Distributed backbone-contact-contact-backbone transmission control scheme

Abstract

Techniques relate to a trunk-contact-contact-trunk (MTTM) power system. The MTTM system may include a first backbone protection relay that controls a first utility circuit breaker and a second backbone protection relay that controls a second utility circuit breaker. The MTTM system may also include a first contact protection relay that controls the first contact circuit breaker and a second contact protection relay that controls the second contact circuit breaker. The MTTM system may also include a common bus communicatively connecting the first backbone protection relay, the second backbone protection relay, the first contact protection relay, and the second contact protection relay together. Each of the first backbone protection relay, the second backbone protection relay, the first contact protection relay, and the second contact protection relay is connected to a common bus via one or more communication lines.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 63 / 541,474, filed on September 29, 2023, the disclosure of which is hereby incorporated by reference. Background Art

[0003] A main-tie-tie-main (MTTM) power distribution system is a power system architecture capable of distributing power to a load from two different power sources. By distributing power from two different power sources, an MTTM power distribution system provides redundancy to the load. In this regard, if one power source is unavailable, power from another power source can be provided to the load.

[0004] Typically, an MTTM distribution system includes two trunk protection relays that constitute the "trunk" of the MTTM, and two liaison protection relays that constitute the "liaison" of the MTTM. The components of the MTTM distribution system are typically controlled by a central controller. However, integrating the central controller into the MTTM distribution system introduces a single point of failure. In this regard, each circuit breaker and / or relay of the MTTM distribution system must be routed to the central controller, where each connection presents a possible point of failure. In addition, an MTTM scheme with a central controller typically requires that all control and monitoring signals be routed to the central controller, which increases the complexity in terms of signal exchange. Furthermore, if the central controller fails, the entire MTTM power system may cease to operate, resulting in a loss of power to the connected loads in the event of a single power source loss.

[0005] In order to solve the single point failure problem and improve the reliability of the MTTM transmission solution, some distribution systems add a backup central controller. However, adding a backup central controller adds cost and complexity, especially the complexity of signal exchange. Summary of the invention

[0006] The present disclosure generally relates to systems and methods for decentralized transmission control of a trunk-tie-tie-trunk power distribution system. Control of the MTTM power distribution system can be performed by a decentralized transmission control system that can be incorporated into a protection relay or other device as a means of controlling an intelligent electronic device other than an intelligent electronic device with a central controller. In this regard, the protection relays of the MTTM power distribution system can take independent actions such as opening and closing circuit breakers based on a shared common bus signal to control the operation of the MTTM power distribution system.

[0007] By implementing a decentralized transmission control system including a protection relay instead of a central controller, single point failures can be resolved. Additionally, compared to a centralized control scheme, the complexity of signal exchange is reduced because not all circuit breakers and relays need to be routed to a central controller. In addition, as further described herein, the decentralized transmission control system can automatically restore the power of the load when a single power source is lost, such as by disconnecting and closing the circuit breaker. The decentralized transmission control system can also reconfigure the MTTM power distribution system to the state before the power failure, so that the power is automatically restored by disconnecting and closing the circuit breaker when the lost power source resumes providing power. In addition, the decentralized transmission control system can reconfigure the MTTM power distribution system, and in some cases, automatically restore power in abnormal situations such as circuit breaker failure, operational failure (failure to disconnect / close the circuit breaker) and relay failure. In addition, as described herein, when taking action will not cause the power recovery of the load, such as when both power sources stop providing power, the transmission control system can determine that no action is taken.

[0008] One aspect of the technology relates to a trunk-tie-tie-trunk (MTTM) power system, comprising: a first trunk protection relay controlling a first utility circuit breaker; a second trunk protection relay controlling a second utility circuit breaker; a first tie protection relay controlling the first tie circuit breaker; a second tie protection relay controlling the second tie circuit breaker; and a common bus communicatively connecting the first trunk protection relay, the second trunk protection relay, the first tie protection relay, and the second tie protection relay together, wherein each of the first trunk protection relay, the second trunk protection relay, the first tie protection relay, and the second tie protection relay is connected to the common bus via one or more communication lines.

[0009] In some cases, the first utility circuit breaker is connected to a first power source and the second utility circuit breaker is connected to a second power source.

[0010] In some cases, the first utility circuit breaker is also connected to the first bus, and the second utility circuit breaker is also connected to the second bus.

[0011] In some cases, the first tie protection relay is connected to the first tie breaker and a first voltage sensing device monitoring a voltage of the first bus, and the second tie protection relay is connected to the second tie breaker and a second voltage sensing device monitoring a voltage of the second bus.

[0012] In some cases, the connecting line connects the first bus and the second bus.

[0013] In some cases, the power system also includes: a first voltage sensor configured to detect a voltage provided by the first power source to the first utility circuit breaker; a second voltage sensor configured to detect a voltage provided by the second power source to the second utility circuit breaker; a third voltage sensor configured to detect a voltage on the first bus; and a fourth voltage sensor configured to detect a voltage on the second bus.

[0014] In some cases, the first voltage sensor is configured to provide a detected voltage provided by the first power supply to a first main trunk protection relay, the second voltage sensor is configured to provide a detected voltage provided by the second power supply to a second main trunk protection relay, the third voltage sensor is configured to provide a detected voltage on the first bus to a first tie protection relay, and the fourth voltage sensor is configured to provide a detected voltage on the second bus to a second tie protection relay.

[0015] In some cases, one or more loads are connected to the first and / or second busses.

[0016] In some cases, the first main trunk protection relay and the first tie protection relay form a first relay pair, and the second main trunk protection relay and the second tie protection relay form a second relay pair.

[0017] In some cases, the first main trunk protection relay and the first tie protection relay are connected together via a first pairing line, and the second main trunk protection relay and the second tie protection relay are connected together via a second pairing line.

[0018] In some cases, the first mainline protection relay is configured to control a first utility circuit breaker, the second mainline protection relay is configured to control a second utility circuit breaker, the first tie protection relay is configured to control the first tie circuit breaker, and the second tie protection relay is configured to control the second tie circuit breaker.

[0019] In some cases, the first mains protection relay may control the first tie circuit breaker via the first paired line, and the first tie protection relay may control the first utility circuit breaker via the first paired line.

