JP2019004661A - Bus protection device - Google Patents

Abstract

To provide a bus protection device that executes a bus protection in regardless to a layout of a current sensor for measuring a current flowing through a bus tie in a double bus system.SOLUTION: A bus protection device 1 is structured by constructing: a second bus comparison differential relay RDfthat, according to an accident occurred in a bus tie connecting a first bus with a second bus, executes a second bus protection operation that at least opens a bus tie breaker installed in the bus tie; an overcurrent detection part CTthat detects an overcurrent flowing in the bus tie; a first bus line abnormal voltage detection part 122that detects an abnormal voltage applied to the first bus line; a measurement value setting part 123that sets a measurement value of the current flowing in the bus tie to 0 when the overcurrent and the abnormal voltage are detected by performing the second bus line protection operation; and a first bus line comparison differential relay RDfthat executes a first bus line protection operation that at least opens a transmission power breaker installed in a transmission line in accordance with the current flowing in the transmission line connected to the first bus line and the measurement value set to 0.SELECTED DRAWING: Figure 2

Description

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

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

  For example, a ratio differential relay is provided for each bus in order to protect the bus in the event of a ground fault or a short circuit accident. The ratio differential relay calculates a difference current between the current flowing from the power transmission line to the bus and the current flowing from the bus to the bus tie. Alternatively, the ratio differential relay calculates the difference current between the current flowing from the bus tie to the bus and the current flowing from the bus to the power transmission line. If the calculated differential current is not zero, the ratio differential relay opens the circuit breaker provided on the bus tie and the circuit breaker provided on the transmission line connected to the bus, and disconnects the bus from the system where the accident occurred. To protect the busbars.

In addition, 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 a single breaker bus system, and includes an auxiliary transformer that converts a bus side CT secondary current, a transformer that converts a bus center side CT secondary current, and two CTs. And an auxiliary transformer that converts the sum current. The distance relay device includes an auxiliary transformer that converts the secondary voltage of the PT connected to the transmission line, means for recognizing the open / closed state of the transmission line disconnector, a CT sum current, and a secondary signal of the PT. It is further comprised by the energized distance relay and the ratio differential relay by bus side CT current and bus center side CT current. Then, the distance relay device 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 only when the transmission line disconnector is open. A means for outputting a break command to the breaker by the operation of the relay is further provided.

  In the bus protection relay device described in Patent Document 2, the bus current “zero” is controlled when the bus breaker is “off”, and the other bus current flowing into the bus breaker and the self-bus inflow current are detected. Detect and protect the busbar. The bus protection relay device is provided with a circuit that takes in the command to turn on the bus breaker and a circuit that cancels the bus current “zero” control by this take-in command. The current “zero” control release delay is eliminated.

  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 an open / close detection means, a current data detection means, and a determination means. The open / close detecting means detects opening / closing of a circuit breaker installed at each terminal. The current data detection means detects current data at the terminal. The judging means is a logical product of that the circuit breaker detected by the open / close detecting means is in an open state and that the current data detected by the current data detecting means exceeds a preset set value. Determine blind spot accident based on

JP-A-5-83844 JP 7-131929 A Japanese Patent Laid-Open No. 9-200946

  However, depending on the arrangement of the current sensor that measures the current flowing through the bus tie, the proportional differential relay does not operate in response to an accident that occurs in the bus tie, and a blind spot accident that cannot protect the bus can occur.

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

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

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

It is a figure which shows the structural example of the electric power grid | system to which the bus-bar protection apparatus according to embodiment is applied. It is a figure which shows the 1st structural example of the bus-bar protection apparatus according to embodiment. It is a figure which shows the example of arrangement | positioning of the current sensor of the bus tie which does not require 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 sensor. It is an exemplary timing chart explaining operation of each part of a bus bar protection device according to an embodiment. It is a figure which shows the 2nd structural example of the bus-bar protection apparatus according to embodiment.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

<Power system including busbar protection device>
FIG. 1 is a diagram illustrating a configuration example of a power system to which the busbar protection device according to the 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 This is a bus 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. FIG. 1 shows a configuration example of a four-line bus in which four power transmission lines are connected to two buses. However, the power system to which the bus protection device according to the embodiment is applied is a four-line bus. However, it may be an n-line bus (n is an integer of 1 or more).

