JPH09308082A - Current differential protective relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy in judgment of a current differential and provide large transmission data in a current differential protective relay used for detecting abnormality and protect a transmission system between power stations. SOLUTION: A changing value (a differential in instantaneous value) time sequentially obtained from instantaneous values (IAT and IBT) in a transmission line and compensated through charging current calculation circuits 7A and 7B is transmitted to the opponent side sequentially, and at the same time the instantaneous value is transmitted at an accident time in transmission or for a given cycle (for each one cycle), and thereby the instantaneous values are calculated through instantaneous value calculation circuits 18A and 18B on the basis of the instantaneous value for each cycle and the changing value. The instantaneous value is calculated in differential judgment units 11A and 11B. Then, the current instantaneous value in the self power station is compared, and the power is interrupted by breakers 3A and 3B when an abnormality state is judge. Since the changing value is transmitted, the amount of data is reduced, and large amount of data is transmitted in the compressed state of data, and at the same time significant figures can be increased and accuracy in judgment can be improved.

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 for efficiently transmitting current data between two points of a transmission line to be protected.

[0002]

2. Description of the Related Art FIG. 15 shows, for example, JP-A-59-1275.
It is a block diagram which shows the conventional current differential protection relay apparatus shown by the 26th publication. In the figure, A and B in the reference numeral are attached to the electric stations A and B, respectively, 1A and 1B are bus bars, 2 is a power transmission line installed between the bus bars 1A and 1B,
3A and 3B are circuit breakers for disconnecting the power transmission line 2 from the electric stations A and B.

4A and 4B are current transformers for measuring instruments provided on the bus side of the circuit breakers 3A and 3B, and 5A and 5B are current transformers 4 for measuring instruments.
Subtractors to which the detected current values of A and 4B are input, 6A and 6B
Is a transformer for a meter provided on the side opposite to the busbars of the circuit breakers 3A and 3B, and 7A and 7B are charging current calculation circuits for calculating a charging current value from the measured voltage value of the transformers 6A and 6B for a meter. The outputs of the calculation circuits 7A and 7B are input to the subtractors 5A and 5B.

Reference numerals 8A and 8B are modulation communication devices for modulating the outputs of the subtractors 5A and 5B, and 9A and 9B are demodulation communication devices for demodulating the modulated signals. The communication device 9B, the modulation communication device 8B, and the demodulation communication device 9A mutually transmit signals via the communication circuit 10.

Reference numerals 11A and 11B are differential judgment sections, which are subtractors 5
Differential calculation and internal accident determination are performed from the outputs of A and 5B and the outputs of the communication devices 9A and 9B. When it is determined that the internal accident occurs, the trip signals of the circuit breakers 3A and 3B are output. In the modulation communication devices 8A and 8B, the opening / closing information of the circuit breakers 3A and 3B is also modulated together with the current information and transmitted to the other end, so that the other party can recognize the opening / closing information.

FIG. 16 is a diagram for explaining current data. An alternating current is sampled at predetermined intervals, and a sampling value (instantaneous value) as current data is obtained at each of the electric stations A and B.
Generated by Normally, the sampling time interval is every 30 electrical degrees.

FIG. 17 is a block diagram of the transmission data.
I1, I2, ... Represent current data, each consisting of one frame. However, I0, I1
, I2, ... Are not transmitted as data, but are described in the description, and are transmission contents of one frame.

SY is a header and is common information, and SD
0, SD1, SD2, ... Are current (instantaneous value) data, and the instantaneous values of the sampled currents of y1, y2, y3 ,.

The current data of SD0, SD1, SD2, ... Is originally about 16 bits, but
Due to the limitation of the number of bits per frame, it is usually 12
Make the data about a bit. This is the sign (±),
This is because the number of bits of the current value becomes about 12 bits out of 16 bits due to the processing such as the decimal point and the truncation of the last value.

F1, F2, F3, ... Are flags, and T
0, T1, T2, ... are times (timings), and CH
0, CH2, CH3, ... Are check codes.

