U.S. patent number RE44,256 [Application Number 13/490,880] was granted by the patent office on 2013-06-04 for electrical instrument platform for mounting on and removal from an energized high voltage power conductor.
This patent grant is currently assigned to Underground Systems, Inc.. The grantee listed for this patent is Paul Alex, Duncan Breese, John Engelhardt, Larry Fish. Invention is credited to Paul Alex, Duncan Breese, James Bright, John Engelhardt, Larry Fish.
United States Patent |
RE44,256 |
Bright , et al. |
June 4, 2013 |
**Please see images for:
( Certificate of Correction ) ** |
Electrical instrument platform for mounting on and removal from an
energized high voltage power conductor
Abstract
An apparatus for monitoring and measuring the electrical,
thermal and mechanical operating parameters of high voltage power
conductors. A toroidal shaped housing, which can be mounted onto an
energized conductor, contains all of the necessary electrical
instruments to monitor the parameters associated with the
conductor. Moreover, the housing includes the processing capability
to analyze disturbance and fault events based on these
parameters.
Inventors: |
Bright; James (Hemet, CA),
Fish; Larry (White Plains, NY), Engelhardt; John
(Greenwich, CT), Alex; Paul (Fairfield, CT), Breese;
Duncan (New Milford, CT) |
Applicant: |
Name |
City |
State |
Country |
Type |
Fish; Larry
Engelhardt; John
Alex; Paul
Breese; Duncan |
White Plains
Greenwich
Fairfield
New Milford |
NY
CT
CT
CT |
US
US
US
US |
|
|
Assignee: |
Underground Systems, Inc.
(Armonk, NY)
|
Family
ID: |
36319516 |
Appl.
No.: |
13/490,880 |
Filed: |
October 31, 2005 |
PCT
Filed: |
October 31, 2005 |
PCT No.: |
PCT/US2005/039064 |
371(c)(1),(2),(4) Date: |
February 07, 2008 |
PCT
Pub. No.: |
WO2006/050156 |
PCT
Pub. Date: |
May 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
60623900 |
Nov 1, 2004 |
|
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Reissue of: |
11666002 |
Feb 7, 2008 |
7733094 |
Jun 8, 2010 |
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Current U.S.
Class: |
324/512; 324/127;
702/59; 702/58 |
Current CPC
Class: |
G01R
15/142 (20130101); G01R 19/2513 (20130101) |
Current International
Class: |
G01R
31/08 (20060101); G01R 15/18 (20060101); G01R
31/00 (20060101) |
Field of
Search: |
;324/512,127
;702/58,59 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: He; Amy
Attorney, Agent or Firm: Frommer Lawrence & Haug LLP
Frommer; William S.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
60/623,900, filed Nov. 1, 2004.
Claims
What is claimed:
1. An apparatus for monitoring the operation of an electric power
conductor, comprising: a housing having a toroidal shape and means
for mounting on said electric power conductor; a plurality of
electrical instruments in said housing for monitoring various
parameters associated with the conductor; recording means in said
housing for recording the various parameters being monitored; and
analyzing means in said housing for analyzing disturbance and fault
events based on the various parameters being monitored, wherein
said analyzing means produces fault location reports based on the
various parameters monitored from one end of the conductor.
2. The apparatus according to claim 1, wherein the plurality of
electrical instruments include: means for measuring an electric
current flowing through the conductor; means for measuring an
electric potential (voltage) of the conductor relative to a ground
potential; and means for determining a phase relationship between
the measured current and voltage.
3. The apparatus according to claim 1, further comprising means for
receiving a global positioning signal (GPS) for use by said
analyzing means.
4. The apparatus according to claim 3, wherein the signal from the
GPS provides a signal for time-stamping the various parameters
being monitored.
5. The apparatus according to claim 1, further comprising power
means in said housing for powering the apparatus by induction from
an electromagnetic field produced by the energized conductor.
6. The apparatus according to claim 5, wherein said power means
includes: energy storage means for powering said apparatus when the
electromagnetic field produced by the energized conductor is below
a first threshold level; and charging means for charging the energy
storage means by induction when the electromagnetic field exceeds a
second threshold level.
7. The apparatus according to claim 1, wherein the plurality of
electrical instruments includes: means for measuring a temperature
of the conductor; means for sensing a pitch angle of the conductor;
means for sensing motion perpendicular to a longitudinal axis of
the conductor.
8. The apparatus according to claim 1, further comprising updating
means for updating a programming of the analyzing means without
removing the apparatus from the power conductor.
9. The apparatus according to claim 1, wherein the housing is
enabled to be mounted while the conductor is energized.
10. An apparatus for monitoring the operation of an electric power
conductor, comprising: a housing having a toroidal shape and means
for mounting on said electric power conductor; a plurality of
electrical instruments in said housing for monitoring various
parameters associated with the conductor; recording means in said
housing for recording the various parameters being monitored; and
analyzing means in said housing for analyzing disturbance and fault
events based on the various parameters being monitored, means for
transmitting and receiving the various parameters being monitored
to another apparatus at a different location on the conductor,
wherein said analyzing means produces fault location reports based
on the various parameters monitored from different locations on the
conductor.
.Iadd.11. An apparatus for monitoring the operation of an electric
power conductor, comprising: a housing adapted to be mounted on
said electric power conductor; a plurality of electrical
instruments in said housing for monitoring various parameters
associated with the conductor; recording means in said housing for
recording the various parameters being monitored; and analyzing
means in said housing for analyzing disturbance and fault events
based on the various parameters being monitored, wherein said
analyzing means produces fault location reports based on the
various parameters monitored from one end of the
conductor..Iaddend.
.Iadd.12. An apparatus for monitoring the operation of an electric
power conductor, comprising: a housing adapted to be mounted on
said electric power conductor; a plurality of electrical
instruments in said housing for monitoring various parameters
associated with the conductor; recording means in said housing for
recording the various parameters being monitored; and analyzing
means in said housing for analyzing real time processes and
disturbance and fault events based on the various parameters being
monitored, wherein said analyzing means produces fault and fault
location reports based on the various parameters monitored from one
end of the conductor..Iaddend.
Description
FIELD OF THE INVENTION
The present invention relates generally to an apparatus for
monitoring and measuring the electrical, thermal and mechanical
operating parameters of high voltage power conductors. More
particularly, the apparatus may be mounted onto overhead power
transmission lines to monitor the operation of electrical power
systems.
BACKGROUND OF THE INVENTION
Numerous instruments for measuring the operating parameters of
power line conductors have been disclosed in the prior art. For
example, U.S. Pat. Nos. 3,428,896; 3,633,191; 4,158,810; 4,268,818;
4,384,289 and 4,794,327 (the disclosures of which are incorporated
herein by reference) each describe instruments for measuring and
analyzing the performance of particular parameters of overhead
power line conductors. Note, the terms power line, transmission
line, and conductor are used interchangeably herein. Typically,
these instruments only measure a subset of the many parameters
needed to completely analyze an electrical power system. For
example, prior art instruments may individually measure, but do not
monitor: current flow in the conductor, conductor temperature,
ambient temperature, conductor tension relative to a supporting
tower, and/or conductor sag. To date, none of the prior art
instruments measures or monitors a complete set of the parameters
needed to fully describe the operational state of a power
conductor. Moreover, prior art instruments do not provide for the
sharing of data between similar instruments or multiple ground
receiving stations. Rather, the above prior art references propose
that individual instruments gather data for transmission through
dedicated local ground receiving stations to central control
stations for correlation and analysis. These instruments are simply
not capable of simultaneously monitoring and analyzing many of the
operating parameters of a transmission line.
In a system having several measuring instruments each transmitting
data to ground based receivers, a means should be provided to
ensure that more than one instrument is not transmitting at any
given time. To avoid interference and data loss caused by more than
one instrument transmitting data at a given time, it has been
suggested that data could be transmitted in finite bursts at random
times. However, under this approach, the possibility still exists
that multiple instruments will transmit data at the same time.
