receiving
system condition/contingency communications, the protocol 540
proceeds from step 544 to step 546. Step 546 of the protocol 540 is
directed to the DSR array controllers 440 communicating with one
another and sharing information regarding their corresponding power
line section 18. From this information, the present state system
condition/contingency is derived (step 548). A derived system
condition/contingency communication is then sent to the various DSR
array controllers 440 pursuant to step 550 of the protocol 540.
Each DSR array controller 440 will then retrieve the modal
configuration information from the first data structure 480 for all
DSRs 30 in its corresponding DSR array 410 (step 552). That is,
each DSR array controller 440 will locate the system
condition/contingency within its first data structure 480 that
corresponds to the derived system condition/contingency
communication, and will then retrieve the associated modal
configuration for each DSR 30 in its DSR array 410 (and for the
associated control objective). Each DSR array controller 440 may
then send a modal communication to each DSR 30 in its corresponding
DSR array 410 (step 556) to specify whether a given DSR 30 should
be in its first or bypass mode, or whether this DSR 30 should be in
its second or injection mode. The controller 54 of a DSR 30 that
receives such a modal communication from its corresponding DSR
array controller 440 will then dispose the DSR 30 in the
communicated mode pursuant to step 560 (either by switching the
mode of the DSR 30, or maintaining the DSR 30 in its then current
mode). It should be appreciated that the protocol 540 could be
configured such that a modal communication is sent by a given DSR
array controller 440 to each of its corresponding DSRs 30 (step
556), or a given DSR array controller 440 could be configured to
send a modal communication (step 556) only to those associated DSRs
30 that have been determined to be in need of a modal change based
upon step 552.
[0161] The operations protocol 540 of FIG. 13G may include what may
be characterized as an optional "temperature override" feature. In
this regard, step 558 of the protocol 540 is directed to
determining if an excessive temperature condition exists on any
given power line section 18 (e.g., determining whether an operating
temperature meets or exceeds a predetermined temperature threshold,
and which may be undertaken in any appropriate manner). Each power
line section 18 may be monitored for the existence of an excessive
temperature condition. This monitoring may be undertaken by the DSR
array controller(s) 440 and/or the DSRs 30 for such a power line
section 18. In any case and in the event that such an excessive
temperature condition has been determined to exist, the protocol
540 may be configured to execute step 562. Step 562 is directed to
configuring one or more of the DSRs 30 on the subject power line
section 18 (with an excessive temperature condition) to inject
inductance into this power line section 18. Injecting inductance
into a given power line section 18 that is experiencing an
excessive temperature condition should reduce the current flow
through such a power line section 18, which in turn should reduce
its operating temperature. It should be appreciated that steps 558
and 562 on the noted temperature override feature may be
implemented at any appropriate location within the protocol 540.
Moreover, it should be appreciated that the temperature override
logic could be incorporated by the DSR array controllers 440 (which
would then send an appropriate communication to the DSRs 30 of
their corresponding DSR array 410, such that step 562 would be
executed by the individual DSRs 30 upon receiving such a
communication from their corresponding DSR array controller(s)
440), that the temperature override logic could be incorporated by
the individual DSRs 30 of each DSR array 410 (e.g., such that each
individual DSR 30 could independently determine when step 562
should be executed), or both.
[0162] Each DSR array controller 440 may incorporate any one of the
protocols 500, 520, and 540, or may incorporate any two or more of
these protocols. For instance, each DSR array controller 440 could
incorporate both the protocol 500 of FIG. 13E and the protocol 520
of FIG. 13F. Each DSR array controller 440 could then determine the
modal configuration for each DSR 30 in its corresponding DSR array
410 based upon the type of communication that is received. Another
option would be for each DSR array controller 440 to incorporate
both the protocol 520 of FIG. 13F and the protocol 540 of FIG. 13G.
Each DSR array controller 440 could be configured to operate
simultaneously in accordance with the protocol 520 of FIG. 13F and
the protocol 540 of FIG. 13G. That is, the protocol 520 would be
used to control a given DSR array control 440 until step 546 of the
protocol 540 of FIG. 13G was reached, in which case the protocol
540 would then be used to control a given DSR array controller
440.
