JP6881068B2 - Busbar protection device - Google Patents

Description

The present invention relates to a bus protection device that outputs an open output to a circuit breaker of the accident bus in order to disconnect the bus on the side where the short circuit / ground fault has occurred from the power system.

As a busbar system of a substation, for example, there is a double busbar system. The double bus system includes two bus lines and a bus tie (bus bar connection) that connects the two bus bars. The transmission line on the generator side and the transmission line on the load side are connected to one of the two buses by switching the disconnector provided between the two buses.

Further, in order to protect the bus in the event of a ground fault, a short circuit, or the like, for example, a ratio differential relay is provided for each bus. The ratio differential relay calculates the difference current between the current flowing from the transmission line into the bus and the current flowing out from the bus to Bustai. Alternatively, the ratio differential relay calculates the difference current between the current flowing from the bus tie into the bus and the current flowing out from the bus to the transmission line. If the calculated difference current is not zero, the ratio differential relay opens the circuit breaker on the bus tie and the circuit breaker on the transmission line connected to the bus to disconnect the bus from the system in which the accident occurred. This protects the bus.

The following techniques described in Patent Documents 1 to 3 are known as related techniques.
The distance relay device described in Patent Document 1 is applied to one circuit breaker bus system, and is an auxiliary transformer that converts the bus side CT secondary current, a transformer that converts the bus center side CT secondary current, and two CTs. It consists of an auxiliary transformer that converts the sum current of. Further, the distance relay uses an auxiliary transformer that converts the secondary voltage of the PT connected to the transmission line, a means for recognizing the open / closed state of the transmission line disconnector, and a CT sum current and a secondary signal of the PT. It is further composed of an urged distance relay and a ratio differential relay with a CT current on the bus side and a CT current on the center side of the bus. Then, the distance relay outputs a cutoff command to the circuit breaker by the operation of the distance relay when the transmission line disconnector is closed, and the ratio difference is only when the transmission line disconnector is open. Further provided is a means for outputting a disconnection command to the disconnector by the operation of the relay.

In the bus protection relay device described in Patent Document 2, the bus current is controlled to "zero" when the bus circuit breaker is "off", and the other-side bus current and the own-side bus inflow current flowing through the bus circuit breaker are controlled. Detect and protect the bus. The bus protection relay device is provided with a circuit that captures the input command of the bus circuit breaker and a circuit that cancels the control of the bus current "zero" by the input command of the bus. It is characterized by eliminating the current "zero" control release delay.

The blind spot failure detection system described in Patent Document 3 detects a blind spot accident that occurs in a multi-terminal transmission line system, and includes open / close detection means, current data detection means, and determination means. The open / close detection means detects the open / close of the circuit breaker installed at each terminal. The current data detecting means detects the current data at the terminal. The determination means is a logical product of the open / closed state of the circuit breaker detected by the open / close detecting means and the current data detected by the current data detecting means exceeding a preset set value. Determine the blind spot accident based on.

Japanese Unexamined Patent Publication No. 5-83844 Japanese Unexamined Patent Publication No. 7-131929 Japanese Unexamined Patent Publication No. 9-240916

However, depending on the arrangement of the current sensor that measures the current flowing through the bus tie, the ratio differential relay does not operate in response to the accident that occurred in the bus tie, and a blind spot accident in which the bus cannot be protected may occur.

An object of one aspect of the present invention is to provide a bus protection device that performs bus protection regardless of the arrangement of a current sensor that measures the current flowing through the bus tie in the double bus system.

The bus protection device according to one embodiment includes a second bus ratio differential relay, an overcurrent detection unit, a first bus abnormal voltage detection unit, a measured value setting unit, and a first bus ratio differential relay. The second bus ratio differential relay performs a second bus protection operation that at least opens the bus tie circuit breaker installed in the bus tie in response to an accident that occurs in the bus tie connecting the first bus and the second bus. The overcurrent detection unit detects the overcurrent flowing through the bus tie. The first bus abnormal voltage detection unit detects the abnormal voltage applied to the first bus. The measured value setting unit sets the measured value of the current flowing through the bus to zero when the second bus protection operation is performed and an overcurrent or an abnormal voltage is detected. The first bus ratio differential relay is the first bus protection that at least opens the transmission line breaker installed on the transmission line according to the current flowing through the transmission line connected to the first bus and the measured value set to zero. Perform the action.

According to the bus protection device according to one embodiment, in the double bus system, bus protection can be performed regardless of the arrangement of the current sensor that measures the current flowing through the bus tie.

It is a figure which shows the configuration example of the electric power system to which the bus protection device according to an embodiment is applied. It is a figure which shows the 1st configuration example of the bus bar protection device according to an embodiment. It is a figure which shows the arrangement example of the current sensor of Bustai which does not need blind spot protection. It is a figure which shows the structural example of one current sensor which has the function of the 5th and 6th current sensors. It is an exemplary timing chart illustrating the operation of each part of the bus protection device according to the embodiment. It is a figure which shows the 2nd configuration example of the bus bar protection device according to an embodiment.

Hereinafter, embodiments will be described in detail based on the drawings.

<Power system including bus protection device>
FIG. 1 is a diagram showing a configuration example of a power system to which a bus protection device according to an embodiment is applied. In the example shown in FIG. 1, the power system PS includes a first bus L _A, and a second bus line L _B, doubly and Busutai BT is provided for connecting the first bus L _A and the second bus line L _B It is a bus-type power system.

The first transmission line _{L 1} ~ fourth transmission line _{L 4} are, by the first generating line _{L A} and the first disconnecting switches DS ₁ ~ eighth disconnecting switches DS ₈ disposed between the second bus line _{L B} is switched , connected to the first busbar _{L a} or the second busbar _{L B.} For example, in the example shown in FIG. 1, the first transmission line L ₁ of the first generator P ₁ side, first disconnecting switches DS ₁ is closed by the second disconnecting switch DS ₂ opened, the power receiving side 1 to connect to the bus line _{L A.} The second transmission line _{L 2} of the second generator _{P 2} side, the fifth disconnecting switches DS ₅ is closed to connect the first bus _{L A} by the sixth disconnecting switches DS ₆ is opened. The third transmission line _{L 3} of the first load LD ₁ side, opens the third disconnecting switches DS _3, by a fourth disconnector DS ₄ is closed, is connected to the second bus line _{L B} of the power transmission. Fourth transmission line _{L 4} of the second load LD ₂ side, the seventh disconnecting switch DS ₇ is opened and connected to the second bus _{L B} by the eighth disconnecting switch DS ₈ is closed. Note that FIG. 1 shows a configuration example of a 4-line bus in which four transmission lines are connected to two busbars, but the power system to which the busbar protection device according to the embodiment is applied is a 4-line busbar. It is not limited to, and may be an n-line bus (n is an integer of 1 or more).