The busbar protection device 1 is an example of a busbar 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. The busbar accident is, for example, a ground fault or a short-circuit accident that has occurred in the first busbar L _A , the second busbar L _B , or the bustie BT. The ground fault is an accident in which the power lines of the respective phases constituting the first bus L _A , the second bus L _B , or the bustie BT are connected to the ground. The short circuit accident is an accident in which the transmission lines of the respective phases constituting the first bus line L _A , the second bus line L _B , or the bustie BT are connected to each other.

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 A first bus protection operation is performed. Specifically, the busbar 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 bustie 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 The second bus protection operation to be protected is executed. Specifically, the busbar protection device 1 outputs a circuit breaker opening command to the third circuit breaker CB ₃ , the fourth circuit breaker CB ₄ , and the bustie circuit breaker CB _BT .

The first circuit breakers CB 1 _~ fourth breaker CB ₄ is a transmission line breakers, a first transmission line L _{1 ~} fault removal switch mounted on the fourth transmission line L ₄ corresponding. Busutai breaker CB _BT is a fault removal switch mounted on Busutai 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 busbar 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 Detached 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 Detached from.

The bus protection device 1 is based on each current flowing through the first power transmission line L ₁ to the fourth power transmission line L ₄ and the bustie BT, and each voltage applied to the first bus L _A and the second bus L _B. The first bus protection operation and the second bus 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 current transformers. The first current sensor CT ₁ to the fourth current sensor CT ₄ are installed in the corresponding first power transmission line L ₁ to fourth power transmission line L ₄ . The first current sensor CT ₁ to the fourth current sensor CT ₄ output the measured current to the busbar 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. Fifth current sensor CT ₅ and sixth current sensor CT ₆ is, for example, a current transformer. The fifth current sensor CT ₅ and the sixth current sensor CT ₆ output the measured current to the busbar protection device 1.

Fifth current sensor CT ₅ and sixth current sensor CT ₆ is installed in Busutai 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.}

Thus, 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, the fifth current sensor CT ₅ and the sixth current sensor CT ₆ are not installed on the bus tie BT across the bus tie circuit breaker CB _BT as shown in FIG. FIG. 3 is a diagram illustrating an arrangement example of a bustie current sensor that does not require blind spot protection. For example, the fifth current sensor CT ₅ and the sixth current sensor CT ₆ may be integrally formed in 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 separately installed.

Further, the direction of the current fifth current sensor CT ₅ and sixth current sensor CT ₆ is measured (positive or negative) are different from each other, the absolute values of both currents are the same. For this reason, it is possible to obtain the current measured by the other current sensor by reversing the direction of the current measured by one current sensor. Therefore, as shown in FIG. 4, in some embodiments, the fifth current sensor CT ₅ and the sixth current sensor CT ₆ may be configured by a single current sensor having the functions of both current sensors. FIG. 4 is a diagram illustrating 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 inverter INV operates as, for example, an analog amplifier with a gain of −1 to invert the measurement value of the sixth current sensor CT ₆ . 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 compared to 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.

<Bus protection device>
A specific example of the bus protection operation executed by the bus protection device 1 will be described below while showing a configuration example of the bus protection device 1.

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

The analog / digital converter 11 receives analog signals of respective currents output from the first current sensor CT ₁ to the sixth current sensor CT ₆ . The analog / digital converter 11 converts an analog signal of each current into a digital signal, and outputs each current that is a digital signal to the processing unit 12.

The analog / digital converter 11 receives analog signals of respective voltages output from the first voltage sensor VT _A and the second voltage sensor VT _B. The analog / digital converter 11 converts an analog signal of each voltage into a digital signal and outputs each voltage that 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, etc.)). Each current and each voltage output from the analog / digital converter 11 are input to the processing unit 12. The processing unit 12 performs a bus protection operation based on the input currents and voltages. 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-bus protection >>
For example, if an accident such as a ground fault or short-circuit accident occurs at any accident point F _{A on} the first bus L _A (see FIG. 1), the accident point F _A exists in the first protected area Z _A. The 1-bus ratio differential relay RDf _A performs the first bus protection operation as described below. The first busbar ratio differential relay RDf _A, a current first current sensor CT ₁ and the second current sensor CT ₂ is measured, the fifth current sensor CT ₅ calculates the difference current between the current measured. 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 when no accident has occurred, the difference current is zero. However, if an accident occurs at an accident point F _A, 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 performs 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 , second circuit breaker CB ₂ , and bustie circuit breaker CB _BT . The breaker open command is, for example, a signal having a logical value “1”. Thus, the first bus ratio differential relay RDf _A functions as a ratio differential relay.

