U.S. patent application number 15/818479 was filed with the patent office on 2018-03-15 for autonomous tie breaker.
The applicant listed for this patent is Aspin Kemp & Associeates Holding Corp., Transocean Sedco Forex Ventures Limited. Invention is credited to Jason Aspin, Edward Peter Kenneth Bourgeau.
Application Number | 20180076615 15/818479 |
Document ID | / |
Family ID | 51526080 |
Filed Date | 2018-03-15 |
United States Patent
Application |
20180076615 |
Kind Code |
A1 |
Bourgeau; Edward Peter Kenneth ;
et al. |
March 15, 2018 |
Autonomous Tie Breaker
Abstract
An autonomous breaker can apply a current through a high
impedance source to a bus coupled to either end of a breaker in
order to measure an impedance of the bus. The status of the bus can
be determined from the measurement. Based on the determined status,
a fault detection procedure can be selected and implemented to
determine if a fault exists on the bus. When the fault detection
procedure has been implemented and no fault has been detected, the
breaker can close, and thus couple the bus to another bus.
Inventors: |
Bourgeau; Edward Peter Kenneth;
(Houston, TX) ; Aspin; Jason; (Charlottetown,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Transocean Sedco Forex Ventures Limited
Aspin Kemp & Associeates Holding Corp. |
George Town Grand Cayman
Owen Sound |
|
KY
CA |
|
|
Family ID: |
51526080 |
Appl. No.: |
15/818479 |
Filed: |
November 20, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14210346 |
Mar 13, 2014 |
9825457 |
|
|
15818479 |
|
|
|
|
61779391 |
Mar 13, 2013 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y04S 10/20 20130101;
H02H 3/04 20130101; H02H 3/05 20130101; H02H 3/06 20130101; H02H
3/162 20130101; H02H 3/00 20130101; H02H 3/066 20130101; H02H 7/22
20130101; H02J 13/0006 20130101; H02H 7/28 20130101; H02H 11/005
20130101; G01R 27/16 20130101 |
International
Class: |
H02H 7/22 20060101
H02H007/22; H02H 3/06 20060101 H02H003/06; H02H 7/28 20060101
H02H007/28 |
Claims
1. A method, comprising: determining, by a breaker coupled between
a first bus and a second bus, that the first bus is over-loaded;
and closing the breaker in response to the determination that the
first bus is over-loaded, thereby coupling the first bus to the
second bus, wherein the second bus is coupled to an AC power
source.
2. The method of claim 1, further comprising: determining, by the
breaker, that the first bus is under-loaded; and opening the
breaker in response to the determination that the first bus is
under-loaded, thereby decoupling the first bus from the second
bus.
3. The method of claim 2, wherein the step of determining, by the
breaker, that the first bus is under-loaded, comprises detecting,
by the breaker, a variation in a frequency of power on the first
bus indicating that the first bus is under-loaded.
4. The method of claim 1, wherein coupling the first bus to the
second bus removes the over-load.
5. The method of claim 1, wherein the step of determining comprises
detecting, by the breaker, a variation in a frequency of power on
the first bus indicating that the first bus is over-loaded.
6. The method of claim 1, further comprising determining that there
is no fault on the first bus prior to coupling the first bus to the
second bus.
7. A method, comprising: determining, by a breaker coupled between
a first bus and a second bus, that the first bus is under-loaded;
and opening the breaker in response to the determination that the
first bus is under-loaded, thereby decoupling the first bus from
the second bus, wherein the second bus is coupled to an AC power
source.
8. The method of claim 7, further comprising: determining, by the
breaker, that the first bus is over-loaded; and closing the
breaker, in response to the determination that the first bus is
over-loaded, thereby coupling the first bus to the second bus.
9. The method of claim 8, further comprising determining, by the
breaker, that there is no fault on the first bus prior to coupling
the first bus to the second bus.
10. The method of claim 8, wherein the step of determining, by the
breaker, that the first bus is over-loaded, comprises detecting, by
the breaker, a variation in a frequency of power on the first bus
indicating that the first bus is over-loaded.
11. The method of claim 7, wherein decoupling the first bus from
the second bus by opening the breaker removes the under-load.
12. The method of claim 7, wherein the step of determining
comprises detecting, by the breaker, a variation in a frequency of
power on the first bus indicating that the first bus is
under-loaded.
13. An apparatus, comprising: a breaker coupled between a first bus
and a second bus; and an AC power source coupled to the second bus;
wherein the breaker comprises a controller configured to: determine
that the first bus is over-loaded; and close in response to the
determination that the first bus is over-loaded, thereby coupling
the first bus to the second bus.
14. The apparatus of claim 13, wherein the controller is further
configured to: determine that the first bus is under-loaded; and
open in response to the determination that the first bus is
under-loaded, thereby decoupling the first bus from the second
bus.
15. The apparatus of claim 14, wherein opening, in response to the
determination that the first bus is under-loaded removes the
under-load from the first bus.
16. The apparatus of claim 13, wherein the controller is further
configured to determine that there is not fault on the first bus
prior to closing in response to the determination that the first
bus is over-loaded.
17. The apparatus of claim 13, in which the breaker is an
autonomous breaker.
18. The apparatus of claim 13, in which the breaker further
comprises a sensor for monitoring a frequency of power on the first
bus.
19. The apparatus of claim 11, wherein determining that the first
bus is over-loaded comprises detecting a variation in a frequency
of power on the first bus with the sensor indicating that the first
bus is over-loaded.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/210,346 to Edward Peter Kenneth Bourgeau
filed Mar. 13, 2014, and entitled "Breaker Design for Power System
Resiliency," which claims the benefit of priority to U.S.
Provisional Patent Application No. 61/779,391 to Edward Peter
Kenneth Bourgeau filed Mar. 13, 2013, and entitled "Breaker Design
for Power System Resiliency," both of which are incorporated by
reference.
TECHNICAL FIELD
[0002] This disclosure is related to power systems. More
specifically, this disclosure is related to a resilient and fault
tolerant breaker for power systems.
BACKGROUND
[0003] Resiliency is an important consideration in any power
system, regardless of the application. The issues to which the
power system must be resilient vary based on the application. For
example, on an offshore drilling vessel, the power system should be
made resilient to flooding, fires, or a fault within an electrical
bus that carries power from generators to electrical devices
throughout the vessel.
[0004] An electrical system on a vessel conventionally includes
multiple generators in compartmentalized units that are separated
against fire and flood. The compartmentalized units prevent damage
from fire or flood to one unit from propagating to another
compartmentalized unit. However, control systems for the power
system are not located in the compartmentalized units. Further, the
control system relies on information from each of the generators in
each of the compartmentalized units to control the power system.
