JP2022099577A - Protection control system - Google Patents

Abstract

To provide a protection control system capable of continuing the operation of bus protection and transmission line protection even when a failure has occurred in an MU.SOLUTION: A first protection control device includes: an input unit that receives an input of a first end current of a first power transmission line, a first end current of a second power transmission line, and a current of a first bus line; a failure detection unit that detects failures of first to third merging units; a communication unit that receives data indicating the second end current of the first power transmission line from a second protection control device; and a relay computation unit that executes a relay computation based on a detection result of the failure detection unit. In the case where a failure of the first merging unit is detected by the failure detection unit, the relay computation unit executes a relay computation for protecting an expanded protection zone including a protection zone of a first bus line and the protection zone of the first power transmission line on the basis of the first end current of the second power transmission line, the current of the first bus line, and the second end current of the first power transmission line received from the second protection control device.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a protection control system.

In recent years, as a form of protection relay device, a protection control system corresponding to a process bus is becoming common. In this protection control system, the function of the conventional protection relay device is divided into two, each of which is composed of individual units.

Specifically, a device for acquiring an amount of electricity called an integrated unit (merging unit (MU)) and a protection control device called an IED (Intelligent Electronic Device) are provided. The MU captures a detection signal of the amount of electricity (that is, current, voltage, etc.) of the power system, and A / D (Analog to Digital) converts the captured signal. The MU transmits the data obtained by the A / D conversion to the IED via the process bus. The IED performs a relay operation based on the received data from the MU.

For example, the protection control system according to Patent Document 1 (Patent No. 5926539) is studying to reduce the amount of hardware in the protection control system to which the process bus is applied.

Japanese Patent No. 5926539

In a protection control system using a process bus, it is conceivable to reduce the number of MUs by taking in the current value of the feeder used for bus protection and transmission line protection via a common MU. In Patent Document 1, a protection control device for protecting transmission lines and a protection control device for protecting bus lines are connected to one MU. Further, Patent Document 1 discloses that a stable power system can be operated by switching to a spare MU when a failure of the MU or the process bus is detected, and providing a spare MU and a spare process bus for redundancy. There is.

However, according to Patent Document 1, the number of MUs and process buses increases due to the above redundancy, and the effect of reducing the number of hardware equipment (that is, the number of MUs and the number of process buses) by using a common MU is reduced. It ends up.

An object of an aspect of the present disclosure is to provide a protection control system capable of continuing the operation of bus protection and transmission line protection even in the event of a MU failure.

A protection control system according to an embodiment obtains a current at the first end of a first transmission line connecting the first bus provided at the first end and the second bus provided at the second end. Acquires the current of the first bus and the second marsing unit that acquires the current of the first end of the second transmission line that connects the first bus to the first bus and the third bus provided at the third end. A third marsing unit is provided, and a first protection control device provided at the first end thereof is provided. The first protection control device includes an input unit that receives the current of the first end of the first transmission line, the current of the first end of the second transmission line, and the current of the first bus, and the first to third merging units. Detection result of the failure detection unit that detects the failure, the communication unit that receives the data indicating the current at the second end of the first transmission line from the second protection control device provided at the second end, and the failure detection unit. Includes a relay calculation unit that executes a relay calculation based on. When a failure of the first marsing unit is detected by the failure detection unit, the relay calculation unit receives the current at the first end of the second transmission line, the current of the first bus, and the first protection control device. Based on the current at the second end of the transmission line, a relay operation for protecting the extended protection section including the protection section of the first bus and the protection section of the first transmission line is executed.

The protection control system according to another embodiment acquires the current of the first end of the first transmission line connecting the first bus provided at the first end and the second bus provided at the second end. The current of the first bus, the second marsing unit that acquires the current of the first end of the second transmission line connecting the first bus, the first bus, and the third bus provided at the third end, and the current of the first bus. It includes a third marsing unit to be acquired, a first protection control device provided at the first end, and a second protection control device provided at the second end. The first protection control device includes an input unit that receives the current of the first end of the first transmission line, the current of the first end of the second transmission line, and the current of the first bus, and the first to third merging units. A failure detection unit that detects a failure, a communication unit that receives data indicating the current at the second end of the first transmission line from the second protection control device, and a relay calculation based on the detection result of the failure detection unit are executed. Includes a relay calculation unit. When a failure of the first marsing unit is detected by the failure detection unit, the relay calculation unit receives the current at the first end of the second transmission line, the current of the first bus, and the first protection control device. Based on the current at the second end of the transmission line, a relay operation for protecting the extended protection section including the protection section of the first bus and the protection section of the first transmission line is executed.

According to the present disclosure, even if a failure occurs in the MU, the operation of the bus protection and the transmission line protection can be continued.

It is a block diagram which shows the structure of protection control system. It is a figure for demonstrating an extended protection section. It is a block diagram which shows an example of the hardware composition of a MU and a protection control device. It is a block diagram which shows the functional structure of the protection control device according to Embodiment 1. FIG. It is a flowchart which shows an example of the processing procedure of the protection control device according to Embodiment 1. It is a figure for demonstrating the operation of the protection control device when an accident occurs on the B end side of a transmission line in an extended protection section. It is a figure for demonstrating the operation of the protection control device when an accident occurs in the bus of the A end electric station. It is a block diagram which shows the functional structure of the protection control device according to Embodiment 2. FIG. It is a flowchart which shows an example of the processing procedure of the protection control device according to Embodiment 2.

Hereinafter, the present embodiment will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Their names and functions are the same. Therefore, the detailed description of them will not be repeated.

Embodiment 1.
<Overall configuration>
FIG. 1 is a block diagram showing a configuration of a protection control system. With reference to FIG. 1, the protection control system 100 is a system for protecting transmission lines and bus lines. The protection control system 100 includes an A-terminal electric station (for example, a substation) 1A, a B-terminal electric station 1B, and a C-terminal electric station 1C. Specifically, the A-end electric station 1A is provided at the A-end of the transmission lines L1 and L3 and at the A-end of the transmission lines L2 and L4. The B-end electric station 1B is provided at the B-end of the transmission lines L1 and L3 and at the B-end of the transmission lines L5 and L6. The C-terminal electric station 1C is provided at the C-terminal of the transmission lines L2 and L4. The sampling synchronization between each device (for example, MU and protection control device) arranged in each electric station 1A, 1B, 1C and the sampling synchronization between each electric station 1A, 1B, 1C are predetermined. It shall be established by the synchronization method.