Further, for example, when an accident such as a ground fault or a short-circuit accident occurs at an arbitrary accident point F _B (see FIG. 1) of the second bus L _B , the accident point F _B exists in the second protected area Z _B. The second bus ratio differential relay RDf _B performs a second bus protection operation as described below. The second bus ratio differential relay RDf _B calculates a difference current between the current measured by the sixth current sensor CT ₆ and the currents 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. The current measured by the third current sensor CT ₃ is a current flowing out from the second bus L _B to the third power transmission line L ₃ , and the current measured by the fourth current sensor CT ₄ is the second bus L _B from a current flowing to the fourth transmission line L _4. During normal operation when no accident has occurred, the difference 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 performs 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 bustie 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, for example, when an accident such as a ground fault or a short-circuit accident occurs at the fault point _FBT (see FIG. 1), the processing unit 12 performs the first busbar protection operation and the second busbar protection operation as described below. Run. As shown in FIG. 1, the fault point _{F BT} is a fault point existing Busutai BT between the fifth current sensor CT ₅ and sixth current sensor CT ₆ and Busutai breaker _{CB BT.}

If an accident occurs in the fault point F _BT, the current sixth current sensor CT ₆ was measured are the same as during normal operation described above. 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 current direction measured by the third current sensor CT ₃ and the fourth current sensor CT ₄ is opposite to the current direction during normal operation. For this reason, 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 performs 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 bustie circuit breaker CB _BT .

Also, if the accident fault point F _BT occurs, the direction of the current first current sensor CT ₁ and the second current sensor CT ₂ is measured is the same as during normal operation described above. 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. For this reason, 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 the opposite. For this reason, 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 performs 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 , second circuit breaker CB ₂ , and bustie 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 There is no blind spot accident.

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 occurred is a blind spot accident, and eliminates the accident. .

As illustrated 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. 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. A product unit AND ₂ , a first measurement value setting unit 123 ₁ , and a second measurement 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 for explaining the operation of each part of the busbar protection device according to the embodiment.

The first overcurrent detection unit 121 _A and the second overcurrent detecting section 121 _B is one example of the overcurrent detection unit that detects an overcurrent flowing through the Busutai BT. The first overcurrent detection unit 121 _A, for detecting an overcurrent flowing in Busutai BT when the current fifth current sensor CT ₅ was measured exceeds a predetermined level. The second overcurrent detection unit 121 _B detects an overcurrent flowing through the Busutai BT when the current sixth current sensor CT ₆ was measured exceeds a predetermined level. When detecting an overcurrent, the first overcurrent detecting section 121 _A and the second overcurrent detecting section 121 _B outputs an overcurrent detection signal indicating the detection of the overcurrent. The overcurrent detection signal indicating the detection of overcurrent is, for example, a signal having a logical value “1”.

For example, in the configuration in which the first bus L _A and the second bus L _B are protected from a ground fault, the first overcurrent detection unit 121 _A and the second overcurrent detection unit 121 _B are configured as a ground fault overcurrent relay (OCG). Function. Specifically, the first overcurrent detecting section 121 _A and the second overcurrent detecting section 121 _B calculates a zero-phase current from the combined value of the current flowing to each phase of the transmission lines constituting Busutai BT. If the zero-phase current exceeds a predetermined level, the first overcurrent detecting section 121 _A and the second overcurrent detecting section 121 _B detects an overcurrent due to a ground fault, over-indicating the detection of the overcurrent 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 ). Specifically, if the current flowing to each phase of the transmission lines constituting Busutai BT exceeds a predetermined level, the first overcurrent detecting section 121 _A and the second overcurrent detecting section 121 _B is caused by the short circuit The overcurrent detected is detected, and an overcurrent detection signal indicating the detection of the overcurrent is output.