[0163] A simplified version of a geomagnetically-induced current or
GIC monitoring system is illustrated in FIG. 14 and is identified
by reference numeral 600. The GIC monitoring system 600 is a
line-mounted device--it is installed on a power line 16. Generally,
the GIC monitoring system 600 is configured to monitor and/or
identify the existence of a geomagnetically-induced current (which
herein may be referred to as a "GIC") on a power line 16, and
furthermore is able to communicate information regarding a GIC on
its corresponding power line 16 to one or more other devices. As
will be discussed in more detail below, the GIC monitoring system
600 may be installed on a power line 16 as a standalone unit.
Another option would be to incorporate the GIC monitoring system
600 with another line-mounted device, such as the above-described
DSR 30.
[0164] The GIC monitoring system 600 includes a magnetic core 602
that at least partially surrounds a power line 16 (e.g., the
magnetic core 602 may extend less than a full 360.degree. about the
power line 16). The magnetic core 602 may be composed of any
suitable high permeability material. Although the magnetic core 602
(e.g., collectively defined by core components 620, 622, and 624,
discussed below) is illustrated as having a round or circular outer
perimeter, other shapes may be appropriate. The magnetic core 602
may have an air gap 604 defined therein, and this air gap 604 may
be incorporated such that the magnetic core 602 does not completely
surround the power line 16 (i.e., the magnetic core 602 may be
configured to not provide a closed perimeter about the power line
16). A magnetic sensor 606 (e.g., a Hall effect sensor) may be
positioned in this air gap 604. The magnetic core 602 may be used
to concentrate the magnetic flux, in the region surrounding the
power line 16, within the magnetic core 602 and within the air gap
604 defined therein. This may greatly increase the sensitivity (or
gain) of the magnetic sensor 606 as compared to a system without a
magnetic core. It may also greatly increase the selectivity of the
magnetic sensor 606, in that magnetic fields from surrounding
devices may be more easily ignored. By design, the magnitude of the
magnetic field in the air gap 604 is proportional to the magnitude
of the current in the power line 16.
[0165] The magnetic sensor 606 may provide an output signal that
may be supplied to a signal processing unit 608 (described further
below) of the GIC monitoring system 600. The signal processing unit
608 may provide one or more signals representative of the GIC (at a
minimum) to a communications interface 610, which may communicate
with an antenna 612 (the communications interface 610 and antenna
612 each may be part of the GIC monitoring system 600). A power
supply 614 may be associated with the GIC monitoring system 600 in
order to provide power to one or more of its components.
[0166] The GIC monitoring system 600 is designed to sense DC or
quasi-DC currents in the power line 16 (as will be discussed below,
the GIC monitoring system 600 can also be configured to measure AC
current in the power line 16 as well, for instance for "on-line
calibration" purposes). These currents may be sensed with the
sensor 606 and determined by the signal processing unit 608. The
communications interface 610 and antenna 612 may be used to provide
GIC information to one or more external devices (e.g., to send a
GIC communication), for instance using the communication
architecture described above in conjunction with the DSR 30, DSR
array controller 440, and other components in the described
network.
[0167] The magnetic core 602 may be designed in any fashion so as
to provide an air gap into which a magnetic sensor can be placed.