The bus protection device 1 is an example of the bus protection device according to the embodiment. Busbar protection device 1 is a device for protecting a first busbar L _A and the second bus line L _B from the bus accident. Bus accident, for example, the first busbar L _A, second busbar L _B, or a ground fault or a short circuit accident occurring in Busutai BT. Ground fault, the first busbar L _A, an accident second busbar L _B, or where the phase of the transmission lines constituting Busutai BT and the ground connection. Short circuit, the first busbar L _A, an accident second busbar L _B, or the phase of the transmission lines that constitute the Busutai BT connection.

For example, if the accident first busbar L _A or Busutai BT is generated in the first protection zone Z _A indicated by a broken line, bus protection device 1 protects separately from the electric power system of the first busbar L _A accident occurred The first busbar protection operation is executed. Specifically, the bus protection device 1 outputs a circuit breaker opening command (trip command) to the first circuit breaker CB ₁ , the second circuit breaker CB ₂ , and the busty circuit breaker CB _BT. For example, when the accident second busbar L _B or Busutai BT is generated in the second protection zone Z _B indicated by broken lines, bus protection device 1 is disconnected from the power system to the second busbar L _B accident occurred Perform a second busbar protection operation to protect. Specifically, the bus protection device 1 outputs a circuit breaker opening command to the third circuit breaker CB ₃ , the fourth circuit breaker CB ₄ , and the busty circuit breaker CB _BT.

The first circuit breaker CB ₁ to the fourth circuit breaker CB ₄ are transmission line circuit breakers, and are accident elimination switches installed on _{the corresponding first transmission line L 1} to fourth transmission line L _4. The Bustai circuit breaker CB _BT is an accident elimination switch installed on the Bustai BT. The first circuit breaker CB ₁ to the fourth circuit breaker CB ₄ and the bus tie circuit breaker CB _BT are opened according to the circuit breaker opening command input from the bus protection device 1. For example, the first circuit breakers CB _1, second circuit breaker CB _2, and Busutai breaker CB _BT is open according to breakers opening command entered in the event of an accident, the first busbar L _A, the power system of an accident Separated from. The third breaker CB _3, fourth breaker CB _4, and Busutai breaker CB _BT is open according to breakers opening command entered when an accident occurs, the second bus line L _B is the power system of an accident Separated from.

Busbar protection device 1, based each current flowing through the first transmission line L _{1 ~} fourth transmission line L ₄ and Busutai BT, to the respective voltage applied to the first busbar L _A and the second bus line L _B, The first busbar protection operation and the second busbar protection operation are executed.

Each current flowing through the first transmission line _{L 1} ~ fourth transmission line _{L 4} are, first current sensor CT ₁ ~ fourth current sensor CT ₄ is measured. The first current sensor CT ₁ to the fourth current sensor CT ₄ are, for example, instrument transformers. The first current sensor CT ₁ to the fourth current sensor CT ₄ are installed on the corresponding first transmission line L ₁ to fourth transmission line L _4. The first current sensor CT ₁ to the fourth current sensor CT ₄ output the measured current to the bus protection device 1.

Current flowing from the first bus bar _{L A} to Busutai BT is measurement fifth current sensor CT _5, current flowing from the Busutai BT to the second bus line _{L B} is sixth current sensor CT ₆ is measured. The fifth current sensor CT ₅ and the sixth current sensor CT ₆ are, for example, instrument transformers. The fifth current sensor CT ₅ and the sixth current sensor CT ₆ output the measured current to the bus protection device 1.

The fifth current sensor CT ₅ and the sixth current sensor CT ₆ are installed in the Bustai BT. Specifically, in the example shown in FIG. 1, the fifth current sensor CT ₅ and sixth current sensor CT ₆ is placed Busutai BT between Busutai breaker _{CB BT} and the first busbar _{L A.}

As described above, in the example shown in FIG. 1, the fifth current sensor CT ₅ and the sixth current sensor CT ₆ are installed on the bus tie BT on one side of the bus tie circuit breaker CB _BT. That is, as shown in FIG. 3, the fifth current sensor CT ₅ and the sixth current sensor CT ₆ are not installed on the Bustai BT with the _{Bustai circuit breaker CB BT in between.} FIG. 3 is a diagram showing an arrangement example of a Bustai current sensor that does not require blind spot protection. The fifth current sensor CT ₅ and the sixth current sensor CT ₆ may be integrally configured in, for example, one housing. If the fifth current sensor CT ₅ and the sixth current sensor CT ₆ are integrally configured, the installation cost can be reduced as compared with the case where the two current sensors are installed separately.

Further, although the directions (positive or negative) of the currents measured by the fifth current sensor CT ₅ and the sixth current sensor CT ₆ are different from each other, the absolute values of both currents are the same. Therefore, by reversing the direction of the current measured by one current sensor, it is possible to obtain the current measured by the other current sensor. Therefore, as shown in FIG. 4, _{depending on the embodiment, the fifth current sensor CT 5} and the sixth current sensor CT ₆ may be configured by one current sensor having the functions of both current sensors. FIG. 4 is a diagram showing a configuration example of one current sensor having the functions of the fifth and sixth current sensors. In the example shown in FIG. 4, the fifth current sensor CT ₅ is not installed, and the reversing device INV inverts the measured value of _{the sixth current sensor CT 6} by operating as, for example, an analog amplifier having a gain of -1. As a result, even without installing a fifth current sensor CT _5, you can obtain the same current value and the measured value of the fifth current sensor CT _5. If the fifth current sensor CT ₅ and the sixth current sensor CT ₆ are configured by one current sensor, the installation cost can be reduced as compared with the case where two current sensors are installed.