For example, as shown in FIG. 5, the first overcurrent detection unit 121 _A and the second overcurrent detection unit 121 _B have a logical value “1” after the required operation time has elapsed since the occurrence of the accident at the accident point _FBT . Outputs an overcurrent detection signal. For the sake of clarity, 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 opening 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 detecting an abnormal voltage, the first bus abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B outputs an abnormal voltage detection signal indicating the detection of an abnormal voltage. The abnormal voltage detection signal indicating the detection of the abnormal voltage is, for example, a signal having a logical value “1”.

For example, in a configuration in which the first bus L _A and the second bus L _B are protected from a ground fault, the first bus abnormal voltage detection unit 122 _A and the second bus abnormal voltage detection unit 122 _B are connected to the ground fault overvoltage relay (OVG). ). More specifically, the first bus abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B, the calculation of the zero-phase voltage from the combined value of the voltage applied to each phase of the transmission lines constituting Busutai BT To do. If calculated zero-phase voltage exceeds the predetermined level, the first bus abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B detects the overvoltage caused by a ground fault, indicating detection of an overvoltage An abnormal voltage detection signal is output.

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 Function as (UV). More specifically, the first bus abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B, of the phase of the transmission lines constituting Busutai BT, the voltage applied to the two-phase power transmission line The line voltage is calculated from the difference. If calculated line voltage falls below a predetermined level, the first bus abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B is a transmission lines between the two phases is the calculation target of the line voltage 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 An abnormal voltage detection signal “” is output. For the sake of clarity, 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 opening command. However, both timings may be different. 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-described overcurrent detection signal is output, but both timings may be different.

The first logical unit the AND ₁ performs a logical product of the first overcurrent overcurrent detection signal detecting unit 121 _A has output an abnormal voltage detection signal is first busbar abnormal voltage detecting unit 122 _A and output, operation The result is output to the first operation delay timer TON ₁ . The second logical unit the AND ₂ performs a logical product of the second overcurrent detection unit 121 overcurrent detection signal _B is output and the abnormal voltage detection signal and the second bus abnormal voltage detection unit 122 _B and output , and it outputs the calculation result to the second operating delay timer TON _2.

When an accident occurs at the fault point _FBT , the first logical product unit AND ₁ and the second logical product unit AND ₂ have a logical value “1” of the overcurrent detection signal and a logical value “1” of the abnormal voltage detection signal. And enter. The first AND unit AND ₁ and the second AND unit AND ₂ output a logical value “1” as a logical product operation result on the input logical value.

The first operation delay timer TON ₁ sets a timing for outputting the ON signal to the first measurement value setting unit 123 ₁ when a ON signal such as a logical value “1” is input from the first AND unit AND ₁ for a predetermined time. It is a delay unit that delays. Predetermined time is the delay time is preset to a time or more after the second busbar ratio differential relay RDf _B outputs breaker opening command to open Busutai breaker CB _BT. The second operation delay timer TON _2, when the ON signal like a logical value "1" is input from the second logical unit the AND _2, the timing of outputting the on-signal to the second measurement value setting unit 123 ₂ It is a delay unit that delays for a predetermined time. Predetermined time is the delay time is preset to a time or more from when the first busbar ratio differential relay RDf _A outputs breaker opening command to open Busutai breaker CB _BT.

When an accident occurs at the accident point _FBT , the logical value “1” is input to the first AND unit AND ₁ and the second AND unit AND ₂ . Therefore, the first operation delay timer TON ₁ and the second operation delay timer TON ₂ execute the above-described delay operation.

