JPH09200947A - Current differential protective relay and its processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent omitted or doubled reception data by transmission path delay time ripples, etc., caused by jitter, with a current differential protective relay device by CPU processing. SOLUTION: A reception data read managing part 9a takes in a sampling number S6a identified with a reception part 8a, and decides the sampling number S8a equivalent to the reception data read address, and reads out data S9a from a reception data memory 10a as data for the operation of a current differential relay, and gives it to a current differential relay operation part 11a. For the decision of the sampling number, when the numbers in double read at one sampling of the sampling number identified with a receiver 8a accord with each other, the number is made an applicable number, and when they are not in accord, the updated number where one is added to the sampling number at the previous operation and the numbers of double read are compared, and the side where they are in accord with each other is made an applicable number.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current differential protection relay device that detects an abnormality in a power system and protects the system.

[0002]

2. Description of the Related Art A current differential protection relay device is provided in order to detect an abnormality in a power system based on electricity quantities sampled at a plurality of electric stations and ON / OFF information.

In the current differential protection relay device, the sampling timing at each end of the power transmission line is the same time. The time from the sending of this sampling data to the reception by the other end, that is, the transmission line delay time is usually longer than the sampling period. Therefore, the same sampling number is given to the data sampled at each terminal at the same time and transmitted. As an example of this, there is a sampling synchronization method of terminal-to-terminal transmission shown in Japanese Patent Laid-Open No. 50-49645, and each terminal loop transmission shown in Japanese Patent Laid-Open No. 1-203939 and B114 Volume 7/8, pages 686 to 691. A sampling synchronization method and the like are known.

In the sampling-synchronous current differential protection relay device, electricity at each end of a transmission line is sampled at a constant cycle and A / D converted, and then the other end electricity is mutually exchanged by using a micro line or the like. Then, the vector sum and the scalar sum are calculated from each electric station data to protect the transmission line.

FIG. 5 shows the configuration of a conventional current differential protection relay device. In order to protect the power transmission line 1 connecting the electric stations A and B via the circuit breakers 3a and 3b, the electric stations A and B are protected.
Current differential protection relay devices 4a and 4b are installed in the respective. The current differential protection relay device 4a at the electric station A detects the current S1 detected through the current transformer 2a at each sampling cycle.
a is converted into a digital signal S2a by the A / D converter 5a and given to the current differential relay operation unit 11a and the transmission unit 6a. The transmission data of the signal S2a is transmitted from the transmission unit 6a,
The current differential protection relay device 4b at the other end via the transmission line 12
Send to Similarly, the data S2b obtained by A / D converting the current S1b synchronously sampled with the electric station A is also transmitted from the transmitting unit 6b to the current differential protection relay device 4a at the electric station B at the other end, and is received by the receiving unit 8a. The received write data S7a is received and written in the memory via the data switching circuits 42a and 43a.

At this time, the reception data write timing from the other end is determined by the transmission line delay time. For this reason,
The reception of data for one sample extends over two samples at the self-end, and the timing is not always convenient for reading the reception data at the self-end. Therefore, a method of duplicating the reception data memory is known.

The reception data memory is duplicated, and one of the memories is an X memory 44a and the other is a Y memory 45a. Each time sampling is performed, the memory switching signal S41a from the memory switching unit 41a is turned ON / OFF, and the logical product 42a output by ON, the logical product 43a output by OFF, and the memory switching signal S41a are ON and output to the Y memory 45a. A switch circuit 46a for turning on the contact is provided.

In one sampling, the X memory 44a is set for writing the received data and the Y memory 45a is set for reading the received data S7a, and the data S from the other end is set.
7a is written in the X memory 44a at the reception timing. On the other hand, the reception data is read from the Y memory 45a at a timing convenient for the terminal itself regardless of the reception timing. In the next sampling, the setting is switched between the X memory 44a for reading received data and the Y memory 45a for writing received data. By repeating this for each sampling, it is possible to always receive the data from the other end at a timing convenient for the own end with a delay of one sampling without being restricted in the reception timing.