The transmission line L1 connects the bus 91a provided at the A end and the bus 91b provided at the B end. The transmission line L2 connects the bus 91a and the bus 91c provided at the C-terminal. The transmission line L3 connects the bus 92a and the bus 92b, and the transmission line L4 connects the bus 92a and the bus 92c. The transmission line L5 is connected to the bus 91b, and the transmission line L6 is connected to the bus 92b.

The protection control system 100 includes a protection control device 5A, MU2a to 2h (hereinafter, also collectively referred to as "MU2A"), current transformers 11a to 16a, and circuit breakers 21a to 25a in the A-end electric station 1A. , Includes voltage transformers 81a, 82a and bus 91a, 92a. The protection control system 100 includes a protection control device 5B, MU2j to 2q (hereinafter, also collectively referred to as “MU2B”), current transformers 11b to 16b, and circuit breakers 21b to 25b in the B-end electric station 1B. , Includes voltage transformers 81b, 82b and bus 91b, 92b. The protection control system 100 includes a circuit breaker 25c and buses 91c and 92c in the C-terminal electric station 1C. The protection control system 100 includes the same configuration as the A-terminal electric station 1A and the B-end electric station 1B in the C-terminal electric station 1C, but for the sake of facilitation of illustration, the circuit breaker 25c and the bus 91c, 92c. Only are shown.

The protection control device 5A is communicably connected to the protection control device 5B of the B-end electric station 1B via the transmission line 300. Similarly, the protection control device 5A is communicably connected to the protection control device (not shown) of the C-terminal electric station 1C via a transmission line (not shown). The protection control device 5A communicates with each MU2A via the process bus. The protection control device 5B communicates with each MU 2B via the process bus.

At the A-end electric station 1A, the current transformer 11a detects the current IL1a at the A end of the transmission line L1, and the current transformer 12a detects the current IL2a at the A end of the transmission line L2. The current transformer 13a detects the current IL3a at the A end of the transmission line L3, and the current transformer 14a detects the current IL4a at the A end of the transmission line L4. The current transformer 15a detects the current IB1a of the bus 91a, and the current transformer 16a detects the current IB2a of the bus 92a. The voltage transformer 81a detects the voltage V1a of the bus 91a, and the voltage transformer 82a detects the voltage V2a of the bus 92a.

The circuit breaker 21a is provided on the A end side of the transmission line L1, and the circuit breaker 22a is provided on the A end side of the transmission line L2. The circuit breaker 23a is provided on the A end side of the transmission line L3, and the circuit breaker 24a is provided on the A end side of the transmission line L4. The circuit breaker 25a is provided on the bus 91a and 92b. Specifically, the circuit breaker 25a is a bus tie circuit breaker (that is, a bus tie circuit breaker) provided on the bus tie connecting the bus 91a and the bus 92a.

The MU2a acquires the current IL2a detected by the current transformer 12a. Specifically, the MU2a samples at a predetermined sampling cycle, and the sampled current IL2a is A / D (Analog to Digital) converted. The MU2a outputs the digital value of the current IL2a after the A / D conversion to the protection control device 5A. Hereinafter, similarly, the MU2b, 2g, and 2h output the digital values of the currents IL4a, IL1a, and IL3a to the protection control device 5A, respectively. The MU2d and 2e output the digital values of the currents IB1a and IB2a to the protection control device 5A, respectively. The MU2c and 2f output the digital values of the voltages V1a and V2a to the protection control device 5A, respectively.

At the B-end electric station 1B, the current transformer 11b detects the current IL1b at the B end of the transmission line L1, and the current transformer 12b detects the current IL5b at the B end of the transmission line L5. The current transformer 13b detects the current IL3b at the B end of the transmission line L3, and the current transformer 14b detects the current IL6b at the B end of the transmission line L6. The current transformer 15b detects the current IB1b of the bus 91b, and the current transformer 16b detects the current IB2b of the bus 92b. The voltage transformer 81b detects the voltage V1b of the bus 91b, and the voltage transformer 82b detects the voltage V2b of the bus 92b.

The circuit breaker 21b is provided on the B end side of the transmission line L1, and the circuit breaker 22b is provided on the B end side of the transmission line L5. The circuit breaker 23b is provided on the B end side of the transmission line L3, and the circuit breaker 24b is provided on the B end side of the transmission line L6. The circuit breaker 25b is a circuit breaker for connecting the bus provided in the bus tie that connects the bus 91b and the bus 92b.

The MU2j, 2k, 2p, and 2q output the digital values of the currents IL1b, IL3b, IL5b, and IL6b to the protection control device 5B, respectively. The MU2m and 2n output the digital values of the currents IB1b and IB2b to the protection control device 5B, respectively. The MU2l and 2o output the digital values of the voltages V1b and V2b to the protection control device 5B, respectively.

The protection control device 5A has electric energy data (for example, current IL1a, IL2a, IL3a, IL4a, IB1a, IB2a data, voltage V1a, V2a data) acquired from each MU2A provided at the A end and a B end. The protection relay calculation is executed using the electric energy data (for example, currents IL1b, IL3b) received from the provided protection control device 5B.

Specifically, the protection control device 5A performs a differential relay calculation based on the current IL1a at the A end of the transmission line L1 and the current IL1b at the B end of the transmission line L1 in order to protect the transmission line L1. Run. In order to protect the bus 91a, the protection control device 5A performs a differential relay calculation based on the currents IL1a and IL2a at the A ends of the transmission lines L1 and L2 connected to the bus 91a and the current IB1a of the bus 91a. Run.

Further, the protection control device 5A executes a differential relay operation based on the current IL3a and the current IL3b in order to protect the transmission line L3, and the current IL3a, the current IL4a, and the current IB2a in order to protect the bus 92a. Performs a differential relay operation based on. The protection control device 5A receives the current at the C-terminal of the transmission lines L2 and L4 from the protection control device (not shown) provided at the C-terminal electric station 1C. The protection control device 5A executes a differential relay operation based on the current and the current IL2a at the C-terminal of the transmission line L2 in order to protect the transmission line L2. The protection control device 5A executes a differential relay operation based on the current and the current IL4a at the C-terminal of the transmission line L4 in order to protect the transmission line L4.