[0020] In some cases, the second mains protection relay may control the second tie circuit breaker via the second paired line, and the second tie protection relay may control the second utility circuit breaker via the second paired line. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a block diagram of an example trunk-tie-tie-trunk power distribution system architecture in accordance with aspects of the present disclosure.

[0022] Figure 2 is a block diagram of an example network system for communication between protection relays of a decentralized transmission control system according to aspects of the present disclosure.

[0023] Figure 3 is a block diagram of an example hardwired communication interface between protection relays of a decentralized transmission control system in accordance with aspects of the present disclosure.

[0024] Figure 4A is an illustration of an example power system operating in a first typical operating scenario in accordance with aspects of the present disclosure.

[0025] Figure 4B is an illustration of an example power system operating in a second typical operating scenario in accordance with aspects of the present disclosure.

[0026] Figure 5A and Figure 5B Operation of a power system operating in a first typical operating scenario when a single power source is unavailable is illustrated in accordance with aspects of the present disclosure.

[0027] Fig. 6A and Figure 6B Operation of a power system operating in a second typical operating scenario when a single power source is unavailable is illustrated in accordance with aspects of the present disclosure.

[0028] Figure 7 Operation of a power system when two power sources are lost is shown in accordance with aspects of the present disclosure.

[0029] FIG. 8A to FIG. 8C Operation of a power system operating in a second typical operating scenario when power sources are sequentially lost in accordance with aspects of the present disclosure is illustrated. DETAILED DESCRIPTION

[0030] Disclosed herein generally is a decentralized transmission control system and corresponding logic capable of transmission control of a trunk-tie-tie-trunk power distribution system architecture. The transmission control system can control the operation of circuit breakers operated by trunk relays and tie relays to automatically restore power to the load when power loss occurs. Additionally, when a preferred source selection is made, the transmission control system can control the operation of circuit breakers operated by trunk relays and tie relays. The transmission control system can maintain at least one disconnected circuit breaker to avoid paralleling two or more independent power sources during normal operation.

[0031] Figure 1A trunk-tie-tie-trunk (MTTM) distribution system architecture 100 is shown, which may also be referred to herein as a "power system". The power system 100 includes four protection relays, including a trunk 1 protection relay 101, a trunk 2 protection relay 102, a tie 1 protection relay 111, and a tie 2 protection relay 112. The power system also includes four circuit breakers, including a utility circuit breaker (UB) 103, UB 104, a tie circuit breaker (TB) 113, and TB 114. As described in detail herein, the four protection relays including the trunk 1 protection relay 101, the trunk 2 protection relay 102, the tie 1 protection relay 111, and the tie 2 protection relay 112 can form a distributed transmission control system.

[0032] Each relay may control the operation of an associated circuit breaker. In this regard, trunk 1 protection relay 101 may control the operation of utility circuit breaker (UB) 103, trunk 2 protection relay 102 may control the operation of UB 104, tie 1 protection relay 111 may control the operation of tie circuit breaker (TB) 113, and tie 2 protection relay 112 may control the operation of TB 114. The operation of circuit breakers 103, 104, 113, and 114 may include the opening and closing of the circuit breakers so as to respectively prevent power from passing through the circuit breakers or enable power to pass through the circuit breakers.

[0033] In addition to the Main 1 Protection Relay 101 monitoring its own circuit breaker (UB 103), the Main 1 Protection Relay 101 can also share the following signals to and from the associated tie circuit breaker (TB 113): Main Protection Relay Open Command to Tie Breaker, Main Protection Relay Close Command to TieBreaker, Tie Breaker Open Status to Main Protection Relay, Tie Breaker Close Status to Main Protection Relay. Similar to the Main 1 protection relay 101, the Tie 1 protection relay 111 may monitor its own circuit breaker (TB 113), and may also share the following signals to and from the associated Main breaker (UB 103): Tie Protection Relay Open Command to Main Breaker, Tie Protection Relay Close Command to Main Breaker, Main Breaker Open Status to Tie Protection Relay, and Main Breaker Close Status to Tie Protection Relay. The Main 2 protection relay 102 and the Tie 2 protection relay 112 may have similar operations to those described for the Main 1 protection relay 101 and the Tie 1 protection relay 111.

[0034] like Figure 1 As further shown, the power distribution system architecture 100 includes two buses, including bus 1 150 and bus 2 160. Loads including loads 122a, 122b, 122c are connected to bus 1150 via corresponding circuit breakers 120a, 120b, and 120c. Loads including loads 123a, 123b, 123c are connected to bus 2 160 via corresponding circuit breakers 121a, 121b, and 121c. Although Figure 1Three loads are shown connected to each of bus 1 150 and bus 2 160, but any number of loads may be connected to each bus. For example, one load may be connected to bus 1 150 and ten loads may be connected to bus 2 160. For clarity and consistency, the term "circuit breaker" as used herein will be understood to mean a circuit breaker (including utility circuit breakers and tie breakers) or a disconnect switch unless otherwise specified.

[0035] Each utility circuit breaker 103, 104 can be connected to a power source. Figure 1 As shown, UB 103 is connected to source A 105, and UB 104 is connected to source B 106. In this regard, UB 103 may control whether power delivered from source A 105 is provided to bus 1 150, and UB 104 may control whether power delivered from source B 106 is provided to bus 2 160. For example, if UB 103 is in an open state, power from source A 105 is not delivered to bus 1 150. However, when UB 103 is closed, power from source A 105 may be provided to bus 1 150.

[0036] The tie breakers 113, 114 can control the power transmission between the buses. In this regard, the TBs 113, 114 are connected via a power cable represented by a connection line 170. Although the connection line 170 is shown as a power cable, an electrical bus can also be used instead. In operation, when the source A 105 delivers power to the bus 1 150 and the TB 113 is closed, the power delivered to the bus 1 150 can be passed through the TB 113 through the connection line 170 to the TB 114. When the TB 114 is closed, the power delivered to the bus 1 150 by the source A 105 can be delivered to the bus 2 160. When the TB 114 is disconnected, the power delivered to the bus 1 150 by the source A 105 can be prevented from being delivered to the bus 2 160. Alternatively, the TB 113 can be disconnected, and the power delivered to the bus 1 150 from the source A 105 can be prevented from being delivered to the connection line 170. Similarly, when source B 106 delivers power to bus 2 160 and TB 114 is closed, the power delivered to bus 2 160 may be transferred to TB 113 through connecting line 170 through TB ​​114. With TB 113 closed, the power delivered to bus 2 160 by source B 106 may be delivered to bus 1 150. With TB 113 open, the power delivered to bus 2 160 by source B 106 may be blocked from being delivered to bus 1 150. Alternatively, TB 114 may be open, and the power delivered to bus 2 160 from source B 106 may be blocked from being delivered to connecting line 170.