The voltage applied to the first busbar L _A is measured first voltage sensor VT _A, the voltage applied to the second bus line L _B is the second voltage sensor VT _B measures. The first voltage sensor VT _A, is installed in the first busbar L _A, and outputs the measured voltage to the busbar protection device 1. Second voltage sensor VT _B is installed in the second bus L _B, and outputs the measured voltage to the busbar protection device 1.

<Busbar protection device>
While showing a configuration example of the bus protection device 1, a specific example of the bus protection operation executed by the bus protection device 1 will be described below.

<< First configuration example >>
FIG. 2 is a diagram showing a first configuration example of the bus protection device according to the embodiment. In the first configuration example shown in FIG. 2, the bus protection device 1 includes an analog / digital (A / D (Analog / Digital)) converter 11 and a processing unit 12.

An analog signal of each current output by the first current sensor CT ₁ to the sixth current sensor CT _{6 is input to the analog / digital converter 11.} The analog / digital converter 11 converts the analog signal of each current into a digital signal, and outputs each current, which is a digital signal, to the processing unit 12.

Further, analog signals of each voltage output by the first voltage sensor VT _A and the second voltage sensor VT _{B are input to the analog / digital converter 11.} The analog / digital converter 11 converts an analog signal of each voltage into a digital signal, and outputs each voltage, which is a digital signal, to the processing unit 12.

The processing unit 12 is, for example, a CPU (Central Processing Unit), a multi-core CPU, or a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), or the like). Each current and each voltage output by the analog / digital converter 11 is input to the processing unit 12. The processing unit 12 executes a bus protection operation based on each input current and each voltage. In the first configuration example shown in FIG. 2, the processing unit 12 includes a first bus ratio differential relay RDf _A and a second bus ratio differential relay RDf _B.

<< One busbar protection >>
For example, if an accident such as ground fault or short-circuit failure occurs in any fault point F _A of the first busbar L _{A (see} FIG. 1), since the fault point F _A is present in the first protected area Z _A, the The 1-bus ratio differential relay RDf _A executes the first bus protection operation as described below. The first bus ratio differential relay RDf _A calculates the difference current between the current measured by the first current sensor CT ₁ and the second current sensor CT ₂ and the current measured by the fifth current sensor CT _5. Current first current sensor CT ₁ is measured is a current flowing from the first transmission line L ₁ to the first busbar L _A, the current second current sensor CT ₂ is measured from the second transmission line L ₂ a current flowing into the first bus L _a. Also, the current fifth current sensor CT ₅ is measured is the current out of the first busbar L _A to Busutai BT. During normal operation, where no accidents have occurred, the differential current is zero. However, if an accident occurs at an accident point F _A, it is greater towards the fault point F _A current flows, the difference current does not become zero. Therefore, the first bus ratio differential relay RDf _A executes the first bus protection operation based on the calculated difference current. That is, the first bus ratio differential relay RDf _A outputs a circuit breaker opening command to the first circuit breaker CB ₁ , the second circuit breaker CB ₂ , and the bus tie circuit breaker CB _BT . The circuit breaker open command is, for example, a signal having a logical value of “1”. As described above, the first bus ratio differential relay RDf _A functions as a ratio differential relay.

For example, when the accident such as ground fault or short-circuit failure occurs in any fault point F _B of the second busbar L _{B (see} FIG. 1), since the fault point F _B is present in the second protection zone Z _B , The second bus ratio differential relay RDf _B executes the second bus protection operation as described below. The second bus ratio differential relay RDf _B calculates the difference current between the current measured by the sixth current sensor CT ₆ and the current measured by the third current sensor CT ₃ and the fourth current sensor CT _4. Sixth current current sensor CT ₆ was measured, a current flowing from the Busutai BT to the second bus L _B. Also, the current third current sensor CT ₃ is measured is the current out of the second busbar _{L B} to the third transmission line _{L 3,} the current fourth current sensor CT ₄ is measured, the second bus line _{L B} from a current flowing to the fourth transmission line L _4. During normal operation, where no accidents have occurred, the differential current is zero. However, if an accident occurs at an accident point F _B, since high current toward the fault point F _B flows, the difference current does not become zero. Therefore, the second bus ratio differential relay RDf _B executes the second bus protection operation based on the calculated difference current. That is, the second bus ratio differential relay RDf _B outputs a circuit breaker opening command to the third circuit breaker CB ₃ , the fourth circuit breaker CB ₄ , and the bus tie circuit breaker CB _BT . As described above, the second bus ratio differential relay RDf _B functions as a ratio differential relay.

<< In case of blind spot accident >>
Further, when an accident such as a ground fault or a short circuit accident _{occurs at the accident point FBT} (see FIG. 1), the processing unit 12 performs the first bus protection operation and the second bus protection operation as described below. Execute. As shown in FIG. 1, the accident point F _BT is an accident point existing in the bus tie BT between the fifth current sensor CT ₅ and the sixth current sensor CT ₆ and the bus tie circuit breaker CB _BT.

When an accident _{occurs at the accident point FBT} , the current measured by the sixth current sensor CT ₆ is the same as in the above-mentioned normal operation. However, if an accident occurs at an accident point _{F BT,} a current flows from the third transmission line _{L 3} and the fourth transmission line _{L 4} to the second bus _{L B.} That is, the direction of the current measured by the third current sensor CT ₃ and the fourth current sensor CT ₄ is opposite to the direction of the current during normal operation. Therefore, the difference current calculated by the second bus ratio differential relay RDf _B does not become zero. Therefore, the second bus ratio differential relay RDf _B executes the second bus protection operation based on the calculated difference current. That is, the second bus ratio differential relay RDf _B outputs a circuit breaker opening command to the third circuit breaker CB ₃ , the fourth circuit breaker CB ₄ , and the bus tie circuit breaker CB _BT .

Further, when an accident _{occurs at the accident point FBT} , the directions of the currents measured by the first current sensor CT ₁ and the second current sensor CT ₂ are the same as those in the above-mentioned normal operation. In the configuration example shown in FIG. 1, since the fifth current sensor CT ₅ is installed, the fifth current sensor CT ₅ measures the Busutai BT between the first busbar L _A and Busutai breaker CB _BT The current is the same as in normal operation. As a result, the difference current calculated by the first bus ratio differential relay RDf _{A becomes zero.} Therefore, the first bus protection operation is not executed based on the difference current as described above.