In one embodiment and as shown in FIGS. 15A and 15B, the magnetic
core 602 is shown to have three separate core components: an upper
core component 620 and two lower core components 622, 624. In this
case, the upper core component 620 is shown to be generally
semi-circular in configuration so as to surround approximately
180.degree. or one-half of the power line 16. The two lower core
components 622 and 624 in this case are configured as generally a
quarter of a circle in angular extent so as to surround
approximately 90.degree. or one quarter of the power line 16. More
specifically, these two lower core components 622 and 624 each
surround just less than 90.degree. of the angular extent. By being
just less than 90.degree., together they provide for the air gap
604 for the sensor 606. Optionally, one of the lower core
components could be 90.degree. or more in extent and the other
lower core component could be an appropriate amount so that
together the two components add up to an extent just less than
180.degree., so as to create an air gap therebetween for the sensor
606. As another option, the air gap for the sensor 606 could be
provided between the upper and lower components of the magnetic
core 602, and in such case there may only be one lower core
component. As another option, there could be a single core
component for the magnetic core 602 that is just less than
360.degree. in angular extent. Having a multi-section or
multi-piece magnetic core 602 (e.g., two or more components that
may be separately moved relative to one another) may facilitate
installation of the GIC monitoring system 600 on the power line 16
(e.g., so as to not require a break in the power line 16 in order
to install the magnetic core 602, although it may be possible to
install a GIC monitoring system 600, having a one-piece magnetic
core 602 and with an appropriate air gap 604, on the power line 16
without requiring a break in the power line 16).
[0168] Further detail on the signal processing unit 608 used by the
GIC monitoring system 600 is provided in FIG. 16. The output signal
from the magnetic sensor 606 may be a differential output signal
provided on a twisted pair 628 of wires that are provided as an
input to the signal processing unit 608. This twisted pair 628 may
be connected to a differential input of an A-to-D (ND) converter
630. A device (not shown) for conditioning the signal (e.g., a
"signal conditioner"), could be disposed between the magnetic
sensor 606 and the ND converter 630, for instance to improve the
signal-to-noise ratio and which could be part of the signal
processing unit 608. In any case and after the differential analog
signal is converted to a digital signal, it is provided to each of
an AC processing portion 632 and a DC processing portion 634 of the
signal processing unit 608.
[0169] The AC processing portion 632 may include a high pass filter
636 to reduce the amount of DC (or lower frequency) signals. After
filtering, the digital signal is provided to an RMS detector 638
which may determine a magnitude of the AC signal. The AC current
magnitude signal is then provided to a ratio determining unit 640.
A reference signal 642 is also provided to the ratio determining
unit 640. The reference signal 642 may be an AC current magnitude
that has been separately determined by an external unit. For
example, the AC current magnitude could be provided from a current
monitor 212 of the DSR 30 (described above). In any case, the ratio
determining unit 640 may provide an output signal based on the
ratio of the reference signal 642 to the AC current magnitude
signal from the RMS detector 638. For example, if the reference
signal 642 has a magnitude corresponding to 120 Amps and the AC
current magnitude signal from the RMS detector 638 has a magnitude
corresponding to 100 Amps, then the output signal from the ratio
determining unit 640 would have a magnitude corresponding to a
ratio of 1.2. As will be seen below, such a ratio can be used to
increase the determined magnitude of the GIC by 20%.
[0170] The DC processing portion 634 of the signal processing unit
608 may include a low pass filter 644 to filter out higher
frequency signals such as AC currents in the 50 to 60 Hz range and
higher-frequency harmonics thereof. After filtering, the signal is
provided to a mean detector 646 that determines the average or mean
value of the DC (or quasi-DC) current. This mean value of the DC
current is then provided to a multiplier 648 which also receives
the ratio signal from the ratio determining unit 640. The two
signals are multiplied together to provide the GIC signal 650.
Continuing with the example from the previous paragraph, where the
ratio determined was 1.2, if the mean value of the DC current
determined by the mean detector 646 was 5 Amps, the GIC signal 650
would be 6 Amps. In this manner, the magnitude of the DC current
determined by the GIC monitoring system 600 is adjusted by the
ratio of the reference signal 642 to the determined AC current
magnitude. In other words, the reference signal 642 is used as a
"truth" or calibration for the proper current magnitude. It should
be appreciated that calibration of the determined DC current
magnitude (while the GIC monitoring system 600 is installed on a
power line 16--an "on-line calibration") may not be required in all
instances (e.g., factory calibration of the GIC monitoring system
600 may be sufficient in at least some instances). In this case,
the signal processing unit 608 of the GIC monitoring system 600 may
eliminate the AC processing portion 632 (i.e., the GIC monitoring
system 600 may then eliminate the ratio determining unit 640 and
the multiplier 648 discussed above).