Therefore, a need exists for an electrical instrument platform
which may be mounted directly on an energized power conductor and
is capable of simultaneously measuring and monitoring a complete
set of parameters of the conductor while communicating those
parameters to other similar instruments and also to local or remote
ground based processors.
SUMMARY OF THE INVENTION
Accordingly, the present invention meets this need by providing an
apparatus for mounting directly on an energized power conductor and
which is capable of simultaneously measuring and monitoring a full
suite of electrical, thermal and mechanical parameters of the
conductor while communicating those values to other similar
instruments and also to local or remote ground based processors.
The present invention may process and analyze data generated by its
own instruments, as well as data received from other such
apparatus.
The present invention has the capability to monitor all necessary
parameters, including disturbance events and fault events that may
occur during the operation of a complete electrical power
transmission system. The present invention provides complete
monitoring by using power line mounted instruments, each capable of
simultaneously sensing voltage, current, phase angle and other
parameters of an associated conductor and communicating the
measured parameters amongst these instruments, as well as to ground
based processors.
As another aspect of the present invention, the apparatus
incorporates all of the required instrument components in its
housing. The apparatus may be installed on the conductor without
shutting down the power transmission circuit. The apparatus may
monitor the parameters being measured by comparing them against
preset levels, and by storing data for later retrieval and
analysis. The measured data may be communicated in real time, using
wireless radio transceivers. Data communicated from the instruments
to the receiving processors, whether local or remote, is already in
condition for processing. This eliminates the need for accessories
(such as auxiliary transformers, transducers, and the like)
otherwise needed for signal conditioning and processing in prior
art substation monitoring systems. The present invention
interrogates each instrument in turn so that no two instruments in
the apparatus are transmitting at the same time. This approach
mitigates the possibility of data loss associated with prior art
methods. The apparatus may be powered by the electro-magnetic field
generated by current flowing through the power conductor to which
it is mounted. A stored energy means (e.g. batteries) may be
provided to power the apparatus when there is insufficient or no
current flowing through the conductor.
Advantages of the present invention include the ability to monitor
the operation of a conductor over time, rather than simply making
single shot measurements; the ability to analyze measured data
on-board and in real time; and the ability to draw its power by
induction from the conductor. Further, the present invention
provides for flexibility in the measurements which can be taken.
Accordingly, the present invention is a significant improvement
over prior art devices in the areas of processing, monitoring,
flexibility, communications, and installation.
Still other objects and advantages of the invention will in part be
obvious and will in part be apparent from the specification and the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the invention, reference is
made to the following description and accompanying drawings, in
which:
FIG. 1 illustrates apparatus of the present invention mounted on a
transmission line;
FIG. 2 is a top-view of the apparatus shown in an open position
ready for mounting on a transmission line;
FIG. 3 is a top-view showing the magnetic core mounted in the
lower-half shell of the housing of apparatus in accordance with the
present invention;
FIG. 4 is a side-view showing the ends of the magnetic core of the
apparatus when in the open position,
FIG. 5 is a top-view showing the battery pack mounted in the
upper-half shell of the housing of the apparatus;
FIG. 6 is a top-view showing the Rogowski coil for measuring
current mounted in the upper-half shell of the housing of the
apparatus;
FIG. 7 illustrates the pick-up lead for measuring voltage mounted
in the housing of the apparatus;
FIG. 8 illustrates one of two temperature probes for measuring
temperature mounted in the housing of the apparatus;
FIG. 9 is a top-view showing the radio antenna used for both
wireless and cellular communications mounted on the housing of the
apparatus; and
FIG. 10 is a schematic diagram of a conventional transmission line
model.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred embodiments of the apparatus and method according to
the present invention will be described with reference to the
accompanying drawings.
I. Physical Description
The present invention provides an apparatus for monitoring and
measuring the electrical, thermal and mechanical operating
parameters of high voltage power conductors. More particularly, the
apparatus is for use in systems that are mounted onto overhead
power transmission lines and that measure parameters necessary to
monitor the operation of single-phase circuits, three phase
circuits, and entire electrical power systems.
The invention has a torus shaped housing with a metallic outer
surface. FIG. 1 illustrates one embodiment of the present invention
mounted on a transmission line. The housing incorporates all the
components/instruments required to measure these parameters. The
invention not only includes the means to monitor various
parameters, but also includes the means to locally record the
parameters for later retrieval, compare them against preset levels,
and analyze disturbance and fault events based on these parameters.
As described more fully below, the housing includes an embedded
information processing capability to perform a complete analysis of
the transmission line.
The toroidal housing has two half-sections that are hinged such
that the housing can be split open to mount the apparatus onto a
conductor, and then closed over the conductor when in the installed
position. FIG. 2 is a top-view of an embodiment of the present
invention shown in an open position ready for mounting on a
transmission line. The axial center of the housing includes a
central supporting member, or "hub," which thermally isolates the
conductor from the housing. This hub fixes the housing to the
conductor so that the housing will not rotate around or move along
the conductor.
The housing typically includes electrical instruments for measuring
the electric current flowing through the conductor, measuring the
electric potential (voltage) of the conductor relative to ground,
determining the phase relationship between the measured current and
voltage, measuring the temperature of the conductor, sensing the
pitch angle of the conductor, and/or sensing motion perpendicular
to the longitudinal axis of the conductor. For example, FIG. 6
shows a top-view of a "Rogowski" coil 610 for measuring current
mounted in the upper-half shell of the housing. FIG. 7 illustrates
a pick-up lead 710 for measuring voltage mounted in the housing.
The phase relationship between the current and voltage can readily
be determined by comparing the phase between similar points (such
as the peaks) on each waveform. The present apparatus may use an
inclinometer to sense the pitch angle and an accelerometer to sense
motion along and/or perpendicular to the axis of the conductor.
One or more temperature probe(s) are mounted in the hub area of the
housing to measure the temperature of the conductor and/or the
ambient temperature. FIG. 8 shows a temperature probe 810 for
measuring the temperature of the conductor. The temperature probes
are thermally insulated so that the housing does not impact the
measurements.
Further description of the instruments and measurements performed
by the apparatus may be found in the commonly owned International
Application No. PCT/US2005/025670, entitled "Dynamic Line Rating
System with Real-Time Tracking of Conductor Creep to Establish the
Maximum Allowable Conductor Loading as Limited by Clearance," filed
Jul. 20, 2005; which is incorporated herein by reference.
More specifically, the apparatus may provide the following data: a)
voltage; b) current; c) phase angle between the voltage and
current; d) the power flow demand resulting from the voltage and
current; e) the power flow reactive demand resulting from the
voltage and current; f) the energy rate due to current flowing
through the conductor resulting from the voltage and current; g)
the reactive energy rate due to current flowing through the
conductor resulting from the voltage and current; h) the
temperature of the conductor in one or more locations around the
circumference of the conductor; i) the vibration of the conductor
in a direction perpendicular to the conductor; i.e. power line
galloping and Aeolian vibration; j) the pitch angle of the
conductor relative to horizontal; and k) other parameters that
characterize the real time operational state of a power conductor
and can communicate real time reports to remote, ground based
systems.
Processors in the apparatus can analyze the voltage and current
waveforms to derive further information such as: disturbance
events, fault events, and detection and mitigation of corona
effects on the voltage and current measurements. Most of the
calculations, processing, and analysis disclosed herein may be
performed by software running on one or more processors located in
the housing of the apparatus. These processors may be part of a
processing unit 530 which might be fit into the housing as shown in
FIG. 5. Analysis software for performing these calculations may be
resident in the processors and/or stored in a memory. An exemplary
memory or storage unit 540 may be fit into the housing as shown in
FIG. 5. As mentioned above, such a storage unit may be used to
record the data being collected by the instruments in the
apparatus.