For example, a control system can determine whether or not and when
generators can couple to a main power distribution bus. Although
the loss of a generator or a control system may not result in a
loss of all generators or control systems, the generators and their
control systems are unable to function independently and can suffer
reduced performance or be further damaged due to incorrect
decisions made by a control system.
[0005] A breaker couples a generator to a power bus and can break
the connection between the power bus and the generator based on
commands from a control system. Each breaker is linked by signal
cables to other breakers, and the status of each breaker is
included in the logic of the control section of the breakers.
Consequently, damage to a breaker in one compartment creates
erroneous behavior in a breaker in another compartment. Thus, the
overall resiliency of the power system is reduced. Each breaker may
include logic that controls the breaker either in the same cabinet
or external to the cabinet.
[0006] FIG. 1 is a schematic representation of a conventional
method for using breakers 112, 114, 116 within a power system 100,
such as in offshore drilling vessels. The breakers 112, 114, 116
are coupled between a main electrical bus 102 and generators 122,
124, 126, respectively. Barriers 150 may be placed between the
generators 122, 124, and 126 to isolate operation of the generators
122, 124, and 126 should a fire, flood, or other catastrophe occur.
Communication links 113, 115 couple the breakers 112, 114, 116 to
each other. The breakers 112, 114, 116 also share a control power
cable 199 used to provide power to the breakers 112, 114, 116. The
main bus 102 can be connected as a single conductor or broken into
multiple segments by tie breaker master/slave sets 151, 152 and
153, 154. Communication links 156, 157 couple the tie breaker sets
151, 152 and 153, 154, respectively, to each other. The tie breaker
master/slave sets 151, 152 and 153, 154 also share a control power
cable 199 used to provide power to the tie breaker master/slave
sets 151, 152 and 153, 154.
[0007] The generator breakers 112, 114, 116 communicate the status
of the generators 122, 124, and 126 over the communication links
113 115, 131. Logic within each of the breakers 112, 114, 116 is
dependent upon the behavior of each of the other breakers 112, 114,
116. For example, if the breaker 112 is instructed to perform
synchronization with the main bus 102, then the breaker 112 must
first indicate to the breaker 114 not to perform synchronization,
or vice versa. If breaker 114 indicates it is performing a
synchronization, no other breaker can perform a synchronization
even if such indication is faulty. Therefore, if a communication
link 131, 132, 133 between the management system 130 and the
generator breakers 112, 114, 116 fails or if the any breaker 112,
114, 116 itself fails, then access to the other healthy breakers is
interrupted.
[0008] Additional communications links may be provided between the
management system 130 and the breakers 112, 114, 116, respectively.
However, the additional communications links increase complexity of
the system 100 and the number of connections that must be made
between barriers 150. Decisions to open and/or close the breakers
112, 114, and 116 may be made by the management system 130 based on
input from a bus sensing units 140, 143, 144 coupled to the main
bus 102. Communication is required between bus sensing units 140,
143, 144 and the management system 130 and between generator
breakers 112, 114, and 116. Communication is required between bus
sensing units 140, 143 and the tie breakers 151, 152 and
communication is required between bus sensing units 143, 144 and
the tie breakers 153, 154. These communications links increase
complexity of the system 100 and the number of connections that
must be made between barriers 150. Successful operation of the tie
breakers sets 151, 152 and 153, 154 require communications between
the tie breaker master 151 and its slave 152 and between the tie
breaker master 153 and its slave 154. These communications links
increase complexity of the system 100 and the number of connections
that must be made between barriers 150. Furthermore, an operator
using a management system 130 can communicate only to the master
breaker 151 or 153 of the tie breaker sets 151, 152 and 153, 154.
Therefore, if a communication link 134, 135 between the management
system 130 and the master breaker 151 or 153, respectively, fails
or if the master breaker 112 itself fails, then access to the other
breaker 152, 154 is interrupted.
[0009] Two issues arise from the network of interconnected breakers
110 that can affect the resiliency of the power system 100. First,
the breaker 112, 113, 114, 151, 152, 153, 154 can close onto the
bus 102 when the bus 102 is unsuitable for receiving additional
power from the generator 122, 124, 126 such as when there is a
fault on bus 102, such as a ground or a short circuit or a fault
caused by the incorrect connection of a faulty generator. Second,
the network of interconnected breakers 110 lacks autonomy of
operation, because the breakers 112, 113, 114, 151, 152, 153, 154
are reliant on data from each other to control the supply of power
to the bus 102.
[0010] One conventional solution to improving resiliency is the use
of barriers 150. The consequences of a fire or flood are limited by
use of barriers 150. However, the fire or flood in a specific
compartment will disturb the signals that cross the barrier 150.
This can cause erroneous data to be passed to the compartments
protected by barrier 150. The consequences erroneous data can
disable or otherwise compromise the operation of the equipment in a
compartment that has not been damaged by a fire or flood.
BRIEF SUMMARY
[0011] Reducing the reliance of a breaker on input from other
breakers can improve the resiliency of a power system. For example,
each breaker can independently execute a method for determining
when a breaker is safe to close. Providing each breaker with the
capability to independently execute such a method can reduce or
eliminate reliance of each breaker on other breakers. The improved
resiliency of a power system employing the autonomous breakers may
result from a lower likelihood that one breaker operating
erroneously can cause all breakers to operate erroneously. Thus, a
power system can continue to operate normally even though one
breaker may become inoperable.
[0012] According to one embodiment, a method for determining when
to close a breaker includes applying a current to a first bus
coupled to a breaker. The method may also include measuring a first
impedance of the first bus after applying the first current to the
first bus in order to determine if a fault exists on the first bus.
If no fault is determined to exist on the first bus, the method may
further include coupling the first bus to a second bus coupled to
the breaker.
[0013] The method can include applying the current to the first bus
through a potential transformer. The method can be initiated by
receiving a command, at a controller, to close the breaker.
Furthermore, the method can include checking the status of the
first bus and instructing, by a controller, a contactor coupled to
a sensor to either close or open. The sensor can be a voltage
sensor, a current sensor, or both a voltage and current sensor.
[0014] According to an embodiment, the method can also include
determining a fault detection procedure to implement based, in
part, on the measured first impedance of the first bus. The method
can also include processing the measured first impedance of the
first bus in order to determine the status of the bus. Instructions
within a controller can be executed to select the fault detection
procedure to implement based, in part, on the determined status of
the first bus.
[0015] The method can include instructing, by a controller, a
contactor coupled to the sensor to close or open when implementing
the selected fault detection procedure. A second current can be
applied to the first bus in order to measure a second impedance of
the first bus. The second measured impedance can be processed by a
controller to determine whether a fault exists on the first
bus.