Hereinafter, in the present embodiment, for the sake of facilitation of explanation, the explanation will be given focusing on the protection of the transmission line L1 and the bus 91a.

When each MU2A has not failed, the protection control device 5A individually protects each transmission line L1 to L4 and each bus line 91a, 92a by the above differential relay calculation. Here, it is assumed that a failure occurs in MU2g that detects the current IL1a at the A end of the transmission line L1. In this case, since the protection control device 5A cannot take in the current IL1a from the MU2g, the differential relay operation using the current IL1a cannot be executed. Therefore, the protection control device 5A uses the current IL1b at the B end of the transmission line L1 instead of the current IL1a, and further uses the current IL2a at the A end of the transmission line L2 and the current IB1a of the bus 91a. The extended protection section including the protection section of L1 and the protection section of the bus 91a is protected.

FIG. 2 is a diagram for explaining an extended protection section. In FIG. 2, some current transformers and MUs, and voltage transformers are not shown for ease of illustration. With reference to FIG. 2, when the protection control device 5A detects a failure of the MU 2g, the protection control device 5A uses the current IL1b received from the protection control device 5B as an alternative value of the current IL1a.

Specifically, the protection control device 5A executes the differential relay calculation based on the current IL2a at the A end of the transmission line L2, the current IB1a of the bus 91a, and the current IL1b at the B end of the transmission line L1. .. The protection control device 5A determines whether or not an accident has occurred in the range of the B end of the bus 91a and the transmission line L1 by the differential relay calculation. That is, the protection control device 5A protects the extended protection section 110 including the protection section of the bus 91a and the protection section of the transmission line L1. In this way, when the MU2g fails, the protection control device 5A protects the protection section of the bus 91a and the protection line L1 instead of individually protecting the protection section of the bus 91a and the protection section of the transmission line L1. The extended protection section 110 including the section is protected.

When a failure of MU2g is detected, the protection control device 5A cannot transmit the current IL1a used for protecting the transmission line L1 in the protection control device 5B. Here, the added current Is (that is, Is = IL2a + IB1a) of the current IL2a at the A end of the transmission line L2 and the current IB1a of the bus 91a can be regarded as equivalent to the current IL1a flowing through the A end of the transmission line L1.

The protection control device 5A transmits the data of the added current Is as an alternative value of the current IL1a and the failure information indicating the failure of the MU 2g to the protection control device 5B. The protection control device 5B executes the differential relay operation based on the added current Is and the current IL1b at the B end of the transmission line L1. The protection control device 5B determines whether or not an accident has occurred in the range of the B end of the bus 91a and the transmission line L1 by the differential relay calculation. That is, the protection control device 5B protects the extended protection section 110 in the same manner as the protection control device 5A.

<Hardware configuration of MU and protection control device>
Hereinafter, the MU2a to 2h, 2j to 2q (hereinafter, also collectively referred to as “MU2”) and the protection control devices 5A, 5B (hereinafter, also collectively referred to as “protection control device 5”) in FIG. 1 are based on a microcomputer. An example of the configuration will be described.

Unlike the following examples, the MU2 and the protection control device 5 may be configured based on an electronic circuit such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). Alternatively, the MU2 and the protection control device 5 may be configured by combining an electronic circuit such as FPGA or ASIC with a microcomputer.

FIG. 3 is a block diagram showing an example of the hardware configuration of the MU2 and the protection control device 5. With reference to FIG. 3, the MU 2 includes an auxiliary transformer 32, an A / D conversion unit 35, an arithmetic processing unit 40, and an interface unit 50.

The auxiliary transformer 32 takes in the amount of electricity from the current transformer or the voltage transformer, converts it into a voltage suitable for signal processing in the relay internal circuit, and outputs it. The A / D conversion unit 35 takes in the voltage output from the auxiliary transformer 32 and converts it into digital data. Specifically, the A / D converter 35 includes an analog filter, a sample hold circuit, a multiplexer, and an A / D converter.

The analog filter removes high frequency noise components from the waveform signal of the current output from the auxiliary transformer 32. The sample hold circuit samples the waveform signal of the current output from the analog filter at a predetermined sampling cycle. The multiplexer sequentially switches the waveform signal input from the sample hold circuit in time series based on the timing signal input from the arithmetic processing unit 40, and inputs the waveform signal to the A / D converter. The A / D converter converts the waveform signal input from the multiplexer from analog data to digital data. The A / D converter outputs the digitally converted waveform signal (that is, digital data) to the arithmetic processing unit 40.

The arithmetic processing unit 40 includes a CPU (Central Processing Unit) 41, a RAM (Random Access Memory) 42, and a ROM (Read Only Memory) 43. Each of these elements is connected to each other via a bus 44. The arithmetic processing unit 40 may include an electrically rewritable non-volatile memory such as a flash memory. The RAM 42 and the ROM 43 are used as the main memory of the CPU 41. The CPU 41 controls the operation of the entire MU2 according to the programs enabled in the ROM 43 and the non-volatile memory.

The interface unit 50 includes a communication circuit 51 (corresponding to “TX / RX” in FIG. 3) that transmits data to the protection control device 5 via the communication line 52 which is a process bus.

The protection control device 5 includes an interface unit 61 and an arithmetic processing unit 70. The interface unit 61 includes a communication circuit 62 (corresponding to "TX / RX1" in FIG. 3), a transmission / reception circuit 63 (corresponding to "TX / RX2" in FIG. 3), and a digital output circuit 64 (D / O: Digital Output) and included.

The communication circuit 62 receives data output from the communication circuit 51 of the MU 2 and transmitted via the communication line 52. The transmission / reception circuit 63 communicates with a higher-level computer via a communication line called a station bus, for example, according to a predetermined protocol. The digital output circuit 64 is an interface circuit for outputting a signal to an external device. For example, the digital output circuit 64 outputs an opening command (for example, a trip signal TS) to each of the circuit breakers 21a to 25a according to the command of the CPU 71. The CPU 71 may output a circuit breaker opening instruction from the communication circuit 62 to the communication circuit 51 of the MU2 via the communication line 52. In this case, the digital output circuit of the MU2 outputs the trip signal TS to the circuit breaker according to the opening instruction of the circuit breaker.

