JP2019176538A - Digital protective relay and monitoring method of data received state in the same - Google Patents

Abstract

To prevent duplication use of waveform data in a protective relay.SOLUTION: A protective relay 14 comprises: an A/D conversion section 15; and a processing section 17. The A/D conversion section 15 comprises an analog channel to which system electric quantity is inputted, and digitally converts inputted waveform data. The processing section 17 transmits a request signal to the A/D conversion section 15, receives the digitally converted waveform data from the A/D conversion section 15, and performs relay operation on the basis of the received waveform data. The processing section 17 determines whether it receives data on the number of all analog channels of the A/D conversion section 15 in a previous sampling period at every sampling period, and locks the relay when data mismatch. The processing section 17 determines whether a request channel is matched with a response channel with respect to the respective channels of the A/D conversion section 15 in the previous sampling period, and locks the relay when they mismatch.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for monitoring a data reception state in a digital type protective relay. In particular, the present invention relates to a method for constantly monitoring the reception state of analog data in a digital type protective relay receiving analog data.

  The protective relay detects short-circuit faults and ground faults that have occurred in power stations, substations, transmission / distribution lines, etc. that make up the power system via the instrument transformer, and selects the fault section so that it can be disconnected from the power system. A control signal is sent to a circuit breaker or the like (for example, Patent Document 1).

  As shown in FIG. 8, the digital protection relay 20 is input with an AC electric quantity such as voltage and current introduced from the power system. The input AC electric quantity is input to an analog-digital conversion unit 21 (hereinafter referred to as A / D conversion unit 21), and the A / D conversion unit 21 converts the AC analog signal into a digital signal. Based on this digital signal, the processing unit 24 performs a relay operation.

Specifically, the A / D converter 21 includes a sampling hold 21a (S / H), a multiplexer 21b (MPX), and an A / D converter 21c. The A / D converter 21 includes secondary voltages (V _A , V _B ) and branch lines (for example, branch lines 9 a to 9 n shown in FIG. 8 of Patent Document 1) of an instrument transformer provided in the power system. The analog information of the currents (1) I to (n) I flowing in the current is input. Then, the A / D converter 21 converts the inputted analog information into digital information and sends it to the common bus 22.

The digital input unit 23 includes, for example, “ON” and “OFF” information of the line switches 3 and 5 and the line switch groups 6a to 6n and 7a to 7n illustrated in FIG. "On" information is given. The digital input unit 23 sends the input information to the common bus 22. Both pieces of information that have flowed to the common bus 22 are taken into the processing unit 24, where switching processing of the instrument transformer is performed, and either the bus voltage V _A or V _B is selected according to the conditions. .

  The processing unit 24 (protection relay) serially outputs a waveform data request to the A / D converter 21c at every sampling interval. In response to a request from the processing unit 24, the A / D converter 21 c serially outputs the waveform data to the processing unit 24. The processing unit 24 performs a relay calculation based on the waveform data received from the A / D converter 21 c and the information input from the digital input unit 23. The result of the relay operation is transmitted to the digital output unit 25, and the digital output unit 25 sends out the output information of the protective relay 20.

JP 05-137232 A JP 2012-063913 A

  In the conventional digital protective relay, when the processing unit cannot receive serial data due to a failure of the A / D converter or the like, serial communication is stopped until the next sampling period. Then, when serial communication is started again in the next sampling period, the waveform data received last time may be used without being updated. Using the previously received waveform data may cause the digital protective relay to malfunction.

  The present invention has been made in view of the above circumstances, and an object thereof is to prevent duplication of waveform data in a digital type protective relay.

One aspect of the digital protective relay of the present invention that achieves the above object is as follows:
Provided with a channel for inputting waveform data of a secondary voltage of an instrument transformer provided on a bus of an electric power system or a secondary current of a current transformer provided on a branch line branched from the bus. An A / D converter for converting waveform data into digital data;
A digital input unit to which "ON" information of a circuit breaker provided in the busbar or "ON" and "OFF" information of a line switch group provided between the branch line and the busbar,
Output information of the A / D converter and a common bus to which output information from the digital input unit is supplied;
A processing unit that receives the waveform data converted by the A / D conversion unit and output information from the digital input unit via the common bus, and performs a relay operation based on the received data;
The processor is
Received from the A / D converter in the previous sampling period before performing serial output for requesting the waveform data converted by the A / D converter to the A / D converter at every predetermined sampling period. It is determined whether or not the number of waveform data matches the number of channels of the A / D converter, and if not, relay lock is performed for a certain time.