The transmission reference signal S3a is output from the transmission unit 6a and the reception reference signal S4a is output from the reception unit 8a to the time measurement unit 7a. The transmission line delay time is obtained from the time difference between the signals S3a and S4a, and sampling synchronization processing is performed. To do. The output S42a of the switch circuit 46a, which is switched by the memory switching signal S41a, is given to the current differential relay computing unit 11a as received data S9a for computation.

The current differential relay operation unit 11a executes a relay operation by vector sum / scalar sum based on its own input data S2a and received data S9a from the other end.
Here, when the power transmission line 1 has a short circuit or a ground fault, the relay operation output S10a of the current differential relay operation unit 11a is output, and the circuit breaker 3a is cut off. The digital operation units 13a and 13b in the dotted line frame are realized by software processing by the CPU.

[0011]

In the above-mentioned conventional technique, there is no problem if the time relationship between the data reception timing and the processing timing at its own end does not change for each sampling. However, this time relationship is due to the fluctuation of the transmission line delay time due to the sampling synchronization pull-in operation accompanying the transmission route change and the influence of the transmission line jitter and wander in the steady state in the station switching control when the transmission line failure occurs. It is known to change from time to time.

Further, in the calculation in the CPU of the current differential protection relay device, the recovery time of the interrupt processing varies, which is also a cause. That is, in the arithmetic processing of the CPU, the relay arithmetic data input processing and the like that need to be matched with the sampling cycle are executed by high-level interrupt processing, and the man-machine interface processing and the constant monitoring processing that are not restricted by the sampling cycle are low-level. It is executed by interrupt processing to improve CPU processing performance. In this case, an interrupt occurs at each sampling cycle, interrupting the low-level processing that was already being executed and shifting to the high-level processing, but since the number of execution steps changes slightly for each sampling, the recovery time It is not constant.

FIG. 6 is a time chart showing the operation when the transmission line delay time fluctuates at times t3 and t5. The other end is D (t1) to D (t
The data a of 5) is transmitted. The transmission data a at the other end is
The signal arrives at the self-end reception unit with a delay of the transmission path delay time TD via the transmission path b. Since the received data c is read alternately from the duplicated memory, the readable data d is delayed by one sample. In order to make it easier to understand the influence of the fluctuation of the delay time, the fluctuations at t3 and t5 are shown extremely in the figure.

Here, when the transmission line delay time TD increases by ΔT1 at time t3 to reach the transmission line delay time TD1,
The data f captured in the relay calculation unit by the reading process e on the receiving side, that is, the self end is D (t
0) and t4 also become D (t0), and data duplication occurs. Further, when the transmission path delay time TD1 decreases by ΔT2 at time t5 to reach the transmission path delay time TD2,
D (t1) at t5, D (t3) at t6,
D (t2) data is lost.

FIG. 7 is a time chart showing the operation when the time relationship between the data reception timing and the processing timing at the self end fluctuates at time t3. The data a of D (t1) to D (t5) transmitted from the other end at each sampling cycle TS reaches the own end receiving part c with a delay of the transmission path delay time TD and becomes readable data d delayed by one sample. . The reception timing and the processing timing are ΔT at time t3.
3 fluctuates, the data f fetched by the relay calculation unit in the read processing e at the self end is at time t3 and time t4.
D (t0) and data are duplicated at time t, and D at time t5
(T1) is missing and becomes D (t2).

As described above, when the time relationship between the data reception timing from the other end and the processing timing at the self end fluctuates at the sampling point, duplication or omission of the received data occurs and it becomes impossible to faithfully reproduce, and the relay The calculation unit may output an incorrect calculation result, which reduces the reliability of the protective relay device.

As a solution to this problem, it is possible to insert a fixed delay time into each sampling, but it is difficult to set a fixed delay time in consideration of all possible cases including transmission path switching. .

An object of the present invention is to provide a highly reliable current differential protection relay device which can overcome the problems of the prior art and ensure continuity of received data from other electrical stations, and an arithmetic processing method thereof. Especially.