FIG. 18 is a diagram showing a sampling state of an AC current waveform, which is an instantaneous value obtained by sampling the AC current waveform as y0, y2, y3, ... At intervals of an electrical angle of 30 degrees. Yes, SD0, SD1, S of FIG.
It becomes current data of D2, ....

Next, the operation will be described. (1) The instrument transformer 6A of the electric station A outputs a secondary voltage value VAM according to the voltage value of the transmission line. (2) This secondary voltage value VAM is calculated by the charging current calculation circuit 7A to calculate the charging current value IAM which is the sum of the line-to-line charging current of the power transmission line 2 and the ground charging current and is given to the subtractor 5A.

(3) The instrument current transformer 4A outputs a secondary current value IA corresponding to the current flowing through the power transmission line 2, and this secondary current value IA is given to the subtractor 5A. (4) The subtractor 5A calculates the charging current value IAM from the secondary current value IA.
Is subtracted, and the charging compensation current value IAT according to the result is output.

(5) This charge compensation current value IAT is given to the differential judgment section 11A and the modulation communication device 8A. (6) The charge compensation current value IAT given to the modulation communication device 8A is the transmission data shown in FIG. 17, which is modulated and sent to the demodulation communication device 9B of the electric station B via the communication line 10.

(7) Such an operation is similarly performed at the electric station B, and is calculated from the secondary current value IB of the instrument current transformer 4B according to the secondary voltage VBM of the instrument transformer 6B. The charging compensation current value IBT obtained by subtracting the charging current value IBM is transmitted to the demodulation communication device 9A at the electric station A.

(8) The electric signal transmitted from the modulation communication device 8B of the electric station B to the demodulation communication device 9A of the electric station A is demodulated to the charge compensation current value IBT and input to the differential judgment section 11A. . (9) The differential determination unit 11A receives the input charge compensation current value I
When a differential operation is performed on AT and IBT, a system failure is determined by comparing the operation result with a predetermined set value, and when it is determined that there is a failure in the protection section,
The tripping signal of the circuit breaker 3A is output, and the circuit breaker 3A removes the fault of the power transmission line 2.

The operation of the device at the electric station A has been described above, but the operation at the device B is also the same.

[0018]

The conventional current differential protection relay device is configured as described above, and at the conventional transmission speed between the terminals, each terminal has an instantaneous current for three phases and each phase. In some cases, the value data can only be transmitted with about 12 bits of transmission data. In this case, there is a problem in that sufficient precision cannot be obtained due to the lack of the number of bits. For example, as described above, the transmission data SD0, SD1, SD2, ...
Even if 16 bits are assigned to, only about 12 bits can be transmitted as a numerical value by processing such as positive / negative (±) signs and decimal points, and processing such as truncation of the last bit.

The present invention has been made in order to solve the above problems, and performs more accurate transmission,
Another object is to obtain a current differential protection relay device that enables high-speed transmission and large-volume data transmission.

[0020]

[Means for Solving the Problems]

(1) A current differential protection relay device according to the present invention detects a power transmission current flowing at each of two points of a power transmission line and detects an abnormality in a power transmission system according to a comparison of the transmission currents. In the electric power device, the time-series change amount of the instantaneous value of the transmission current at one of the two points is sequentially transmitted to the other point side, and the transmission current of the transmission current is changed at regular intervals or when a transmission abnormality occurs. Means for transmitting the instantaneous value to the other point side,
A means for restoring an instantaneous value from the transmitted instantaneous value and the time-series variation, and detecting an abnormality in the power transmission system according to the comparison between the restored instantaneous value and the instantaneous value of the transmission current at the other point And means.

(2) Further, in the current differential protection relay device which detects the transmission current flowing at each of two points of the transmission line and detects the abnormality of the transmission system according to the comparison of the transmission currents, The time series change amount of the instantaneous value of the transmission current at one of the points is sequentially transmitted to the other point side, and at regular intervals,
Alternatively, means for transmitting the current reference value to the other point side when a transmission abnormality occurs, means for restoring an instantaneous value from the transmitted current reference value and the time series change amount, and the restored instantaneous value And means for detecting an abnormality in the power transmission system according to the comparison with the instantaneous value of the transmission current at the other point.