Another aspect of the digital protection relay of the present invention that achieves the above object is the above digital protection relay,
The processing unit performs the A / D conversion unit in the previous sampling cycle before performing serial output for requesting the waveform data converted by the A / D conversion unit to the A / D conversion unit at every predetermined sampling cycle. It is determined for each channel of the A / D converter whether the channel requested to the D converter matches the channel received from the A / D converter, and any of the channels of the A / D converter is determined. If the channels do not match, the relay is locked for a certain time.

In addition, one aspect of the method for monitoring the data reception state in the digital type protective relay of the present invention that achieves the above object is as follows.
Provided with a channel for inputting waveform data of a secondary voltage of an instrument transformer provided on a bus of an electric power system or a secondary current of a current transformer provided on a branch line branched from the bus. An A / D converter that converts the waveform data into digital data, a processing unit that receives the waveform data converted by the A / D converter by serial communication, and performs a relay operation based on the received waveform data; A data reception status monitoring method executed by a digital protection relay comprising:
Before every serial sampling requesting the waveform data converted by the A / D conversion unit to the A / D conversion unit, the A / D conversion unit performs the A / D conversion in the previous sampling cycle every predetermined sampling cycle. Determining whether the number of waveform data received from the D converter matches the number of channels of the A / D converter;
In the step, when the number of waveform data received from the A / D converter does not match the number of channels of the A / D converter, a step of relay-locking for a predetermined time is executed.

Further, the method for monitoring the data reception state in the digital protection relay of the present invention that achieves the above object is the method for monitoring the data reception state in the digital protection relay.
Before every serial sampling requesting the waveform data converted by the A / D conversion unit to the A / D conversion unit, the A / D conversion unit performs the A / D conversion in the previous sampling cycle every predetermined sampling cycle. Determining, for each channel of the A / D converter, whether the channel requested to the D converter matches the channel received from the A / D converter;
The channel requested by the processing unit to the A / D conversion unit does not match the channel received by the processing unit from the A / D conversion unit in any of the channels of the A / D conversion unit. In this case, a step of performing relay lock for a predetermined time is performed.

  According to the above invention, it is possible to prevent the waveform data from being duplicated in the digital protection relay.

It is explanatory drawing explaining the digital type protective relay which concerns on embodiment of this invention. 1 is a system configuration diagram of a digital protection relay according to an embodiment of the present invention. It is a time chart of serial data. It is a check flow regarding a sampling interval. It is a flow regarding relay lock. It is a check flow regarding serial transmission and reception. It is a check flow of the digital protection relay which concerns on other embodiment of this invention, (a) Check flow regarding sampling interval, (b) Check flow regarding serial transmission / reception. It is a system block diagram of the digital type protective relay based on a prior art.

  A digital protection relay according to an embodiment of the present invention and a data reception state monitoring method in the digital protection relay will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram illustrating a digital protection relay 14 (hereinafter referred to as protection relay 14) according to an embodiment of the present invention.

  The buses 1 and 2 are connected to the line switches 3 and 5 by the bus bar breaker 4. Between the buses 1 and 2, line switch groups 6a to 6n and 7a to 7n connected in series are connected. Circuit breakers 10a to 10n and current transformers 11a to 11n are provided at common connection points 8a to 8n of the line switch groups 6a to 6n and 7a to 7n.

The busbars 1 and 2 are respectively provided with instrument transformers 12 and 13, and the secondary voltages (V _A and V _B ) of the instrument transformers 12 and 13 are input to the protective relay 14. The protection relay 14 receives “ON” and “OFF” information of the line switch groups 6a to 6n and 7a to 7n. The protective relay 14 relays the branch lines 9a to 9n based on the input secondary voltage (V _A , V _B ) and “ON” and “OFF” information of the line switch groups 6a to 6n and 7a to 7n. Operation information V _{a to} V _n (not shown) is output.