Incidentally, if, in the case (FIG. 3) of the fifth current sensor CT ₅ is installed in Busutai BT between Busutai breaker CB _BT and second bus L _B, the first busbar protection operation based on the difference current Is executed. Specifically, if the accident fault point F _BT occurs, current flows from the second bus L _B in Busutai BT, the fifth current sensor CT ₅ was measured current orientation normal during operation of the current The direction is opposite. Therefore, the difference current calculated by the first bus ratio differential relay RDf _A does not become zero. Therefore, the first bus ratio differential relay RDf _A executes the first bus protection operation based on the calculated difference current. That is, the first bus ratio differential relay RDf _A outputs a circuit breaker opening command to the first circuit breaker CB ₁ , the second circuit breaker CB ₂ , and the bus tie circuit breaker CB _BT . Therefore, in a case where the fifth current sensor CT ₅ is installed in Busutai BT between Busutai breaker _{CB BT} and second bus _{L B} (FIG. 3), the first generating line _{L A} is not disconnected from the power system No blind spot accident occurs.

As described above, when the fifth current sensor CT ₅ is installed in position as shown in Figure 1, may blind spot accident from the electric power system of an accident first busbar L _A not disconnected occurs is there. However, when an accident _{occurs at the accident point FBT} , the processing unit 12 executes the first bus protection operation as described below, detects that the accident that has occurred is a blind spot accident, and eliminates the accident. ..

As shown in FIG. 2, the processing unit 12 includes a first overcurrent detection unit 121 _A , a second overcurrent detection unit 121 _B , a first bus abnormal voltage detection unit 122 _A , and a second bus abnormal voltage detection unit 122 _B. Is further included. Further, the processing unit 12 includes a first operation delay timer TON ₁ , a second operation delay timer TON ₂ , a first return delay timer TOFF ₁ , a second return delay timer TOFF ₂ , a first AND unit AND ₁ , and a second logic. The product unit AND ₂ , the first measured value setting unit 123 ₁ , and the second measured value setting unit 123 ₂ are included.

Further illustrating the operation of each portion of the busbar protection device 1 when an accident occurs in the fault point F _BT below along with the timing chart shown in FIG. FIG. 5 is an exemplary timing chart illustrating the operation of each part of the bus protection device according to the embodiment.

The first overcurrent detection unit 121 _A and the second overcurrent detection unit 121 _B are examples of the overcurrent detection unit that detects the overcurrent flowing through the Bustai BT. The first overcurrent detection unit 121 _A detects the overcurrent flowing through the Bustai BT when the current measured by the fifth current sensor CT _{5 exceeds a predetermined level.} Further, the second overcurrent detection unit 121 _B detects the overcurrent flowing through the Bustai BT when the current measured by the sixth current sensor CT _{6 exceeds a predetermined level.} When an overcurrent is detected, the first overcurrent detection unit 121 _A and the second overcurrent detection unit 121 _B output an overcurrent detection signal indicating the detection of the overcurrent. The overcurrent detection signal indicating the detection of the overcurrent is, for example, a signal having a logic value of “1”.

For example, in a configuration that protects the first busbar _{L A} and the second bus line _{L B} from a ground fault, the first overcurrent detecting section 121 _A and the second overcurrent detecting section 121 _B as ground fault overcurrent relay (OCG) Function. Specifically, the first overcurrent detection unit 121 _A and the second overcurrent detection unit 121 _B calculate the zero-phase current from the combined value of the currents flowing through the transmission lines of each phase constituting the Bustai BT. When the zero-phase current exceeds a predetermined level, the first overcurrent detection unit 121 _A and the second overcurrent detection unit 121 _B detect the overcurrent caused by the ground fault and indicate the overcurrent detection. Outputs a current detection signal.

Further, for example, in a configuration that protects the first busbar _{L A} and the second bus line _{L B} from short circuit, the first overcurrent detecting section 121 _A and the second overcurrent detecting section 121 _B is phase overcurrent relay (OC ) Functions. Specifically, when the current flowing through the transmission lines of each phase constituting the Bustai BT exceeds a predetermined level, the first overcurrent detection unit 121 _A and the second overcurrent detection unit 121 _B are caused by a short circuit accident. The overcurrent is detected, and an overcurrent detection signal indicating the detection of the overcurrent is output.

For example, as shown in FIG. 5, after the required operating time has elapsed from the occurrence of the accident at the _{accident point FBT , the first overcurrent detection unit 121 A} and the second overcurrent detection unit 121 _B have a logical value of “1”. Outputs an overcurrent detection signal. In order to clarify the explanation, in the example shown in FIG. 5, the timing at which the overcurrent detection signal is output is the same as the timing at which the second bus ratio differential relay RDf _B outputs the circuit breaker open command. However, both timings may be different.

The first bus abnormal voltage detecting unit 122 _A, in accordance with the voltage first voltage sensor VT _A is measured, is a unit for detecting the applied abnormal voltage to the first bus L _A. The second bus abnormal voltage detection unit 122 _B, in accordance with the voltage which the second voltage sensor VT _B was measured, which is a unit for detecting the applied abnormal voltage to the second bus L _B. When the abnormal voltage is detected, the first bus abnormal voltage detection unit 122 _A and the second bus abnormal voltage detection unit 122 _B output an abnormal voltage detection signal indicating the detection of the abnormal voltage. The abnormal voltage detection signal indicating the detection of the abnormal voltage is, for example, a signal having a logic value of “1”.

For example, in a configuration that protects the first busbar _{L A} and the second bus line _{L B} from a ground fault, the first bus abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B is ground fault over-voltage relay (OVG ) Functions. Specifically, the first bus abnormal voltage detection unit 122 _A and the second bus abnormal voltage detection unit 122 _B calculate the zero-phase voltage from the combined value of the voltages applied to the transmission lines of each phase constituting the Bustai BT. To do. When the calculated zero-phase voltage exceeds a predetermined level, the first bus abnormal voltage detection unit 122 _A and the second bus abnormal voltage detection unit 122 _B detect the overvoltage caused by the ground fault and indicate the detection of the overvoltage. Outputs an abnormal voltage detection signal.