[0019]

In order to achieve the above object, the present invention provides a sampling means for synchronously sampling the electric quantity of the system at a constant cycle at each electric station of the multi-terminal power system, and an A / D conversion. The same sampling number is assigned to each sampled data at each sampling time, and a predetermined calculation is performed based on the transmitting means and the receiving means for transmitting and receiving each other, and the data of the own electric station having the same sampling number and the received data from other electric stations. In a current differential protection relay device including a calculation unit that outputs a predetermined control command when an abnormality is detected based on the result of calculation and calculation, a reception unit that receives a sampling number and received data from another electrical station, and a past unit. The received data memory that stores multiple received data from the sampling time of the present to the present in correspondence with the sampling number while updating them in time series, and the past data Based on a plurality of sampling numbers from the pulling time to the present, reception data read management means for determining a sampling number for reading from the reception data memory so as to maintain continuity of reception data used for calculation is provided. It is characterized by being

The reception data read management means stores each of the plurality of sampling numbers, and reads the sampling numbers of the storage area scheduled for the present calculation twice at a predetermined time when one sampling is performed and two times. If the sampling numbers match, the received data with that number is read from the received data memory for this time calculation, and if they do not match, the sampling number used in the previous calculation matches the updated one. It is characterized in that the received data to which the sampling number of is added is read out for this time calculation.

The arithmetic means and the received data read management means are realized by software processing of the CPU.

Further, according to the arithmetic processing method of the current differential protection relay device of the present invention, the sampling numbers and data identified at the time of reception are stored in time series in correspondence with each other, and the identified sampling numbers are stored twice in one sampling. It is characterized in that the data is read out and when the two match, the data corresponding to the sampling number is read out and used for the calculation.

When the sampling numbers obtained by the double reading do not match, the sampling numbers are compared with the numbers obtained by updating the sampling numbers of the previous calculation by one, and the data corresponding to the matching sampling numbers are read and used for the calculation. It is characterized by doing.

When the one that matches the two sampling numbers cannot be obtained, the processing of the arithmetic means is bypassed.

The predetermined time between the two readings is set to be a variation time width or more when the time relationship between the data reception timing from another electrical station and the processing timing at the own electrical station varies. To do.

According to the present invention, the received data is stored while being updated in time series corresponding to the sampling number, and the sampling numbers for a plurality of sampling times traced back from the present are also stored in time series while being updated. There is. The read address of the received data for calculation is determined by reading the temporarily stored scheduled area of the sampling number (the area in which the number next to the previous calculation is stored) twice during one sampling.

That is, when there is no change in the time relationship between the data reception / writing timing and the reception data reading timing at the end of each sampling, the sampling numbers of the two samplings have the same value. However, if the time relationship between the reception timing and the processing timing at the own electric power station changes due to changes in the delay time due to system switching, changes in the number of steps when interrupting the main processing, etc. The sampling numbers of two times do not match. At this time, the sampling number corresponding to the number obtained by adding 1 to the sampling number used for the previous calculation indicates the correct data for the current calculation.

Therefore, by always determining the correct sampling number and reading the received data by using it as the address, it is possible to prevent the missing or duplication of the received data due to the influence of the time fluctuation, and avoid the erroneous output due to the erroneous data. , The effect of improving the reliability of the current differential protection relay device.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of a current differential protection relay device according to this embodiment. In order to protect the power transmission line 1 that connects the electric stations A and B via the circuit breakers 3a and 3b, current differential protection relay devices 4a and 4b are installed at the electric stations A and B, respectively. .

The current differential protection relay device 4a of the electric station A is
The current S1a detected through the current transformer 2a every sampling cycle is converted into a digital signal S2 by the A / D converter 5a.
a and the current differential relay operation unit 11a and the transmission unit 6a
Give to. The transmitter 6a transmits the transmission data of the signal S2a to the current differential protection relay device 4b at the other end via the transmission line 12. Similarly, the electric power station B at the other end has a current S1b.
Is synchronously sampled with the electric station A, and the data S2b obtained by A / D conversion is transmitted from the transmission unit 6b to the current differential protection relay device 4a.

The receiving section 8a receives the data S2b and stores the identified sampling number and the data in the received data memory 10a as received write data S7a in association with each other. The reception data memory 10 stores data up to at least the past two sampling points in time series. The sampling number is the minimum value (= 1)
Since the serial numbers from to the maximum value are repeatedly given at the time-series sampling time, the data area for all the sampling numbers may be prepared and the received data for one round may be stored.