[0037] The power distribution system architecture 100 may also include sensors to detect the presence or absence of voltage on the lines and / or buses. Figure 1 As further shown, voltage sensor 131 can detect the voltage on the line connecting source A 105 and UB 103, and voltage sensor 132 can detect the voltage on the line connecting source B 106 and UB 104. Voltage sensors 133 and 134 can detect the voltage (or the lack of voltage) on buses 150 and 160, respectively. Voltage sensor 131 can be connected to or otherwise communicate with trunk 1 protection relay 101, and voltage sensor 132 can be connected to or otherwise communicate with trunk 2 protection relay 102. Similarly, voltage sensors 133 and 134 can be connected to or otherwise communicate with tie 1 protection relay 111 and tie 2 protection relay 112, respectively. The voltage sensors can include voltage transformers, low power voltage transformers, live line detectors, or any other sensor type that detects voltage. Although Figure 1 A voltage sensor is shown, but other sensors such as a current sensor may be used instead of or in addition to a voltage sensor.

[0038] Although the sensors, circuit breakers and protection relays are shown as separate components, it will be appreciated that these components may be implemented in a single unit. For example, the trunk 1 protection relay 101 may include the UB 103 and the sensor 131. In another example, the tie 2 protection relay 112 may include the TB 114 and the sensor 134.

[0039] During operation, bus 1 150 can provide power to loads 122a-122c, and bus 2 160 can provide power to loads 123a-123c. In this regard, bus 1 150 can provide a voltage received from a power source, power source A 105 or source B 106, to loads 122a-122c via CB 120a-120c. However, when the CB is disconnected or there is no power on the bus, the load may not receive power. For example, if CB 120b is disconnected, load 122b will not receive power.

[0040] The wiring and bus layout of the power system architecture 100 is merely one example of a potential layout of wiring and bus layouts in the power system architecture. In this regard, the power system architecture may include any number of wiring and buses, including intermediate buses and wiring. For example, the wiring connecting the power source A 105 and the UB 103 may include any number of intermediate wirings, such that the power delivered from the power source A traverses more than a single wiring before reaching the UB 103. In another example, although the bus 1 150 is shown as a single bus, the bus 1 150 may include two or more buses.

[0041] Figure 2 A block diagram of an example network system 200 for communication between feeder unit controllers is depicted. In this example, the trunk 1 protection relay 101, the trunk 2 protection relay 102, the tie 1 protection relay 111, and the tie 2 protection relay 112 include corresponding communication interfaces 201, 202, 203, 204, monitoring units 211, 212, 213, 214, and control units 221, 222, 223, 224.

[0042] The communication interfaces 201, 202, 203, 204 may be able to communicate directly and indirectly with each other through the network 270. The network 270 may include various configurations and protocols, including the Internet, the World Wide Web, an intranet, a virtual private network, a wide area network, a local area network, a private network using a communication protocol, point-to-point communication or an international standard defining a communication protocol, hard wiring, Ethernet, WiFi, and RPC, HTTP, and various combinations of the foregoing.

[0043] The control units 221, 222, 223, 224 may include one or more processors, memory, and other components typically found in a computing device. The memory may store information accessible by the processor, including instructions that may be executed by the processor, such as controlling the operation of one or more circuit breakers. The memory may include data that may be retrieved, manipulated, or stored by the processor. The memory may be a type of non-transitory computer-readable medium capable of storing information accessible by the processor, such as a hard drive, a solid-state drive, a tape drive, optical storage, a memory card, a ROM, a RAM, a DVD, a CD-ROM, a writable memory, and a read-only memory.

[0044] The monitoring units 211, 212, 213, 214 may monitor the voltage (or current) on the bus or power line to detect power and / or power loss. For example, the monitoring units 211, 212, 213, 214 may monitor a voltage sensor such as voltage sensors 131, 132, 133, and / or 134 to detect the presence (or absence) of a voltage on the line or bus to which the corresponding sensor is attached. In some cases, the sensor may provide information related to the voltage detected by the sensor, such as a voltage value, a frequency of the power signal, a phase of the power signal, etc.

[0045] For example, the monitoring unit 211 may be wirelessly and / or wiredly connected to the voltage sensor 131. The monitoring unit 211 may monitor a signal provided by the voltage sensor 131 indicating the presence (or absence) of a voltage on a line connecting the source A 105 to the UB 103. In another example, the monitoring unit 212 may monitor a signal provided by the voltage sensor 132 indicating the presence (or absence) of a voltage on a line connecting the source B 106 to the UB 104.

[0046] The monitoring unit of the contact protection relay (including the monitoring unit 213 of the contact 1 protection relay 111 and the monitoring unit 214 of the contact 2 protection relay 112) can operate similarly to the monitoring unit of the trunk protection relay. For example, the monitoring unit 213 can monitor the signal provided by the voltage sensor 133, which indicates the presence (or absence) of the voltage on the bus 1 150. Similarly, the monitoring unit 214 can monitor the signal provided by the voltage sensor 134, which indicates the presence (or absence) of the voltage on the bus 2160. In some cases, the sensor can provide information related to the voltage detected by the sensor, such as the voltage value, the frequency of the power signal, the phase of the power signal, etc. The information collected by the monitoring unit of the relay can be provided to the control unit of the corresponding relay. Although the communication interface, the monitoring unit and the control unit are shown as separate components, the interface and the unit can be combined in a single component. For example, the communication interface 201, the monitoring unit 211 and the control unit 221 can be implemented as a single component.

[0047] Although the communication interface, monitoring unit and control unit are shown as integrated into the protection relay, such components may also be implemented by other intelligent electronic devices (IEDs) in addition or alternatively. In this case, in addition to or instead of the protection relay, the decentralized transmission control system described herein may also be implemented by the IED.