[0171] The communications interface 610 for the GIC monitoring
system 600 may be a conventional communication interface capable of
transmitting information to one or more remote devices. This
interface 610 could include a transmitter, a transmitter and
receiver, or a transceiver. The interface 610 may work together
with an antenna 612 of an appropriate type. Further detail on an
exemplary communications interface and antenna are provided above
in conjunction with the discussion of the DSR 30.
[0172] The power supply 614 for the GIC monitoring system 600 may
be a conventional power supply capable of providing appropriate
types of power to the remaining portions of the system 600. The
power supply 614 may harvest power from the power line 16 in a
conventional manner. An exemplary power supply is discussed above
in conjunction with the DSR 30.
[0173] As noted, the GIC monitoring system 600 could be
incorporated into another line-mounted device. A variation of the
above-discussed DSR 30 is presented in FIG. 17 in the form of a DSR
30''. Corresponding components of these two embodiments are
identified by the same reference numerals. Those corresponding
components that differ are further identified by a "double prime"
designation in FIG. 17. Unless otherwise noted, the DSR 30''
includes the same features as the DSR 30.
[0174] One difference between the DSR 30 and the DSR 30'' is that
there is a current sensor 660 including an upper portion in the
upper core assembly 50'' and a lower portion in the lower core
assembly 50''. There is also a circuit card 662 that may contain
all or portions of one or more of the signal processing unit 608,
the communications interface 610 and antenna 612, and the power
supply 614. As can be appreciated, when the DSR 30'' is assembled,
the upper and lower components of the current sensor 660 surround
the power line 16 and leave an air gap 604 in which the magnetic
sensor 606 is positioned (see FIG. 14). As the DSR 30'' may include
the above-noted current monitor 212, the GIC monitoring system 600
could be configured to incorporate the noted optional AC processing
portion 632 to provide for an on-line calibration functionality as
discussed above.
[0175] A standalone version of the GIC monitoring system 600 is
shown in FIG. 18. A power line 16 is shown with a pair of line
guards 20 located thereon. In this exploded view, upper and lower
housing portions 670, 672 are provided. Also included are an upper
core segment 620, a lower core segment 622, and a lower core
segment 624, the latter two of which provide for an air gap 604
therebetween. The magnetic sensor 606 is also provided for
positioning within the air gap 604. A pair of circuit cards is
shown containing the signal processing unit 608 and the
communications interface 610 and power supply 614. Although
illustrated as provided on two circuit cards, these electronics
could all be placed on one circuit card or on more than two circuit
cards. It can be appreciated that when the GIC monitoring system
600 is assembled and the upper and lower housing portions 670, 672
are connected together, the core components 620, 622, 624 are held
in a position surrounding the power line 16, with the exception of
an air gap 604 into which the magnetic sensor 604 is positioned. As
the GIC monitoring system 600 shown in FIG. 18 does not include a
separate current monitor, the GIC monitoring system 600 may be
configured without the above-noted AC processing portion 632.
However, a stand-alone GIC monitoring system 600 could include a
separate current monitor to accommodate on-line calibration in
accordance with the foregoing.
[0176] As can be seen, the GIC monitoring system 600 can be part of
a unit with other components, such as part of a DSR 30'' (as shown
in FIG. 17) or it can be part of a standalone unit (as shown in
FIG. 18). While the GIC monitoring system 600 described herein is
only directed to monitoring and measuring GICs, it would be
possible to attempt to control GICs in a similar manner that AC
line currents are controlled by injecting impedance as described in
conjunction with the DSR 30. As another alternative, the system 600
could be implemented without a magnetic core 602, or with a
completely different type of magnetic core. Some or all of the
functionality of the signal processing unit 608 and communications
interface 610 could be implemented in a microprocessor, or any
other suitable form of electronics. It may be possible to provide
inputs to the signal processing unit 608 so that the
characteristics of the high pass filter 636 and low pass filter 644
can be varied. This may include effectively eliminating the effects
of filter 636 and 644.