The time measuring section 7a has a transmission reference signal S3a from the transmission section 6a and a reception reference signal S4 from the reception section 8a.
The transmission line delay time is obtained from the time difference of a and sampling synchronization processing is performed.

The reception data read management unit 9a is provided in the reception unit 8
The sampling number S6a identified by a is temporarily stored while updating it in a time series at a plurality of points retroactively from the present time, processing this as described later to determine a read address S8a, and receiving current differential relay calculation data. Data memory 1
It is read from 0a and given to the current differential relay operation unit 11a as reception read data S9a.

The current differential relay operation unit 11a executes a relay operation by vector sum / scalar sum based on its own input data S2a and reception data S9a from the other end.
Here, when the power transmission line 1 has a short circuit or a ground fault, the current differential relay operation unit 11a outputs the relay operation output S10a.
Is output and the circuit breaker 3a is cut off. It should be noted that there may be three or more electric stations that transmit and receive mutually.

In the configuration of FIG. 1, the inside of the dotted line frame is the digital operation units 13a and 13b, which are realized by the processing of the CPU in this embodiment. FIG. 2 shows the configuration of a current differential protection relay device using a CPU. The CPU 25 executes a processing program stored in the ROM 23 via the system bus 26 and realizes a digital arithmetic unit by software processing.

The current S1 sampled by the current transformer 2a
Is converted into a predetermined voltage amount by the input converter 20, converted into a digital amount S2 by the A / D converter 5 via the filter 21, and stored in the RAM 22. CPU25 is R
The data S2 stored in the AM 22 is set in the transmitter 6. Further, a current differential relay operation is performed based on the data S2 stored in the RAM 22 and the received data S7 and S9 from the receiving unit 8, and the relay operation output S10 is output via the DI / O 24 based on the result. . In addition, D
The status of the external device is also fetched from the I / O 24.

The configuration of the conventional digital arithmetic unit is A / D
Although it was set directly from the converter 5 to the transmission unit 6 with a hardware configuration, by setting it via the CPU 25 as in the present embodiment, the protection relay device can be standardized, which is advantageous in terms of versatility. Is.

FIG. 3 is a flowchart mainly showing the received data reading process of the current differential protection relay device. This process is started every time sampling is performed.

First, the temporary storage area of the sampling number SR (t) corresponding to the received data used in this calculation is read, and the first read result SR1 is acquired (S010). Next, the dummy timer process waits for a time that is about the same as or longer than the fluctuation time of the data reception timing and the processing timing at the self end (S020). For example, if the time for transitioning from the low level interrupt processing to the high level interrupt arithmetic processing for each sampling varies in the range of 0 to 15 microseconds, TR1 = 20 microseconds with a margin. . Further, instead of the dummy timer processing, another processing that always takes 20 microseconds or more may be executed.

After the dummy timer processing, the second read result SR2 is obtained from the same sampling number storage area as the first read (S030). Then, the first and second sampling numbers SR1 and SR2 are compared (S
040), if they are the same, SR1 or SR2 is set as the read data sampling number SR (t). In the figure, SR
(T) = SR1 is set (S080).

When the comparison result of the sampling numbers SR1 and SR2 is different, the sampling number SR (t) '(= SR (t
-1) +1) and SR1 and SR2 are compared (S05).
0, S060). If the sampling numbers SR (t) 'and SR1 are the same, SR (t) = SR1 is set (S08).
0). Also, the sampling numbers SR (t) 'and SR
If 2 is the same, SR (t) = SR2 is set (S07).
0). When the comparison results of SR1, SR2 and SR (t) 'are all different, the current differential relay arithmetic processing is bypassed. In this case, since it is determined that a data error has occurred due to a defective transmission path or the like, the data is discarded and the erroneous output of the current differential relay operation unit is prevented. Since any abnormality detection such as a transmission path defect and measures such as output lock are well known, the description thereof will be omitted.