Data Transfer and Communication
The apparatus includes a communication unit for transmitting and
receiving various measured and analyzed parameters to other similar
apparatus at different locations on the conductor. Communications
may be conducted in real-time, e.g. using wireless radio
transceivers, and/or may be on-demand using, for example, cellular
telephone technology. FIG. 9 is a top-view of a communications
transceiver 910 used for both wireless and cellular communications
mounted on the housing of the apparatus in accordance with the
present invention.
As discussed previously, prior art power line instruments require
local, ground based devices to coordinate the collection of data,
and to forward this data to remote processing units. Such ground
based devices may be mounted on towers, or placed on pads at ground
level. The present invention, because it is fitted with a
communications transceiver, can be used without local ground based
equipment.
Additionally, as part of its analysis capability, the present
invention can receive global positioning signals (GPS). Typically,
the time stamp from the GPS signal is extracted and used to ensure
accurate calculations. A GPS unit may be included with the
communications transceiver 910 shown in FIG. 9.
Another aspect of the present invention is data transfer using a
time-multiplexed methodology. The present invention uses a modified
time division multiple access (TDMA) data transfer protocol to
transfer data between devices in the system. Data output from the
devices, including to and from ground based processors, is cast in
terms of a defined data communications protocol. The various data
values produced by a device, as well as communication management
parameters associated with the device (such as its address) are
included in the data communications protocol. One device is
selected to be the data transfer controller, i.e. the master
device. All other devices are slaved to the master device for any
data transfers. Typically, a ground based processor would be
designated as the controller.
The data communications protocol defines a message frame, a message
address and a message body. Each device in the system is assigned a
unique system address. The message body may contain a command or a
data response to the command. The controller sends an interrogation
poll command simultaneously to all other devices and only the
device whose address is contained in the message may respond. This
methodology prevents data collisions thereby mitigating the loss of
data. The format and commands used in the data communications
protocol are described below.
All devices in the system are capable of decoding digital messages
conforming to this protocol. In addition, each device may operate
as both a controller and as a slaved device. This allows the system
to relay messages between devices that might otherwise be out of
the direct radio communication range.
The present invention also uses file and data formats and file
naming conventions conforming to the IEEE C37.111-1992 "Standard
Common Format for Transient Data Exchange (COMTRADE) for Power
Systems."
Also, the present invention allows for its instrument and/or
analysis software to be updated without removing the apparatus from
the power conductor. Such software updates could be uploaded to the
housing through the communications transceiver and stored in
on-board memory and/or used by the processors.
Power System
The present invention derives it primary power from the energized
conductor onto which the housing is mounted. The housing contains a
magnetic core which is coupled by induction to the electromagnetic
field generated when current flows in the power line conductor.
FIG. 3 is a top-view showing the magnetic core 310 mounted in the
lower-half shell of the housing. The magnetic core extends around
the interior of the housing to surround the conductor. The core is
divided into two magnetized sections such that opposed pole faces
are separated when the housing is "opened" and in contact with each
other when the housing is "closed" and mounted onto the conductor.
FIG. 4 is a side-view picture showing two ends 410, 420 of the
magnetic core of the present apparatus when in the open position.
The magnetic core has a minimal set of secondary power pick-off
coils and power conditioners that are used to power the components
in the housing.
As a secondary power source, the apparatus includes a rechargeable
battery to power the components in the housing when there is
insufficient or no current flowing through the conductor. FIG. 5 is
a top-view showing the battery pack 510 mounted in the upper-half
shell of the housing of the present apparatus.
The current level in the conductor is monitored by sensing
circuitry in the housing to determine whether the flow is above
predetermined minimum threshold values. The apparatus is powered by
the battery when the line current is below a first threshold value.
If the current flow is above this first threshold, the apparatus
may be powered by electromagnetic induction from the conductor.
When the current is above a second threshold value, excess
induction current is used by a charger in the battery pack 510 to
charge the battery. If an insufficient current condition (i.e.
below the first threshold) persists in the conductor beyond a
predetermined time limit, the apparatus can reduce the frequency of
data transmission to conserve battery power. If the battery voltage
drops below a second threshold level, all battery-powered
transmission is stopped until the battery is recharged.
Because the apparatus is attached directly on the power conductor,
and measures current and voltage from the electrical and magnetic
field surrounding the conductor, the present invention eliminates
the need for many of the auxiliary ground based transformers,
transducers, test switches, terminal blocks, fault monitors and
hard wiring required in previous power monitoring systems.
II. Data Processing
A. Disturbance Event Processing
The processing performed by the present invention is capable of
analyzing instrument inputs to produce at least the following types
of disturbance reports: a. Disturbance location reports based on 60
Hz voltage (V) and current (I) measurements from one end of a line;
b. Disturbance location reports based on the Takagi algorithm using
data from one end of a line; c. Disturbance location reports based
on phasor data from both ends of a line; d. Disturbance location
information based on ratios of currents from both ends of a line;
and e. Disturbance location reports based on traveling waves
captured at both ends of a line.
The terms disturbance and fault are used interchangeably herein.
However, disturbance recording typically requires data acquisition
for at least five minutes while fault recording generally captures
data over intervals of less than one second. Accordingly, fault
recording may be viewed as a subset of disturbance recording.
Because most faults are temporary and the location of a fault is
not always easy to find, it is advantageous to have accurate fault
location information. Nevertheless, utilities still routinely
examine transmission line hardware via helicopters to locate a
fault. It often takes a long time to find the site of a fault, even
for common problems such as cracked insulators from arc-over due to
lightning strikes.
The distance along a transmission line to a fault can be calculated
from one end of the line using voltage and current measurements.
Fault voltage and current data is used to calculate the reactance
from the measuring site to the fault and establish the distance
based on the reactance per mile of the transmission line. Reactance
is used rather than impedance so as to minimize the effect of fault
resistance. However, this technique does not entirely eliminate the
effect of fault resistance because of the voltage drop caused by
line current flowing into the fault resistance from the other end
of the line. The error in this type of calculation can be up to 5
or 10 percent. For example, an error of .+-.5% on a 100 mile line
would be .+-.5 miles. Although this does limit the search range, a
more accurate calculation is needed.
The Takagi algorithm was first published in 1980 and has proven to
be quite accurate. This algorithm was first applied in the U.S. in
the Schweitzer Distance Relay and remains today the preferred
algorithm for fault location based on voltage and current
measurements from one end of a line. However, it is still dependent
on the accuracy of the voltage and current inputs from one end of
the line.
Fault location can also be accurately computed using phasor
information from both ends of a transmission line. In this case,
the location calculation is independent of the fault resistance and
is therefore immune to the effects of out-of-phase sources feeding
into the fault. In this calculation, remote phasors are
synchronized analytically in a double-ended algorithm, thereby
eliminating the need for phasor synchronization. This is
accomplished by expressing the voltage angle at one end of the line
as a known measured angle plus an unknown synchronization error.
Applying this approach to a conventional transmission line model,
as shown in FIG. 10, results in three unknown parameters: the
synchronization angle (error), the location of the fault (m), and
the fault resistance (R.sub.fault). FIG. 10 shows that the fault
voltage (V.sub.fault) can be expressed by two equations written in
terms of the fault current flowing from each terminal of the line
(I.sub.From).sub.fault and (I.sub.TO).sub.Fault. The resistance can
be eliminated mathematically from these equations by equating the
two expressions in terms of the fault voltage. Separating the
complex equations into real and imaginary parts results in two
equations with two unknown parameters: the synchronization error
between the remote measurements and the fault location. Both of the
unknown parameters can be computed using the two equations.
Another method for calculating fault location, especially for
longer transmission lines (over 300 miles), is based on the ratios
of the currents feeding into the fault as measured from both ends
of the line. A fault in the center of the line would result in the
some current at both ends. This calculation must also take into
account the impedance to the generating sources at each end of the
line and the current measurements must be corrected for offset.