[0048] Figure 3381-384 and a common bus 380. The common bus 380 can relay information referred to herein as a "shared signal" from one relay of the transmission control system to another relay. The shared signals further described herein may include: Open Point At Bus 1, Open Point at Bus 2, Voltage Common Bus High, Open Point Ready to Close, Open Point Failed to Close, Transfer in Progress, Preferred Source A, and / or Preferred Source B. Although the common bus 380 is shown as a hardwired connection between relays, the common bus 380 may include various configurations and protocols. For example, the common bus 380 may be a connection between the communication interfaces 201 , 202 , 203 , 204 via the network 270 .

[0049] like Figure 3 As shown, each relay may have between "1" and "n" communication lines, where "n" depends on the number of shared signals sent and received by the relay. In this regard, each relay may include a separate communication line for each shared signal, some of which have separate communication lines for shared signal reception and transmission. For example, the trunk 1 protection relay 101 may have a communication line for communicating whether the UB 103 has a disconnect point, receiving (or providing) a shared signal indicating whether the transmission in progress signal is on the common bus 380, and receiving (or providing) a shared signal indicating a failure to close the disconnect point, etc. The control units 221-224 of the protection relays 101, 102, 111, 112 can continuously monitor the signals on the common bus 380, which are received via the corresponding communication interfaces 201-204.

[0050] The shared signal "disconnection point at bus 1" may be a signal provided to the common bus 380 by the trunk 1 protection relay 101 and / or the tie 1 protection relay 111 indicating that the bus 1 150 has at least one disconnection point. The disconnection point may correspond to an open circuit breaker. In this regard, the disconnection point associated with the disconnection point at bus 1 may be UB 103 and / or TB 113.

[0051] The shared signal "disconnection point at bus 2" may be a signal provided to the common bus 380 by the trunk 2 protection relay 102 and / or the tie 2 protection relay 112, indicating that the bus 2 160 has at least one disconnection point. In this regard, the disconnection point associated with the disconnection point at bus 2 may be UB 104 and / or TB 114.

[0052] The shared signal "voltage common bus high" may be a signal provided to the common bus 380 to indicate that at least one of the protection relays involved in the transmission control system senses a healthy voltage, which indicates that appropriate power is being provided. In this regard, when the monitoring unit of the protection relay detects a healthy voltage indicating power, the control unit may output a "voltage common bus high" signal to the common bus 380. For example, the monitoring unit 214 of the contact 2 protection relay 112 may detect a healthy voltage on the bus 2160 based on a signal provided by the voltage sensor 134. Based on the detected voltage, the control unit 224 may output a voltage common bus high signal to the common bus 380.

[0053] The protection relay may implement a "Voltage OK" check before sending a voltage common bus high share signal. The voltage OK check may be a user defined test that is a prerequisite to sending a voltage common bus high share signal. When a sensor associated with the protection relay detects a voltage, a controller in the protection relay determines whether the voltage is healthy based on a list of user defined criteria. When the healthy voltage criteria are met, the protection relay may send a voltage common bus high share signal. The voltage check is to ensure that only healthy voltage is supplied to the load.

[0054] The list of user defined criteria for voltage normality check at the main protection relays 101, 102 may include one or more of the following: the operating values ​​used below are received from voltage sensors such as voltage sensors 131 and 132, which detect the voltage on the line connecting source A 105 and UB 103 and the voltage on the line connecting source B 106 and UB 104, respectively; the phase-to-phase voltage is higher than 90% of the nominal voltage; the phase-to-phase voltage is lower than 110% of the nominal voltage; the frequency is higher than 99% of the nominal frequency; the frequency is lower than 101% of the nominal frequency; the MCB in the path from the voltage transformer to the protection relay is not tripped. The aforementioned percentages and values ​​provided for the list of user defined criteria for voltage normality check at the main protection relays 101, 102 are merely examples, and other percentages and values ​​may be used instead. For example, the user defined criterion may be that the phase-to-phase voltage is higher than 85%.

[0055] The list of user-defined criteria for voltage normality check at the contact protection relays 111, 112 may include one or more of the following: the operating values ​​used below are received from voltage sensors such as voltage sensors 133 and 134, which detect voltages on bus 1 150 and bus 2 160, respectively; the phase-to-phase voltage is higher than 90% of the nominal voltage; the phase-to-phase voltage is lower than 110% of the nominal voltage; the frequency is higher than 99% of the nominal frequency; the frequency is lower than 101% of the nominal frequency; and / or the MCB in the path from the voltage transformer to the protection relay is not tripped. The aforementioned percentages and values ​​provided for the list of user-defined criteria for voltage normality check at the main protection relays 101, 102 are merely examples, and other percentages and values ​​may be used instead. For example, the user-defined criterion may be a frequency higher than 95%.

[0056] The shared signal "disconnect point ready to close" can be a signal provided to the common bus 380 by the protection relay controlling the circuit breaker of the disconnection that can be closed. In other words, the disconnect point ready to close signal indicates that when the disconnect point is ready to close, there is no limit or fault known to the associated protection relay that will prevent the disconnect point from closing. For example, TB 113 can be disconnected and can be closed. Therefore, the contact 1 protection relay 111 that monitors and controls TB 113 can output the disconnect point ready to close signal to the common bus 380. Other protection relays can use the disconnect point ready to close signal to obtain the disconnect permission of the automatic control mode. As further discussed herein, the disconnect point ready to close signal can be used to ensure that the original disconnect point is closed once a new disconnection is created.

[0057] The shared signal "disconnect point closure failure" can be a signal provided to the common bus 380 by a protection relay controlling a disconnect point that has attempted to close but failed. In other words, as further described herein, the disconnect point closure failure signal indicates that the movement of the disconnect point was unsuccessful, thereby providing an instruction to any newly created disconnect point to close again to maintain the voltage on the bus (e.g., bus 1 150 and / or bus 2 160).

[0058] The shared signal "transfer in progress" can be a signal provided by the protection relay to the common bus 380, which indicates that a transfer is pending and that the opening / closing of the circuit breaker can occur. When the protection relay is about to trigger the closing of the circuit breaker under its control, the protection relay can activate the "transfer in progress" signal. For example, the trunk 1 protection relay 102 can be set to close UB 104. Before doing so, the trunk 1 protection relay 102 can send a transfer in progress signal to the common bus 380. Then, the trunk 1 protection relay 102 can trigger the closing of UB 104. After the closing of UB 104 is completed (or the closing fails), the trunk 1 protection relay 102 can stop providing the transfer in progress signal to the common bus 380.