Further, for example, in a configuration that protects the first busbar L _A and the second bus line L _B from short circuit, the first bus abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B is phase undervoltage relay Functions as (UV). Specifically, the first bus abnormal voltage detection unit 122 _A and the second bus abnormal voltage detection unit 122 _B are of the voltage applied to the two phase transmission lines among the transmission lines of each phase constituting the Bustai BT. Calculate the line voltage from the difference. When the calculated line voltage falls below a predetermined level, the first bus abnormal voltage detection unit 122 _A and the second bus abnormal voltage detection unit 122 _B are placed between the two-phase transmission lines for which the line voltage is calculated. The undervoltage caused by the short-circuit accident is detected, and an abnormal voltage detection signal indicating the detection of the undervoltage is output.

For example, as shown in FIG. 5, after the required operation time elapses from accident at the fault point F _BT, first bus abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B is a logical value "1 Outputs an abnormal voltage detection signal. In order to clarify the explanation, in the example shown in FIG. 5, the timing at which the abnormal voltage detection signal is output is the same as the timing at which the second bus ratio differential relay RDf _B outputs the circuit breaker open command. However, both timings may be different. Further, in the example shown in FIG. 5, the timing at which the abnormal voltage detection signal is output is the same as the timing at which the above-mentioned overcurrent detection signal is output, but both timings may be different.

The first logical product unit AND ₁ calculates the logical product of the overcurrent detection signal output by the first overcurrent detection unit 121 _A and the abnormal voltage detection signal output by the first bus abnormal voltage detection unit 122 _A. The result is output to the first operation delay timer TON _1. Further, the second logical product unit AND ₂ calculates the logical product of the overcurrent detection signal output by the second overcurrent detection unit 121 _B and the abnormal voltage detection signal output by the second bus abnormal voltage detection unit 122 _B. , The calculation result is output to the second operation delay timer TON _2.

When an accident occurs at the _{accident point FBT} , the logical value “1” of the overcurrent detection signal and the logical value “1” of the abnormal voltage detection signal are _{stored in the first} AND 1 and the second AND _2. And enter. The first logical product unit AND ₁ and the second logical product unit AND ₂ output the logical value "1" as the operation result of the logical product with respect to the input logical value.

The first operation delay timer TON ₁ sets the timing of outputting the on signal to the first measurement value setting unit 123 ₁ for a predetermined time when an on signal such as a logic value “1” is _{input from the first logical product unit AND 1.} It is a delay part that is delayed. The predetermined time, which is the delay time, is set in advance to be _{equal to or longer than the time from when the second bus ratio differential relay RDf B} outputs the circuit breaker open command to _{when the bus tie circuit breaker CB BT opens.} Further, the second operation delay timer TON ₂ sets the timing at which the ON signal is output to the second measurement value setting unit 123 ₂ when the ON signal such as the logic value “1” is _{input from the second AND 2 unit.} It is a delay part that is delayed for a predetermined time. The predetermined time, which is the delay time, is set in advance to be _{equal to or longer than the time from when the first bus ratio differential relay RDf A} outputs the circuit breaker opening command _{until the bus tie circuit breaker CB BT opens.}

When an accident _{occurs at the accident point FBT} , the logical value "1" is input to the _first AND 1 and the second AND _2. Therefore, the first operation delay timer TON ₁ and the second operation delay timer TON ₂ execute the above-mentioned delay operation.

The first return delay timer TOFF ₁ sets the off signal as the first measured value when an off signal such as a logic value "0" indicating a non-output of the circuit breaker open command is _{input from the second bus ratio differential relay RDf B.} This is a delay unit that delays the timing of output to the setting unit 123 _{1 by a predetermined time.} The predetermined time, which is the delay time, is set in advance to be equal to or longer than the time from when the first bus ratio differential relay RDf _A outputs the circuit breaker opening command until the first circuit breaker CB ₁ and the second circuit breaker CB ₂ are opened. To. Further, the second return delay timer TOFF ₂ outputs the off signal to the second when an off signal such as a logic value "0" indicating a non-output of the circuit breaker open command is _{input from the first bus ratio differential relay RDf A.} This is a delay unit that delays the timing of output to the measurement value setting unit 123 _{2 by a predetermined time.} The predetermined time, which is the delay time, is set in advance to be equal to or longer than the time from when the second bus ratio differential relay RDf _B outputs the circuit breaker opening command until the third circuit breaker CB ₃ and the fourth circuit breaker CB ₄ are opened. To.

In the example shown in FIG. 5, the second bus ratio differential relay RDf _B outputs a circuit breaker open command based on the calculated difference current (“operation” in FIG. 5). As a result, the logical value "1" indicating the output of the circuit breaker open command is input from the second bus ratio differential relay RDf _B to the first return delay timer TOFF ₁ . Therefore, the first return delay timer TOFF ₁ outputs the input logical value "1" to the first measurement value setting unit 123 ₁ without executing the delay operation.

Further, the first bus ratio differential relay RDf _A has a calculated difference current at the timing when the second bus ratio differential relay RDf _B outputs a circuit breaker open command (timing shown as “operation” in FIG. 5). Do not output the circuit breaker open command based on. Therefore, the logical value “0” indicating non-output is continuously input to _{the second return delay timer TOFF 2.} Therefore, the second return delay timer TOFF ₂ outputs the input logical value "0" to the second measurement value setting unit 123 ₂ without executing the delay operation.

The first measurement value setting unit 123 ₁ calculates the logical product of the logical value output by the first operation delay timer TON ₁ and the logical value output by the first return delay timer TOFF ₁ , and calculates the logical value which is the calculation result. Output to the first bus ratio differential relay RDf _A. Further, the second measurement value setting unit 123 ₂ calculates the logical product of the logical value output by the second operation delay timer TON ₂ and the logical value output by the second return delay timer TOFF _{2, and is the logic resulting from the calculation.} The value is output to the second bus ratio differential relay RDf _B.