[0016] According to an embodiment, the measuring of the impedance
of a bus can be performed by measuring a voltage, a current, or
both a voltage and a current of the bus. Furthermore, the coupling
of the first bus to at least a second bus can be performed by first
synchronizing the first bus to a second bus, and then closing the
breaker between the first and the second bus. Moreover, the
coupling of the first bus to the second bus can result in the
coupling of a generator to a load on a drilling vessel.
[0017] According to another embodiment, an apparatus includes a
breaker coupled between a first and a second bus. The apparatus
also includes a controller coupled to the breaker that allows the
apparatus to operate autonomously. The controller can be configured
to apply the first current to the first bus coupled to the breaker.
The controller can also be configured to measure a first impedance
of the first bus, and to determine if a fault exists on the first
bus. The apparatus can also include at least one potential
transformer coupled to the controller and the first bus and at
least one other potential transformer coupled to the controller and
the second bus.
[0018] The apparatus can also include devices that protect, such as
a protection circuit coupled to the breaker and an external
protection system, or devices that control the internal components
of the breaker, such as an operator interface. The apparatus can
also include a device for performing measurements on the breaker,
such as a universal measuring transducer, coupled to the controller
and to an external bus. Furthermore, the apparatus can include
synchronization circuitry, such as a synchronizer coupled to an
external power source. Other synchronization circuitry can include
a sync check relay coupled to the operator interface and to an
external power source control circuit. The protection circuit,
universal measuring transducer, synchronizer, sync check relay,
and/or the controller can be part of a control circuit within the
apparatus.
[0019] According to an embodiment, the controller can be further
configured to control the apparatus autonomously and to manage
control commands. The controller can also be configured to monitor
and control the status of switchgear, and to determine the status
of the breaker. Moreover, the controller can be configured to
control the process by which potential transformers are coupled,
and to monitor voltage and current existing on a bridge between
potential transformers.
[0020] According to an embodiment, the controller can be further
configured to autonomously detect the status of the bus and
determine based on bus status only the requirement to connect or
remove generators from the bus without participation from a central
control system. Bus status, in addition to faults such as grounding
or short circuit, would include such conditions as an overload
under-load, of either real or reactive power. The apparatus may
operate autonomously and to manage control commands to open and/or
close a breaker. Based on bus status, the controller can also be
configured to monitor and control the status of switchgear, and to
determine the status and control the breaker.
[0021] The foregoing has outlined rather broadly the features and
technical advantages of the present disclosure in order that the
detailed description of the disclosure that follows may be better
understood. Additional features and advantages of the disclosure
will be described hereinafter which form the subject of the claims
of the disclosure. It should be appreciated by those skilled in the
art that the conception and specific embodiment disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present
disclosure. It should also be realized by those skilled in the art
that such equivalent constructions do not depart from the spirit
and scope of the disclosure as set forth in the appended claims.
The novel features which are believed to be characteristic of the
disclosure, both as to its organization and method of operation,
together with further objects and advantages will be better
understood from the following description when considered in
connection with the accompanying figures. It is to be expressly
understood, however, that each of the figures is provided for the
purpose of illustration and description only and is not intended as
a definition of the limits of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] For a more complete understanding of the disclosed system
and methods, reference is now made to the following descriptions
taken in conjunction with the accompanying drawings.
[0023] FIG. 1 is a schematic representation of a conventional
breaker within a power system common on the current generation of
offshore drilling vessels and standalone power plants.
[0024] FIG. 2A is schematic representation of a power system with
independent breakers according to one embodiment of the
disclosure.
[0025] FIG. 2B is a schematic representation of a power system with
independent breakers according to one embodiment of the
disclosure.
[0026] FIG. 3A is a flow chart illustrating a method for
determining a status of a power bus with an independent breaker
according to one embodiment of the disclosure.
[0027] FIG. 3B is a flow chart illustrating a method for
determining a status of a power bus by scanning multiple
frequencies with an independent breaker according to one embodiment
of the disclosure.
[0028] FIG. 3C is a flow chart illustrating a method for
determining when it is safe to close a breaker according to one
embodiment of the disclosure.
[0029] FIG. 3D shows a flow chart illustrating a method for
determining whether to open or close a breaker according to one
embodiment of the disclosure.
[0030] FIG. 4 is a schematic representation of a breaker with
autonomous behavior according to one embodiment of the
disclosure.
[0031] FIG. 5 is a schematic representation of a breaker with
additional sensors according to one embodiment of the
disclosure.
[0032] FIG. 6 is a schematic representation of an operator
interface according to one embodiment of the disclosure.
[0033] FIG. 7 is a flow chart illustrating an embodiment of a
method for determining when to close a breaker.
DETAILED DESCRIPTION
[0034] Resiliency within a power system can be improved by reducing
reliance of components in one compartment on components in other
compartments. According to one embodiment, reliance can be reduced
by reducing the amount of communication between components. For
example, a breaker can include logic that executes methods with
little or no input from other breakers. This improves the
resiliency of the power system, because each breaker in a
compartment can continue operating while another breaker is
erroneously behaving in another compartment. Furthermore, each
breaker can communicate directly to the management system.
Therefore, the breaker can receive instructions, such as whether to
open or close a breaker, without relying on other breakers to
receive the instructions.
[0035] According to an embodiment, a high energy collision on a
main power distribution bus can be prevented by testing the status
of a bus, such as through the use of high impedance potential
transformers that reduce the energy in a collision on the bus. The
high energy collision can result from different breakers that
couple different unsynchronized generator buses to a main power
distribution bus closing at the same time onto the distribution
bus, which can be dead at the time. A low energy collision can be
generated by the high impedance potential transformer and used to
measure an impedance of the bus, identify the status of the bus,
and to determine whether or not to close a breaker coupled to the
bus. By performing this impedance sensing, and measuring the bus
impedance, such as through transformers prior to closing the
breaker, the breaker can ensure that a collision occurs through the
transformers. This collision through the transformers can avoid a
high energy bus-to-bus collision that could be damaging to the
power system. Thus, the resiliency of the power system is further
enhanced with a high impedance potential transformer.
[0036] FIG. 2A depicts a schematic representation of a power system
200 with breakers 212, 214, 216 according to one embodiment of the
disclosure. The breakers 212, 214, 216 may operate autonomously.
Each of the breakers 212, 214, 216 may be provided power from the
generators 222, 224, 226, respectively, through control power
lines. According to one embodiment, the control power cable can be
a low voltage DC bus.
[0037] In the power system 200, an erroneously operating breaker
may not cause erroneous behavior in another breaker. Each breaker
212, 214, 216 can independently execute a method, using internal
circuitry with little or no information from other breakers 212,
214, 216, to determine whether it is safe to close the breaker 212,
214, 216 and couple the generators 222, 224, 226, respectively, to
the main power bus 202.