[0059] Shared signals "preferred source A" and "preferred source B" may be used to indicate which source is selected as the preferred source. Selection of the preferred source may be made via a switch, such as a switch on a switchgear of the power distribution system architecture 100, or remotely, such as via a supervisory control and data acquisition (SCADA) system (not shown). For example, if source A 105 is the preferred source, a "preferred source A" signal may be provided on the common bus 380. Alternatively, if source B 106 is the preferred source, a "preferred source B" signal may be provided on the common bus 380.

[0060] Where selection of a preferred source is made by SCADA, the selection may be provided to the protection relays 101, 102, 111, and 112 via a network such as network 270. When SCADA is used, there may also be a signal referred to herein as a "default preference." The default preference signal may instruct the protection relays to return the system to an original state, with either the tie 1 protection relay or the tie 2 protection relay having an open point, and both utility circuit breakers 103, 104 closed, feeding each respective bus 150, 160.

[0061] In the event that selection of a preferred source is made by the switches, the selection may be provided to the protection relays 101 , 102 , 111 , and 112 , and the protection relays may energize the common bus 380 .

[0062] Selection of preferred source A or preferred source B will result in single ended operation. For example, if maintenance is required on the line connecting source B to UB 104, the operator can select preferred source A and both buses 150 and 160 will be fed by source A.

[0063] Each trunk protection relay can be paired with a tie protection relay to form a relay pair. For example, trunk 1 protection relay 101 can be paired with tie 1 protection relay 111, and trunk 2 protection relay 102 can be paired with tie 2 protection relay 112. Each relay pair can communicate via a pairing line. For example, and as Figure 3 As shown, a relay pair including trunk 1 protection relay 101 and tie 1 protection relay 111 can communicate via pairing line 321. Similarly, a relay pair including trunk 2 protection relay 102 and tie 2 protection relay 112 can communicate via pairing line 322. As further described herein, each relay in a relay pair can control a circuit breaker associated with another circuit breaker in the relay pair. Although Figure 3 Pairing lines 321 and 322 are shown as being separate from other communication channels such as common bus 380 , but the pairing lines may be implemented through network 270 .

[0064] One of the relays in the relay pair may be designated as a main relay, and the other relay may be designated as an auxiliary relay. The main relay may be the relay that first issues a command to open and / or close the circuit breaker under the control of the main circuit breaker and the auxiliary circuit breaker. For example, the trunk 1 protection relay 101 may be designated as the main relay, and the tie 1 protection relay 111 may be designated as the auxiliary relay. When the circuit breaker UB 103 and / or TB 113 is to be opened or closed, the main relay-the trunk 1 protection relay 101-may send a signal to UB 103 and / or TB 113 to open or close. After a predefined amount of time, if UB 103 and / or TB 113 are not opened or closed as indicated by the trunk 1 protection relay 101, the auxiliary relay-the tie 1 protection relay 111-may send a signal to UB 103 and / or TB 113 to open or close. Although the above examples describe the trunk protection relay as the primary relay and the tie protection relay as the secondary relay, the roles may be reversed with the tie protection relay being the primary relay and the trunk protection relay being the secondary relay.

[0065] The signal sent from the trunk 1 protection relay 101 to the tie 1 protection relay 111 and the signal sent from the trunk 2 protection relay 102 to the tie 2 protection relay 112 may include a "trunk protection relay fault". When the trunk protection relay fails, the trunk protection relay fault signal may be sent from the trunk protection relay to the tie protection relay using, for example, a communication line such as the communication line 321 or 322.

[0066] Each trunk protection relay in the relay pair can monitor and control the circuit breaker associated with the trunk protection relay and the circuit breaker of the paired tie protection relay. To this end, the relays in the relay pair can communicate one or more signals through the paired lines 321, 322. Such signals can include "trunk protection relay disconnect command to tie circuit breaker" and "trunk protection relay close command to tie circuit breaker" commands sent from the trunk protection relay to the tie protection relay, and "tie circuit breaker disconnect status to the trunk protection relay" and "tie circuit breaker closed status to the trunk protection relay" signals sent from the tie protection relay to the trunk protection relay.

[0067] Each tie protection relay in the relay pair can monitor and control the circuit breaker associated with the tie protection relay and the circuit breaker of the paired main trunk protection relay. To this end, the relays in the relay pair can communicate one or more signals through the paired lines. Such signals can include "tie protection relay disconnect command to main trunk circuit breaker" and "tie protection relay close command to main trunk circuit breaker" commands sent from the tie protection relay to the main trunk protection relay, and "main trunk circuit breaker open status to the tie protection relay" and "main trunk circuit breaker closed status to the tie protection relay" signals sent from the main trunk protection relay to the tie protection relay.

[0068] Figure 4A and Figure 4B The power system architecture 100 is depicted operating under typical operating conditions. Figure 4A and Figure 4B In both, UB 103 and UB 104 are closed, and power is supplied by Source A 105 and Source B 106. Thus, power from Source A powers Bus 1 150, and power from Source B powers Bus 2 160.

[0069] Figure 4A A first typical operating state is shown where TB 114 is closed and TB 113 is open (shown by the dashed box). TB 113 opening prevents power from Bus 1 150 from flowing to Bus 2 160 and vice versa. Figure 4B A second typical operating state is shown in which TB 114 is open (shown by the dashed box) and TB 113 is closed. Thus, power from source A powers bus 1 150 and power from source B powers bus 2 160. TB 114 opening prevents power from bus 1 150 from flowing to bus 2 160 and vice versa.

[0070] exist Figure 4AIn the illustrated operating state, the tie 1 protection relay 111 outputs a disconnect point ready to close signal to the common bus 380 because the associated circuit breaker TB 113 of the tie 1 protection relay 111 can be closed. The trunk 1 protection relay 101 and the tie 1 protection relay 111 each output a disconnect point signal at bus 1 to the common bus 380 because the disconnect point - TB 113 - is on bus 1 150. The trunk 1 protection relay 101 is informed of the state of TB 113 by the tie 1 protection relay 111. In this regard, the tie 1 protection relay 111 provides the tie circuit breaker disconnect state to the trunk 1 protection relay 101 via the paired line 321.