The arithmetic processing unit 70 includes a CPU 71, a RAM 72, and a ROM 73. Each of these elements is connected to each other via a bus 74. The arithmetic processing unit 70 may include an electrically rewritable non-volatile memory such as a flash memory. The RAM 72 and ROM 73 are used as the main memory of the CPU 71. The CPU 71 operates according to the programs enabled for the ROM 73 and the non-volatile memory.

<Functional configuration of protection control device>
FIG. 4 is a block diagram showing a functional configuration of the protection control device 5 according to the first embodiment. With reference to FIG. 4, the protection control device 5A includes an input unit 210, a failure detection unit 220, communication units 230A and 230B, and a relay calculation unit 240. Typically, these functions are realized by a processing circuit. The processing circuit may be dedicated hardware, or may be a CPU 71 that executes a program stored in the internal memory (for example, RAM 72, ROM 73) of the arithmetic processing unit 70 of FIG. When the processing circuit is dedicated hardware, the processing circuit is composed of, for example, FPGA, ASIC, or a combination thereof. The protection control device 5B also has the same functional configuration as the protection control device 5A. Here, the functional configuration related to the protection function of the transmission line L1 and the bus 91a in the protection control device 5A will be described.

The input unit 210 receives inputs of the current IL1a at the A end of the transmission line L1 acquired by the MU2g, the current IL2a at the A end of the transmission line L2 acquired by the MU2a, and the current IB1a of the bus 91a acquired by the MU2d. ..

The failure detection unit 220 detects the failure of each MU2A. For example, each MU2A has a self-diagnosis function. When a failure occurs in itself, each MU 2A transmits a failure signal indicating the failure to the protection control device 5A. The failure detection unit 220 detects that the transmission source MU2A has failed based on the received failure signal. Further, the failure detection unit 220 detects the failure of each MU2A by periodically checking the communication state with each MU2A. Specifically, the failure detection unit 220 determines that the MU2A has failed when communication with a certain MU2A becomes impossible. When the failure detection unit 220 detects a failure of the MU2A, the failure detection unit 220 outputs the failure detection signal of the MU2A to the relay calculation unit 240.

The communication unit 230A communicates with the protection control device 5B provided in the B-end electric station 1B. Specifically, the communication unit 230A receives the data of the current IL1b at the B end of the transmission line L1 from the protection control device 5B. Specifically, the protection control device 5B receives the input of the current IL1b acquired by the MU2j and transmits the data of the current IL1b to the communication unit 230A.

The communication unit 230B communicates with the protection control device provided at the C-terminal electric station 1C. Specifically, the communication unit 230B receives the data of the current IL2c at the C-terminal of the transmission line L2 from the protection control device.

The relay calculation unit 240 executes various relay calculations using the detection result of the failure detection unit 220, the current data received by the input unit 210, and the current data received by the communication units 230A and 230B. Specifically, the relay calculation unit 240 includes a transmission line relay element 241,243 and a bus relay element 245.

The transmission line relay element 241 executes the differential relay calculation based on the current IL1a at the A end of the transmission line L1 and the current IL1b at the B end of the transmission line L1 received from the protection control device 5B. Specifically, the transmission line relay element 241 synchronizes the current IL1a with the received current IL1b in time. Specifically, the transmission line relay element 241 adjusts the sampling time of the current IL1a to match the sampling time of the current IL1b, and is the same as the sampling time of the received current IL1b according to the transmission delay time of the transmission line 300. Time synchronization is performed by selecting the current data of the current IL1a sampled at the time.

The transmission line relay element 241 calculates the vector sum of the current IL1a and the current IL1b after the time synchronization processing, and calculates the magnitude of the calculated vector sum as the differential current IDL1. The transmission line relay element 241 determines whether or not the differential current IDL1 is larger than the threshold value K1 (that is, whether or not IDL1> K1 holds). When IDL1> K1 is established, the transmission line relay element 241 determines that an accident has occurred in the transmission line L1 and outputs an operation signal indicating the operation of the transmission line relay element 241. In this case, the transmission line relay element 241 outputs the trip signal TS to, for example, the circuit breaker 21a provided at the A end of the transmission line L1. As a result, the transmission line relay element 241 protects the protected section of the transmission line L1.

However, when the failure of the MU2g that acquires the current IL1a is detected by the failure detection unit 220, the transmission line relay element 241 cannot accurately determine the accident of the transmission line L1 using the current IL1a. Therefore, when a failure of MU2g is detected, the output of the transmission line relay element 241 (that is, the output of the operation signal) is locked.

The transmission line relay element 243 has the same function as the transmission line relay element 241. Specifically, the transmission line relay element 243 calculates the magnitude of the vector sum of the current IL2a and the current IL2c after the time synchronization process as the differential current IDL2. The transmission line relay element 243 determines whether or not the differential current IDL2 is larger than the threshold value K2 (that is, whether or not IDL2> K2 holds). When IDL2> K2 is established, the transmission line relay element 243 determines that an accident has occurred in the transmission line L2 and outputs an operation signal (for example, a trip signal to the circuit breaker 22a provided at the A end of the transmission line L2). Output TS). As a result, the transmission line relay element 243 protects the protected section of the transmission line L2.

Even when the failure of the MU 2g is detected by the failure detection unit 220, the transmission line relay element 243 can accurately determine the accident of the transmission line L2. Therefore, even if a failure of MU2g is detected, the output of the transmission line relay element 243 is not locked. On the other hand, when a failure of the MU2a that acquires the current IL2a is detected, the output of the transmission line relay element 243 is locked.

The bus relay element 245 detects an accident on the bus 91a by differential relay calculation. First, the function of the bus relay element 245 when the failure of the MU 2g is not detected by the failure detection unit 220 will be described.