(3) Further, in the current differential protection relay device which detects the transmission currents flowing at the two points of the transmission line and detects the abnormality of the transmission system according to the comparison of the transmission currents, The time series variation of the instantaneous value of the transmission current at one of the points is transmitted to the other point side in sequence, and if there is a request to transmit the instantaneous value from the other point side, the instantaneous value of the transmission current at the one point is transmitted to the other side. Means for transmitting to the point side, means for restoring the instantaneous value from the transmitted instantaneous value and the time series change amount, and comparison of the restored instantaneous value with the instantaneous value of the transmission current at the other point. And means for detecting an abnormality in the power transmission system.

(4) In addition, in the current differential protection relay device which detects the transmission currents flowing at the two points of the transmission line and detects the abnormality of the transmission system according to the comparison of the transmission currents, The time series variation of the instantaneous value of the transmission current at one of the points is sequentially transmitted to the other point side, and if there is a request for the transmission of the reference value from the other point side, then from one point side to the other point side. Means for transmitting a current reference value, means for restoring an instantaneous value from the transmitted current reference value and the time series change amount, and comparison of the restored instantaneous value with the instantaneous value of the transmission current at the other point And means for detecting an abnormality in the power transmission system in accordance with the above.

(5) Further, in any one of the above items (1) to (4), the instantaneous value of the transmission current is an instantaneous value obtained by correcting the charging current of the transmission system to be protected.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a current differential protection relay device. In the figure, reference symbols A and B are electrical stations A and B, respectively.
It is attached to B. 1A and 1B are busbars, 2 is busbar 1
Transmission lines 3A and 3B installed between A and 1B are circuit breakers for disconnecting the transmission line 2 from the electric stations A and B, 4A,
Reference numeral 4B is an instrument current transformer provided on the busbar side of the circuit breakers 3A and 3B.

Reference numerals 5A and 5B are subtractors into which the detected current values of the instrument current transformers 4A and 4B are input, and 6A and 6B are circuit breakers 3.
A transformer for instrument provided on the opposite side of A and 3B, 7A,
7B is a charging current calculation circuit for calculating a charging current value from the measured voltage values of the instrument transformers 6A, 6B. The outputs of the charging current calculation circuits 7A, 7B are input to the subtracters 5A, 5B.

Reference numerals 17A and 17B denote deviation calculation circuits, which sequentially calculate the deviation (current change amount) dy of the sampling value of the current waveform from the outputs of the subtractors 5A and 5B as shown in FIG. This calculates the deviation (change amount) at each of the electric stations A and B as shown in FIG.

8A and 8B are deviation calculation circuits 17A and 17B.
A modulation communication device that modulates the output of B modulates the transmission data shown in FIG. 4 and transmits it via the communication line 10. In the transmission data of FIG. 4, the difference from the conventional FIG. 17 is the contents of the data of SD0, SD1, SD2, ... In SD0, the instantaneous value y0 is the transmission data. Deviation of the instantaneous value, not the instantaneous value of the current
1, dy2, dy3, ... Are transmitted.

That is, as shown in FIG. 5, dyn = yn-
yn-1 is calculated and the deviation (change amount) is used as the transmission data. In FIG. 4, the timing at which the instantaneous value is used as the transmission data is
For example, it is performed at time intervals for each cycle.

Reference numerals 9A and 9B are demodulation communication devices for receiving and demodulating the modulated signal. Reference numerals 12A and 12B are instantaneous value calculation circuits that calculate an instantaneous current value from the amount of change in current output from the demodulation communication devices 9A and 9B.