[0038] As described herein, "breakers" may include a generator
breaker, such as breakers 212, 214, 216 between the generators 222,
224, 226 and the main power bus 202. "Breakers" may also include a
tie breaker, such as breakers 271, 272, 273, 274 between segments
of the power buses 202. Each of these breakers 271, 272, 273, 274
may be powered by autonomous control power 281, 282, 283, 284,
respectively.
[0039] FIG. 2B is a schematic representation of a power system with
independent breakers according to one embodiment of the disclosure.
The system may include a breaker 232 between a bus 252A and a main
power bus 202. The breaker 232 may be controlled by autonomous tie
control 264A, which may include bus impedance sensing circuitry and
synchronizing circuitry. The control 264A may be integrated with
the breaker 232 or operate as a separate component. The control
264A controls the breaker 232 to check a status of the health of
the main power bus 202 before coupling the bus 252A to the main
power bus 202. Current for testing the health of the main power bus
202 may be received through a bus point transformer 262A to a tie
point transformer 266A.
[0040] A similar configuration may exist for the breaker 234
through autonomous tie control 264B coupled to bus point
transformer 262B and tie point transformer 266B. In one embodiment,
a vessel management system 256 may be used to instruct the breakers
232 and/or 234 to close to provide additional power to the main
power bus 202, such as when additional power is desired. After the
vessel management system 256 instructs the breakers 232 and/or 234
to close, the autonomous tie control 264 operates to determine a
status of the main bus 202 and to decide whether to close the
breakers 232, 234. In one embodiment, tie breakers 232, 234 may be
used to couple a starboard bus and a port bus on a ship, such as a
drilling rig.
[0041] The autonomous tie control 264 may execute one of the
methods illustrated in FIGS. 3A-C, although other methods may also
be executed by control 264. FIG. 3A is a flow chart illustrating a
method for determining a status of a power bus with an independent
breaker according to one embodiment of the disclosure. A method 350
begins at block 352 with applying a first current to a first bus.
Then, at block 354 an impedance of the first bus is measured with
the first current. At block 356, a status of the first bus may be
determined based, at least in part, on the measured impedance of
block 354. If the status is determined to be faulty at block 358
then the method 350 proceeds to block 362 to report a fault on the
first bus. The breaker may not be closed when a fault is detected.
If the status is determined to be not faulty at block 358 then the
method 350 proceeds to block 360 with closing the breaker between
the first bus and the second bus.
[0042] The first current applied to the first bus may be received
from second bus. The first current may also be manipulated before
being applied to the first bus. For example, the current may be
passed through a variable drive device to adjust a voltage and/or a
frequency of the first current. The first bus may be tested through
measurements of impedance across a range of voltages and/or
frequencies to improve determination of the status of the first
bus. FIG. 3B is a flow chart illustrating a method for determining
a status of a power bus by scanning multiple frequencies with an
independent breaker according to one embodiment of the disclosure.
A method 370 begins at block 372 with applying a first current at a
first frequency to a first bus. At block 374, a first impedance of
the first bus is measured at the first frequency. At block 376, a
second current is applied at a second frequency to the first bus.
At block 378 a second impedance of the first bus is measured at the
second frequency. Then, at block 380 a status of the first bus may
be determined based, at least in part, on the measured first and
second impedances of blocks 374 and 378. At block 382, a breaker
between the first bus and the second bus may be closed when the
status of the first bus is healthy.
[0043] FIG. 3C shows a flow chart illustrating a method 300 for
determining when it is safe to close a breaker according to one
embodiment. The method 300 begins at block 302 with a breaker
receiving a command, at a controller, to close a breaker. In one
embodiment, the close command can be a digital signal generated
when a momentary dry contact is made in an offshore drilling
vessel's management system to signal the breaker to initiate a
close sequence. Excitation to the dry contact can be provided by
the breaker. The excitation can be a pulsed output from the vessel
management system to the breaker. The signal received can originate
locally, such as within the breaker of FIG. 2. The signal can also
originate remotely, such as at a management system external to the
breaker, and be transmitted to the breaker via a communication link
between the management system and the breaker. The signal received
can be generated either automatically within the breaker or the
management system, or the signal can be generated manually by an
operator of the breaker. In one embodiment, the close signal can be
generated when there is a need for more power on the bus. The
status of a bus, or multiple buses, coupled to the breaker can be
checked at blocks 304, 306, 308, and 310 after receiving a command
to close the breaker at block 302.
[0044] At block 304, a first current can be applied through a first
high impedance transformer to a first bus coupled to a breaker. In
certain embodiments, two currents can be applied through two high
impedance transformers to two buses coupled to the breaker. The
number of currents that can be applied by a breaker to buses
coupled to a specific breaker is not limited to one or two buses.
For example, four currents can be applied through four high
impedance transformers to four buses coupled to the breaker.
[0045] Although a high impedance transformer is described above,
currents can be applied by the breaker to multiple buses through
devices other than high impedance transformers. For example,
currents can be applied to the buses through networks of
capacitors, inductors, or combination of capacitors and inductors.
These networks can be configured as matching networks that perform
similar to a transformer by converting voltage and/or current from
one port to another port depending on the configuration of the
capacitors, inductors, or combination of capacitors and inductors.
As another example, currents can be applied to the buses through
transmission lines that present a high impedance to the buses.
[0046] At block 306, the impedance of the first bus can be measured
after applying the first current by measuring a voltage and/or a
current. A universal measuring transducer can perform the
measurement at block 306. The impedance of a plurality of buses to
which currents have been applied can also be measured with one or
more devices that can measure the voltage and/or current of a
bus.
[0047] At block 308, the first bus impedance can be processed to
determine the status of the first bus. The status of the first bus
can be represented by a Boolean indicator indicating whether the
bus is dead or alive. In an embodiment, a controller can be used to
perform the processing disclosed at block 308. In determining
whether a bus is dead or alive, a bus may be considered dead if no
signal exists on the bus, and the bus may be considered alive if a
signal exists on the bus. The impedance of multiple buses can be
processed by one or more controllers to determine the status of
each of the buses.
[0048] At block 310, a fault detection procedure, such as a
collision detection procedure, can be selected based, in part, on
the status of the first bus. The fault detection procedure can
ensure that no high energy collision occurs on the bus when the
breaker closes. In an embodiment with two buses coupled to the
breaker, there can be three distinct fault detection procedures. A
first fault detection procedure can be executed when both buses are
dead. A second fault detection procedure can be executed when both
buses are live. A third fault detection procedure can be executed
when one bus is dead and one bus is live. The number of fault
detection procedures available can vary by application.