[0071] exist Figure 4B In the illustrated operating state, the tie 2 protection relay 112 outputs a disconnect point ready to close signal to the common bus 380 because the associated circuit breaker TB 114 of the tie 2 protection relay 112 can be closed. The trunk 2 protection relay 102 and the tie 2 protection relay 112 each output a disconnect point signal at bus 2 to the common bus 380 because the disconnect point - TB 114 - is on bus 2 160. The trunk 2 protection relay 102 is informed of the state of TB 114 by the tie 2 protection relay 112. In this regard, the tie 2 protection relay 112 provides the tie breaker disconnect state to the trunk 2 protection relay 102 via the paired line 322.

[0072] Reference again Figure 4A and Figure 4B Both, since each relay detects voltage from its corresponding voltage sensor, all relays output a voltage common bus high signal to the common bus 380. In this regard, the monitoring units 211, 212 of the trunk 1 protection relay 101 and the trunk 2 protection relay 102 may receive voltage indications from the voltage sensors 131 and 132, respectively. In this regard, the voltage sensor 131 may detect a voltage on a line connecting the source A 105 and the UB 103, and the voltage sensor 132 may detect a voltage on a line connecting the source B 106 and the UB 104. These detected voltages may be provided to the monitoring units 211, 212 of the trunk protection relays.

[0073] Similarly, the monitoring units 213, 214 of the tie 1 protection relay 111 and the tie 2 protection relay 112 may receive voltage indications from the voltage sensors 133 and 134, respectively. In this regard, the voltage sensor 133 may detect the voltage on the bus 1 150, and the voltage sensor 134 may detect the voltage on the bus 2 160. These detected voltages may be provided to the monitoring units 213, 214 of the tie protection relays.

[0074] During operation, the transmission control system of the power system 100 can perform control checks to ensure that the power system 100 is operating as expected. As described herein, if the power system architecture 100 is not operating under expected conditions, a transmission control can be performed. The control check can include determining whether the signals sent between the paired relays and / or the signals received from the voltage sensors are expected based on the information contained in the shared signal.

[0075] Loss of a single power supply

[0076] Figure 5A and Figure 5B The power system 100 is shown in a first typical operating state (eg, Figure 4A In Figure 5A In the example shown, the power system architecture 100 is missing source B 106, such as due to a failure of source B or the power system 100 being disconnected from source B 106. The loss of source B 106 is illustrated by source B 106 being shaded.

[0077] The loss of source B 106 causes power to no longer be supplied to bus 2 160. This is because TB 113 is open, thereby preventing power from source A 105 from being supplied from bus 1 150 through communication line 170 to bus 2 160. Since voltage sensors 132 and 134 no longer detect the voltage on the line between source B 106 and UB 104 and the voltage on bus 2 160, respectively, monitoring units 212 and 214 also stop detecting voltage. Therefore, trunk 2 protection relay 102 and tie 2 protection relay 112 stop providing voltage common bus high signals through common bus 380. However, trunk 1 protection relay 101 and tie 1 protection relay 111 continue to provide voltage common bus high signals and disconnect point signals at bus 1 to common bus 380. Tie 1 protection relay 111 continues to provide disconnect point ready to close signals through common bus 380.

[0078] The trunk 2 protection relay 102 can detect a voltage common bus high signal indicating that a portion of the power system has power, a disconnect point signal at bus 1 indicating that a disconnect point (TB 113) exists in the power system 100, and a disconnect point ready to close signal indicating that the disconnect point (TB 113) can be closed. Based on these signals, the trunk 2 protection relay 102 can trigger the UB 104 to open.

[0079] Once UB 104 is disconnected, Figure 5BAs shown by the dashed line in FIG, both the tie 2 protection relay 112 and the trunk 2 protection relay 102 may output a disconnect point signal at bus 2 on the common bus 380. The tie 2 protection relay 112 may determine that UB 104 is disconnected based on the trunk protection relay disconnect signal sent by the trunk 2 protection relay 102 via the paired line 332.

[0080] Both the trunk 1 protection relay 101 and the tie 1 protection relay 111 can detect the disconnect point signal at bus 2 on the common bus 380. Based on detecting the disconnect point signal at bus 2, the disconnect point ready to close signal, and the voltage common bus high signal, the trunk 1 protection relay 101 as the master relay can instruct the TB 113 to close.

[0081] Figure 5B The operating state of the power system 100 is shown after TB 113 is closed. As shown, UB 103, TB 113, and TB 114 are closed, and UB 104 is disconnected (as shown by the dashed line). Therefore, power from source A 105 can be delivered to bus 1 150 and delivered to bus 2 160 through connecting line 170. Disconnecting UB 104 prevents power from source A from being accidentally transferred to source B 106. When power is restored, UB 104 also prevents power from source B from accidentally combining with power from source A.

[0082] Fig. 6A and Figure 6B The power system 100 is shown in a second typical operating state (eg, Figure 4B In Fig. 6A In the example shown, the power system architecture 100 is missing source B 106, such as due to a failure of source B or the power system 100 being disconnected from source B 106. The loss of source B 106 is illustrated by the shading of source B 106.

[0083] The loss of source B 106 causes power to no longer be supplied to bus 2 160. This is because TB 114 is disconnected, thereby preventing power from source A 105 from being supplied from bus 1 150 through communication line 170 to bus 2 160. Since voltage sensors 132 and 134 no longer detect the voltage on the line between source B 106 and UB 104 and the voltage on bus 2 160, respectively, monitoring units 212 and 214 also stop detecting voltage. Accordingly, trunk 2 protection relay 102 and tie 2 protection relay 112 stop providing voltage common bus high signals through common bus 380, but continue to output disconnect point signals at bus 2. Trunk 1 protection relay 101 and tie 1 protection relay 111 continue to provide voltage common bus high signals to common bus 380. Tie 2 protection relay 112 continues to provide disconnect point ready to close signals through common bus 380.

[0084] The trunk 2 protection relay 102 can detect a voltage common bus high signal indicating that a portion of the power system has power, a disconnect point signal at bus 2 indicating that a disconnect point (TB 114) exists in the power system 100, and a disconnect point ready to close signal indicating that the disconnect point (TB 114) can be closed. Based on these signals, the trunk 2 protection relay 102 can trigger UB 104 to open.

[0085] Once UB 104 is disconnected, Figure 6B As shown by the dashed line in FIG, both the tie 2 protection relay 112 and the trunk 2 protection relay 102 may output a disconnect point signal at bus 2 on the common bus 380. The tie 2 protection relay 112 may determine that UB 104 is disconnected based on the trunk protection relay disconnect signal sent by the trunk 2 protection relay 102 via the paired line 332.