Specifically, the bus relay element 245 calculates the magnitude of the vector sum of the current ILa of the transmission line L1, the current IL2a of the transmission line L2, and the current IB1a of the bus 91a as the differential current IDb1. The bus relay element 245 determines whether or not the differential current IDb1 is larger than the threshold value K3 (that is, whether or not IDb1> K3 holds). When IDb1> K3 is established, the bus relay element 245 determines that an accident has occurred in the bus 91a and outputs an operation signal. Specifically, the bus relay element 245 trips to the circuit breaker 21a provided at the A end of the transmission line L1, the circuit breaker 22a provided at the A end of the transmission line L2, and the circuit breaker 25a provided at the bus tie. Output the signal TS. As a result, the bus relay element 245 protects the protection section of the bus 91a.

Next, the function of the bus relay element 245 when a failure of MU2g is detected will be described. When the bus relay element 245 receives a failure detection signal indicating a failure of the MU 2g from the failure detection unit 220, the bus relay element 245 changes from the protection section of the bus 91a to the extended protection section including the protection section of the transmission line L1 and the protection section of the bus 91a. Change the protection target. In this case, the bus relay element 245 stops the individual protection of the bus 91a based on the differential current IDb1.

Specifically, the bus relay element 245 executes a differential relay calculation based on the current IL1b at the B end of the transmission line L1, the current IL2a at the A end of the transmission line L2, and the current IB1a of the bus 91a. The bus relay element 245 synchronizes the currents IL2a and IB1a with the received current IL1b in time. Subsequently, the bus relay element 245 calculates the magnitude of the vector sum of the current IL1b, the current IL2a, and the current IB1a as the differential current IDx. The bus relay element 245 determines whether or not the differential current IDx is larger than the threshold value K4 (that is, whether or not IDx> K4 holds). When IDx> K4 is established, the bus relay element 245 determines that an accident has occurred in the extended protection section and outputs an operation signal. For example, the bus relay element 245 outputs the trip signal TS to the circuit breaker 21a, the circuit breaker 22a, and the circuit breaker 25a. As a result, the bus relay element 245 protects the extended protection section.

As described above, the relay calculation unit 240 executes the relay calculation based on the detection result of the failure detection unit 220. Specifically, when the failure detection unit 220 does not detect the failure of the MU2g, the relay calculation unit 240 executes a differential relay calculation for protecting the transmission line L1 based on the current IL1a and the current IL1b. A differential relay operation for protecting the bus 91a is performed based on the current IL1a, the current IL2a, and the current IB1a. As a result, the relay calculation unit 240 individually protects the transmission line L1 and the bus 91a.

On the other hand, when a failure of MU2g is detected by the failure detection unit 220, the relay calculation unit 240 extends the protection section of the transmission line L1 and the protection section of the bus 91a based on the current IL2a, the current IB1a, and the current IL1b. Perform a differential relay operation to protect the protection section. The relay calculation unit 240 determines whether or not an accident has occurred in the extended protection section based on the differential relay calculation result. When the relay calculation unit 240 determines that an accident has occurred in the extended protection section, the relay calculation unit 240 opens the circuit breakers 21a, 22a, 25a. Specifically, the relay calculation unit 240 outputs the trip signal TS to the circuit breakers 21a, 22a, 25a.

When a failure of MU2g is detected, the protection control device 5A cannot transmit the current IL1a used for protecting the transmission line L1 in the protection control device 5B. As described above, the added current Is of the current IL2a and the current IB1a can be regarded as equivalent to the current IL1a. Therefore, the communication unit 230A transmits the failure information indicating the failure of the MU 2g and the data of the added current Is to the protection control device 5B. The communication unit 230A may transmit the protection section information indicating that the relay calculation unit 240 protects the extended protection section to the protection control device 5B in response to the failure detection of the MU 2g.

By receiving the failure information and the data of the added current Is, the protection control device 5B can determine that the MU 2g has failed and that the added current Is is a substitute value for the current IL1a. In this case, the relay calculation unit (for example, the transmission line relay element) of the protection control device 5B executes the differential relay calculation based on the added current Is and the current IL1b at the B end of the transmission line L1. As a result, the relay calculation unit protects the extended protection section including the protection section of the transmission line L1 and the protection section of the bus 91a based on the differential relay calculation result. When the differential current (that is, the magnitude of the vector sum of the added current Is and the current IL1b) is larger than the threshold value, the relay calculation unit determines that an accident has occurred in the extended protection section and outputs an operation signal. For example, the relay calculation unit outputs the trip signal TS to the circuit breaker 21b.

<Processing procedure>
FIG. 5 is a flowchart showing an example of the processing procedure of the protection control device 5A according to the first embodiment. Typically, each step in FIG. 5 is performed by the processing circuit of the protection control device 5A (eg, CPU 71). In the example of FIG. 5, it is assumed that a failure occurs in MU2g. It is assumed that the protection control device 5A acquires electric energy data from each MU2A and acquires current data from the protection control device 5B at a predetermined cycle.

With reference to FIG. 5, the protection control device 5A detects the failure of the MU 2g (step S10). The protection control device 5A locks the output of the transmission line relay element 241 that individually protects the transmission line L1 (step S12). The protection control device 5A changes the protection section of the bus relay element 245 from the protection section of the bus 91a to the extended protection section (step S14). The protection control device 5A calculates the added current Is of the current IL2a and the current IB1a, and transmits the data of the added current Is and the failure information of the MU 2g to the protection control device 5B (step S16).

The protection control device 5A executes a differential relay operation based on the current IL2a, the current IB1a, and the current IL1b, and determines whether or not an accident has occurred in the extended protection section (step S18). When an accident occurs (YES in step S18), the protection control device 5A outputs the trip signal TS to the circuit breakers 21a, 22a, 25a (step S20). On the other hand, when no accident has occurred (NO in step S18), the protection control device 5A executes the process of step S18. That is, the protection control device 5A continues to protect the extended protection section.

<Advantage>
According to the first embodiment, when a failure occurs in one MU2g that takes in the current IL1a at the A end of the transmission line L1, the protection target section becomes an extended protection section including the protection section of the transmission line L1 and the protection section of the bus 91a. Be changed. As a result, even if a failure occurs in the MU 2g, the protection control device 5A can continue the operation of the bus protection and the transmission line protection in the extended protection section.