  FIG. 2 is a system configuration diagram of the protective relay 14 according to the embodiment of the present invention. The protective relay 14 includes an analog-digital conversion unit 15 (hereinafter referred to as A / D conversion unit 15), a digital input unit 16, a processing unit 17, and a digital output unit 18.

The A / D converter 15 includes a transformer PT (for example, the instrument transformers 12 and 13 shown in FIG. 1) and a current transformer CT (for example, the current transformer 11a shown in FIG. 1) provided in the system. ˜11n), the grid electricity quantity (V _A , V _B , (1) I,..., (N) I) is input.

  The A / D converter 15 is provided with an A / D converter 15a. The A / D converter 15a converts the input system electric quantity from analog waveform data into digitized waveform data. Is done. Then, the A / D conversion unit 15 sends the converted waveform data to the common bus 19. Although not shown, the A / D converter 15 includes a sampling hold (SH) circuit and a multiplexer (MPX) circuit as in the conventional case.

  The digital input unit 16 includes “ON” and “OFF” information of a line switch (for example, the line switch groups 6a to 6n and 7a to 7n and the line switches 3 and 5 shown in FIG. For example, the “ON” information of the bus bar breaker 4) shown in FIG. 1 is input. The digital input unit 16 sends the input information to the common bus 19.

These pieces of information that have flowed into the common bus 19 are taken into the processing unit 17, where switching processing of the instrument transformers 12 and 13 is performed, and either of the bus voltages V _A and V _B depending on the conditions. Is selected.

  The processing unit 17 includes a CPU (arithmetic unit) that performs arithmetic processing, a storage unit (flash ROM and the like) that stores programs and the like, and a memory that is a work area of the CPU, which are not shown. For example, the CPU executes a program stored in the storage unit, and each step shown in FIGS. 4 to 7 described in detail later is executed. That is, each step of the monitoring method of the data reception state of the serial communication in the processing unit 17 is realized by the cooperative operation of the CPU and the program stored in the storage unit.

  The processing unit 17 includes a protective relay arithmetic processing unit 17a and an instrument switching processing unit 17b, and arithmetic processing (relay arithmetic) of the protective relay 14 and switching processing of the instrument transformers 12 and 13 are performed. More specifically, the processing unit 17 performs a normal relay operation of the protective relay based on the data input from the A / D conversion unit 15 and the digital input unit 16, and calculates the output information of each relay. Done. That is, a request signal for obtaining waveform data information is transmitted from the processing unit 17 to the A / D conversion unit 15 every predetermined sampling period, and the waveform data obtained by digitizing the A / D conversion unit 15 in accordance with the request signal. Information is transmitted to the processing unit 17. The processing unit 17 removes high-frequency components that cause errors in the digitized waveform data, and then performs relay computation (relay based on the amplitude value computation, phase difference computation, phase computation, etc. of the waveform data) based on the waveform data information. (Operation determination calculation).

  The digital output unit 18 transmits output information of a relay (not shown) processed by the processing unit 17.

  Next, transmission / reception of waveform data between the A / D conversion unit 15 and the processing unit 17 will be described. In the description of the transmission / reception of waveform data, the case where the digitized waveform data is 8 channels will be described as an example. The number of channels can be arbitrarily set according to the type of device.

  As shown in FIG. 3, the processing unit 17 performs serial output for requesting waveform data in order from the first channel to the A / D conversion unit 15 at every predetermined sampling period (analog input SP interval).

  After receiving the serial output from the processing unit 17, the A / D conversion unit 15 receives the waveform data information of the requested channel (the waveform digitally processed by the A / D converter 15 a) according to the request from the processing unit 17. Data) is transmitted to the processing unit 17.

  The processing unit 17 receives the waveform data from the A / D conversion unit 15 and performs serial output for requesting the waveform data of the next channel. When the processing unit 17 receives the eighth channel, transmission / reception of waveform data ends.

  If serial data cannot be received by the processing unit 17 halfway, serial communication is interrupted, and transmission / reception of waveform data is resumed from the first channel when the next sampling period is reached.