[0049] The implementation of a selected fault detection procedure
can begin at block 312, when a contactor coupled to a sensor is
instructed to close or open. In an embodiment, the contactor can
also be coupled to either current sensors, voltage sensors, or both
current and voltage sensors to allow for the measuring of voltage
and/or current of a bus.
[0050] As one example with two buses coupled to a breaker, if the
determined status of a first and second bus coupled to a breaker is
that both buses are dead, then the contactor coupled to the first
bus can be instructed to close while the contactor coupled to the
second bus can be instructed to open. As another example with two
buses coupled to a breaker, if the determined status of a first and
second bus coupled to a breaker is that both buses are live, then
the contactor coupled to the first bus and the contactor coupled to
the second bus can both be instructed to open. In general, separate
fault detection procedures can be selected depending on whether
both buses are dead, both are live, or one bus is live and one bus
is dead.
[0051] At block 314, a second current can be applied through the
first high impedance transformer to the first bus. As described at
block 304, several currents can be applied through several high
impedance transformers.
[0052] At block 316, a voltage and/or current measurement can be
obtained after the second current has been applied. In one
embodiment, a universal measuring transducer can perform the
measurements disclosed at block 316.
[0053] At block 318, it is determined whether a fault exists on the
first bus based, in part, on the second voltage and/or current
measurement. In one embodiment, determining whether a fault was
detected can be performed by the same device, such as a controller,
that determined the status of the bus at block 308. The controller
can also process the measurements to determine whether a fault
exists on the buses, such as rounding or averaging measurements. In
certain embodiments, a fault can occur in the breaker. In such an
embodiment, a digital signal, representing the breaker fault
signal, can be sent to a vessel management system.
[0054] At block 320, the first bus can be synchronized to a second
bus, also coupled to the breaker, if it was determined at block 318
that no fault exists. The synchronization of the buses can be
performed automatically or manually. In performing the
synchronization automatically, a synchronizer, such as a Woodward
SPM-D Synchronizer, can perform synchronization without an operator
manually biasing the generators. In another embodiment, the
synchronization can be performed manually through the use of a sync
check relay, also referred to as a synchroscope, that allows an
operator to manually bias generators coupled to the breaker.
According to one embodiment, the first bus can be synchronized to a
plurality of buses also coupled to the breaker.
[0055] At block 322, the breaker between the first and second buses
can be closed. Thus, the first bus is coupled to the second bus. In
an embodiment, this can comprise coupling a generator to a load on
a drilling vessel. In another embodiment, the first bus can be
coupled to a plurality of buses also coupled to the breaker.
[0056] The method described in FIG. 3C can assume that all other
signals that allow for the closing of a breaker permit the breaker
to close. The breaker may not close if other signals indicate
faults that can prevent the breaker from functioning correctly.
These signals can include a signal indicating that the synchronizer
is powered up and healthy and a signal indicating that a spring
drive motor is charged.
[0057] According to an embodiment, there can exist a plurality of
fault detection procedures that can be implemented to determine
whether a fault exists on a bus as specified at block 310. Each
procedure can perform the actions at blocks 312 through 322 of FIG.
3 in a different order based on the status of the first bus or the
status of a plurality of buses identified at block 310. The order
in which the actions at blocks 312 through 322 of FIG. 3 are
performed can signify the specific fault detection procedure being
implemented. For example, after two separate currents through two
separate high impedance transformers to two buses coupled to the
breaker have been applied, the breaker can determine that both
buses are dead at block 310. In this case, the breaker can begin
the implementation of the selected fault detection procedure at
block 312 by instructing, by a controller, a contactor coupled to
one high impedance transformer to open and instructing, by a
controller, a contactor coupled to the other high impedance
transformer to close. However, if it is determined that both buses
are live, then the breaker can begin the implementation of the
selected fault detection procedure at block 312 with both
contactors coupled to each of the high impedance transformers open.
Hence, the actions in other blocks can be performed in different
order with different instructions based on the determined status of
a bus or a plurality of buses at block 310.
[0058] The breakers may decide autonomously whether to open or
close based on conditions other than whether a bus is faulty. For
example, the breakers may also determine another type of status of
the bus, such as whether the bus is overloaded or under-loaded.
FIG. 3D shows a flow chart illustrating a method 390 for
determining whether to open or close a breaker according to one
embodiment of the disclosure. A method 390 begins at block 392 with
determining a status of a bus. The status of the bus may include
measuring voltages, currents, frequencies, bus resonances, and/or
other characteristics of the bus to determine electrical failures
or electrical conditions of the bus. For example, variations in the
bus frequency may indicate a load level on the bus, such that lower
frequencies (e.g., 59 Hz when an optimal frequency is 60 Hz)
indicates an overloaded bus. At block 394 it is determined whether
the bus is overloaded or under-loaded. If the bus is overloaded or
under-loaded, then the method 390 proceeds to determine whether to
open or close the breaker. For example, when the bus is overloaded,
the breaker may be opened to detach a generator from the main bus
or close, to allow the generator to contribute energy to remove the
overload. Other blocks may include detection of electrical faults
such has high harmonic distortion, high or low voltage, high or low
fundamental frequency or bus resonance. The local controller will
take action based in status and timing to correct the electrical
condition or to segregate the two buses to limit the fault
condition to only one bus. These measurements can detect insulation
failure and breaker failure (such as one or more poles failing to
conduct or not conduct as commanded.
[0059] The schematic flow chart diagrams of FIG. 3A, FIG. 3B, and
FIG. 3C are generally set forth as a flow chart diagram. As such,
the depicted order and labeled steps are indicative of one
embodiment of the presented method. Other steps and methods can be
conceived that are equivalent in function, logic, or effect to one
or more steps, or portions thereof, of the illustrated method.
Additionally, the format and symbols employed are provided to
explain the logical steps of the method and are understood not to
limit the scope of the method. Additionally, the order in which a
particular method occurs may or may not strictly adhere to the
order of the corresponding steps shown.
[0060] FIG. 4 shows an embodiment 400 of a breaker 410 with
autonomous behavior. The breaker 410 can be used to determine when
to close a contactor 412, and therefore couple a main power
distribution bus 402 to a generator bus 404. In one embodiment, a
breaker can be a Siemens NXPLUS-C Medium Voltage breaker section
rated at 2000A. A breaker 410 can be equipped with voltage inputs
411, 413 coupled to the main bus 402 and the generator bus 404,
respectively, through potential transformers 416, 418,
respectively. The potential transformers 416, 418 can be coupled to
the controller 414 and used to sense a bus voltage of the main bus
402 and the generator bus 404, respectively. The controller 414 can
control the potential transformers 416, 418 to obtain a voltage
measurement of the main bus 402 or the generator bus 404. For
example, the controller 414 can process the voltage measurements
and communicate via a communication link 415 to the contactor 412.