Numerals 11A and 11B perform differential calculation and internal accident determination from the outputs of the subtractors 5A and 5B and the output from the instantaneous value calculation circuits 12A and 12B, and when it is determined to be an internal accident, the circuit breaker 3A. , 3B for outputting the trip signal. In the modulation communication devices 8A and 8B, the opening / closing information of the circuit breakers 3A and 3B is also modulated together with the current information and transmitted to the other end so that the other party can recognize the opening / closing information.

The operation of the apparatus having the above configuration will be described with reference to the flow charts of FIGS. 6 and 7. FIG. 6 is a flowchart on the transmitting side.

(1) The output from each subtracter 5A, 5B obtained by subtracting the compensation current of each charging current calculation circuit 7A, 7B from the detected current value of each current transformer 4A, 4B is the deviation calculation circuit 12A. , 12B. This output is y in FIG.
1, y2, ...

(2) Each deviation calculating circuit 12A, 12B
It is judged whether or not the transmission is in an abnormal state or the timing is at a predetermined time such as every constant cycle (S1). (3) If the transmission is in the abnormal state or at every constant cycle, the instantaneous value flag is set to ON ( S2).

The fixed period is, for example, one cycle of each waveform or a time interval in units of minutes, and the transmission abnormal state means that there is no transmission from the other side, the content of the data is abnormal (abnormally large). When the result of self-diagnosis is bad, etc. In addition, the timing of sending the instantaneous value may be set to other conditions besides the fixed period and the abnormal transmission state.

(4) When the instantaneous value flag is ON, the state shown in FIG.
Instantaneous values such as the current data SD0 (y0) shown in (3) are used as transmission data (S3), and (5) each of the modulation communication devices 8A and 8B modulates and transmits (S4).

(6) On the other hand, in the case of "NO" in step S1, as the transmission data, change amount = present instantaneous value-previous instantaneous value is calculated (S5). That is, as shown in FIGS. 4 and 5, the current data of SD1, SD2, ...
The deviation dy1 between the previous input y0 and the current input y1 is output as a change amount to each of the modulation communication devices 8A and 8B.

(7) Each modulation communication device 8A, 8B modulates the input from each deviation calculation circuit 12A, 12B and outputs a signal to each demodulation communication device 9B, 9A via the communication circuit 10.

FIG. 7 is a flowchart on the receiving side. (1) Each of the demodulation communication devices 9A and 9B demodulates the input modulated signal. (2) Each of the instantaneous value flag detection units 12A and 12B determines whether or not the instantaneous value flag of the demodulated signal is ON (S1).
1).

(3) Instantaneous value calculation circuits 18A and 18B
If the instantaneous value flag is ON, the currently received data (instantaneous value) is output as it is (S12). (4) If the instantaneous value flag is not ON, the value obtained by adding the current output data (instantaneous value) to the currently received data (variation amount) is output as the current instantaneous value.

(5) The differential decision sections 11A and 11B respond to the data (instantaneous value) from the subtracters 5A and 5B and the data (instantaneous value) from the instantaneous value calculating circuits 18A and 18B. When a differential operation is performed and a result of the operation is compared with a predetermined set value to determine a system failure, and when it is determined that there is a failure in the protection section, each circuit breaker 3A,
The trip signal of 3B is output, and each of the circuit breakers 3A and 3B removes the fault of the power transmission line 2.

As described above, the variation of the instantaneous value is always transmitted, and the instantaneous value is transmitted together with the instantaneous value flag at a fixed cycle or when the transmission is abnormal, so that the received data is initialized. As a result, it is possible to reduce the reproduction failure of the current value (when the reproduction waveform is incorrect) and to maintain the soundness of the data by initializing the reproduction failure data.

As described above, accurate data can be transmitted by transmitting the deviation (change amount). For example,
As can be seen from FIG. 2, in the case of an AC waveform having a peak value of 100V, the deviation amount is 1 / 100V.
Since it is 2 or less, the effective number is increased and the accuracy is improved, so that the abnormal current of the current differential protection relay device can be accurately determined. The transmission of this variation is a kind of data compression transmission.