Embodiment 2.
The protection control device 5A according to the first embodiment protects the extended protection section from the bus 91a to the transmission line L1 when a failure of the MU 2g is detected. Therefore, when an accident occurs in the extended protection section, It is not possible to distinguish whether an accident has occurred on the transmission line L1 or an accident on the bus 91a. Therefore, the protection control device 5A according to the first embodiment uniformly opens the circuit breakers 21a, 22a, and 25a when it is determined that an accident has occurred in the extended protection section. In the second embodiment, a configuration in which the circuit breaker is opened according to the location where the accident occurs will be described.

FIG. 6 is a diagram for explaining the operation of the protection control device 5A when an accident occurs on the B end side of the transmission line L1 in the extended protection section. In FIG. 6, some current transformers and MUs are not shown for ease of illustration. Further, in the example of FIG. 6, it is assumed that a failure of MU2g has occurred and an accident has occurred at the accident point F1 near the B end of the transmission line L1.

With reference to FIG. 6, the protection control device 5A according to the second embodiment detects a failure of the MU 2g and executes a differential relay operation based on the current IL2a, the current IB1a and the current IL1b to protect the extended protection section. .. Since the accident point F1 is near the B end of the transmission line L1, the accident is within the extended protection section. Therefore, the protection control device 5A determines that an accident has occurred in the extended protection section based on the differential relay calculation result.

In the second embodiment, the protection control device 5A further determines whether or not the accident point F1 is in the vicinity of the bus 91a based on the voltage V1a of the bus 91a. Specifically, the voltage V1a of the bus 91a reflects the accident voltage proportional to the distance from the bus 91a to the accident point. Therefore, when the voltage V1a is equal to or higher than the reference voltage Vs, the protection control device 5A determines that no accident has occurred in the vicinity of the bus 91a. On the other hand, when the voltage V1a is less than the reference voltage Vs, the protection control device 5A determines that an accident has occurred in the vicinity of the bus 91a. In the example of FIG. 6, since the fault point F1 is not in the vicinity of the bus 91a, the voltage V1a is equal to or higher than the reference voltage Vs. Therefore, the protection control device 5A determines that the accident in the extended protection section is not in the vicinity of the bus 91a. The reference voltage Vs is set to, for example, about 10% of the set value of the undervoltage element for detecting the voltage drop of the bus voltage.

The protection control device 5B receives the failure information of the MU 2g and the added current Is from the protection control device 5A, and executes a differential relay operation based on the added current Is and the current IL1b to protect the extended protection section. The protection control device 5B determines that an accident has occurred in the extended protection section based on the differential relay calculation result.

In the second embodiment, the protection control device 5B further determines whether or not the accident point F1 is in the vicinity of the bus 91b based on the voltage V1b of the bus 91b. In the example of FIG. 6, since the accident point F1 is generated on the B end side of the transmission line L1 and is in the vicinity of the bus 91b, the voltage V1b is less than the reference voltage Vs. Therefore, the protection control device 5B determines that the accident in the extended protection section is in the vicinity of the bus 91b. In this case, the protection control device 5B outputs the trip signal TS to the circuit breaker 21b and transmits the release request signal of the circuit breaker 21a to the protection control device 5A.

The protection control device 5A outputs a trip signal TS to the circuit breaker 21a based on the received open request signal of the circuit breaker 21a. When the protection control device 5A determines that an accident has occurred in the extended protection section based on the differential relay calculation and determines that the voltage V1a is equal to or higher than the reference voltage Vs, the accident occurs in the vicinity of the bus 91a. It can be determined that there is no such thing. Therefore, the circuit breaker 22a provided at the A end of the transmission line L2 and the circuit breaker 25a provided in the bus tie are not opened. That is, the protection control device 5A does not output the trip signal TS to the circuit breaker 22a and the circuit breaker 25a.

FIG. 7 is a diagram for explaining the operation of the protection control device 5A when an accident occurs in the bus 91a of the A-end electric station 1A. In FIG. 7, some current transformers and MUs are not shown for ease of illustration. In the example of FIG. 7, it is assumed that a failure of MU2g has occurred and an accident has occurred at the accident point F2 inside the bus 91a.

With reference to FIG. 7, the protection control device 5A according to the second embodiment detects a failure of the MU 2g and executes a differential relay operation based on the current IL2a, the current IB1a and the current IL1b to protect the extended protection section. .. Since the accident point F2 is inside the bus 91a, the accident is within the extended protection section. Therefore, the protection control device 5A determines that an accident has occurred in the extended protection section based on the differential relay calculation result.

Further, the protection control device 5A determines whether or not the accident point F2 is in the vicinity of the bus 91a based on the voltage V1a of the bus 91a. In the example of FIG. 7, since the fault point F2 is inside the bus 91a, the voltage V1a is less than the reference voltage Vs. Therefore, the protection control device 5A determines that the accident in the extended protection section is in the vicinity of the bus 91a.

The protection control device 5B receives the failure information of the MU 2g and the added current Is from the protection control device 5A, and executes a differential relay operation based on the added current Is and the current IL1b to protect the extended protection section. The protection control device 5B determines that an accident has occurred in the extended protection section based on the differential relay calculation result.

Further, the protection control device 5B determines whether or not the accident point F2 is in the vicinity of the bus 91b based on the voltage V1b of the bus 91b. In the example of FIG. 7, since the fault point F2 is inside the bus 91a, the voltage V1b is equal to or higher than the reference voltage Vs. Therefore, the protection control device 5B determines that the accident in the extended protection section is not in the vicinity of the bus 91b. Since the protection control device 5B has determined that an accident has occurred in the extended protection section, the trip signal TS is output to the circuit breaker 21b even in this case. As a result, the circuit breaker 21b is opened, so that the protection control device 5B transmits a release request signal for opening the circuit breaker 21a at the other end to the protection control device 5A.

The protection control device 5A outputs a trip signal TS to the circuit breaker 21a based on the received open request signal of the circuit breaker 21a. Further, when the protection control device 5A determines that an accident has occurred in the extended protection section based on the differential relay calculation and determines that the voltage V1a is less than the reference voltage Vs, the accident occurs in the vicinity of the bus 91a. It can be determined that it has occurred. Therefore, the protection control device 5A may be configured to output the trip signal TS to the circuit breaker 21a based on the determination result without being based on the opening request signal of the circuit breaker 21a. Further, the protection control device 5A outputs a trip signal TS to the circuit breaker 22a and the circuit breaker 25a based on the determination result.