[0086] Next, since the trunk 2 utility breaker (UB 104) status is wired to the tie 2 protection relay 112, the tie 2 protection relay 112 detects the disconnect point. The trunk 2 protection relay 102 is healthy and it is the master relay that will first issue a close command to the tie breaker 2 (TB 114). The trunk 2 protection relay 102 also sees the disconnect point ready to close signal high and the voltage common bus signal high. The trunk 2 protection relay 102 issues a command to close the tie 2 breaker (TB 114) and power is restored to bus 1 150.

[0087] Figure 6BThe operating state of the power system 100 is shown after the TB 114 is closed. As shown, the UB 103, TB 113, and TB 114 are closed, and the UB 104 is disconnected (as shown by the dashed line). Therefore, the power from the source A 105 can be delivered to the bus 1150 and delivered to the bus 2 160 through the connecting line 170. Disconnecting the UB 104 can prevent the power from the source A from being accidentally transferred to the source B 106. When the power is restored, the UB 104 also prevents the power from the source B from being accidentally combined with the power from the source A.

[0088] Loss of both power supplies

[0089] Figure 7 The power system 100 is shown in a second typical operating state (eg, Figure 4B In Figure 7 In the example shown, the power system architecture 100 loses source A 105 and source B 106, such as due to a failure of power sources A and B or the power system 100 is disconnected from source A 105 and source B 106. The loss of source A 105 is illustrated by the shading of source A 105. The loss of source B 106 is illustrated by the shading of source B 106. The loss of source A 105 and source B 106 results in power no longer being supplied to bus 1 150 or bus 2 160.

[0090] During a typical operating state, before the power source A 105 and the power source B 106 are lost, the tie 2 protection relay 112 can output a disconnect point ready to close signal to the common bus 380 because the associated circuit breaker TB 114 of the tie 2 protection relay 112 can be closed. The trunk 2 protection relay 102 and the tie 2 protection relay 112 each output a disconnect point signal at bus 2 to the common bus 380 because the disconnect point - TB 114 - is on bus 2 160. The trunk 2 protection relay 102 is notified of the state of TB 114 by the tie 2 protection relay 112. Since each relay detects a voltage from its corresponding voltage sensor, all relays output a voltage common bus high signal to the common bus 380.

[0091] After power is lost from source A 105 and source B, the trunk 2 protection relay and the tie 2 protection relay do not contribute to the voltage common bus high signal because their corresponding sensors 132, 134 no longer detect voltage (or detect a healthy voltage). Similarly, the trunk 1 protection relay and the tie 1 protection relay do not contribute to the voltage common bus high signal because their corresponding sensors 131, 133 no longer detect voltage (or detect an unhealthy voltage).

[0092] Since the voltage common bus high signal is not high (or does not otherwise indicate that voltage is present on the power bus (e.g., Bus 1 150 or Bus 2 160)), the power system 100 will not create an Open Point or Close an Open Point, as this would result in unnecessary actions. In other words, taking actions such as opening or closing a circuit breaker (e.g., UB 103, UB 104, TB 113, TB 114) will not restore power to Bus 1 150 or Bus 2 160. Therefore, the state of the system will remain the same as before the power was lost.

[0093] The gradual loss of sources

[0094] Fig. 8A , Figure 8B and Figure 8C 1 shows that when power sources 105 and 106 become unavailable in sequence and TB 114 is disconnected, power system 100 is in a second typical operating state (eg, Figure 4B Specifically, Fig. 8A , Figure 8B and Figure 8C The operation of the power system 100 is shown when source 106 becomes unavailable and then source 105 becomes unavailable. The loss of source A 105 is illustrated by the shading of source A 105. The loss of source B 106 is illustrated by the shading of source B 106.

[0095] The initial loss of source B 106 results in power no longer being supplied to bus 2 160. This is because TB 114 is disconnected, thereby preventing power from source A 105 from being supplied from bus 1 150 through communication line 170 to bus 2 160. When source B 106 is lost, the power system 100 will function as described above. Fig. 6A and Figure 6B The operation, wherein the power system 100 ends at Figure 8B The state shown is the same as the state shown in FIG. 6 .

[0096] However, after source A is lost, if Figure 8CAs shown, the trunk 1 protection relay 101 and the tie 1 protection relay 111 will also not contribute to the voltage common bus high signal because their corresponding sensors 131, 133 are no longer detecting voltage (or detecting unhealthy voltage). Since the voltage common bus high signal is not high (or does not otherwise indicate that voltage is present on the power bus (e.g., bus 1 150 or bus 2 160)), the power system 100 will not create a disconnect point or close a disconnect point because this would result in unnecessary action. In other words, taking actions such as opening a circuit breaker (e.g., UB 103, TB 113, TB 114) or closing a circuit breaker (e.g., UB 104) will not restore power to bus 1 150 or bus 2 160. Therefore, the state of the system will remain the same as Figure 8B The same as in (before source A105 is lost).

[0097] Automatic recovery

[0098] In the event that a single source that has never provided power or provided unclean power is restored, the system can automatically return to a typical operating state, such as Figure 4A The first typical operating state shown or Figure 4B For example, and referring to Figure 6B , the power system 100 is not receiving power from source B 106. However, if power from source B is restored, the following operations may occur.

[0099] The trunk 2 protection relay 102 can see a healthy voltage via the voltage sensor 132. When a healthy voltage is detected, the trunk 2 protection relay 102 can wait for a period of time, called the "Voltage Healthy Time Delay". The Voltage Healthy Time Delay can be set to a time that ensures stable power delivery from source B 106, for example, such as 1 minute, 5 minutes, 10 minutes, 1 hour, etc. Once the Voltage Healthy Time Delay is met (or bypassed), the trunk 2 protection relay 102 can detect the high voltage common bus signal (internally) and can also detect the disconnect point ready to close signal from UB 104. Thereafter, the trunk 2 protection relay 102 can trigger TB 114 to disconnect. After confirming that TB 114 has been disconnected, the trunk protection relay 102 can issue a command to close UB 104. Once UB 104 is closed, the system returns to the second typical operating state, such as Figure 4B shown.

[0100] Open / Close Failure

[0101] In the event that the circuit breaker fails to open or close in response to a command issued by the main relay, the auxiliary relay can provide a backup command. For example, in the event that TB 113 fails to close when the trunk 1 protection relay 101 issues a command to close, the tie 1 protection relay 111 can issue another command to close to TB 113. In the event that TB 113 does not close in response to any command, no further action will occur.