[0177] One of the advantages of the GIC monitoring system 600 is
that the system can be directly and easily mounted onto a power
line 16 without a break in the power line. Further, the system 600
can be powered from the power line 16. It may be desirable to have
an entire array of GIC monitoring systems 600 that are located
throughout the power transmission grid. With more systems, it may
be possible to get more accurate measurements, and to measure GICs
on power lines that are at different orientations with respect to
the Earth (e.g., with respect to latitude and longitude lines).
[0178] A schematic of one embodiment of a power transmission system
is presented in FIG. 19 and is identified by reference numeral 700.
The power transmission system 700 may be in the form of an
electrical grid for a region or territory (e.g., the electrical
grid for the United States or any portion thereof). One
characterization of the power transmission system 700 is that it
includes a plurality of zones (zone 710a-7101 in the illustrated
embodiment; more generally a "zone 710" in accordance with the GIC
monitoring protocol 750 that will be discussed below in relation to
FIG. 20). The power transmission system 700 may be separated into
any appropriate number of zones 710.
[0179] A "zone 710" for purposes of the power transmission system
700 may be characterized as encompassing a predetermined geographic
area or region of the power transmission system 700. Each zone 710
encompasses a different geographic region, although a given zone
710 could partially overlap (geographically) with one or more other
zones 710. In any case, each zone 710 of the power transmission
system 700 includes at least one power line 16, and more typically
a plurality of power lines 16 (e.g., part of a network or grid of
power lines 16). The power lines 16 for purposes of the power
transmission system 700 may be of any appropriate type, for
instance in the form of a power transmission line (e.g., higher
capacity) or in the form of a distribution line (e.g., lower
capacity). A group of power lines 16 of the power transmission
system 700 may each extend from one common location to another
common location, as well as along the same general path. This may
be referred to as a "power transmission section" in accordance with
the foregoing. In a three-phase power transmission system, each
such "power transmission section" may have three different power
lines 16 that are at three different phases (and may optionally
have a neutral line).
[0180] One or more zones 710 of the power transmission system 700
include at least one GIC device 730. Each GIC device 730 may be in
the form of the above-described GIC monitoring system 600. One or
more GIC devices 730 could be installed on one or more power lines
16 within each zone 710, thereby encompassing a configuration for
the power transmission system 700 where at least one GIC device 730
is installed on each power line 16 within each of its zones 710.
Each GIC device 730 communicates (directly or indirectly) with a
utility-side control system 720 (FIG. 20) and over a communication
link of any appropriate type. At least one-way communication is
available between each GIC device 730 and the utility-side control
system 720 (from a given GIC device 730 to the utility-side control
system 720), although the power transmission system 700 could be
configured to allow for two-way communication between each GIC
device 730 and the utility-side control system 720.
[0181] The utility-side control system 720 for purposes of the
power transmission system 700 may be at least generally in
accordance with the above-described utility-side control system 430
of FIG. 13A (e.g., an energy management system (EMS); a supervisory
control and data acquisition system (SCADA system); a market
management system (MMS)). In the embodiment of FIG. 19, the
utility-side control system 720 is illustrated as including a first
utility-side control unit 720a and a second utility-side control
unit 720b. However, the control architecture of the utility-side
control system 720 may be distributed in any appropriate fashion,
including where utility-side control units of the utility-side
control system 720 are able to communicate with at least one other
utility-side control unit of the utility-side control system
720.
[0182] One embodiment of a GIC monitoring protocol is presented in
FIG. 20, is identified by reference numeral 750, and will be
discussed in relation to the power transmission system 700 of FIG.
19. The GIC monitoring protocol 750 includes monitoring at least
one power line 16, and in at least one zone 710 of the power
transmission system 700, for the existence of a
geomagnetically-induced current or a GIC 740 (step 752). Step 752
of the GIC monitoring protocol 750 may be executed in any
appropriate manner, including through a GIC device 730 that is
installed on a power line 16 of the power transmission system 700.
