JP2021019420A - Protective relay - Google Patents

Abstract

To provide a protective relay in which power supply voltage is generated by an electric quantity signal based on output of a voltage transformer or a current transformer, and which securely records data on an electric quantity at the time of a failure in a short period of time.SOLUTION: An over-current relay 30 includes: a power supply circuit 50 for generating power supply voltage from an electric quantity signal based on output of a voltage transformer or a current transformer 21. A nonvolatile memory 36 includes a first block and a second block as storage regions. A controller 34, when determining on the basis of the electric quantity signal that a power system has failed, sequentially stores a first management number, electric quantity data at the time of occurrence of the failure, and a second management number in an empty block in which no data is stored of the first block and the second block. Every time a failure occurs in the power system, the controller 34 updates the first management number and the second management number.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to protective relays.

One of the functions of the protective relay that protects the power system is the function of recording the data of the amount of electricity (current or voltage) in the event of an accident in the power system. The recording of the electric energy data is performed to analyze the accident occurrence situation (see, for example, Patent Document 1 (Patent No. 6116767)).

Japanese Patent No. 6116767

Depending on the model of the protective relay, the power supply voltage may be generated by the electric quantity (current or voltage) signal based on the output of the voltage transformer or the current transformer without using the power supply voltage supplied from the battery power supply. In the case of such a model, if the circuit breaker is opened because a trip signal is output from the protective relay to the circuit breaker when a failure occurs in the power system, the power supply for operating the protective relay is lost. Therefore, it is necessary to record the data in the non-volatile memory when a failure occurs in a short time of, for example, within 3 cycles from the output of the trip signal to the operation of the circuit breaker. In addition, it is necessary to limit the data to be stored in the non-volatile memory to the minimum such as the effective value of the amount of electricity at the time of failure.

In particular, when the protective relay is an overcurrent relay, the power supply voltage is generated based on the output of the current transformer. Therefore, depending on the magnitude of the load current when the power system is normal, the power supply voltage required to drive the protective relay May not be generated. In such a case, the protective relay starts operating only when a large fault current flows through the power system when a fault occurs. Therefore, it is necessary to record data in the non-volatile memory in a shorter time. Conventional overcurrent relays having the above configuration usually do not have a data recording function because the processing time required for data recording at the time of failure cannot be secured.

The present disclosure has been made in consideration of the above problems. An object of the present disclosure is to reliably record the data of the amount of electricity at the time of failure in a short time and surely in a protective relay in which a power supply voltage is generated by an electric amount signal based on the output of a voltage transformer or a current transformer.

The protective relay of one embodiment includes a power supply circuit, an analog input circuit, a non-volatile memory, and a controller. The power supply circuit generates a power supply voltage to be supplied to the protective relay from an electric quantity signal based on the output of a voltage transformer or a current transformer provided in the power system. The analog input circuit generates time series data by analog-to-digital conversion of the electric energy signal. The non-volatile memory includes a first block and a second block as a storage area. The controller determines whether or not a failure has occurred in the power system based on the above time series data. When the controller determines that the power system has failed, the first block and the second block, which are empty blocks in which data is not stored, are sequentially assigned to the first control number and the time-series data at the time of failure. Stores the based electricity amount data and the second control number. The controller updates the first control number and the second control number every time a power system failure occurs.

According to the above embodiment, the controller is in the free block of the first block and the second block provided in the non-volatile memory, in order, the first control number, the electric energy data as the electric energy data, and so on. Stores the second control number. As a result, it is possible to reliably record the data of the amount of electricity at the time of failure in a short time.

It is a block diagram which shows the whole structure of an overcurrent relay. It is a figure for demonstrating the storage area for storing the electric energy data at the time of operation of a relay. It is a figure for demonstrating the modification about the storage area for storing the electric energy data at the time of operation of a relay. This is the timing showing the operation of the overcurrent relay shown in FIG. It is a flowchart which shows the flash memory processing after starting the relay of FIG. It is a flowchart which shows the flash memory processing after the operation of a relay of FIG.