The distance to a fault can also be determined by capturing a
traveling wave at both ends of the line. Lightning strikes are a
common cause of traveling waves on transmission lines. Typically,
the waveform of a lightning surge voltage on a high voltage power
transmission line flattens as the voltage surge travels further
along the transmission line. The conventional method for picking up
traveling waves is to use an inductor or high frequency transformer
in series with a voltage connection between the power line and the
case of the measuring instrument. However, in the present
invention, the voltage waveform is monitored by means of capacitive
coupling. The apparatus may include a conductor to short (or
alternatively, a capacitor to couple) the power line to the
housing. Current will flow out from the housing to ground in
proportion to the surface area of the housing. The voltage may be
measured from this current flow.
B. Data Acquisition Triggering Schemes
A triggering mechanism is required to capture fault current and
voltage waveforms. The trigger mechanism should be based on a
change from a zero state to some value (referred to as
all-or-nothing sensing) rather than on particular signal levels
because the operating conditions of the line demand different level
settings for different operating conditions.
One method used in the present invention is to trigger far-end
fault data capture upon a current reversal of the current direction
to feed the fault. This method requires a phase comparator to
compare the previous cycle with the current cycle on a rolling half
cycle basis. In this situation, fault data is only needed at one
end of the line and therefore eliminates the need to transmit a
trigger to the other end. However, triggering must be relayed
between all three phases within 5 cycles of 60 Hz in order to
capture voltage and current waveforms with at least 5 cycles of
pre-fault; assuming that the detecting phase has 10 cycles of
pre-fault.
Pre-fault and fault data should be captured with a frequency
response of 1200 Hz (or better) in order to capture breaker
re-strikes. Any anti-aliasing filters should be of the linear phase
response type so as to eliminate overshoot and ringing on step
inputs. The corresponding band limits will be at the 6 db points.
Sixty cycles of post-fault data should also be captured in order to
include the re-close and potential beginning of a power swing, but
only the 60 Hz component needs to be recorded. If the fault still
exists upon re-closing, the response should revert back to 1200 Hz
in the pre-fault and fault interval before dropping back to 60 Hz
in the post-fault period.
If a current reversal is detected at both ends of the line, the
fault record captured for that line section should be deleted
within a second or so after the fault record is captured. Those
fault records should be deleted because the fault is not within
those line sections that have current reversals at both ends. The
fault will be in the Hue section that has a current reversal at one
end only. This is a definite improvement over standard fault
recorders that capture data at every fault recorder site. It then
becomes necessary to find the record that is closest to the fault
for analysis.
The present invention may additionally, or alternatively, use one
or more of the following triggering methods: capture data following
a fault to obtain data on instabilities; use a timed impedance
trajectory instrument for power swings; trigger on under-frequency
fur under-frequency conditions; trigger on timed positive sequence
under-voltage for voltage collapse; and trigger on period jumps in
60 Hz waveforms to capture data on power redistributions following
a reconfiguration of the system after a fault or loss of generation
or transmission. A change in system configuration causes a change
in voltage angle at every node in the system so as to conform to
the new conditions for power flow.
C. Real Time Voltage Phase Angle Measurements
The present invention measures the voltage phase angle once a
second and transmits it to an operations center on a real time
basis. The angle is determined by recording the time difference
between the exact time [to a resolution of 10 microseconds (0.22
degrees of 60 Hz)] of the measurement to the next positive zero
crossing of the voltage waveform. Simultaneous measurements could
be taken at both ends of the line to determine the phase angle from
one end of the line to the other.
The voltage phase angle M may be calculated from the power flow P
by solving the following equation: P=V.sub.SV.sub.R sin(M)/X where
V.sub.S and V.sub.R are the sending and receiving end voltages, X
is the reactance between these two voltages, and M is the angle by
which V.sub.S leads V.sub.R.
D. Power Swing Measurements
Ideally, disturbance recorders should be installed at every
backbone interconnection between the 10 NERC (North American
Electric Reliability Council) regions in the U.S. in order to
rapidly analyze disturbances and improve reliability. This need has
been largely ignored over the past two decades because utilities
have no incentive to improve system reliability and consistently
face obstacles to new transmission lines and generating plants.
System disturbances can be described as: power swings, out-of-step
conditions, load shedding, or voltage collapse.
Shocks to a transmission system may be caused by faults, loss of
generation, or tripping a line. Such shocks may cause power swings
(oscillations) whereby power flows back and forth through a line.
Power swings may be a short duration "instability" swing which
quickly normalizes or a sustained "oscillation" in the bus voltage
and line current. Data on the character, duration, and period of a
power swing is valuable in preventing future power swings. Power
swings are often relatively slow events, typically having a period
of around 15-20 cycles of 60 Hz. For example, the power may
propagate in one direction for a period of 15 cycles and then back
in the other direction for 15 cycles. It is only necessary to
record the RMS (root mean squared) current values of each cycle of
60 Hz. Recording should continue for one or two minutes, or until
the power swing stops.
If allowed to continue, a power swing may result in an out-of-step
condition when one or more generators slip a pole. This out-of-step
condition severely strains generator shafts and affected machines
must be inspected for damage. Generators typically include damping
to prevent such oscillations, but the required damping factors are
not known to a high degree of certainty. The data collected for a
power swing will indicate the degree of damping applied.
An under-frequency condition occurs when there is insufficient
power to supply the existing load. This occurs when a major source
of power is lost; such as when a major line trips out or a major
generator drops off line. Under such conditions, load shedding is
practiced in order to preserve balance in the system. Frequency
relays are used to trip out sections of load at particular
frequencies as the frequency decreases. For example, the first
relay might trip out at 59.8 Hz, the second at 59.4 Hz and a third
at 59.2 Hz. Shedding continues until the frequency begins
increasing back towards 60.0 Hz. The frequency is typically
recorded to an accuracy of 0.01 Hz in order to verify the
performance of the load shedding relays.
When a line trips out, the operator reconfigures the system and
reroutes power over the new system configuration. To increase the
transmission capacity of a system, capacitors have been installed
on many transmission lines. However, these lines are more sensitive
to an overload, which in turn makes the system more susceptible to
a voltage collapse. It is therefore important to monitor line
loading and voltage levels throughout a power system so that
cascading events, such as a voltage collapse, can be understood and
prevented.
E. Data Acquisition for Fault Location
As discussed previously, the present invention may acquire
disturbance/fault location data based on a method of capturing the
arrival time (to the nearest microsecond) of traveling waves at
both ends of a line section. The critical factors in this method
are to provide accurate time synchronization between the ends and
inter-end communication. A GPS receiver may be used for the time
synchronization by combining the "time of day" serial message and
the 1 pps time strobe in the GPS signal. The inter-end
communication can be by any convenient means and does not have to
be in real time.
The distance to the fault from the two ends of a line section are
given by: Distance from end A=(linelength/2)+(T1A-T1B)*V/2 Distance
from end B=(linelength/2)+(T1B-T1A)*V/2 wherein the distance is
calculated in miles; linelength is the length of the line section
in miles; A and B designate each end of the line segment; T1A and
T1B represent the respective arrival times at each end for the
first occurrence of the traveling wave; and V is the speed of light
(186,280 miles per second).
The present invention uses a Rogowski coil to pickup the current
signal in the line section. The current, rather than the voltage,
should be used to detect the traveling wave. The magnitude of the
current signal will be the value of the voltage wave divided by the
characteristic impedance of the power line (approximately 500
ohms).
The current signal is converted to voltage and passed through a 30
kHz single pole, high pass filter. The signal is then clipped to
prevent overdriving the system's electronics. The signal passes
through a 350 kHz single pole low pass filter to limit the
bandwidth for an improved signal to noise ratio. Note, a 350 kHz
filter is used to pass one microsecond rise time pulses, which
roughly correspond to the distance between transmission towers.