The controller 414 can also be configured to perform the following
actions: apply a current to the buses 402, 404 coupled to the
contactor 412; measure an impedance of the buses 402, 404 after
applying a current; and/or determine if a fault exists on the buses
402, 404. In one embodiment, the controller can be a Siemens
SIMOCODE controller.
[0061] According to an embodiment, the controller 414 can be
further configured to control the breaker 410 autonomously, and
manage control commands. The controller 414 can also be configured
to monitor and control the status of switchgear (not shown), and to
determine the availability and status of the contactor 412. The
switchgear can be a combination of electrical disconnect switches,
fuses, or circuit breakers used to control, protect, and/or isolate
electrical equipment. Moreover, the controller 414 can be
configured to control the process by which potential transformers
416, 418 are coupled, and can be configured to monitor voltage and
current existing on a bridge between potential transformers 416,
418. It should be understood that the controller 414 can be
configured to perform various other actions, and its functionality
should not be limited in scope to the actions described within this
disclosure. Furthermore, other actions can be conceived that are
equivalent in function, logic, or portions thereof, of the actions
the controller disclosed here is configured to perform.
[0062] According to one embodiment, the breaker 410 can be part of
an offshore vessel distribution system. The breaker 410 can
synchronize two independent buses by performing measurements on the
contactor 412 and providing speed bias signals to generators. The
breaker 410 can also open a contactor 412 to segregate the vessel's
power sources due to an electrical fault.
[0063] FIG. 5 shows an embodiment 500 of a breaker 510. The breaker
510 can include a breaker 512 coupled to a main bus 502 on one end
and to a generator bus 504 on another end. In an embodiment, the
breaker 510 can be used to determine when to close a breaker 512 to
couple the main bus 502 and the generator bus 504.
[0064] In an embodiment, the breaker 510 can have a potential
transformer 516 coupled between the main bus 502 and the control
circuit 540. Another potential transformer 518 can be coupled
between the generator bus 504 and the control circuit 540. The
inner circuitry of the control circuit 540 can include a controller
563. The potential transformers 516, 518 can provide protection to
the control circuit 540 from the buses 502, 504 by presenting a
high impedance to the buses 502, 504, and therefore attenuating any
high energy fault that can occur on the buses 502, 504. The breaker
510 can direct a collision through the high impedance potential
transformers 516, 518 rather than the buses 502, 504. The high
impedance potential transformers 516, 518 can also be used by the
breaker 510 to assist in the sensing of a bus voltage.
[0065] The potential transformers 516, 518 can include primary bus
potential transformers 521, 523, respectively, and secondary
potential transformers 522, 524, respectively. The secondary
potential transformers 522, 524 can be arranged in a broken delta
configuration with a burden resistor (not shown). The potential
transformers 521, 523 can be used to sense a bus voltage, for the
purposes of synchronization, and/or to detect a dead or live bus.
As another example, the potential transformers 521, 523 can also
energize a bus during the impedance sensing process prior to
closing the breaker 512. Furthermore, the potential transformers
521, 523 can detect ground faults on the buses 502, 504,
respectively. In an embodiment, the secondary set of potential
transformers 522, 524 can be used to detect a dead bus condition on
the buses 502, 504.
[0066] The high impedance potential transformers 516, 518 can be
coupled to the controller 563 within the control circuit 540
through other devices, sensors, switches, and/or relays. For
example, the high potential transformers 516, 518 can be coupled to
the controller 563 through fault sensors 562, 564, respectively.
The fault sensors 562, 564 and secondary potential transformers
522, 524 can be used to by the controller 563 to determine if there
exists a fault on either bus 502, 504. In another example, the high
impedance potential transformers 516, 518 can be coupled to the
controller 563 through dead bus relays 567, 568, respectively,
which can detect whether the bus 502, 504 coupled through a
potential transformer 516, 518 is dead or alive. In a further
example, the high impedance potential transformers 516, 518 can be
coupled to the controller 563 through contactors 565, 566, voltage
sensors 569, and current sensors 561. According to this
arrangement, the controller 563 can measure a voltage and/or a
current. The voltage and/or current measurements can be used to
determine a fault detection procedure to implement or for
determining if a fault exists on a bus 502, 504. Further, a
variable frequency drive (VFD) 570 may be used to manipulate a
current passed between the transformers 516, 518.
[0067] In an embodiment, the breaker 510 can also have protection
circuitry (not shown) within the control circuit 540. The
protection circuitry can trip the breaker 512 under fault
conditions determined elsewhere, such as in a generator protection
system (not shown).
[0068] The breaker 510 can further include a synchronizer (not
shown) within the control circuit 540. The synchronizer can be used
to synchronize two independent AC power sources, such as
generators, and allow a breaker between two live buses to close. In
an embodiment the synchronizer can synchronize two isolated buses,
502, 504, using a bias signal applied to one of the power sources.
After the synchronizer detects that the two isolated buses 502, 504
are appropriately synchronized, the synchronizer can issue a signal
allowing the contactor 512 in the breaker 510 to close. In an
embodiment, the synchronizer, such as a Woodward SPM-D
Synchronizer, allows the synchronization of the buses to be
performed automatically without the aid of manual biasing of power
sources by an operator.
[0069] The breaker 510 can also include a sync check relay (not
shown) within the control circuit 540. The sync check relay, such
as a synchroscope, graphically displays the phase difference
between two unsynchronized sources and issues a signal when the
sources have been appropriately synchronized, thus allowing the
breaker to be closed. The sync check relay can be a passive device
that allows the synchronization of the buses to be performed
manually through the use of a sync potentiometer to bias the power
source coupled to one of the isolated buses.
[0070] The breaker 510 can further include a universal measuring
transducer (not shown) within the control circuit 540. The
universal measuring transducer can determine the electrical
parameters of the contactor 512 and report the parameters to the
management system via the operator interface 530. Bus parameters
that can be processed using the universal measuring transducer
include a voltage, current, frequency, real and reactive power, and
a power factor.
[0071] The breaker 510 can also include an operator interface 530
in an embodiment. The operator interface can include an output
device, such as a monitor display, and an input device, such as a
keyboard, to allow an administrator to monitor and control a power
system. FIG. 6 shows an embodiment 600 of the operator interface
530 of FIG. 5. The operator interface 610 can include a sync mode
selection switch 611. The sync mode selection switch 611 can allow
the breaker to toggle between being operated remotely or locally
and also between being operated automatically or manually.