Further, if the precision is made constant by this data compression, the number of bits can be reduced, so that the transmission speed is improved, which enables a large amount of data transmission.

Further, the change of the existing transmission format can be realized on a significantly small scale.

Embodiment 2 In the first embodiment, the means for compressing the transmission data and enabling a large amount of data transmission has been described. However, the same transmission data is also compressed in the present embodiment, and the "reference value" is used instead of the "instantaneous value flag". A "value flag" is provided so that the instantaneous value is reproduced from the change amount based on the reference value.

The second embodiment of the present invention will be described below with reference to FIGS. 8 is a configuration diagram, FIG. 9 is a flowchart of the transmitting side, and FIG. 10 is a flowchart of the receiving side.

In FIG. 8, reference value flag detectors 13A and 13B determine whether or not the reference value is received by turning the reference value flag ON or OFF.

Next, the operation will be described with reference to the flowcharts of FIGS. (1) The output from each subtractor 5A, 5B obtained by subtracting the compensation current of the charging current calculation circuit 7A, 7B from the detected current value of each current transformer 4A, 4B for the meter is the deviation calculation circuit 12A, 12B.
B is input. This output is y1, y2, ...
It is.

(2) The deviation calculating circuits 12A and 12B are
It is determined whether or not the transmission is in an abnormal state or the timing is every fixed cycle (S21). (3) If the transmission is in the abnormal state or the fixed cycle is the timing, the reference value flag is set to ON (S22).

(4) When the reference value flag is ON, the reference value is used as transmission data (S23), and (5) each of the modulation communication devices 8A and 8B modulates the data and transmits it (S24). If the reference value is, for example, 100V, the constant value is 100V.

(6) On the other hand, if "NO" in the step S21, it is determined whether or not the previously transmitted data is the reference value (S2).
5), (7) If it is the previous reference value, the transmission data = current instantaneous value−reference value is calculated as the transmission data and output to each of the modulation communication devices 8A and 8B (S26).

(8) Each of the modulation communication devices 8A and 8B modulates the input from each of the deviation calculation circuits 12A and 12B and transmits it to each of the demodulation communication devices 9B and 9A via the communication circuit 10 (S24).

FIG. 10 is a flowchart on the receiving side. (1) Each of the demodulation communication devices 9A and 9B demodulates the input modulated signal. (2) Each of the reference value flag detection units 13A and 13B determines whether or not the reference value flag of the demodulated signal is ON (S3).
1).

(3) The instantaneous value calculation circuits 18A and 18B are
If the reference value flag is ON, the reference value is set as the current reception data but is not output (S32). (4) If the instantaneous value flag is not ON, the current value obtained by adding the currently received data (change amount) to the reference value is output as the current instantaneous value (S33).

(5) The differential decision units 11A and 11B make a difference between the data (instantaneous value) from the subtracters 5A and 5B and the data (instantaneous value) from the instantaneous value calculating circuits 18A and 18B. A dynamic operation is performed, a system failure is determined by comparing the operation result with a predetermined set value, and when it is determined that there is a failure in the protection section, each circuit breaker 3A, 3
The trip signal of B is output, and each of the circuit breakers 3A and 3B removes the fault of the power transmission line 2.

In this way, the amount of change in the instantaneous value is always transmitted, and the reference value is transmitted together with the reference value flag in a fixed cycle or when there is a transmission error, so that the received data is initialized. As a result, it is possible to reduce the failure to reproduce the current value and to maintain the soundness of the data by initializing the failed data.

As described above, the data compression for transmitting the deviation (change amount) as in the first embodiment makes it possible to transmit highly accurate data.

Further, if the precision is made constant by this data compression, the number of bits can be reduced as in the first embodiment, so that the transmission speed is improved, which also enables a large amount of data transmission.

Further, by unifying the reference values, it is possible to improve the detection rate of data transmission / reception failure.