Logic value first measured value setting unit 123 ₁ is output, the current fifth current sensor CT ₅ is measured, i.e., whether to set the measured value of the current flowing out of the first busbar L _A to Busutai BT zero It is a logical value indicating. The logic value second measurement value setting unit 123 ₂ is outputted, the current sixth current sensor CT ₆ was measured, i.e., set to zero the measured value of the current flowing from Busutai BT to the second bus line L _B It is a logical value indicating whether or not. For example, the logical value "1" is a logical value indicating that the measured value is set to zero, and the logical value "0" is a logical value indicating that the measured value is not set to zero. As described above, the first measured value setting unit 123 ₁ and the second measured value setting unit 123 ₂ are units that set the measured value of the current flowing through the bus tie to zero.

If an accident in the accident point F _BT occurs, the logical value indicating the output of the circuit breaker opening command from the second bus ratio differential relay RDf _B "1" and the logic value first operating delay timer TON ₁ has output " 1 ”is input to the first measured value setting unit 123 _1. The first measured value setting unit 123 ₁ calculates the logical product of the two input logical values, and outputs the logical value “1” as the calculation result to the first bus ratio differential relay RDf _A.

Further, at the timing when the second bus ratio differential relay RDf _B outputs the circuit breaker open command, the logical value “0” indicating the non-output of the circuit breaker open command from the first bus ratio differential relay RDf _{A and the first} 2 The logical value “1” output by the operation delay timer TON ₂ is input to the second measured value setting unit 123 ₂ . The second measured value setting unit 123 ₂ calculates the logical product of the two input logical values, and outputs the logical value “0” as the calculation result to the second bus ratio differential relay RDf _B.

The first busbar ratio differential relay RDf _A, current fifth current sensor CT ₅ was measured according to the logic value input from the first measurement value setting unit 123 _1, i.e., the current flowing from the first bus bar _{L A} to Busutai BT Change the measured value of. The second busbar ratio differential relay RDf _B has current sixth current sensor CT ₆ is measured in accordance with a second logic value received from the measuring value setting unit 123 _second inflow, i.e., the second busbar _{L B} from Busutai BT Change the measured value of the current.

In the above example accident fault point F _BT is generated, the input from the logic value "0" is second measurement value setting unit 123 ₂ indicating that no setting the measured value to zero in the second bus ratio differential relay RDf _B To do. Therefore, unless the difference current between the current measured by the sixth current sensor CT ₆ and the current measured by the third current sensor CT ₃ and the fourth current sensor CT ₄ is zero, the second bus ratio differential relay RDf _B is used. The second bus protection operation as described above is executed.

On the other hand, in the above example an accident in the accident point F _BT occurs, first busbar ratio differential from the first measurement value is a logical value "1" setting unit 123 ₁ indicates to set the measured value to zero relay RDf _A Enter in. Therefore, the first bus ratio differential relay RDf _A changes the current measured by _{the fifth current sensor CT 5} to zero according to the input logical value. When the current measured by the fifth current sensor CT ₅ is changed to zero, the difference between the current measured by _{the first current sensor CT 1} and the second current sensor CT ₂ and the current measured by the fifth current sensor CT _5. The current does not go to zero. Therefore, the first bus ratio differential relay RDf _A executes the first bus protection operation based on the calculated difference current. That is, the first bus ratio differential relay RDf _A outputs a circuit breaker opening command to the first circuit breaker CB ₁ , the second circuit breaker CB ₂ , and the bus tie circuit breaker CB _BT . As a result, the first circuit breaker CB ₁ and the second circuit breaker CB ₂ are opened according to the input circuit breaker opening command, and the first bus LA is protected from the accident at the accident _{point FBT.}

Thus, if the detection and overvoltage in the second bus ratio differential relay RDf _B detects a first generatrix of overcurrent at Busutai BT after outputting the breaker opening command L _A is continued , The current measurement value by the fifth current sensor CT ₅ is changed to zero. As a result, the first bus ratio differential relay RDf _A executes the first bus protection operation based on the calculated difference current. Therefore, according to the bus protection device according to the embodiment, in the double bus system, bus protection can be performed regardless of the arrangement of the current sensor that measures the current flowing through the bus tie.

Incidentally, if, when the open signal indicating the opening of Busutai breaker CB _BT constituted the busbar protection device to enter the Busutai breaker CB _BT to the first busbar ratio differential relay RDf _A is first busbar ratio The differential relay RDf _A can change the current measurement value in the busbar to zero according to the open signal. However, the opening and closing signals of Busutai breaker CB _BT for outputting the Busutai breaker CB _BT needs to output terminals for the switching signal is provided Busutai breaker CB _BT side. It may be difficult to provide such an output terminal on the CB _BT side of the bus tie circuit breaker depending on the configuration of the switchboard of the substation. As described above, in the busbar protection device in accordance with an embodiment, an open signal indicating the opening of Busutai breaker CB _BT can perform also protection of double busbar without input from Busutai breaker CB _BT.

<< Second configuration example >>
FIG. 6 is a diagram showing a second configuration example of the bus protection device according to the embodiment. In the second configuration example shown in FIG. 6, the same components as those in the first configuration example shown in FIG. 2 are designated by the same reference numerals. In the second configuration example shown in FIG. 6, the bus protection device 2 includes an analog / digital (A / D) converter 11 and a processing unit 13.

The processing unit 13 is, for example, a CPU, a multi-core CPU, or a programmable device (FPGA, PLD, etc.). Each current and each voltage output by the analog / digital converter 11 is input to the processing unit 13. The processing unit 13 executes the bus protection operation based on each input current and each voltage.

<< One busbar protection >>
Similar to the first configuration example shown in FIG. 2, the processing unit 13 includes a first bus ratio differential relay RDf _A and a second bus ratio differential relay RDf _B.

For example, if an accident such as ground fault or short-circuit failure occurs in any fault point F _A of the first busbar L _A, the first busbar ratio differential relay RDf _A, as in the first configuration example, the first the busbar protection operation, disconnecting the first busbar L _a from the power grid of an accident, to protect the first busbar L _a. Also, if an accident such as ground fault or short-circuit failure occurs in any fault point F _B of the second busbar L _B, second busbar ratio differential relay RDf _B, similar to the first configuration example, the second the busbar protection operation, disconnect the second busbar L _B from the power grid of an accident, to protect the second bus L _B.

<< In case of blind spot accident >>
For example, if an accident such as ground fault or short-circuit fault occurs in the fault point F _BT, since the fault point F _BT is present in the first protected area Z _A and a second protected area Z _B, processor 13, the following The first bus protection operation and the second bus protection operation as described are performed.