Furthermore, the breaker can have a network interface coupled to
the controller, in which the controller is further configured to
allow remote access to the operator interface. The network
interface can include a connection to a propriety bus or signaling
system or a connection to a public network, such as the
Internet.
[0072] In an embodiment, the operator interface 610 within the
breaker can also include a sync and close pushbutton 612. The sync
and close pushbutton 612 can initiate a sync and close operation
within the breaker. The resulting sync and close operation
initiated can be an automated process that uses a synchronizer (not
shown) to bias isolated power sources automatically. In certain
embodiments, the synchronizer can be coupled to the controller that
provides instruction to the synchronizer and an external power
source to bias. The operator interface 610 can also include a sync
and close cancel pushbutton 613 to cancel the sync and close
operation initiated by the sync and close pushbutton 612. The
operator interface 610 can further include a sync potentiometer 614
to bias the speeds of a generator on a tie bus. The operator
interface 610 can also include a synchroscope 615 to measure and
display the phase angle difference between the two sides of a
breaker. The sync potentiometer 614 can be adjusted until the
phase, as indicated in the synchroscope 615, is matched across an
open breaker. The operator interface 610 can further include a
breaker switch 616 to provide direct control of the breaker. In an
embodiment, the switch can be a three-position, spring return to
center. The breaker switch 616 can be used to open the breaker at
any time.
[0073] The operator interface 610 can also include an ammeter 618
to display the current through the breaker, a voltmeter 620 to show
a voltage across the breaker, and/or an impedance meter 621 to show
bus impedance. Furthermore, the operator interface 610 can include
pilot lamps 619 to provide the status of the breaker 412, 512. In
an embodiment, the operator interface 610 disclosed here can be
accessed locally or remotely. For example, the operator interface
610 can be a door on which all the features described in FIG. 6, as
well as others, are available for manual local control. As another
example, the operator interface 610 can be an offshore drilling
vessel's management system that provides instruction to the breaker
remotely.
[0074] FIG. 7 shows a flow chart illustrating a method 700 for
determining when to close a breaker according to an embodiment. In
this embodiment, a breaker can have a breaker coupled to a first
and second bus. Furthermore, the first bus can be a generator bus
and the second bus can be a main distribution bus in this
embodiment. The method 700 begins at block 702 with a breaker
receiving a command, at a controller, to close a breaker. At block
704 a relay coupled to a first bus and a relay coupled to the
second bus can be checked to determine whether the first and second
buses are dead or alive. According to an embodiment, checking
relays coupled to the first and second buses to determine whether
the buses are dead or alive can include applying currents through
high impedance transformers to the first and second buses coupled
to the breaker. After applying the currents, the impedance of the
buses can then be measured by measuring a voltage and a
current.
[0075] At block 706, the measured impedances can be processed to
determine the status of the buses. In this embodiment, the bus
status can be whether a bus is dead or alive. Furthermore, at block
706, a controller can select a fault detection procedure to
implement based, in part, on the status of the buses. In an
embodiment, there can be three distinct fault detection procedures.
A first fault detection procedure can be executed when both buses
are dead. A second fault detection procedure can be executed when
both buses are live. A third fault detection procedure can be
executed when one bus is dead and one bus is live.
[0076] In one embodiment, if the controller determines at block 706
that both buses are dead, then the method proceeds to block 710 to
instruct a first contactor to open and a second contactor to close.
At block 711, a second voltage and current measurement can be
performed after the contactors open or close as instructed at block
710. A second current can be applied through the high impedance
transformers to the first and second buses coupled to the breaker
in order to make the second voltage and current measurements. The
voltage and current measured at block 711 can be processed to
determine whether a fault exists on either the first or second bus.
In one embodiment, the voltage and current measured at block 711
may be approximately zero for the breaker to close.
[0077] At block 712, the first contactor can be instructed to close
and the second contactor can be instructed to open. At block 713, a
third voltage and current measurement can be performed after the
contactors open or close as instructed at block 712. A third
current can be applied through the high impedance transformers to
the first and second buses coupled to the breaker in order to make
the third voltage and current measurements. The voltage and current
measured at block 713 can be processed to determine whether a fault
exists on either the first or second bus. In one embodiment, the
voltage and current measured at block 713 may be approximately zero
for the breaker to close.
[0078] At block 714, the broken delta resistor voltage on both the
main first and second bus can be checked by reading the voltage of
secondary potential transformers arranged in a broken delta
configuration with a burden resistor as shown in FIG. 5. The
checking of the voltage of the broken delta resistors can also be
used to determine whether a fault exists on either the first or
second bus. In an embodiment, the voltages of the broken delta
resistors may be approximately zero for the breaker to close. Then,
at block 715 the breaker is closed.
[0079] Optionally, if it is determined at block 714 that no fault
exists on either the first or second bus, then a signal can be
transmitted to a synchronizer (not shown) instructing the
synchronizer to synchronize the first and second bus coupled to the
breaker. The breaker between the first and second buses can then be
closed to couple the two buses to each other. In the case that a
fault is detected, the breaker may not close. Furthermore, the
breaker can open, if previously closed, when a fault is detected.
In one embodiment, the command to open can be a digital signal
generated when a momentary dry contact is made in an offshore
drilling vessel's management system to signal the breaker to open.
According to the embodiment, excitation to the dry contact is
provided by the breaker. The excitation can be a pulsed output from
the vessel management system to the breaker.
[0080] In another embodiment, if the controller determines at block
706 that both buses are live, then the method proceeds to block
720, wherein a first contactor can be instructed to open and a
second contactor can also be instructed to open. At block 721, a
second voltage and current measurement can be performed after the
contactors open as instructed at block 720. A second current can be
applied through the high impedance transformers to the first and
second buses coupled to the breaker in order to perform the second
voltage and current measurements. The voltage and current measured
at block 721 can be processed to determine whether a fault exists
on either the first or second bus. In one embodiment, the voltage
and current measured at block 721 may be approximately zero for the
breaker to close.
[0081] At block 722, the second contactor can be instructed to
close. At block 723, the voltage on the second bus can be checked
after the second contactor closes as instructed at block 722. The
current can also be measured while the voltage of the second bus is
checked. A third current can be applied through the high impedance
transformers to the first and second buses coupled to the breaker
in order to check the voltage of the second bus and measure a
current. The voltage and current measured at block 723 can be
processed to determine whether a fault exists on the second bus. In
one embodiment, the current measured at block 723 may be
approximately zero for the breaker to close.