  FIG. 4 shows a check flow regarding the sampling interval (SP interval).

  At every sampling period (SP interval), whether the data for the number of all analog channels has been received in the previous serial transmission / reception is checked based on the number of serial receptions (responses). Specifically, the reception counter is compared with the number of analog channels, and if they do not match, it is determined as NG, and if they match, NG is cleared. When NG is set, the relay is locked for a certain time. When the relay is locked, the processing unit 17 transmits an output signal that causes an alarm device or the like to output that the waveform data transmission / reception state is abnormal, and continuously monitors whether the reception NG state continues. Can do. When NG is cleared, an output signal for stopping an alarm such as an alarm device is transmitted from the processing unit 17.

  Also, NG is set when there is a mismatch between the check result of the request channel and its response channel in the previous serial transmission / reception, and NG is cleared when both match. When NG is set, the relay is locked for a certain time. When the relay is locked, the processing unit 17 can transmit an output signal that causes an alarm device or the like to output that the waveform data transmission / reception state is abnormal, and can continuously monitor whether the reception NG state continues. . When NG is cleared, an output signal for stopping an alarm such as an alarm device is transmitted from the processing unit 17.

  Then, the processing unit 17 clears the reception counter and serially outputs the head channel request to the A / D conversion unit 15. The A / D converter 15 serially outputs the requested channel and waveform data obtained by digitally converting the analog data input to the channel to the processing unit 17.

  FIG. 5 shows a flow regarding the relay lock. Based on this flow, the relay lock when NG is set in the flow of FIG. 4 will be described.

If there is analog reception NG (NG is set in the flow of FIG. 4), the time (T ₁ ) for locking the relay lock counter is set. If the relay lock counter is 0, the relay lock is turned off and the counter is 0 Otherwise, 1 countdown and relay flag are turned on. The relay performs a relay operation based on the waveform data received from the A / D converter 15. If the relay lock flag is on, the relay is cleared.

  FIG. 6 shows a check flow regarding serial transmission / reception.

  During serial reception, the reception counter is increased. Also, the request channel and response channel are checked for coincidence. If they do not match, the reception NG flag for each request channel is set. If they match, the reception channel is cleared and the next channel is serially output until the final request channel is reached. ) When the reception NG flag is set, NG in the flow of FIG. 4 is set. When NG is set in the flow of FIG. 4, the relay is locked for a certain time according to the flow shown in FIG. Thereby, malfunction of the protective relay 14 due to the serial reception state being NG is prevented.

  According to the digital protection relay 14 and the data reception status monitoring method in the digital protection relay 14 according to the embodiment of the present invention as described above, the reception status of the digitized waveform data is monitored, and the waveform data Duplicate use can be prevented.

  Specifically, for each sampling period, the processing unit 17 determines whether the number of waveform data (reception counter) received in the previous sampling period matches the number of channels of the A / D conversion unit 15. When the reception counter and the number of analog channels do not match, it is detected that the serial communication has been stopped. For each sampling period, the processing unit 17 determines for each channel whether the channel requested in the previous sampling period matches the response channel received from the A / D conversion unit 15. When the request channel and the response channel do not match, it is detected that there has been a transmission / reception timing shift or missing. As a result, when the transmission / reception state is NG, the relay is locked for a certain period of time or an alarm is output to prevent the protective relay 14 from malfunctioning. Can be monitored.

  As a result, when serial communication is stopped for some reason, it is possible to prevent the waveform previously received in the next sampling period from being duplicated and to provide a digital protection relay with excellent reliability.

  In addition, since the digital protection relay 14 according to the embodiment of the present invention monitors the data transmission / reception state by software, the burden on the CPU is small, and no new hardware (device or component) is required for monitoring. It becomes.

  The method for monitoring the data reception state in the digital protection relay and the digital protection relay according to the present invention has been described above with reference to a specific embodiment. The data reception state in the digital protection relay and the digital protection relay according to the present invention has been described above. The monitoring method is not limited to the embodiment, and the design can be changed as appropriate without departing from the characteristics of the monitoring method. The design change also belongs to the technical scope of the present invention.