Hereinafter, embodiments will be described in detail with reference to the drawings. In the following, an overcurrent relay will be described as an example, but the protective relay according to the present disclosure is not limited thereto. The following techniques can be applied to other types of protective relays as long as the power supply voltage is generated by an electric quantity signal based on the output of a voltage transformer or a current transformer. In the following description, the same or corresponding parts may be designated by the same reference numerals and the description may not be repeated.

Embodiment 1.
[Overall configuration of overcurrent relay]
FIG. 1 is a block diagram showing an overall configuration of an overcurrent relay. With reference to FIG. 1, the overcurrent relay 30 is connected to a current transformer 21 provided on the three-phase AC line 20 of the power system. A circuit breaker 22 is further provided on the three-phase AC line 20. The direction from the top to the bottom of the paper is the tidal current direction 23.

Although different from the case of FIG. 1, in the case of a protective relay that determines a failure based on the voltage of the power system, the protective relay is located on the secondary side of the voltage transformer provided on the three-phase AC line 20. Be connected.

As shown in FIG. 1, the overcurrent relay 30 includes an input converter 31, an analog input circuit 32, an arithmetic processing circuit 33, a display device 40, a digital output circuit 41, a power supply circuit 50, a power supply monitoring circuit 51, and the like. The display device 40 is, for example, a liquid crystal display.

The input converter 31 includes an auxiliary transformer (not shown). The primary winding of the auxiliary transformer is connected to the output terminal of the current transformer 21. The auxiliary transformer converts the output signal of the current transformer 21 into a current signal having a size suitable for the internal circuit of the overcurrent relay 30. In this disclosure, the current signal and the voltage signal may be collectively referred to as an electric energy signal.

The analog input circuit 32 includes an analog filter (not shown), a sample hold circuit (not shown), an A / D (Analog to Digital) converter (not shown), and the like. The analog filter is a low-pass filter provided for removing a folding error during A / D conversion. The sample hold circuit samples and holds the current signal that has passed through the analog filter at a specified sampling frequency. The A / D converter converts the current signal held in the sample hold circuit into a digital value. As a result, time series data is generated.

The arithmetic processing circuit 33 of FIG. 1 is configured based on a computer. Unlike the example of FIG. 1, the arithmetic processing circuit 33 may be configured based on a circuit such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

Specifically, the arithmetic processing circuit 33 includes a CPU (Central Processing Unit) 34 as a controller, a RAM (Random Access Memory) 35, and a flash memory 36. The flash memory 36 is a type of non-volatile memory that can be electrically rewritten, and stores programs and data. The CPU 34 operates according to the program stored in the flash memory 36. The RAM 35 is used as the main memory of the CPU 34. These components are connected to each other via a bus 37.

Here, in the case of the flash memory 36, new data cannot be overwritten in the area where the data has already been written, and it is necessary to erase the data once and then write the new data. Further, it is not possible to erase data for each memory cell, and it is necessary to erase data for each erase unit composed of a large number of memory cells. Therefore, it takes a certain amount of time to erase the data.

The CPU 34 performs an operation based on the time series data output from the analog input circuit 32. Specifically, the CPU 34 determines whether or not the current flowing through the three-phase AC line 20 exceeds the threshold value, that is, whether or not it is an overcurrent based on the time series data. When the CPU 34 determines that the current of the power system is an overcurrent, the CPU 34 outputs a trip signal 42 to the circuit breaker 22 by the digital output circuit 41. Further, the CPU 34 may display on the display device 40 that the power system is out of order. Further, the CPU 34 stores one or more values (referred to as electric energy data) regarding the electric energy at the time of failure of the electric power system in the flash memory 36. For example, the current effective value at the time of failure is stored in the flash memory 36.