Even if the protection control device 5A is configured to output the trip signal TS to the circuit breaker 21a and output the trip signal TS to the circuit breaker 22a and the circuit breaker 25a after a predetermined time (for example, 50 ms) has elapsed from the output. good. The reason for this will be described below.

Specifically, in the example of FIG. 7, since the MU 2g is out of order, the protection control device 5A cannot acquire the current IL1a. Therefore, even if the protection control device 5A can determine that an accident has occurred in the vicinity of the bus 91a, it clearly determines whether the accident is an accident at the A end of the transmission line L1 or an internal accident of the bus 91a. It is not possible.

Therefore, for example, a method of confirming a change in the fault current waveform can be considered by opening the circuit breaker 21a provided on the transmission line L1 and then delaying the opening of the circuit breaker 22a and the circuit breaker 25a. Specifically, it is possible to confirm which circuit breaker is opened when the accident current is removed. For example, if the accident current is removed after opening the circuit breaker 21a, it can be estimated that the accident is not an internal accident of the bus 91a but an accident at the A end of the transmission line L1. On the other hand, if the fault current is removed after the circuit breaker 21a is opened and the circuit breaker 22a and the circuit breaker 25a are opened, it can be estimated that the fault is an internal fault of the bus 91a. As a result, it is possible to confirm whether the accident is an internal accident of the bus 91a or an accident of the transmission line L1, and it is possible to shorten the recovery time after removing the accident.

<Functional configuration of protection control device>
FIG. 8 is a block diagram showing a functional configuration of the protection control device 5 according to the second embodiment. With reference to FIG. 8, the protection control device 5A according to the second embodiment has a configuration in which the input unit 210 and the relay calculation unit 240 in the protection control device 5A of FIG. 4 are replaced with the input unit 210X and the relay calculation unit 240X, respectively. Equivalent to. The relay calculation unit 240X includes a transmission line relay element 241,243 and a bus relay element 245X. In the following description, detailed description will not be repeated for the parts similar to the functional configuration of FIG.

The input unit 210X receives the input of the voltage V1a of the bus 91a acquired by the MU2c. When a failure of MU2g is detected, the bus relay element 245X executes a differential relay calculation based on the current IL1b, the current IL2a, and the current IB1a, and determines whether or not an accident has occurred in the extended protection section. .. Further, the bus relay element 245X determines whether or not the voltage V1a is equal to or higher than the reference voltage Vs.

In one aspect, the bus relay element 245X determines that an accident has not occurred in the vicinity of the bus 91a when it is determined that an accident has occurred in the extended protection section and the voltage V1a is equal to or higher than the reference voltage Vs. In this case, the bus relay element 245X opens the circuit breaker 21a provided at the A end of the transmission line L1. Specifically, the bus relay element 245X outputs a trip signal TS to the circuit breaker 21a.

In another aspect, the bus relay element 245X determines that an accident has occurred in the vicinity of the bus 91a when it is determined that an accident has occurred in the extended protection section and the voltage V1a is less than the reference voltage Vs. In this case, the bus relay element 245X opens the circuit breaker 21a, the circuit breaker 22a provided at the A end of the transmission line L2, and the circuit breaker 25a provided on the bus 91a. Specifically, the bus relay element 245X outputs the trip signal TS to the circuit breakers 21a, 22a, 25a. In this case, the bus relay element 245X outputs a command for opening the circuit breaker 21a (that is, a trip signal TS), and issues a command for opening each of the circuit breakers 22a and 25a after a lapse of a specified time from the output. It may be output.

<Processing procedure>
FIG. 9 is a flowchart showing an example of the processing procedure of the protection control device 5A according to the second embodiment. Each step of FIG. 9 is executed by the processing circuit of the protection control device 5A. In the example of FIG. 5, it is assumed that a failure occurs in MU2g. It is assumed that the protection control device 5A acquires current data and voltage data from each MU2A and acquires current data from the protection control device 5B at a predetermined cycle.

With reference to FIG. 9, the processes of steps S10 to S18 are the same as the processes of each step of FIG. 4, and therefore the detailed description thereof will not be repeated.

When an accident occurs in the extended protection section (YES in step S18), the protection control device 5A determines whether or not the accident has occurred in the vicinity of the bus 91a (step S50). Specifically, the protection control device 5A determines that the accident has not occurred in the vicinity of the bus 91a when the voltage V1a is equal to or higher than the reference voltage Vs, and when the voltage V1a is less than the reference voltage Vs. Determines that the accident has occurred in the vicinity of the bus 91a.

When the accident occurs in the vicinity of the bus 91a (YES in step S50), the protection control device 5A outputs the trip signal TS to the circuit breakers 21a, 22a, 25a (step S52). Specifically, the protection control device 5A outputs the trip signal TS to the circuit breaker 21a, and outputs the trip signal TS to the circuit breakers 22a and 25a after a lapse of a predetermined time from the output. When the accident has not occurred in the vicinity of the bus 91a (NO in step S50), the protection control device 5A outputs the trip signal TS to the circuit breaker 21a (step S54).

<Advantage>
According to the second embodiment, it is possible to determine whether or not an accident has occurred in the vicinity of the bus 91a in the extended protection section. Therefore, if the accident is not in the vicinity of the bus 91a (for example, the accident at the B end of the transmission line L1), only the circuit breaker 21a is opened and the circuit breakers 22a and 25a are not opened, so that the bus 91a and the transmission line are not opened. The operation of L2 can be continued.

Other embodiments.
(1) In the above-described embodiment, the configuration in which the bus system of the electric station is the double bus system has been described, but the bus system may be the single bus system.

(2) In the above-described embodiment, the relay calculation unit 240 has described a configuration in which an accident determination is performed by a differential relay calculation using only a differential current, but the configuration is not limited to this. For example, the relay calculation unit 240 may be configured to perform an accident determination by a ratio differential relay calculation using a differential current and a suppression current.