The pulse detection circuit should include an adjustable threshold
detector to permit triggering on the lowest expected input current
for the traveling wave. Primary current pulse magnitudes on a 345
kv line (200 kv to ground) should range between 56 and 400 amperes
depending on how far the fault is located from the end of the line;
assuming a 100 mile section. The magnitude of a voltage pulse
versus distance is given by the following formula:
E=E.sub.0/(KSE.sub.0+1) wherein E.sub.0 is the initial voltage in
kilovolts, S is the travel distance in miles, and K is an empirical
constant.
Once a pulse has been detected, the pulse detection circuit must
lockout for one second to prevent the detection of subsequent
reflections and breaker operations. It should be noted that
traveling waves could be generated by switching operations and
faults outside the monitored section. Therefore a means must be
provided to verify that the detected waves are from a fault in the
section of line being monitored.
To verify that a fault did in fact occur within the monitored line
section, a phase comparison scheme is recommended. The phase
comparison technique compares the arrival times of the first
positive zero crossing of the current waveform at each end of the
line following the receipt of a traveling wave. If the fault is
within the monitored section of line, the times will be nominally
different by 180 (+/-90) degrees of 60 Hz. The 180 degree
difference stems from current being fed from both ends of the line
into the fault. Otherwise, the currents at both ends would be in
phase. It is expected that the phase information can be
communicated from one end of the line to the other within a second.
This will allow for verification of the fault around the time the
pulse detectors' one-second-lockout interval ends.
III. Disturbance Reports
Ideally, a system operator will receive a complete disturbance
report after a fault occurs so that repair crews can be informed
and dispatched. Unfortunately, prior art fault recording devices
can only provide records consisting of traces of 60 Hz waveforms
for the relay engineers to analyze. Clearly defined fault
information sets, such as listed below, are generally not available
until the relay engineers analyze these traces.
Advantageously, the present invention can capture fault data
waveforms and perform an automatic analysis on the data so as to
extract the information required for a fault report. As discussed
above, this analysis is performed by software running on one or
more processors in the apparatus. The present invention can provide
disturbance reports which include the following fault data: 1. Date
and time of fault (e.g. to the nearest second) 2. Nature of fault
(e.g. temporary or permanent) 3. Type of fault: a. Three-phase b.
Phase-to-phase (e.g. 1-2, 2-3, 3-1) c. Two phase-to-ground (e.g.
1-2-G, 2-3-G, 3-1-G) d. Phase-to-ground (e.g. 1-G, 2-G, 3-G) 4.
Maximum fault amperage 5. Time to clear the fault (e.g. in cycles
of 60 Hz) 6. Damage estimate (e.g. low, medium, high)
A fault should be considered permanent if the fault still exists
upon re-closing the line. The fault is considered temporary if it
is not present upon re-closing. Re-closing may be automatic or
manual. Manual re-closing is preferable for extremely high voltage
lines where re-closing on a fault could cause significant damage.
As used herein, re-closing refers to the act of resetting,
reconnecting, and/or re-powering a line after the line has been
opened such as when a fault occurs which trips a breaker/relay in
the line.
The type of fault can be ascertained by noting which phases have
fault current. The presence of a zero sequence component during the
fault indicates that a ground is involved in the fault. A zero
sequence is computed as follows:
E.sub.0=(E.sub.a+E.sub.b+E.sub.c)/3 where a, b, c, each represent a
phase The maximum fault amperage is determined by which phase has
the maximum current during the fault. The time to clear the fault
is the time interval from the beginning of the fault current to
when the fault current is no longer present (i.e. a breaker is
open). Damage estimates can be made by calculating a value
KA.sup.2, where K is the number of cycles to clear the fault and A
is the value of fault amperes (in 1,000 s). This value is
correlated to an expected level of damage which allows a dispatcher
to tell a repair crew what to expect at the fault site. IV. Data
Communications Protocol Introduction
This section describes the data communications protocol used by the
present invention. Data exchange can occur between: two apparatus
(electrical instrument platforms); an apparatus and a ground
station; and between processors (microcontrollers) within an
apparatus. For example, the power supply's processor may
communicate with the main board's processor.
The apparatus normally communicates using wireless radio
communication systems. A hard-wired connection is provided for
configuration and maintenance purposes via a "Configuration and
Test" port. This port uses a three wire version of the RS 232
signal format (see Tables 1A and 1B) to connect with a laptop
computer. This port is used when the wireless system in the
electrical instrument platform is a cellular-based
telecommunication system.
TABLE-US-00001 TABLE 1A Computer with DB25 Connector RS232 Pin
Assignments (DB25 PC signal set) Pin 1 Protective Ground Pin 2
Transmit Data Pin 3 Received Data Pin 4 Request To Send--Not
Required Pin 5 Clear To Send--Not Required Pin 6 Data Set
Ready--Not Required Pin 7 Signal Ground Pin 8 Received Line Signal
Detector (Data Carrier Detect)--Not Required Pin 20 Data Terminal
Ready--Not Required Pin 22 Ring Indicator--Not Required
TABLE-US-00002 TABLE 1A Computer with DB9 Connector RS232 Pin
Assignments (DB9 PC signal set) Pin 1 Received Line Signal Detector
(Data Carrier Detect)--Not Required Pin 2 Received Data Pin 3
Transmit Data Pin 4 Data Terminal Ready--Not Required Pin 5 Signal
Ground Pin 6 Data Set Ready--Not Required Pin 7 Request To
Send--Not Required Pin 8 Clear To Send--Not Required Pin 9 Ring
Indicator--Not Required
Conventions And Terminology
The following conventions are used throughout this specification:
1. Single ASCII characters are enclosed in single quotes; 2. ASCII
strings (two or more characters) are enclosed in double quotes; and
3. HEX values are preceded by 0x.
Communicating devices, such as main controllers, power supply
controllers, maintenance laptop computers, ground stations or
"master stations" are each referred to herein as communicating
"units". Communications occur when an "external" unit transmits a
message to a "receiving" unit. Messages may be "requests" for data,
or may be "commands" to cause the receiving unit to take some
action such as change configuration parameters, reset the internal
clock, etc. . . . .
Data Transpon Link Format
Device Identification
Each electrical instrument platform "unit" is assigned a unique
base address, which is downloaded into the devices' firmware. The
address is a fifteen (15) bit quantity transmitted as four ASCII
character bytes. The address settings are selected as HEX numerals
starting at 1 (one) up to 7FFF (representing 32,767 possible
addresses). The upper bit is reserved for data routing within the
device.
Data Link Format
The protocol uses a 10 bit character frame. The default
communications setup is: Baud Rate: up to 115 kbaud Start Bits: 1
Data Bits: 8 Stop Bits: 1 Parity: None Data Transport Session
Control
The electrical instrument platform employs a point to is
multi-point communications protocol. The system design assumes one
master controlled as an "external" unit. One master controller can
communicate with multiple recipients.
Data transport sessions begin when the external unit polls a
recipient unit. The polled device responds when its unique address
is detected in the poll message. The response includes the
recipient's address. It is assumed that there is only one external
device to receive the message.
The electrical instrument platform microcontrollers process one
command at a time. If a laptop computer is connected to the field
test port, there is a possibility that commands could arrive on
both the wireless port and the field test port at the same time. In
that case, the processor will handle a message from the first port,
complete the message turn-around before processing a message on a
second port. The ports are scanned sequentially.
Data Interchange Format
Data is transmitted as a comma-delimited, ASCII-encoded HEX string
formatted record. The ASCII string is transmitted as a continuous
string with no extra spaces, carriage returns or form feeds between
characters.
Data Format--General
The data message is defined by the packet format shown in Table 2
below. Each device is permitted to maintain specific information in
each field of its message.