The power supply circuit 50 generates a power supply voltage for operating the analog input circuit 32, the arithmetic processing circuit 33, the display device 40, the digital output circuit 41, and the like, based on the current signal output from the input converter 31. ..

The power supply monitoring circuit 51 determines whether or not the power supply voltage generated by the power supply circuit 50 is lower than the reference value. The power supply monitoring circuit 51 outputs the determination result to the CPU 34. Even if the CPU 34 determines that the current of the power system is an overcurrent, if the power supply voltage generated by the power supply circuit 50 is lower than the reference value, the CPU 34 stores the electric amount data at the time of failure in the flash memory 36. do not do. As a result, it is possible to avoid a situation in which the power supply is lost during the data storage in the flash memory 36.

The power supply monitoring circuit 51 does not necessarily have to be provided. In this case, the power supply may be lost while the data is stored in the flash memory 36. However, as will be described below, the overcurrent relay 30 is configured to detect in advance whether or not the electric energy data during the operation of the relay is reliably stored in the flash memory 36, so that there is no problem.

[Storage area for relay operation data]
FIG. 2 is a diagram for explaining a storage area for storing electric energy data during operation of the relay.

With reference to FIG. 2, the flash memory 36 includes two areas, block 1 and block 2, as storage areas for electric energy data during relay operation. In the case of FIG. 2, the capacity of each block is set to be equal to the capacity of the erasing unit of the flash memory 36.

The CPU 34 records the electric energy data at the time of operation of the relay while alternately switching between the block 1 and the block 2. Block management numbers 61, 63, 71, and 73 are used to switch blocks. It is possible to determine whether the data stored in the block 1 or the data stored in the block 2 is newer by the block management number. In this disclosure, the block control number may be simply referred to as a control number.

For example, the initial value of the block management number may be 0x0001, and the block management number may be set so that the values up to 0xFFFE can be sequentially taken. To avoid confusion with 2's complement, 0x0000 and 0xFFFF are not used. After starting the overcurrent relay 30, the block control number is updated by adding 1 to the current block control number. When the value after the addition process becomes 0xFFFF, the initial value 0x0001 is used as a new block management number. On the contrary to the above, the block management number may be updated by subtracting 1 from the current block management number. The block management number may be updated in any way as long as the plurality of electric energy data stored each time a failure occurs in the power system can be distinguished from each other.

In the present embodiment, when the CPU 34 determines that the current flowing through the power system is an overcurrent, the block management number (61; 71) is placed in an empty block in the block 1 and the block 2 in which no data is stored. ), The electric energy data (62; 72) at the time of operation of the relay, and the block control number (63; 73) are stored in this order. Here, the first block management number (61; 71) of the stored data may be referred to as the first block management number, and the last block management number (63; 73) of the stored data may be referred to as the second block management number. is there.

In the present embodiment, the block control numbers 61 and 71 are written at the start of writing, and the block control numbers 63 and 73 having the same values as at the start of writing are written at the end of writing. That is, the block control numbers 61 and 71 before and after the electric energy data 62 and 72 and the block control numbers 63 and 73 are set to equal values. As a result, if the block control numbers 61 and 71 at the beginning of the stored data and the block control numbers 63 and 73 at the end do not match, it can be seen that an error has occurred when storing the data in the flash memory 36.

As shown in FIG. 2, each block may have blank areas 64,74 in which data is not stored. The data amount of the electric energy data 62 and 72 may be adjusted so that the blank areas 64 and 74 become 0.

In the present embodiment, the power supply voltage required for the operation of the overcurrent relay 30 is generated by the current signal based on the output of the current transformer 21, so that the processing time of the CPU 34 for data storage is limited. Therefore, the minimum required electric energy data 62 and 72 are stored in each block. For example, the current effective value at the time of failure is stored in each block.