If an accident occurs in the fault point F _BT, second busbar ratio differential relay RDf _B, similar to the first configuration example, executes the second busbar protection operation based on the calculated difference current. However, when an accident _{occurs at the accident point FBT} , the first bus protection operation is not executed based on the difference current as in the first configuration example. Therefore, the processing unit 13 executes the first bus protection operation as described below, detects that the accident that has occurred is a blind spot accident, and eliminates the accident.

As shown in FIG. 6, similarly to the first configuration example, the processing unit 13 includes the first overcurrent detection unit 121 _A , the second overcurrent detection unit 121 _B , the first bus abnormal voltage detection unit 122 _A , and The second bus abnormal voltage detection unit 122 _B is included. These units perform the same operations as in the first configuration example.

The processing unit 13 includes a first operation delay timer TON ₁ , a second operation delay timer TON ₂ , a first return delay timer TOFF ₁ , a second return delay timer TOFF ₂ , a first logical product AND ₁ , and a second logical product. Does not include part AND _2. The processing unit 13 includes an exclusive OR unit EXOR in place of these units.

An abnormal voltage detection signal output by the first bus abnormal voltage detection unit 122 _A and the second bus abnormal voltage detection unit 122 _{B is input to the exclusive OR unit EXOR.} Busutai breaker CB _BT is accident is closed in normal operation has not occurred, the first generating line L _A and the second bus line L _B is connected through Busutai breaker CB _BT. Thus, a first busbar _{L A} side first bus abnormal voltage detecting unit 122 _A of the second busbar _{L B} side of the second bus abnormal voltage detection unit 122 _B operates and reset simultaneously. Therefore, when one of the first bus abnormal voltage detection unit 122 _A and the second bus abnormal voltage detection unit 122 _B outputs an abnormal voltage detection signal, it can be determined that the Bustai circuit breaker CB _BT has changed from closed to open. Is. _{Therefore, when the busty circuit breaker CB BT} is opened by the second bus ratio differential relay RDf _B executing the second bus protection operation, for example, the signal having the logic value “1” as the abnormal voltage detection signal is exclusively ORed. Input to the part EXOR.

The processing unit 13 includes a third measured value setting unit 123 ₃ and a fourth measured value setting unit 123 ₄ instead of the first measured value setting unit 123 ₁ and the second measured value setting unit 123 ₂ .

The logical value output by the first overcurrent detection unit 121 _A and the logical value output by the exclusive OR unit EXOR are input to the third measurement value setting unit 123 _3. The third measurement value setting unit 123 ₃ calculates the logical product of the two input logical values, and outputs the logical value which is the calculation result to the first bus ratio differential relay RDf _A. Further, the fourth measured value setting unit 123 _4, a logical value exclusive portion EXOR logical value by the second overcurrent detecting section 121 _B and output is output to the input. Fourth measurement value setting unit 123 ₄ performs a logical product of the two logical values, and outputs a logical value which is the operation result to the second busbar ratio differential relay RDf _B.

Boolean third measurement value setting unit 123 ₃ outputs the current fifth current sensor CT ₅ is measured, i.e., whether to set the measured value of the current flowing out of the first busbar L _A to Busutai BT zero It is a logical value indicating. The logic value the fourth measurement value setting unit 123 ₄ outputs the current sixth current sensor CT ₆ was measured, i.e., set to zero the measured value of the current flowing from Busutai BT to the second bus line L _B It is a logical value indicating whether or not. For example, the logical value "1" is a logical value indicating that the measured value is set to zero, and the logical value "0" is a logical value indicating that the measured value is not set to zero. In this way, similarly to the first measured value setting unit 123 ₁ and the second measured value setting unit 123 ₂ , the third measured value setting unit 123 ₃ and the fourth measured value setting unit 123 ₄ are the currents flowing through the bus tie. It is a unit that sets the measured value to zero.

When the event of an accident in the accident point F _BT second busbar ratio differential relay RDf _B executes the second busbar protection operation, the second overcurrent detection unit 121 _B detects the overcurrent flowing to Busutai BT. As a result, the fourth measured value setting unit 123 ₄ outputs a logical value "1" indicating that you set the measured value to zero to the second busbar ratio differential relay RDf _B. Further, the first overcurrent detecting section 121 _A detects the overcurrent flowing in Busutai BT, the first bus abnormal voltage detecting unit 122 _A detects an abnormal voltage applied to the first busbar L _A. As a result, the third measured value setting unit 123 ₃ outputs a logical value “1” indicating that the measured value is set to zero to the first bus ratio differential relay RDf _A.

The first busbar ratio differential relay RDf _A, current fifth current sensor CT ₅ according to the logic values input from the third measurement value setting unit 123 ₃ is measured, i.e., current flowing out of the first busbar _{L A} to Busutai BT Change the measured value of. The second busbar ratio differential relay RDf _B has current sixth current sensor CT ₆ is measured according to the logic values input from the fourth measurement value setting unit 123 ₄ flows, i.e., the second busbar _{L B} from Busutai BT Change the measured value of the current.

In the above example accident fault point F _BT has occurred, the input has the logical value "1" indicating that you set the measured value to zero from the fourth measurement value setting unit 123 ₄ to the second busbar ratio differential relay RDf _B To do. The difference current second bus ratio differential relay RDf _B changes the current measured by _{the sixth current sensor CT 6} to zero according to the input logical value. When the current measured by the 6th current sensor CT ₆ is changed to zero, the difference between the current measured by _{the 3rd current sensor CT 3} and the 4th current sensor CT ₄ and the current measured by the 6th current sensor CT _6. The current does not go to zero. Therefore, the second busbar ratio differential relay RDf _B executes the second busbar protection operation as described above.