  For example, the digital type protective relay of the present invention is not limited to being used for the application of the embodiment, and can be applied to a power plant, a substation, a transmission / distribution line, or the like constituting an electric power system.

  Further, the digital protection relay that performs a part of the processing of the processing unit 17 in the digital protection relay 14 according to the present invention also belongs to the technical scope of the present invention, and exhibits some of the effects of the digital protection relay 14. Can do. For example, as shown in FIG. 7, at a predetermined sampling period (SP interval), whether or not data for all analog channels is received in the previous serial transmission / reception is checked by the number of serial reception (response) (reception counter and The aspect of comparing the number of analog channels also belongs to the technical scope of the digital protective relay of the present invention.

DESCRIPTION OF SYMBOLS 1, 2 ... Bus-bar 3, 5 ... Line switch 4 ... Bus-line connection circuit breaker 6a-6n, 7a-7n ... Line switch group 8a-8n ... Common contact 9a-9n ... Branch line 10a-10n ... Breaker 11a-11n ... Current transformers 12, 13 ... Instrument transformer 14 ... Protective relay (digital type protective relay)
DESCRIPTION OF SYMBOLS 15 ... A / D conversion part, 15a ... A / D converter 16 ... Digital input part 17 ... Processing part, 17a ... Protection relay arithmetic processing part, 17b ... Instrument switching processing part 18 ... Digital output part 19 ... Common bus

Claims (4)

Provided with a channel for inputting waveform data of a secondary voltage of an instrument transformer provided on a bus of an electric power system or a secondary current of a current transformer provided on a branch line branched from the bus. An A / D converter for converting waveform data into digital data;
A digital input unit to which "ON" information of a circuit breaker provided in the busbar or "ON" and "OFF" information of a line switch group provided between the branch line and the busbar,
Output information of the A / D converter and a common bus to which output information from the digital input unit is supplied;
A processing unit that receives the waveform data converted by the A / D conversion unit and output information from the digital input unit via the common bus, and performs a relay operation based on the received data;
The processor is
Received from the A / D converter in the previous sampling period before performing serial output for requesting the waveform data converted by the A / D converter to the A / D converter at every predetermined sampling period. A digital protective relay characterized in that it is determined whether or not the number of waveform data matches the number of channels of the A / D converter, and if not, relay lock is performed for a fixed time.   The processing unit performs the A / D conversion unit in the previous sampling cycle before performing serial output for requesting the waveform data converted by the A / D conversion unit to the A / D conversion unit at every predetermined sampling cycle. It is determined for each channel of the A / D converter whether the channel requested to the D converter matches the channel received from the A / D converter, and any of the channels of the A / D converter is determined. 2. The digital protective relay according to claim 1, wherein when the channels do not match, the relay lock is performed for a predetermined time. Provided with a channel for inputting waveform data of a secondary voltage of an instrument transformer provided on a bus of an electric power system or a secondary current of a current transformer provided on a branch line branched from the bus. An A / D converter that converts the waveform data into digital data, a processing unit that receives the waveform data converted by the A / D converter by serial communication, and performs a relay operation based on the received waveform data; A data reception status monitoring method executed by a digital protection relay comprising:
Before every serial sampling requesting the waveform data converted by the A / D conversion unit to the A / D conversion unit, the A / D conversion unit performs the A / D conversion in the previous sampling cycle every predetermined sampling cycle. Determining whether the number of waveform data received from the D converter matches the number of channels of the A / D converter;
In the step, when the number of waveform data received from the A / D converter does not match the number of channels of the A / D converter, a step of relay-locking for a predetermined time is executed. To monitor the data reception status in a protective relay. Before every serial sampling requesting the waveform data converted by the A / D conversion unit to the A / D conversion unit, the A / D conversion unit performs the A / D conversion in the previous sampling cycle every predetermined sampling cycle. Determining, for each channel of the A / D converter, whether the channel requested to the D converter matches the channel received from the A / D converter;
The channel requested by the processing unit to the A / D conversion unit does not match the channel received by the processing unit from the A / D conversion unit in any of the channels of the A / D conversion unit. 4. The method of monitoring a data reception state in a digital type protective relay according to claim 3, wherein the step of relay-locking for a predetermined time is executed.

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