[0102] Under certain circumstances, the mains protection relay may fail. For example, refer to Fig. 6A and Figure 6B , consider that the trunk 2 protection relay 102 fails. When the trunk 2 protection relay fails, the tie 2 protection relay 134 becomes the master relay. The tie 2 protection relay 134 can provide a disconnect point signal at bus 2, which indicates that bus 2 160 has a disconnect point. When source B 106 is lost, the trunk 2 protection relay 102 and the tie 2 protection relay 112 will not contribute to the voltage common bus high signal because the trunk 2 protection relay 102 has failed and the voltage sensor 134 associated with the tie 2 protection relay 112 does not sense voltage or senses unhealthy voltage. However, the trunk 1 protection relay 101 and the tie 1 protection relay 111 still see healthy voltage via their respective sensors 131, 133. Trunk 1 incoming line VT and MV bus A1 VT. The tie 2 protection relay 112 detects the high voltage common bus signal and also detects the high disconnect point ready to close signal (internal). Therefore, the tie 2 protection relay continues to disconnect UB 104. After the tie 2 protection relay 112 disconnects UB 104, the tie 2 protection relay can detect that UB 104 has been disconnected via line 322. The tie 2 protection relay is healthy and it is the master relay and will issue a close command to TB 114. After the close command is sent to TB 114, TB 114 closes, thereby restoring power to bus 2 160.

[0103] In some cases, the relay may provide a "transfer in progress" signal to the common bus 380 before instructing the circuit breaker to take action. The auxiliary relay may start a timer by detecting the transfer in progress signal before the auxiliary relay issues a backup command. For example, before the trunk 1 protection relay 101 issues a command to close the TB 113, the trunk 1 protection relay 101 may have output a transfer in progress signal to the common bus 380. The tie 1 protection relay 111 may detect the signal and start a timer. If the TB 113 has not closed before the timer reaches a predefined amount of time, the tie 1 protection relay 111 may issue a backup command to the TB 113 instructing it to close.

[0104] Although the technology has been described herein with reference to specific examples, it should be understood that these examples are merely illustrative of the principles and applications of the present technology. Therefore, it should be understood that various modifications may be made to the illustrative examples, and other arrangements may be designed without departing from the spirit and scope of the present technology as defined by the appended claims. For example, although the example operations are illustrated using certain components of the power system architecture, it should be understood that similar operations may be performed by similar components of the power system architecture.

[0105] Unless otherwise stated, the aforementioned alternative examples are not mutually exclusive, but can be implemented in various combinations to achieve unique advantages. Since these and other variations and combinations of the features discussed above can be utilized without departing from the subject matter defined by the claims, the aforementioned description of the examples should be made in an illustrative manner rather than in a manner that limits the subject matter defined by the claims. In addition, the examples described herein, and the clauses expressed as "such as", "including", etc., should not be interpreted as limiting the subject matter of the claims to specific examples; rather, these examples are intended to illustrate only one of many possible embodiments. In addition, the same reference numerals in different figures can identify the same or similar elements.

Claims

1. A trunk-tie-tie-trunk MTTM power system, characterized in that: include: a first mains protection relay that controls a first utility circuit breaker; a second mains protection relay that controls a second utility circuit breaker; a first contact protection relay, which controls the first contact circuit breaker; a second contact protection relay, which controls the second contact circuit breaker; as well as A common bus that communicatively connects the first main trunk protection relay, the second main trunk protection relay, the first liaison protection relay, and the second liaison protection relay together, wherein each of the first main trunk protection relay, the second main trunk protection relay, the first liaison protection relay, and the second liaison protection relay is connected to the common bus via one or more communication lines.

2. The power system according to claim 1, characterized in that The first utility circuit breaker is connected to a first power source, and the second utility circuit breaker is connected to a second power source.

3. The power system according to claim 2, characterized in that: The first utility circuit breaker is also connected to a first bus, and the second utility circuit breaker is also connected to a second bus.

4. The power system according to claim 3, characterized in that: The first tie protection relay is connected to the first tie breaker and a first voltage sensing device monitoring a voltage of the first bus, and the second tie protection relay is connected to the second tie breaker and a second voltage sensing device monitoring a voltage of the second bus.

5. The power system according to claim 1, characterized in that: A connecting line connects the first bus and the second bus.

6. The power system according to claim 4, characterized in that: Also includes: a first voltage sensor configured to detect a voltage provided by the first power source to the first utility circuit breaker; a second voltage sensor configured to detect a voltage provided by the second power source to the second utility circuit breaker; a third voltage sensor configured to detect a voltage on the first bus; as well as A fourth voltage sensor is configured to detect a voltage on the second bus.

7. The power system according to claim 6, characterized in that: The first voltage sensor is configured to provide the detected voltage provided by the first power supply to the first trunk protection relay, the second voltage sensor is configured to provide the detected voltage provided by the second power supply to the second trunk protection relay, the third voltage sensor is configured to provide the detected voltage on the first bus to the first connecting protection relay, and the fourth voltage sensor is configured to provide the detected voltage on the second bus to the second connecting protection relay.

8. The power system according to claim 3, characterized in that: One or more loads are connected to the first bus and / or the second bus.

9. The power system according to claim 1, characterized in that: The first main trunk protection relay and the first tie protection relay form a first relay pair, and the second main trunk protection relay and the second tie protection relay form a second relay pair.

10. The power system according to claim 9, characterized in that The first main trunk protection relay and the first tie protection relay are connected together via a first pairing line, and the second main trunk protection relay and the second tie protection relay are connected together via a second pairing line.

11. The power system according to claim 10, characterized in that: The first main trunk protection relay is configured to control the first utility circuit breaker, the second main trunk protection relay is configured to control the second utility circuit breaker, the first tie protection relay is configured to control the first tie circuit breaker, and the second tie protection relay is configured to control the second tie circuit breaker.

12. The power system according to claim 11, characterized in that The first mains protection relay is capable of controlling the first tie circuit breaker via the first paired line, and the first tie protection relay is capable of controlling a first utility circuit breaker via the first paired line.

13. The power system according to claim 11, characterized in that The second mains protection relay can control the second tie circuit breaker via the second paired line, and the second tie protection relay can control the second utility circuit breaker via the second paired line.

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