If there is a margin in the processing time and the storage capacity of the block, the electric energy data 62 and 72 stored in the flash memory 36 may be increased. For example, the flash memory 36 may store the effective value of each electric energy and the number of times the relay operates when a plurality of power system failures occur from a specific point in the past to the present time. .. These data can be used to identify the faulty part of the power system and can be used for examination when inspecting and updating equipment.

For example, when the data has already been written in the block 1 and the data is newly written in the block 2, the CPU 34 erases the data in the block 1 after the data writing in the block 2 is completed. As a result, even if an error occurs when writing data to the block 2, the block 1 can be left as a normal block, so that the block management number can be referred to from the normal block 1.

FIG. 3 is a diagram for explaining a modified example of a storage area for storing electric energy data during relay operation. In FIG. 3, the capacity of each block is equal to the capacity of the two erasing units 60. Further, the capacity of each block may be set equal to an integral multiple of the capacity of the flash memory erasing unit 60.

Similarly, in the case of FIG. 3, when the CPU 34 determines that the current flowing through the power system is an overcurrent, the block management number (61) is assigned to an empty block in the block 1 and the block 2 in which no data is stored. 71), the amount of electricity data (62A, 62B; 72A, 72B) when the relay is operating, and the block control number (63; 73) are stored in this order.

[Operation of overcurrent relay]
FIG. 4 shows the timing showing the operation of the overcurrent relay of FIG. FIG. 5 is a flowchart showing the flash memory processing after the relay of FIG. 4 is started. FIG. 6 is a flowchart showing the flash memory processing after the operation of the relay of FIG. Hereinafter, the operation of the overcurrent relay 30 when a failure occurs in the three-phase AC line 20 will be described with reference to FIGS. 4 to 6.

It is assumed that a failure occurs in the three-phase AC line 20 at time t0 in FIG. As a result, a failure current exceeding the load current flows through the three-phase AC line 20, so that the power supply circuit 50 generates a power supply voltage at a level required for the operation of the overcurrent relay 30. The overcurrent relay 30 is activated by the generated power supply voltage.

Between the time t0 and the time t1, the CPU 34 performs the initialization process of the overcurrent relay 30.

From the next time t1 to time t3, the flash memory processing after starting the relay shown in FIG. 5 is executed. Specifically, steps S100 to S120 of FIG. 5 correspond to the necessity determination of the erasing process executed between the time t1 and the time t2 of FIG. Steps S130 to S160 of FIG. 5 correspond to the block erasing process executed when necessary between the time t2 and the time t3 of FIG.

As shown in FIG. 5, in step S100, the CPU 34 selects the block numbers (i = 1, 2).

In the next step S110, the CPU 34 determines whether or not data is stored in the i-th block. As a result, if the data is stored in the i-th block (YES in step S110), the CPU 34 advances the process to step S120. In step S120, the CPU 34 determines whether or not the block management number is correct. In the case of the present embodiment, when the block management number (61; 71) at the beginning of the stored data and the block management number (63; 73) at the end of the stored data are equal, the CPU 34 determines that the block management number is correct. judge. If the block management number is correct, it means that the data is normally stored in the block.

The necessity determination of the above erasing process is executed for each of the block numbers (i = 1, 2).

In the next step S130, the CPU 34 determines whether or not the data is normally stored in both blocks as a result of the necessity determination of the erasing process. As a result, if it is determined that both blocks are normal (YES in step S130), the CPU 34 erases the data of the older block based on the control number in step S140.

On the other hand, if both blocks are not normal (NO in step S130), in the next step S150, the CPU 34 determines whether or not any of the blocks is abnormal. Specifically, when the block management number (61; 71) at the beginning of the stored data and the block management number (63; 73) at the end of the stored data are not equal, it is determined as an abnormal block. Further, even if at least one of the first block management number (61; 71) and the last block management number (63; 73) is missing, it is determined as an abnormal block. If there is an abnormal block (YES in step S150), the CPU 34 erases the data of the abnormal block.