TABLE-US-00003 TABLE 2 Protocol Format Generic Structure # Values:
Bytes Context ASCII HEX Description 1 <STX> Cntl B 0x02 Start
of Message Packet 4 AAAA "1"-"FFFF" 0x31- 16 Bit Device Address
0x46464646 1 delimiter `,` 0x2C ASCII comma field delimiter 1-m
Field 1 Variable length data field 1 delimiter `,` 0x2C ASCII comma
field delimiter 1-m Field 2 Variable length data field 1 delimiter
`,` 0x2C ASCII comma field delimiter 1-m Field n add additional
fields with delimiter 1 delimiter `,` 0x2C ASCII comma field
delimiter 2 CS "00"-"FF" 0x3030- 8 Bit checksum calculation 0x4646
1 <EOT> Cntl D 0x04 End of Text Character Notes: 1. The
checksum is the MOD 256 addition of the characters in the message,
including the first Byte <STX>. 2. The address field contains
the ordinal value of the HEX address. For example, if the unique
address is HEX `1`, the return address field from the IED will
contain the ASCII representation for the HEX value 1, which is "1"
or 0x31.
Message Formats
The electrical instrument platform incorporates several
microcontrollers that communicate with each other. Communications
dialog consists of requests and commands. A request is a message
code that causes the recipient to send a particular data block. A
command is a message that instructs the recipient to carry out a
specific activity. Table 2.6 is a list of the valid message
codes.
Message Routing
Message Addressing
The power supply controller hoard has three ports: The "radio" port
that is normally used for external communications. The radio port
is used by the spread spectrum radios and also the cell-phone
radio. The "Field Test and Maintenance" port is used for external
communications. The field test port allows a laptop computer to be
connected with the electrical instrument platform for field setup
and testing. The field test port can be active at the same time as
the radio port. The inter-processor communications port. This port
connects the power supply controller with the Main Controller.
Message routing is controlled by the power supply and
communications expansion controller. This controller and the main
controller both have the same 16 bit address. When bit 16 of the
address is set, the message is routed to the power supply
controller. When bit 16 is clear, the message is routed to the main
controller.
Message Sequencing
Message transactions are processed sequentially, one message
transaction at a time. When a message arrives at the power supply
controller, whether it is routed to the main controller or to
itself, its complete process shall be completed before a second
message can be processed. Should a second message arrive before the
response has been transmitted for the first message, the second
message shall be held in a wait buffer until the first transaction
has been completed.
TABLE-US-00004 TABLE 3 Valid Message Codes # Values: Bytes Context
ASCII HEX Description 1 <STX> Cntl B 0x02 Start of TNP
Message Packet 4 AAAA "0001"- 0x30303031- 16 Bit Device Address
"FFFF" 0x46464646 1 delimiter `,` 0x2C ASCII comma field delimiter
2 Poll Type "AA" 0x41 0x41 Analog Alarm Configuration Command 2
Poll Type "AC" 0x41 0x43 Analog Configuration Request 2 Poll Type
"AD" 0x41 0x44 Address Configuration Command 2 Poll Type "AH" 0x41
0x48 Analog Historical Data Request 2 Poll Type "AN" 0x41 0x4E
Analog values data request 2 Poll Type "AR" 0x41 0x52 Analog Alarm
Report From Main Controller 2 Poll Type "AS" 0x41 0x53 Autoscaling
Command 2 Poll Type "BC" 0x42 0x43 Battery Charger threshold config
Reg/Com 2 Poll Type "CA" 0x43 0x41 Offset Calibration Command 2
Poll Type "DC" 0x44 0x43 Discretes Configuration Req/Com 2 Poll
Type "DI" 0x44 0x49 Report Discrete Input Status 2 Poll Type "EN"
0x45 0x4E Energy Data Request (kW/kVar) 2 Poll Type "FT" 0x46 0x54
Send FFT Coefficients 2 Poll Type "GP" 0x47 0x50 Send Power Supply
Data Main to Power Board 2 Poll Type "GS" 0x47 0x53 Got Discrete
Alarm Status From Main Controller 2 Poll Type "HD" 0x48 0x44 Erase
Historical Data Command 2 Poll Type "LO" 0x4C 0x4F Start Loader
Command 2 Poll Type "MA" 0x4D 0x41 Metering Alarm Configuration
Command 2 Poll Type "MC" 0x4D 0x43 Metering Configuration Req/Com 2
Poll Type "MH" 0x4D 0x48 Meter historical Data Request 2 Poll Type
"MS" 0x4D 0x53 Meter Analog Alarm Status from Main Controller 2
Poll Type "OL" 0x4F 0x47 Communications On Line Status Report 2
Poll Type "PC" 0x50 0x43 Serial Port Configuration Req/Com 2 Poll
Type "RS" 0x52 0x53 Reset all Accumulated(s) kWhr etc 2 Poll Type
"SA" 0x53 0x41 Save Configuration Command 2 Poll Type "SC" 0x53
0x43 Site Specific Configuration Req/Com 2 Poll Type "SN" 0x53 0x4E
Unit Serial Number Request 2 Poll Type "SP" 0x53 0x50 Send Power
Supply Data Power Board to Main 2 Poll Type "TS" 0x54 0x53 Time
Sync 2 Poll Type "WA" 0x57 0x41 Send Amp Waveform 2 Poll Type "WC"
0x57 0x43 Waveforms Configuration Req/Com 2 Poll Type "WV" 0x57
0x56 Send Voltage Waveform 1-m Opt. flds. additional fields with
delimiters before and after 2 Chcksum "00"-"FF" 0x3030- 8 Bit
checksum calculation 0x4646 1 <EOT> Cntl D 0x04 End of Text
Character
Outgoing messages are always routed through the same port that they
are entered through. This means that when a "radio" port message is
received by the power supply controller, the response is sent out
of the same port. When a message is received on the field test and
maintenance port, the response is routed out of that port. When a
message arrives on the radio port at the same time that a message
is being processed via the field test and maintenance port, the
radio port message is held in the waiting buffer until the
currently processing message transaction is completed.
Error Handling
If a received message is corrupted, the recipient should reject the
data string as not conforming to specifications. This may occur for
one of two reasons: 1. Two devices have been provided with the same
address; Corrective Action: Change one of the devices address. 2.
The poll message originating with the ground station was corrupted
after reception by the first device; Corrective Action: Retry the
poll message. Specific Message Formats Data Message Description
The electrical instrument platform message, in addition to its 16
bit device address, provides the following data in its message
packet response to the unique address poll:
AN--Analog Data Request
The Analog Data Request can be initiated by any microcontroller in
the system. The recipient decodes the message, and responds with a
valid data block. poll.fwdarw.<STX>address, AN, {start
channel}, {end channel}, CS<ETX> valid channels are 0 to 26
(for a list of the channel assignments see io_chan.h) start channel
must be less than end channel if the start channel field is empty,
the start channel will be the first analog input channel, channel 0
if the end channel field is empty, the end channel will be the last
analog input channel, channel 25
response.fwdarw.<STX>address, AN, start channel, end channel,
first requested channel value, . . . , last requested channel
value, CS<ETX> values are floating point any channels not
enabled in the configuration are empty ME--Metering Data
Request
The Metering Data Request can be initiated by any microcontroller
in the system. The recipient decodes the message, and responds with
a valid data block. poll.fwdarw.<STX>address, ME,
CS<ETX> response.fwdarw.<STX>address, ME, voltage,
current, watts, vars, phase angle, CS<ETX> EN--Energy Data
request
The Energy Data Request can be initiated by any microcontroller in
the system. The recipient decodes the message, and responds with a
valid data block. poll.fwdarw.<STX>address, EN, CS<ETX>
response.fwdarw.<STX>address, EN, Whr in, V Arhr in, Whr out,
V Arhr out, CS<ETX> any channels not enabled are empty
DI--Digital Data Request
The Discrete Input Data Request can be initiated by any
microcontroller in the system. The Recipient decodes the message,
and responds with a valid data block.