The first return delay timer TOFF ₁ receives the off signal such as a logical value “0” indicating non-output of the circuit breaker opening command from the second bus ratio differential relay RDf _B , and outputs the off signal to the first measured value. This is a delay unit that delays the output timing to the setting unit 123 ₁ for a predetermined time. The predetermined time that is the delay time is set in advance to be longer than the time from when the first bus ratio differential relay RDf _A outputs the circuit breaker opening command to when the first circuit breaker CB ₁ and the second circuit breaker CB ₂ open. The The second return delay timer TOFF ₂ receives the off signal when the off signal such as the logical value “0” indicating the non-output of the circuit breaker opening command is input from the first bus ratio differential relay RDf _A. the timing of outputting the measured value setting unit 123 ₂ is a delay unit for delaying a predetermined time. The predetermined time which is the delay time is set in advance to be longer than the time from when the second bus ratio differential relay RDf _B outputs the circuit breaker opening command to when the third circuit breaker CB ₃ and the fourth circuit breaker CB ₄ are opened. The

In the example shown in FIG. 5, the second bus ratio differential relay RDf _B outputs a circuit breaker opening 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 opening command is input to the first return delay timer TOFF ₁ from the second bus ratio differential relay RDf _B. Therefore, the first return delay timer TOFF ₁ outputs the input logical value “1” to the first measured value setting unit 123 ₁ without executing the delay operation.

Further, the first bus ratio differential relay RDf _A has the calculated difference current at the timing when the second bus ratio differential relay RDf _B outputs the circuit breaker opening command (the timing shown as “operation” in FIG. 5). Based on this, the breaker open command is not output. Therefore, the logical value “0” indicating non-output is continuously input to the second return delay timer TOFF ₂ . Accordingly, the second return delay timer TOFF ₂ does not perform a delay operation, and outputs a logical value "0" input to the second measurement value setting unit 123 _2.

The first measurement value setting unit 123 ₁ calculates a logical product of the logical value output from the first operation delay timer TON ₁ and the logical value output from the first return delay timer TOFF ₁ , and calculates the logical value as the calculation result. Output to the first bus ratio differential relay RDf _A. The second measurement value setting unit 123 ₂ calculates a logical product of the logical value output from the second operation delay timer TON ₂ and the logical value output from the second return delay timer TOFF _2, and calculates the logical value that is the calculation result. 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 that. 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. Thus, the first measurement value setting unit 123 ₁ and the second measurement value setting unit 123 ₂ is a unit for setting to zero the measured value of the current flowing through the Busutai.

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 measurement value setting unit 123 ₁ . The first measurement value setting unit 123 ₁ calculates a logical product of the two input logical values, and outputs a logical value “1” as a 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 opening command, the logical value “0” indicating the non-output of the circuit breaker opening command from the first bus ratio differential relay RDf _A , 2 operating delay timer logic value TON ₂ has output "1" and is inputted to the second measurement value setting unit 123 _2. Second measurement value setting unit 123 ₂ performs a logical product of the two logical values, and outputs a logical value "0" as the operation result to the second busbar 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 current value.

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, as long as the difference current between the current at which the current sixth current sensor CT ₆ was measured and third current sensor CT ₃ and the fourth current sensor CT ₄ is measured is not zero, the second bus bar ratio differential relay RDf _B is The second bus protection operation as described above is performed.

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 To enter. Therefore, the first busbar ratio differential relay RDf _A, fifth current sensor CT ₅ is changed to zero current measured according to the logic values entered. If the current fifth current sensor CT ₅ are measured is changed to zero, the current first current sensor CT ₁ and the second current sensor CT ₂ are measured, the difference between the current fifth current sensor CT ₅ was measured The current is not zero. Therefore, the first bus ratio differential relay RDf _A performs 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 , second circuit breaker CB ₂ , and bustie circuit breaker CB _BT . As a result, the first circuit breakers CB ₁ and a second circuit breaker CB ₂ opens according breaker opening command entered, the first busbar LA is protected from accidents at fault point F _BT.

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 , current measurement values of the fifth current sensor CT ₅ is changed to zero. As a result, the first bus ratio differential relay RDf _A performs the first bus protection operation based on the calculated difference current. Therefore, according to the busbar protection device according to the embodiment, in the double busbar system, busbar protection can be executed regardless of the arrangement of the current sensor that measures the current flowing through the bustie.

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 at the bus tie 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. Providing such an output terminal Busutai breaker CB _BT side may be difficult depending switchboard configuration 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 illustrating a second configuration example of the busbar protection device according to the embodiment. In the second configuration example shown in FIG. 6, the same reference numerals are given to the same components as those in the first configuration example shown in FIG. 2. In the second configuration example shown in FIG. 6, the busbar 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, or the like). Each current and each voltage output from the analog / digital converter 11 are input to the processing unit 13. The processing unit 13 performs a busbar protection operation based on each input current and each voltage.