[0082] At block 724, the first contactor can be instructed to close
and the second contactor can be instructed to open. At block 725,
the voltage on the first bus can be checked after the contactors
open or close as instructed at block 724. The current can also be
measured while the voltage of the first bus is checked. A fourth
current can be applied through the high impedance transformers to
the first and second buses coupled to the breaker in order to check
the voltage of the first bus and measure a current. The voltage and
current measured at block 725 can be processed to determine whether
a fault exists on the first bus. In one embodiment, the current
measured at block 725 must be zero if a breaker is to ultimately
determine that the breaker should close. In one embodiment, the
current measured at block 725 may be approximately zero for the
breaker to close.
[0083] At block 726, the first bus voltage can be monitored with
the first contractor remaining closed. At block 727, the broken
delta resistor voltage on both the first and the second bus can be
checked by reading the voltage of secondary potential transformers
arranged in a broken delta configuration with a burden resistor as
described with reference to FIG. 5. The checking of the voltage of
the broken delta resistors can also determine whether a fault
exists on either the first or second bus. In an embodiment, the
voltages of the broken delta resistors may be approximately zero
for the breaker to close. Then, at block 729 the breaker may be
closed.
[0084] Optionally, if it is determined at block 727 that no fault
exists on either the first or second bus, then a signal can be
transmitted to a synchronizer instructing the synchronizer to
synchronize the first and second bus coupled to the breaker. The
breaker between the first and second buses can then be closed to
couple the two buses. In the case that a fault is detected, the
breaker may not close. Furthermore, the breaker can open, if
previously closed, when a fault is detected. In one embodiment, the
command to open can be a digital signal generated when a momentary
dry contact is made in an offshore drilling vessel's management
system to signal the breaker to open. According to the embodiment,
excitation to the dry contact is provided by the breaker. The
excitation can be a pulsed output from the vessel management system
to the breaker.
[0085] In another embodiment, if the controller determines at block
706 that one bus is dead and one bus is live, then the method
proceeds to block 730, where a first contactor can be instructed to
open and a second contactor can also be instructed to open. At
block 731, a second voltage and current measurement can be
performed after the contactors open at block 730. A second current
can be applied through the high impedance transformers to the first
and second buses coupled to the breaker in order to make the second
voltage and current measurements. The voltage and current measured
at block 731 can be processed to determine whether a fault exists
on either the first or second bus. In one embodiment, the voltage
and current measured at block 731 may be approximately zero for the
breaker to close.
[0086] At block 732, the contactor coupled to the live bus can be
instructed to close. At block 733, the voltage on the live bus can
be checked after the contactor coupled to the live bus closes as
instructed at block 732. The current can also be measured while the
voltage of the live bus is checked. A third current can be applied
through the high impedance transformers to the first and second
buses coupled to the breaker in order to check the voltage of the
live bus and measure a current. The voltage and current measured at
block 733 can be processed to determine whether a fault exists on
the live bus. In one embodiment, the current measured at block 733
may be approximately zero for the breaker to close.
[0087] At block 734, the broken delta resistor voltage on both the
first and second bus can be checked by reading the voltage of
secondary potential transformers arranged in a broken delta
configuration with a burden resistor as described with reference to
FIG. 5. The checking of the voltage of the broken delta resistors
can also be used to determine whether a fault exists on either the
first or second bus. In an embodiment, the voltages of the broken
delta resistors must be zero if the method is to ultimately
determine that the breaker should close.
[0088] At block 735, the contactor coupled to the dead bus can be
instructed to close. At block 736, the current through the closed
contactors can be monitored, and the broken delta resistor voltage
can also be monitored to check for faults.
[0089] In an embodiment, if an abnormal bus condition is detected
then one of the contactors must be opened. The breaker may not be
allowed to close if an abnormal condition is detected. The
controller can wait a programmable time before attempting to close
both of the contactors again. A single repeat of the process can be
allowed. This can allow for the case where two ties might excite
the bus coupling between them at exactly the same time, causing an
abnormal reaction in a system that is fundamentally healthy. If the
previously dead bus appears to respond normally to excitation
through a transformer, then the excitation can be maintained for a
short period of time while continuing to monitor the current
through the contactors and the broken delta resistor voltages.
[0090] Optionally, if a fault has not been detected on either the
first or second bus, then a signal can be transmitted to a
synchronizer instructing the synchronizer to synchronize the first
and second bus coupled to the breaker. The breaker between the
first and second buses can then be closed to couple the two buses.
In the case that a fault is detected, the breaker may not close.
Furthermore, the breaker can open, if previously closed, when a
fault is detected. In one embodiment, the command to open can be a
digital signal generated when a momentary dry contact is made in an
offshore drilling vessel's management system to signal the breaker
to open. According to the embodiment, excitation to the dry contact
is provided by the breaker. The excitation can be a pulsed output
from the vessel management system to the breaker.
[0091] At block 737, after the breaker has been closed, the second
contactor can be opened while the first contactor remains closed.
Then, at block 738 the breaker may be closed.
[0092] If implemented in firmware and/or software, the functions
described above, such as with described with reference to FIG. 3A,
FIG. 3B, FIG. 3C, and FIG. 7 may be stored as one or more
instructions or code on a computer-readable medium. Examples
include non-transitory computer-readable media encoded with a data
structure and computer-readable media encoded with a computer
program. Computer-readable media includes physical computer storage
media. A storage medium may be any available medium that can be
accessed by a computer. By way of example, and not limitation, such
computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or
other optical disk storage, magnetic disk storage or other magnetic
storage devices, or any other medium that can be used to store
desired program code in the form of instructions or data structures
and that can be accessed by a computer. Disk and disc includes
compact discs (CD), laser discs, optical discs, digital versatile
discs (DVD), floppy disks and blu-ray discs. Generally, disks
reproduce data magnetically, and discs reproduce data optically.
Combinations of the above should also be included within the scope
of computer-readable media.
[0093] In addition to storage on computer readable medium,
instructions and/or data may be provided as signals on transmission
media included in a communication apparatus. For example, a
communication apparatus may include a transceiver having signals
indicative of instructions and data. The instructions and data are
configured to cause one or more processors to implement the
functions outlined in the claims.
[0094] Although the present disclosure and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations can be made herein without departing
from the spirit and scope of the disclosure as defined by the
appended claims. Moreover, the scope of the present application is
not intended to be limited to the particular embodiments of the
process, machine, manufacture, composition of matter, means,
methods and steps described in the specification. As one of
ordinary skill in the art will readily appreciate from the present
processes, disclosure, machines, manufacture, compositions of
matter, means, methods, or steps, presently existing or later to be
developed that perform substantially the same function or achieve
substantially the same result as the corresponding embodiments
described herein may be utilized according to the present
disclosure. Accordingly, the appended claims are intended to
include within their scope such processes, machines, manufacture,
compositions of matter, means, methods, or steps.
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