poll.fwdarw.<STX>address, DI, {start channel}, {end channel},
CS<ETX> valid channel numbers are 0 to 27 (0 to 26 are actual
digital inputs; 27 is the battery charger error status) start
channel must be less than end channel if start channel is empty,
then the start channel is 0 if end channel is empty, then the end
channel is 27 response.fwdarw.<STX>address, DI, first
requested channel value, . . . , last requested channel value,
CS<ETX> values are 0 or 1 channels that are not enabled in
the configuration are empty TS--Time Synch Command
The Time Sync Command can be initiated by any microcontroller in
the system. The recipient resets its real time clock using the data
in the message, and responds with an ACK (acknowledged) or NAK (not
acknowledged). poll.fwdarw.<STX>address, TS, year, month,
day, hour, minute, second, millisecond, CS<ETX> the year is 2
digit response.fwdarw.ACK or NAK RS--Reset Accumulators Command
The Reset Accumulators Command can be initiated by any
microcontroller in the system. The Recipient resets its energy
accumulators, and responds with an ACK or NAK.
poll.fwdarw.<STX>address, RS, CS<STX>
response.fwdarw.ACK or NAK FT--FFT Coefficients Request not
programmed WV--Voltage Waveform Request not programmed WA--Current
Waveform Request not programmed AH--Historical Data Request
The Analog History Data Request can be initiated by any
microcontroller in the system. The recipient responds with the data
block requested. poll.fwdarw.<STX>address, AH, channel,
number of values, start year, start month, start day, start hour,
start minute, CS<ETX> valid channel numbers are 0 to 26;
requests X number of values starting at (and including) the start
time and going back in time (reverse chronological order); e.g.,
<STX>address, AH, 0, 3, 4, 4, E, 2, 2D, CS<ETX>will
return (with a logging interval of 15 minutes) the three values for
channel 0 for Apr. 14, 2004 at 2:45, 2:30 and 2:15 in that order;
the time is optional (all or nothing--all time fields fill in or
none of them)--if empty, the start time is the time of the most
recent logged value for the channel; maximum number of values
returned is 50 (it accepts requests for more but will only return
50). response.fwdarw.<STX>address, AH, channel, logging
interval, number of values, start year, start month, start day,
start hour, start minute, most recent value, . . . , least recent
value, CS<ETX> maximum of 50 values in the response,
regardless of the number requested; the number of values may be
less than the number requested if the number of values requested is
less than the number of values available (e.g. asking for older
data than is stored in the device). MH--Metering Historical Data
Request
The Metering History Data Request can be initiated by any
microcontroller in the system. The recipient responds with the data
block requested.
poll.fwdarw.<STX>address, MH, channel, number of values,
start year, start month, start day, start hour, start minute,
CS<ETX>
channels are: voltage=0, current=1, watts=2, vars=3, phase angle=4.
response.fwdarw.<STX>address, MH, channel, logging interval,
number of values, start year, start month, start day, start hour,
start minute, CS<ETX> HD--Delete Historical Data Command
The Delete Historical Data Command can be initiated by any
microcontroller in the system. The recipient responds with and ACK
for success or NAK for failure to carry out the command. The main
controller deletes the specified historical data.
poll.fwdarw.<STX>address, HD, CS<ETX>
response.fwdarw.ACK if ok SN--Serial Number Request
The Serial Number Request can be initiated by any microcontroller
in the system. The recipient responds with the data block
requested. poll.fwdarw.<STX>address, SN, CS<ETX>
response.fwdarw.<STX>address, SN, serial number,
CS<ETX> AD--Address Configuration Command
The Address Configuration Command can be initiated by any
microcontroller in the system. The recipient responds with and ACK
for Success or NAK for failure to carry out the command. Both the
main controller and the power supply controller change their
communications address in response to this command.
poll.fwdarw.<STX>address, AD, new address, CS<ETX>
response.fwdarw.ACK note that the address in the ACK message is the
old address. AC--Analog Configuration Request
The Analog Configuration Request can be initiated by any
microcontroller in the system. The recipient responds with the data
block requested. request.fwdarw.analog configuration
poll.fwdarw.<STX>address, AC, channel, CS<ETX> channel
is 0 to 26. response.fwdarw.<STX>address, AC, channel,
logging interval, channel enabled, multiplier, offset, upper bound
engineering, lower bound engineering, CS<ETX> channel enabled
value is 0 for not enabled, 1 for enabled; logging interval is
integer, all conversion fields are floating point; conversion
fields may be empty, for example, if the conversion uses a
multiplier and offset then upper and lower bound fields will be
empty and if the conversion uses upper and lower bounds, the
multiplier and offset fields will be empty; if all conversion
fields are empty it assumes a multiplier of 1 and an offset of 0
(no upper and lower bounds); logging intervals are in minutes. A 0
in this field or an empty field means that the channel is not
logged; valid logging intervals are 1, 5, 10, 15, 30 and 60
minutes. AC--Set Analog Configuration Command
The Analog Configuration Command can be initiated by any
microcontroller in the system. The recipient accepts the input data
block to replace the current configuration information.
poll.fwdarw.<STX>address, AC, channel, logging interval,
channel enabled, multiplier, offset, upper bound engineering, lower
bound engineering, CS<ETX> response.fwdarw.ACK or NAK
MC--Metering Configuration Request
The Metering Configuration Request can be initiated by any
microcontroller in the system. The recipient responds with the data
block requested. request.fwdarw.metering configuration
poll.fwdarw.<STX>address, MC, CS<ETX>
response.fwdarw.<STX>address, MC, volts logging interval,
volts multiplier, volts offset, volts upper bound engineering,
volts lower bound engineering, current logging interval, current
multiplier, current offset, current upper bound engineering,
current lower bound engineering, watts logging interval, watts
multiplier, watts offset, watts upper bound engineering, watts
lower bound engineering, vars logging interval, vars multiplier,
vars offset, vars upper bound engineering, vars lower bound
engineering, phase angle logging interval, voltage gain, current
gain, fall scale input, line frequency, phase angle error,
CS<ETX> voltage gain, current gain, full scale input and line
frequency are integers, everything else is the same as in the
analog configuration message. MC--Set Metering Configuration
Command
The Metering Configuration Command can be initiated by any
microcontroller in the system. The recipient accepts the input data
block to replace the current configuration information.
poll.fwdarw.<STX>address, MC, volts logging interval, volts
multiplier, volts offset, volts upper bound engineering, volts
lower bound engineering, current logging interval, current
multiplier, current offset, current upper bound engineering,
current lower bound engineering, watts logging interval, watts
multiplier, watts offset, watts upper bound engineering, watts
lower bound engineering, vars logging interval, vars multiplier,
vars offset, vars upper bound engineering, vars lower bound
engineering, phase angle logging interval, voltage gain, current
gain, full scale input, line frequency, phase angle error,
CS<ETX> response.fwdarw.ACK or NAK EC--Energy Configuration
Request
The Energy Configuration Request can be initiated by any
microcontroller in the system. The recipient responds with the data
block requested. request.fwdarw.energy configuration
poll.fwdarw.<STX>address, EC, CS<ETX>
response.fwdarw.<STX>address, EC, logging interval, Whr in
enabled, V Arhr in enabled, Whr out enabled, V Arhr out enabled,
reset time year, reset time month, reset time day, reset time hour,
reset time minute, reset time second, CS<ETX> 0 for not
enabled, 1 for enabled; logging interval is for future use; reset
time is for all accumulated values and is defined by filling in the
appropriate fields; filling in month, day, hour, minute and second
will cause accumulators to reset yearly on the given day and time;
filling in day, hour, minute, second will cause accumulators to
reset monthly on the given day and time; filling in hour, minute,
second will cause accumulators to reset daily at the given time;
filling in all of the time fields, including the year, will cause
it to reset only once. EC--Set Energy Configuration
The Set Energy Configuration Command can be initiated by any
microcontroller in the system, The recipient accepts the input data
block to replace the current configuration information.
poll.fwdarw.<STX>address, EC, logging interval, Whr in
enabled, V Arhr in enabled, Whr out enabled, V Arhr out enabled,
reset time year, reset time month, reset time day, reset time hour,
reset time minute, reset time second, CS<ETX>
response.fwdarw.ACK or NAK DC--Configuration Request
The Digital Configuration Request can be initiated by any
microcontroller in the system. The recipient responds with the data
block requested. request.fwdarw.digital configuration
poll.fwdarw.<STX>address, DC, CS<ETX>
response.fwdarw.<STX>address, DC, channel 0 logged, channel 1
logged, . . . channel 27 logged, CS<ETX> 0 for not logged, 1
for logged. DC--Set Digital Configuration
The Set Digital Configuration Command can be initiated by any
microcontroller in the system. The recipient accepts the input data
block to replace the current configuration information.
poll.fwdarw.<STX>address, DC, channel 0 logged, channel 1
logged, . . . , channel 27 logged, CS<ETX>
response.fwdarw.ACK or NAK WC--Waveform Capture Configuration
Request not programmed WC--Waveform Capture Configuration Command
not programmed PC--Serial Port Configuration Request
The Serial Port Configuration Request (for the extra port, not the
radio port) can be initiated by any microcontroller in the system.