<< One-bus 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, when an accident such as a ground fault or a short-circuit accident occurs at an arbitrary accident point F _A of the first bus L _A , the first bus ratio differential relay RDf _A is the same as the first configuration example. 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 A first bus protection operation and a second bus protection operation as described are executed.

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 bar protection operation as described below, detects that the accident that occurred is a blind spot accident, and removes the accident.

As shown in FIG. 6, similarly to the first configuration example, the processing unit 13 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 including a second bus abnormal voltage detection unit 122 _B. These units perform the same operation 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 unit AND ₁ , and a second logical product. The part AND ₂ is not included. The processing unit 13 includes an exclusive OR unit EXOR instead of these units.

The exclusive OR unit EXOR, abnormal voltage detection signal first busbar abnormal voltage detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B is output is input. 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 detecting unit 122 _A and the second bus abnormal voltage detection unit 122 _B has output an abnormal voltage detection signal is Busutai breaker CB _BT available determined to have changed from the closed to the open It is. Therefore, when the open Busutai breaker CB _BT by the second busbar ratio differential relay RDf _B executes the second busbar protection operation, for example, a signal of a logical value "1" as the abnormal voltage detection signal is exclusive OR Input to the part EXOR.

Processing unit 13, in place of the first measurement value setting unit 123 ₁ and the second measurement value setting unit 123 _2, a third measurement value setting section 123, _third and fourth measurement value setting unit 123 _4.

The third measurement value setting unit 123 _3, a logical value exclusive portion EXOR logical value which the first overcurrent detecting section 121 _A and output is output to the input. The third measurement value setting unit 123 ₃ performs a logical product of the two logical values, and outputs a logical value which is the operation result to the first busbar 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. The fourth measured value setting unit 123 ₄ calculates the logical product of the two input logical values, and outputs the logical value as the calculation result to the second bus 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 that. 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. Thus, similarly to the first measurement value setting unit 123 ₁ and the second measurement value setting unit 123 _2, third measured value setting section 123, _third and fourth measurement value setting unit 123 _4, the current flowing through the Busutai This unit 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 you set the measured value to zero to the first busbar 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 current value.

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. Differential current second busbar ratio differential relay RDf _B is sixth current sensor CT ₆ changes to zero current measured according to the logic values entered. When the current measured by the sixth current sensor CT ₆ is changed to zero, the difference between the current measured by the third current sensor CT ₃ and the fourth current sensor CT ₄ and the current measured by the sixth current sensor CT ₆ The current is not zero. Therefore, the second bus ratio differential relay RDf _B performs the second bus 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 To enter. Therefore, the first busbar ratio differential relay RDf _A, fifth current sensor CT ₅ is changed to zero current measured according to the logic values entered. If the current fifth current sensor CT ₅ are measured is changed to zero, the current first current sensor CT ₁ and the second current sensor CT ₂ are measured, the difference between the current fifth current sensor CT ₅ was measured The current is not zero. Therefore, the first bus ratio differential relay RDf _A performs 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 , second circuit breaker CB ₂ , and bustie circuit breaker CB _BT . As a result, the first circuit breakers CB ₁ and a second circuit breaker CB ₂ opens according breaker opening command entered, the first busbar LA is protected from accidents at fault point F _BT.

  As described above, even when the busbar protection device according to the embodiment is configured as in the second configuration example, as in the first configuration example, in the double bus system, the current for measuring the current flowing through the bustie is measured. Busbar protection can be performed regardless of sensor placement.

In the first configuration example, in order to determine that one bus is protected and the other bus is not connected in a double bus accident, time adjustment using a timer is performed. In timed adjustment, and operation time of Busutai breaker _{CB BT,} and the recovery time of the first busbar ratio differential relay RDf _A or the second busbar ratio differential relay RDf _B is considered. Further, the timed adjustment, operation time and of the first overcurrent detecting section 121 _A or the second overcurrent detecting section 121 _B, a first bus abnormal voltage detecting unit 122 _A or the second bus abnormal voltage detection unit 122 operating time _B And are considered. On the other hand, in the second configuration example, the double bus can be protected with a simpler configuration without performing time adjustment using a timer as in the first configuration example.