With the above, the processing after starting the relay is completed. By this process, either block 1 or block 2 is normally stored with data and the other is empty, or both blocks are empty. From the beginning, if data is normally stored in one of the blocks and the other is empty, or if both blocks are empty (NO in both steps S130 and S150), the CPU 34 erases. No need to do.

Returning to FIG. 4, the normal processing of the overcurrent relay 30 is executed between the time t3 and the time t4. Specifically, the CPU 34 determines whether or not the current of the three-phase AC line 20 is an overcurrent based on the time series data. Further, the CPU 34 displays the determination result on the display device 40.

At time t4, the CPU 34 determines that the current of the three-phase AC line 20 is an overcurrent. That is, the overcurrent relay 30 operates. Further, the digital output circuit 41 outputs a trip signal 42 to the circuit breaker 22. As a result, the circuit breaker 22 starts operating at time t7, which is about three cycles after time t4, and the overcurrent relay 30 is in a power loss state at time t8.

During the period from time t4 to time t6 before the circuit breaker 22 operates, the flash memory processing after the relay operation shown in FIG. 6 is executed. Specifically, steps S200 to S240 in FIG. 6 correspond to data writing processing executed between the time t4 and the time t5 in FIG. Steps S250 to S260 of FIG. 6 correspond to the block erasing process executed between the time t5 and the time t6 of FIG.

As shown in FIG. 6, in step S200, the CPU 34 updates the block management number. In the present embodiment, 1 is added to the block management number currently stored in the flash memory 36.

In the next step S210, the power supply monitoring circuit 51 determines whether or not the power supply voltage generated by the power supply circuit 50 is lower than the reference value. When the power supply voltage is lower than the reference value, the CPU 34 waits for the power supply voltage to recover to the reference value or more without executing the data writing process to the flash memory 36. As a result, it is possible to avoid a situation in which power is lost during data writing.

In the next step S220, the CPU 34 writes the updated block management number in the empty block of the blocks 1 and 2.

In the next step S230, the CPU 34 writes the electric energy data at the time of operation of the relay to the block. As the electric energy data, for example, the current effective value at the time of operation of the relay is used.

In the next step S240, the CPU 34 writes the same block management number as in step S220 to the block. With the above, the data writing to the empty block is completed.

In step S250 after the data writing is completed, the CPU 34 determines whether or not data is stored in both blocks. As a result, if data is stored in both blocks (YES in step S250), the CPU 34 advances the process to step S260. In step S260, the CPU 34 erases the data of the older block based on the block management number. By emptying one block at this stage, data can be written immediately after the overcurrent relay 30 is started. Even if the power is lost during the data erasure, there is no problem because the data of the abnormal block is erased in step S160 of FIG.

[effect]
As described above, according to the overcurrent relay 30 of the present embodiment, when the CPU 34 determines that the power system is out of order, the CPU 34 manages blocks in the empty blocks of the blocks 1 and 2 provided in the flash memory 36. The number (61; 71), the electric energy data (62; 72) at the time of relay operation, and the block management number (63; 73) are stored in this order. By using the block management number, it is possible to determine whether or not the electric energy data is normally stored in the block, so that the electric energy data can be reliably stored in the flash memory 36. Further, by alternately using the blocks 1 and 2, the data of one block can be erased in advance, so that the time required for storing the data can be shortened.

Further, by monitoring the power supply voltage generated by the power supply circuit 50 using the power supply monitoring circuit 51, data is not stored in the flash memory 36 when the power supply voltage drops below the reference value. This makes it possible to prevent data storage from being interrupted due to power loss.

[Modification example]
In the above, the first control number at the beginning and the second control number at the end of the data stored in each block are set equally. Unlike this, the first control number and the second control number may be set to different values having a predetermined relationship. Also in the above case, whether or not the data is normally stored in the block by determining whether or not the first control number and the second control number have the above-mentioned predetermined relationship for each block. Can be detected.