Further, in the above example an accident in the accident point F _BT occurs, first busbar ratio differential logic value "1" indicating that you set the measured value to zero from the third measurement value setting unit 123 ₃ relay RDf _A Enter in. Therefore, the first bus ratio differential relay RDf _A changes the current measured by _{the fifth current sensor CT 5} to zero according to the input logical value. When the current measured by the fifth current sensor CT ₅ is changed to zero, the difference between the current measured by _{the first current sensor CT 1} and the second current sensor CT ₂ and the current measured by the fifth current sensor CT _5. The current does not go to zero. Therefore, the first bus ratio differential relay RDf _A executes the first bus protection operation based on the calculated difference current. That is, the first bus ratio differential relay RDf _A outputs a circuit breaker opening command to the first circuit breaker CB ₁ , the second circuit breaker CB ₂ , and the bus tie circuit breaker CB _BT . As a result, the first circuit breaker CB ₁ and the second circuit breaker CB ₂ are opened according to the input circuit breaker opening command, and the first bus LA is protected from the accident at the accident _{point FBT.}

In this way, even when the bus protection device according to the embodiment is configured as in the second configuration example, the current for measuring the current flowing through the bus tie in the double bus system is the same as in the first configuration example. Busbar protection can be performed regardless of sensor placement.

Further, in the first configuration example, a time adjustment using a timer is performed in order to determine that one bus is protected and the other bus is not used in a double bus accident. In the timed adjustment, _{the operating time of the bus tie circuit breaker CB BT} and the return time of the first bus ratio differential relay RDf _A or the second bus ratio differential relay RDf _B are taken into consideration. In the timed adjustment, the operating time of the first overcurrent detection unit 121 _A or the second overcurrent detection unit 121 _{B and} the operating time of the first bus abnormal voltage detection unit 122 _A or the second bus abnormal voltage detection unit 122 _B. And are considered. On the other hand, in the second configuration example, the double bus can be protected by a simpler configuration without time adjustment using a timer as in the first configuration example.

Further, although the first configuration example and the second configuration example use digital circuits, the present invention is not limited thereto. The present invention can also be configured with a combination of a single protection relay and a timer relay.

The present invention is not limited to the above embodiments, and various improvements and changes can be made without departing from the gist of the present invention.

1, 2 Bus circuit breaker 11 Analog / digital (A / D) converter 12, 13 Processing unit 121 _A 1st overcurrent detection unit 121 _B 2nd overcurrent detection unit 122 _A 1st bus abnormal voltage detection unit 122 _B 2 Bus circuit abnormal voltage detection unit 123 ₁ 1st measurement value setting unit 123 ₂ 2nd measurement value setting unit 123 ₃ 3rd measurement value setting unit 123 ₄ 4th measurement value setting unit AND ₁ 1st logical product unit AND ₂ 2nd logic Stacked part BT Bustai CB ₁ 1st circuit breaker CB ₂ 2nd circuit breaker CB ₃ 3rd circuit breaker CB ₄ 4th circuit breaker CB _BT Bustai circuit breaker CT ₁ 1st current sensor CT ₂ 2nd current sensor CT ₃ 3rd current Sensor CT ₄ 4th current sensor CT ₅ 5th current sensor CT ₆ 6th current sensor DS ₁ 1st circuit breaker DS ₂ 2nd circuit breaker DS ₃ 3rd circuit breaker DS ₄ 4th circuit breaker DS ₅ 5th circuit breaker DS ₆ the sixth disconnecting switch DS ₇ seventh disconnecting switch DS ₈ eighth disconnecting switches EXOR exclusive portions _{F 1, F 2, F BT} fault point INV inverter _{L A} first busbar _{L B} second busbar _{L 1} first Transmission line L ₂ 2nd transmission line L ₃ 3rd transmission line L ₄ 4th transmission line LD ₁ 1st load LD ₂ 2nd load P ₁ 1st _{circuit breaker P 2} 2nd circuit breaker PS Power system RDf _A 1st bus Ratio differential relay RDf _B 2nd bus ratio differential relay TOFF ₁ 1st return delay timer TOFF ₂ 2nd return delay timer TON ₁ 1st operation delay timer TON ₂ 2nd operation delay timer VT _A 1st voltage sensor VT _B 1st 2 Voltage sensor Z _A 1st protected area Z _B 2nd protected area

Claims (6)

A second bus ratio differential relay that executes a second bus protection operation that at least opens the bus tie circuit breaker installed in the bus tie in response to an accident that occurred in the bus tie that connects the first bus and the second bus.
An overcurrent detection unit that detects the overcurrent flowing through the bus tie, and
The first bus abnormal voltage detection unit that detects the abnormal voltage applied to the first bus, and
A measurement value setting unit that sets the measurement value of the current flowing through the bus tie to zero when the second bus protection operation is performed and the overcurrent and the abnormal voltage are detected.
A first busbar protection operation is performed to at least open the transmission line circuit breaker installed on the transmission line according to the current flowing through the transmission line connected to the first bus and the measured value set to zero. Busbar protection for double busbars, including with a busbar ratio differential relay. An overcurrent detector that detects the overcurrent flowing through the bus tie that connects the first bus and the second bus,
The first bus abnormal voltage detection unit that detects the abnormal voltage applied to the first bus, and
A second bus abnormal voltage detection unit that detects the abnormal voltage applied to the second bus, and
A measurement value setting unit that sets the measurement value of the current flowing through the bus tie to zero when the overcurrent is detected and the abnormal voltage of the first bus or the second bus is detected.
A first busbar protection operation is performed to at least open the transmission line circuit breaker installed on the transmission line according to the current flowing through the transmission line connected to the first bus and the measured value set to zero. Busbar protection for double busbars, including with a busbar ratio differential relay. The overcurrent detection unit detects the overcurrent with respect to the zero-phase current of the bustai, and then detects the overcurrent.
The bus protection device according to claim 1 or 2, wherein the first bus abnormal voltage detection unit detects an overvoltage with respect to the zero-phase voltage of the first bus. The overcurrent detection unit detects an overcurrent with respect to the current flowing through the transmission line of each phase constituting the busty.
The bus protection device according to claim 1 or 2, wherein the first bus abnormal voltage detection unit detects an undervoltage with respect to the line voltage generated between the transmission lines of each phase constituting the first bus. .. The bus protection device according to claim 1, further comprising a delay unit that delays the detection of the overcurrent and the abnormal voltage for a predetermined time and outputs the measurement value setting unit. The bus according to any one of claims 1 to 5, wherein the current value flowing from the first bus to the second bus is obtained based on the measured value of the current flowing from the second bus to the first bus. Protective device.

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