  Moreover, although the first configuration example and the second configuration example use digital circuits, the present invention is not limited to this. The present invention can also be configured by combining a single protection relay and timer relay.

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

1, 2 Bus protection device 11 Analog / digital (A / D) converters 12 and 13 Processing unit 121 _A First overcurrent detection unit 121 _B Second overcurrent detection unit 122 _A First bus abnormal voltage detection unit 122 _B No. 2 bus abnormal voltage detection unit 123 ₁ first measurement value setting unit 123 ₂ second measurement value setting unit 123 ₃ third measurement value setting unit 123 ₄ fourth measurement value setting unit AND ₁ first AND unit AND ₂ second logic Product BT Bustie CB ₁ First circuit breaker CB ₂ Second circuit breaker CB ₃ Third circuit breaker CB ₄ Fourth circuit breaker CB _BT bustie circuit breaker CT ₁ First current sensor CT ₂ Second current sensor CT ₃ Third current Sensor CT ₄ Fourth current sensor CT ₅ 5th current sensor CT ₆ 6th current sensor DS ₁ 1st disconnector DS ₂ 2nd disconnector DS ₃ 3rd disconnector DS ₄ 4th disconnector DS ₅ 5th disconnector DS ₆ the sixth disconnecting switch DS ₇ 7 disconnecting 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} second transmission line _{L 3} a 3 transmission line L ₄ 4th transmission line LD ₁ 1st load LD ₂ 2nd load P ₁ 1st generator P ₂ 2nd generator PS Electric power system RDf _A 1st bus ratio differential relay RDf _B 2nd bus ratio Dynamic relay TOFF ₁ First return delay timer TOFF ₂ Second return delay timer TON ₁ First operation delay timer TON ₂ Second operation delay timer VT _A First voltage sensor VT _B Second voltage sensor Z _A First protection zone Z _B Second protected area

Claims (6)

A second bus ratio differential relay that performs a second bus protection operation that opens at least a bus tie breaker installed in the bus tie in response to an accident occurring in the bus tie connecting the first bus and the second bus;
An overcurrent detector for detecting an overcurrent flowing through the bustie;
A first bus abnormal voltage detector for detecting an abnormal voltage applied to the first bus;
A measurement value setting unit for setting the measurement value of the current flowing through the bus tie to zero when the second busbar protection operation is performed and the overcurrent and the abnormal voltage are detected;
A first bus protection operation for opening at least a power line breaker installed in the power transmission line according to the current flowing in the power transmission line connected to the first bus and the measured value set to zero is performed. A bus protection device for a double bus including a bus ratio differential relay. An overcurrent detection unit for detecting an overcurrent flowing in the bus tie connecting the first busbar and the second busbar;
A first bus abnormal voltage detector for detecting an abnormal voltage applied to the first bus;
A second bus abnormal voltage detector for detecting an abnormal voltage applied to the second bus;
A measurement value setting unit for setting a measurement value of a 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 bus protection operation for opening at least a power line breaker installed in the power transmission line according to the current flowing in the power transmission line connected to the first bus and the measured value set to zero is performed. A bus protection device for a double bus including a bus ratio differential relay. The overcurrent detection unit detects the overcurrent with respect to the zero-phase current of the bustie,
The busbar protection device according to claim 1 or 2, wherein the first busbar abnormal voltage detection unit detects an overvoltage with respect to a zero-phase voltage of the first busbar. The overcurrent detection unit detects an overcurrent with respect to a current flowing through a transmission line of each phase constituting the bustie,
3. The bus protection device according to claim 1, wherein the first bus abnormal voltage detection unit detects an undervoltage with respect to a line voltage generated between power transmission lines of each phase constituting the first bus. .   2. The busbar protection device according to claim 1, further comprising a delay unit that delays detection of the overcurrent and the abnormal voltage for a predetermined time and outputs the delayed value to the measurement value setting unit. The bus value according to any one of claims 1 to 5, wherein a current value flowing from the first bus bar to the second bus bar is acquired based on a measured value of a current flowing from the second bus bar to the first bus bar. Protective device.

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