As noted above in the discussion of the power transmission system
700, one or more GIC devices 730 may be installed on at least one
power line 16 within one or more zones 710 of the power
transmission system 700, including having multiple GIC devices 730
installed on each power line 16 within each zone 710 of the power
transmission system 700 (e.g., including where multiple GIC devices
730 are spaced along a given power line 16 within a given zone
710).
[0183] The power line(s) 16 within one or more zones 710 of the
power transmission system 700 may be monitored on at least some
basis (e.g., continually) pursuant to step 752 of the GIC
monitoring protocol 750. In the event that a GIC 740 is identified
on a given power line 16 within a given zone 710 (step 754), a GIC
communication may be sent (directly or indirectly) to the
utility-side control system 720 regarding such a GIC 740 (step
756). A given GIC device 730 of the power transmission system 700
may be used to execute each of steps 754 and 756 of the GIC
monitoring protocol 750. In any case, a communication pursuant to
step 756 could embody information such as the magnitude of the
identified GIC 740, a time at which the GIC 740 was identified
(e.g., a time stamp), the power line 16 on which the GIC 740
exists, at least the general location of the GIC 740, and the
like.
[0184] A communication pursuant to step 756 of the GIC monitoring
protocol 750 may be utilized in any appropriate manner and for any
appropriate purpose(s) by the utility-side control system 720 of
the power transmission system 700. For instance, the utility-side
control system 720 could use information on a GIC 740 identified by
the GIC monitoring protocol 750 to initiate one or more actions.
Consider the case where a GIC 740 is identified in a given zone 710
of the power transmission system 700 through the GIC monitoring
protocol 750. A communication pursuant to step 756 of the protocol
750 could be used to predict when the identified GIC 740 may arrive
at one or more other zones 710 of the power transmission system 700
(e.g., based upon the movement of the Sun relative to the Earth).
Steps could be taken by or through the utility-side control system
720 to protect one or more electrical components that may be part
of or otherwise linked to the power transmission system 700 within
one or more zones 710 that may at some later point-in-time be
exposed to the GIC 740 (or a similar current) that was identified
pursuant to the GIC monitoring protocol 750.
[0185] Based upon the foregoing, it should be appreciated that the
GIC monitoring protocol 750 of FIG. 20 could be implemented by the
power transmission system 400 of FIG. 13A and discussed above. At
least one DSR 30 in one or more DSR arrays 410 of the power
transmission system 400 could include a GIC monitoring system 600
(thereby encompassing having multiple DSRs 30 in a given DSR array
410 each include a GIC monitoring system 600, having at least one
DSR 30 in each DSR array 410 of the power transmission system 400
include a GIC monitoring system 600, or both). Each DSR 30 in one
or more DSR arrays 410 of the power transmission system 400 could
include a GIC monitoring system 600, including where each DSR 30 in
each DSR array 410 of the power transmission system 400 includes a
GIC monitoring system 600. In any case, communications pursuant to
step 756 of the GIC monitoring protocol 750 of FIG. 20 could
utilize the communication architecture discussed above in relation
to the power transmission system 400 (e.g., having DSRs 30 within a
given DSR array 410 communicate directly with their corresponding
DSR array controller(s) 410, which in turn may communicate
(directly or indirectly) with the utility-side control system 430;
using DSRs 30 of a given DSR array 410 to relay a communication to
their corresponding DSR array controller(s) 410, which in turn may
communicate (directly or indirectly) with the utility-side control
system 430).
[0186] The foregoing description of the present invention has been
presented for purposes of illustration and description.
Furthermore, the description is not intended to limit the invention
to the form disclosed herein. Consequently, variations and
modifications commensurate with the above teachings, and skill and
knowledge of the relevant art, are within the scope of the present
invention. For instance, unless otherwise noted herein to the
contrary, other shapes or geometries may be appropriate for various
components of the illustrated embodiments. The embodiments
described hereinabove are further intended to explain best modes
known of practicing the invention and to enable others skilled in
the art to utilize the invention in such, or other embodiments and
with various modifications required by the particular
application(s) or use(s) of the present invention. It is intended
that the appended claims be construed to include alternative
embodiments to the extent permitted by the prior art.
* * * * *