The recipient responds with the data block requested.
request.fwdarw.serial port configuration
poll.fwdarw.<STX>address, PC, port, CS<ETX>
response.fwdarw.<STX>address, PC, port, baud rate, parity,
data bits, stop bits, CS<ETX> port is always 1; if the port
is not in use then all of the setup fields are empty; parity is 0
for even, 1 for odd and 2 for none; data bits are 7 or 8; stop bits
are 1 or 2. PC--Set Serial Port Configuration
The Set Serial Port Configuration Command can be initiated by any
microcontroller in the system. The recipient accepts the input data
block to replace the current configuration information.
poll.fwdarw.<STX>address, PC, port, baud rate, parity, data
bits, stop bits, CS<ETX> response.fwdarw.ACK or NAK SC--Site
Specific Configuration Request
The Site Specific Configuration Request can be initiated by any
microcontroller in the system. The recipient responds with the data
block requested. request.fwdarw.site specific configuration
poll.fwdarw.<STX>address, SC, CS<ETX>
response.fwdarw.<STX>address, SC, voltage multiplier, phase
angle offset, CS<ETX> floating point engineering values.
SC--Set Site Specific Configuration
The Set Site Specific Configuration Command can be initiated by any
microcontroller in the system. The recipient accepts the input data
block to replace the current configuration information.
poll.fwdarw.<STX>address, SC, voltage multiplier, phase angle
offset, CS<ETX> response.fwdarw.ACK or NAK BC--Battery
Charger Threshold Configuration Request
The Battery Charger Threshold Configuration Request can be
initiated by any microcontroller in the system. The recipient
responds with the data block requested. request.fwdarw.battery
changer configuration poll.fwdarw.<STX>address, BC,
CS<ETX> response.fwdarw.<STX>address, BC, battery
changer threshold, CS<ETX> floating point engineering value.
BC--Set Battery Charger Configuration
The Set Battery Charger Configuration Command can be initiated by
any microcontroller in the system. The recipient accepts the input
data block to replace the current configuration information.
poll.fwdarw.<STX>address, BC, battery changer threshold,
CS<ETX> response.fwdarw.ACK or NAK CA--Offset Calibration
Command
The Set Offset Calibration Configuration Command can be initiated
by any microcontroller in the system. The recipient accepts the
input data block to replace the current configuration information.
poll.fwdarw.<STX>address, CA, CS<ETX> perform a
calibration. response.fwdarw.ACK or NAK or,
poll.fwdarw.<STX>address, CA, 0, CS<ETX> reset voltage
and current offsets to 0. response.fwdarw.ACK or NAK LO--Start
Loader Command
The Start Loader Command can be initiated by any microcontroller in
the system. The recipient accepts the input data block to replace
the current configuration information.
poll.fwdarw.<STX>address, LO, CS<ETX>
response.fwdarw.sends an ACK then starts the loader SA--Save
Configuration Command
The Save Configuration Command can be initiated by any
microcontroller in the system. The recipient accepts the input data
block to replace the current configuration information.
poll.fwdarw.<STX>address, SA, CS<ETX> saves the
configuration to EEPROM. response.fwdarw.ACK or NAK AS--Autoscaling
Configuration Command
The Autoscaling Configuration Command can be initiated by any
microcontroller in the system. The recipient accepts the input data
block to replace the current configuration information.
poll.fwdarw.<STX>address, AS, volts engineering, current
engineering, CS<ETX> performs autoscaling.
response.fwdarw.ACK or NAK SP--Send Power Supply Data Command
The Send Power Supply Data request is initiated by the power supply
controller and is sent to the main controller.
poll.fwdarw.<STX>address, SP, power supply voltage, power
supply temperature, shunt voltage, CS<ETX> from power supply
to main controller; response.fwdarw.<STX>address, SP,
CS<ETX> from main controller to power supply; all values are
16 bit integer "raw" readings. GP--Get Power Supply Data
Command
Receives Power Supply data from the main controller (for
verification). Command: "GP" Data: None Response: "GP" Data: Power
supply voltage (16-bit raw reading) Power supply temperature
(16-bit raw reading) Shunt voltage (16-bit raw reading) GS--Get
Main Controller Status Request
Returns alarm and other status information from the main
controller. The power supply controller polls the Main controller,
which returns the data to the power supply:
poll.fwdarw.<STX>address, GS, CS<ETX>--from power
supply to main controller response.fwdarw.<STX>address, GS,
X, CS<ETX> where X is 0 for no alarms, 1 if there is an
alarm. The power supply needs only the presence or absence of
alarms--"call home" or don't call home. OL--Line Status Report
The power supply needs to send a message to the main controller
when it connects to the ground station.
poll.fwdarw.<STX>address, OL, CS<ETX>--from power
supply to ground station response.fwdarw.the ACK message AA--Analog
Alarm Configuration Command
The Analog Alarm Configuration Command is sent from an external
processor to provide alarm set up parameters to the main
controller. poll.fwdarw.<STX>address, AA, channel, low alarm
level, high alarm level 1, high alarm level 2, high alarm level 3,
alarm dead-band, CS<ETX> response.fwdarw.ACK message
MA--Metering Alarm Configuration Command
The Metering Alarm Configuration Command is sent from an external
processor to provide alarm set up parameters to the main
controller. poll.fwdarw.<STX>address, MA, channel, low alarm
level, high alarm level 1, high alarm level 2, high alarm level 3,
alarm dead-band, CS<ETX> response.fwdarw.ACK message
AR--Alarm Report Status
The Analog Alarm Report Status is sent in response to a poll from
the power supply controller. poll.fwdarw.<STX>address, AR,
CS<ETX> response.fwdarw.<STX>address, AR, first channel
alarm type, first channel alarm value, . . . , last channel alarm
type, last channel alarm value, CS<ETX> where the "alarm
type" is 1 for low, 2 for high alarm level 1, 3 for high alarm
level 2, 4 for high alarm level 3 and "alarm value" is the value
that caused the alarm. MS--Analog Alarm Status
The Metering Alarm Status report is sent in response to a poll from
the power supply controller. Metering alarms need not be polled as
often as analog alarms. poll.fwdarw.<STX>address, MS,
CS<ETX> response.fwdarw.<STX>address, MS, first channel
alarm type, first channel alarm value, . . . , last channel alarm
type, last channel alarm value, CS<ETX> where the "alarm
type" is 1 for low, 2 for high alarm level 1, 3 for high alarm
level 2, 4 for high alarm level 3 and "alarm value" is the value
that caused the alarm.
It will thus be seen that the objects set forth above, among those
made apparent from the preceding description, are efficiently
attained and, because certain changes may be made in carrying out
the above method and in the construction(s) set forth without
departing from the spirit and scope of the invention, it is
intended that all matter contained in the above description and
shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described and all statements of the scope of the invention
which, as a matter of language, might be said to fall there
between.
* * * * *