For example, the first control number may be an odd number, and the second control number may be set to an even number obtained by adding 1 to the first control number. In this case, it is possible to detect whether or not the data is normally stored in the block depending on whether or not the value obtained by subtracting the first control number from the second control number becomes 1.

The embodiments disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of the present invention is shown by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the claims.

20 Three-phase AC line, 21 Current transformer, 22 Circuit breaker, 23 Power flow direction, 30 Overcurrent relay, 31 Input converter, 32 Analog input circuit, 33 Arithmetic processing circuit, 34 CPU, 35 RAM, 36 Flash memory, 37 Bus, 40 display device, 41 digital output circuit, 42 trip signal, 50 power supply circuit, 51 power supply monitoring circuit, 60 erasure unit, 61, 63, 71, 73 block control number, 62, 72 Electric current data at the time of failure.

Claims (11)

It ’s a protective relay,
A power supply circuit that generates a power supply voltage to be supplied to the protective relay from an electric quantity signal based on the output of a voltage transformer or a current transformer provided in the power system.
An analog input circuit that generates time series data by analog / digital conversion of the electric energy signal, and
A non-volatile memory containing a first block and a second block as a storage area,
A controller for determining whether or not a failure has occurred in the power system based on the time series data is provided.
When the controller determines that the power system is a failure, the first control number is set in an empty block of the first block and the second block in which data is not stored, and the time when the failure occurs. The electric energy data based on the series data and the second control number are stored in order,
The controller is a protective relay that updates the first control number and the second control number each time a failure occurs in the power system. The controller determines whether or not data is stored in each of the first block and the second block at the time of starting the supply of the power supply voltage from the power supply circuit.
The controller is normal in the block determined to store data when the stored first control number and the second control number satisfy a defined relationship. The protective relay according to claim 1, wherein it is determined that data is stored in the relay. When the controller determines that data is normally stored in both the first block and the second block at the time of activation, the first control number stored in each block and the said first. The protective relay according to claim 2, which erases the older data based on the second control number. At the time of activation of the controller, either the first block or the second block does not satisfy the predetermined relationship between the first control number and the second control number, or the controller does not satisfy the predetermined relationship. The protective relay according to claim 2 or 3, which erases the data of the block when at least one of the first control number and the second control number is missing. As a result of the controller determining that the power system is a failure and storing the first control number, the electricity amount data, and the second control number in an empty block, the first block and the first The protective relay according to any one of claims 1 to 4, which erases the old data when both of the two blocks store data. The protective relay further includes a power supply monitoring circuit that determines whether or not the power supply voltage generated by the power supply circuit is lower than a reference value.
Even if the controller determines that the power system is out of order, if the power supply monitoring circuit determines that the power supply voltage is lower than the reference value, the first control number and the electricity The protective relay according to any one of claims 1 to 5, which does not store the quantity data and the second control number in the non-volatile memory. The non-volatile memory is configured to erase stored data for each erase unit.
The capacity of any one of claims 1 to 6, wherein the respective capacities of the first block and the second block are equal to the capacity of the erasing unit or an integral multiple of the capacity of the erasing unit. Protective relay. The protective relay according to any one of claims 1 to 7, wherein the electric energy data includes an effective value of the electric energy when a failure of the electric power system occurs. Any of claims 1 to 7, wherein the electric energy data includes an effective value of the electric energy in each case determined by the controller to be a failure of the power system from a specific time in the past to the present time. The protective relay according to item 1. The protective relay is an overcurrent relay and
The power supply circuit generates the power supply voltage from a current signal based on the output of the current transformer when the current of the power system becomes overcurrent, and starts supplying the power supply voltage to the protective relay. The protective relay according to any one of 9 to 9. The protective relay according to any one of claims 1 to 10, wherein the first control number and the second control number included in the same block are equal to each other.

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