In this way, the first SR1 and the second SR
2. Furthermore, when the current sampling number SR (t) is obtained from the comparison of SR (t) ', which is obtained by updating the sampling number read in the previous calculation by one, the corresponding reception data is read from the reception memory 10 accordingly. , Together with the transmission data of the same sampling number of the own electric power station, is input to the light bulb differential relay calculation unit 11 (S090), the current differential relay calculation is performed (S100), and whether or not the current differential relay output is necessary for the calculation result. Is determined (S110), and if a failure is recognized in the power transmission line 1, a cutoff command is output via the DI / O 24 (S120). Then, the preparation process for the next sampling cycle is performed (S130), and the sampling number SR (t) calculated this time is updated by one. That is, SR (t) = SR (t) +1 is set, and the sampling number SR (t) for the next read address processing is set.
(S130).

The contents of the current differential relay calculation are well known and will not be described. The calculation may include an ON / OFF state input from the DI / O 24.

FIG. 4 is a time chart showing the operation of the current differential protection relay device according to this embodiment. In the figure, the other end is D (t1) to D (t
3), data a of D (tn) to D (tn + 3) is transmitted. The transmission data a from the other end reaches the self-end receiving unit c via the transmission line b with a delay of the transmission line delay time TD. The readable data d of the self-end reception unit is read after the data reception for one sampling is completed, and therefore is delayed by one sample.

The reading process e at the self end is performed as follows. First, at the sampling at time t1, the sampling number is read twice, R1 and R2. The interval TR1 between the readings R1 and R2 is the time by the dummy timer. Since the sampling numbers read by R1 and R2 match SR (t-1) as shown in the figure, the data f captured by the relay calculation unit is D (t-).
1).

Even at the sampling at time t2, the reading of sampling numbers R3 and R4 is performed. Here, since the time relationship between the data reception timing and the processing timing at the self end is fluctuating, the number SR of the read R3 is
(T-1) and the number SR (t0) of R4 do not match. Therefore, the SR (t) obtained by updating the sampling number SR (t-1) at time t1 of the previous sampling by one
0). As a result, the result SR of the read R4
It is confirmed that the data coincides with (t0), and the data f captured by the relay calculation unit becomes D (t0).

In the sampling at the time point t3, the time relationship is restored to normal, and the result SR (t1) of the read R5 and R6.
And the data f captured by the relay calculation unit is D
(T1).

In the sampling at the time tn + 1, the sampling numbers SR (tn-2) of the read R7 and R8 match, and the data f taken in by the relay calculation unit is D (t.
n-2). However, in the sampling at the time tn + 2, the readings R9 and R10 are again caused by the change in the time relationship.
Sampling numbers of SR (tn-2) and SR (t
It becomes n-1) and does not match. Therefore, the sampling number SR (tn-2) of the previous sampling is compared with the updated SR (tn-1). As a result, read R10
Of the data D (tn-).
1) is taken into the relay calculation unit. Even at the subsequent sampling at time tn + 3, the sampling numbers of the read R11 and R12 do not match, and SR (tn
The data (tn) of the read SR (tn) of the read R12 that matches SR (tn) obtained by updating -1) is fetched into the relay calculation unit.

The sampling period TS is generally 50 Hz.
1.667 (ms) in the system, 1.3 in the 60 Hz system
It is 89 (ms). Further, the fluctuation range of the data reception timing and the processing timing at its own end is about several microseconds to hundreds of ten microseconds, and TR1 is determined in consideration of this. As described above, when the fluctuation width of the TR1 time is 0 to 15 microseconds, it is preferable to set TR1 = 20 microseconds with a margin.

Although the above embodiment is an example of the sampling synchronization method of the terminal-to-terminal transmission, the electric station A is the master station (also called the main station), the electric station B is the folding station, and the electric station B is the returning station. By adding the data of its own end (electrical place B) to the signal from the electric place A and transmitting it to the other end (electrical place A), the sampling synchronization method of each terminal loop transmission can be applied as it is.

[0052]

According to the present invention, the reception sampling data used for the calculation is switched in consideration of the confirmation by reading the sampling number twice and the update from the previous sample. Even if the time relationship between the processing timing at the end and the processing timing at each end fluctuates with each sampling, it is possible to prevent erroneous output due to erroneous received data and prevent current differential protection continuation in order to prevent the received data from being dropped or repeated. There is an effect that the reliability of the electric device can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a current differential protection relay device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a digital arithmetic unit of a current differential protection relay device according to the present invention.