For example, when a failure of MU2g is detected, the bus relay element 245 calculates the current IL1b, the current IL2a, and the current IB1a having the largest magnitude as the suppression current IRx. The bus relay element 245 may calculate the scalar sum of the current IL1b, the current IL2a, and the current IB1a as the suppression current IRx.

Subsequently, the bus relay element 245 determines whether or not the relationship between the suppression current IRx and the differential current IDx satisfies a predetermined relationship. Specifically, the bus relay element 245 determines whether the differential current IDx is larger than the value obtained by multiplying the suppression current IRx by the constant α and adding the constant β (that is, whether IDx> α × IRx + β holds. Whether or not) is determined. When IDx> α × IRx + β is established, the bus relay element 245 determines that an accident has occurred in the extended protection section. When the failure of the MU2g is not detected, the bus relay element 245 executes the same ratio differential relay calculation as described above based on the current IL1a, the current IL2a, and the current IB1a, and causes an accident of the bus 91a. Is determined. Similarly, the transmission line relay elements 241,243 may be configured to use the ratio differential relay operation.

(3) The configuration exemplified as the above-described embodiment is an example of the configuration of the present embodiment, can be combined with another known technique, and is not deviating from the gist of the present disclosure. It is also possible to change the configuration by omitting the part.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present disclosure is shown by the scope of claims, not the description described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1A A end electric station, 1B B end electric station, 1CC end electric station, 5A, 5B protection control device, 32 auxiliary transformer, 35 A / D conversion unit, 40,70 arithmetic processing unit, 41,71 CPU, 42 , 72 RAM, 43,73 ROM, 44,74 bus, 50,61 interface section, 51,62 communication circuit, 52 communication line, 63 transmission / reception circuit, 64 digital output circuit, 100 protection control system, 110 extended protection section, 210 , 210X input unit, 220 failure detection unit, 230A, 230B communication unit, 240, 240X relay calculation unit, 241,243 transmission line relay element, 245,245X bus relay element, 300 transmission line.

Claims (9)

A first marsing unit that acquires the current at the first end of the first transmission line that connects the first bus provided at the first end and the second bus provided at the second end.
A second marsing unit that acquires the current at the first end of the second transmission line that connects the first bus and the third bus provided at the third end.
A third marsing unit that acquires the current of the first bus, and
A first protection control device provided at the first end is provided.
The first protection control device is
An input unit that receives inputs for the current at the first end of the first transmission line, the current at the first end of the second transmission line, and the current at the first bus.
A failure detection unit that detects a failure of the first to third marsing units, and
A communication unit that receives data indicating a current at the second end of the first transmission line from a second protection control device provided at the second end, and a communication unit.
Including a relay calculation unit that executes a relay calculation based on the detection result of the failure detection unit.
When a failure of the first marsing unit is detected by the failure detection unit, the relay calculation unit uses the current of the first end of the second transmission line, the current of the first bus, and the second protection. A relay for protecting an extended protection section including a protection section of the first bus and a protection section of the first transmission line based on the current of the second end of the first transmission line received from the control device. A protection control system that performs operations. The relay calculation unit executes a differential relay calculation based on the current at the first end of the second transmission line, the current at the first bus, and the current at the second end of the first transmission line. The protection control system according to claim 1, wherein it is determined whether or not an accident has occurred in the extended protection section based on the differential relay calculation result. When an accident occurs in the extended protection section, the relay calculation unit includes a first transmission line circuit breaker provided on the first end side of the first transmission line and the first end of the second transmission line. The protection control system according to claim 2, which opens the second transmission line circuit breaker provided on the side and the bus circuit breaker provided on the first bus. A fourth marsing unit for acquiring the voltage of the first bus is further provided.
The input unit receives the input of the voltage of the first bus acquired by the fourth marsing unit, and receives the input.
When an accident occurs in the extended protection section and the voltage of the first bus is less than the reference voltage, the relay calculation unit is a first transmission line provided on the first end side of the first transmission line. The protection according to claim 2, which opens the circuit breaker, the second transmission line circuit breaker provided on the first end side of the second transmission line, and the bus circuit breaker provided on the first bus. Control system. The relay calculation unit outputs a command for opening the first transmission line circuit breaker, and a command for opening each of the second transmission line circuit breaker and the bus circuit breaker after a lapse of a predetermined time from the output. 4. The protection control system according to claim 4. When an accident occurs in the extended protection section and the voltage of the first bus is equal to or higher than the reference voltage, the relay calculation unit opens the first transmission line circuit breaker, claim 4 or 5. The protection control system described in. The relay calculation unit protects a protection section of the first transmission line based on the current of the first end of the first transmission line and the current of the second end of the first transmission line. Including
The protection control system according to any one of claims 1 to 6, wherein when the failure detection unit detects a failure of the first marsing unit, the output of the transmission line relay element is locked. When the failure of the first marsing unit is detected, the communication unit has the failure information indicating the failure of the second marsing unit, the current of the first end of the second transmission line, and the current of the first bus. The protection control system according to any one of claims 1 to 7, wherein the data indicating the added current of the above is transmitted to the second protection control device. A first marsing unit that acquires the current at the first end of the first transmission line that connects the first bus provided at the first end and the second bus provided at the second end.
A second marsing unit that acquires the current at the first end of the second transmission line that connects the first bus and the third bus provided at the third end.
A third marsing unit that acquires the current of the first bus, and
The first protection control device provided at the first end and
A second protection control device provided at the second end is provided.
The first protection control device is
An input unit that receives inputs for the current at the first end of the first transmission line, the current at the first end of the second transmission line, and the current at the first bus.
A failure detection unit that detects a failure of the first to third marsing units, and a failure detection unit.
A communication unit that receives data indicating the current at the second end of the first transmission line from the second protection control device, and
Including a relay calculation unit that executes a relay calculation based on the detection result of the failure detection unit.
When a failure of the first marsing unit is detected by the failure detection unit, the relay calculation unit uses the current of the first end of the second transmission line, the current of the first bus, and the second protection. A relay for protecting an extended protection section including a protection section of the first bus and a protection section of the first transmission line based on the current of the second end of the first transmission line received from the control device. A protection control system that performs operations.

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