FIG. 3 is a flowchart for explaining the operation of the current differential protection relay device according to the present invention.

FIG. 4 is a time chart for explaining the operation of the current differential protection relay device according to the present invention.

FIG. 5 is a configuration diagram of a conventional current differential protection relay device.

FIG. 6 is a time chart explaining the operation of a conventional current differential protection relay device.

FIG. 7 is a time chart explaining the operation of a conventional current differential protection relay device.

[Explanation of Codes] 1 ... Transmission line, 2a, 2b ... Current transformer, 3a, 3b ... Circuit breaker, 4a, 4b ... Current differential protection relay device, 5a, 5b ...
A / D converter, 6a, 6b ... Transmitting section, 7a, 7b ... Time measuring section, 8a, 8b ... Receiving section, 9a, 9b ... Received data read managing section, 10a, 10b ... Received data memory, 1
1a, 11b ... Current differential relay arithmetic unit, 12 ... Transmission line,
13a, 13b ... Digital operation section, 20 ... Input converter, 21 ... Filter (FIL), 22 ... RAM, 23 ...
ROM, 24 ... DI / O, 25 ... CPU.

Front Page Continuation (72) Inventor Mitsuyasu Kido 1-1-1 Kokubuncho, Hitachi City, Ibaraki Hitachi Kokubun Plant, Hitachi Ltd.

Claims (7)

[Claims] 1. A sampling means for synchronously sampling the electricity quantity of the system at a constant cycle at each electric station of the multi-terminal power system, and the same sampling number is given to the A / D converted data at each sampling time so that they are mutually associated. Calculation of transmitting and receiving means of transmission and reception, predetermined calculation based on data of own electric station of the same sampling number and received data from other electric station, and outputting predetermined control command when abnormality is detected by the result of calculation In the current differential protection relay device equipped with a means, a receiving means for receiving from another electric power station to identify the sampling number and the received data, and a plurality of received data from the past sampling time to the present are associated with the sampling number. To store the received data memory, which is stored while updating in time series, and multiple sampling numbers from the past sampling time to the present. On the basis of the above, the current differential protection relay is provided with reception data read management means for determining a sampling number for reading from the reception data memory so as to maintain continuity of reception data used for calculation. Electrical equipment. 2. The reception data read management means according to claim 1, wherein the plurality of sampling numbers are respectively stored, and the sampling numbers of the storage area scheduled for the present calculation are separated by a predetermined time at the time of one sampling. When two times of reading and two times of sampling numbers match, the received data with the corresponding number is read from the reception data memory for this time calculation, and when they do not match, one sampling number used for the previous calculation is used. A current differential protection relay device characterized in that received data having a sampling number corresponding to an updated number is read out for current calculation. 3. The CP according to claim 1, wherein the calculation unit and the received data read management unit are CPs.
A current differential protection relay device, which is realized by U software processing. 4. The same sampling number is sequentially assigned from the sequence number for each sampling time, and the data obtained by synchronously sampling the electricity amount of the system at each electric station of the electric power system are transmitted and received by the same, respectively. In a current differential protection relay device that performs a current differential relay calculation based on the data of the own electric station of the sampling number and the received data from other electric stations, and outputs a predetermined control command when an abnormality is detected as a result of the calculation, The sampling number identified at the time of reception and the data are stored in time series in correspondence with each other, and the identified sampling number is set to 2 at the time of one sampling.
An arithmetic processing method for a current differential protection relay device, which is characterized in that the data corresponding to the sampling number is read out and used for arithmetic operation when the both times are read. 5. The sampling number according to claim 4, when the sampling numbers obtained by the double reading do not match, the sampling numbers are compared with the numbers obtained by updating the sampling numbers of the previous calculation by one, and the corresponding sampling numbers are corresponded. An arithmetic processing method for a current differential protection relay device, which is characterized in that data is read and used for arithmetic. 6. The current differential protection relay device arithmetic processing method according to claim 5, wherein the processing of the arithmetic means is bypassed when there is no match with the two sampling numbers. 7. The predetermined time between the two readings according to claim 4, 5, or 6, when the time relationship between the data reception timing from another electric station and the processing timing at the own electric station changes. And a variation time width of the current differential protection relay device.