Embodiment 3 In the first embodiment, the "instantaneous value" is transmitted from the transmitting side at a fixed period or when there is a transmission error, but in this embodiment, the instantaneous value is transmitted in response to the reference value transmission request from the other side (reception side). It was done like this. Therefore, it is possible to initialize the received data from the receiving side in response to the reference value transmission request at a fixed cycle or when a transmission error occurs.

The third embodiment of the present invention will be described below with reference to FIGS. 11 and 12. FIG. 11 is a block diagram, and FIG.
2 is a flowchart on the receiving side. Note that the flowchart on the transmitting side is almost the same as the flowchart in FIG.

Next, the operation will be described. (1) An instantaneous value transmission request is transmitted when the receiving side detects a fixed period or an abnormal transmission state (S4).
1). (2) On the transmitting side, the instantaneous value flag is turned on based on the instantaneous value transmission request, and the instantaneous value is transmitted.

(3) On the receiving side, each of the demodulation communication devices 9A, 9
The signal is received at B and demodulated (S42). (4) Each of the instantaneous value detectors 14A and 14B determines whether the instantaneous value flag is ON (S43).

(5) If the instantaneous value flag is ON, this time output data (instantaneous value) is output (S44). (6) If the instantaneous value flag is not ON, each of the instantaneous value calculation circuits 18A and 18B adds the current received data (variation amount) to the previous output data (instantaneous value) and outputs it (S45).

As described above, the third embodiment has the same effect as that of the first embodiment, and the transmission data can be initialized from the receiving side as needed.

Fourth Embodiment In the second embodiment, the “reference value” is transmitted from the transmitting side at a fixed period or when there is a transmission error, but in this embodiment, the reference value is transmitted according to the reference value transmission request from the other side (reception side). It is the one.
Therefore, it is possible to initialize the received data from the receiving side in response to the reference value transmission request at a fixed cycle or when a transmission error occurs.

The fourth embodiment of the present invention will be described below with reference to FIGS. 13 and 14. FIG. 13 is a block diagram, and FIG.
4 is a flowchart on the receiving side. The flow chart on the transmitting side is almost the same as the flow chart of FIG.

Next, the operation will be described. (1) A reference value transmission request is transmitted when the receiving side detects a fixed period or an abnormal transmission state (S5).
1). (2) On the transmitting side, the reference value flag is turned on based on the reference value transmission request, and the reference value is transmitted.

(3) On the receiving side, the demodulation communication devices 9A, 9
The signal is received by B and demodulated (S52). (4) The reference detection units 15A and 15B determine whether the flag is ON (S53),

(5) If the reference value flag is ON, the reference value is the current received data but is not output (S54). (6) If the reference value flag is not ON, the instantaneous value calculation circuits 18A and 18B set the reference value to the currently received data (change amount).
Are added and output (S55).

As described above, the fourth embodiment has the same effect as that of the second embodiment, and the transmission data can be initialized from the receiving side as needed.

Embodiment 5 In the above description of the respective embodiments, the case of the two-terminal power transmission line has been described, but the same means can be applied to the case of the multi-terminal power transmission line.

Further, in each of the above embodiments, the current differential protection relay device for detecting the current differential value by using the transmission line current obtained by compensating the charging current of the transmission line has been described. It may be applied to a current differential protection relay device using a means or a device without compensation.

[0075]

Since the present invention is configured as described above, by compressing the transmission data, the determination accuracy can be improved and a large amount of data can be transmitted. It becomes possible to send data that could not be sent,
Further, it becomes possible to shorten the data transmission time.

[Brief description of drawings]

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

FIG. 2 is a diagram illustrating a sampling state of the current differential protection relay device according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining the amount of change in current due to sampling in the current differential protection relay device according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of transmission data of the current differential protection relay device according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating the current data of FIG.

FIG. 6 is a flowchart on the transmitting side of the current differential protection relay device according to the first embodiment of the present invention.

FIG. 7 is a flowchart on the receiving side of the current differential protection relay device according to the first embodiment of the present invention.

FIG. 8 is a configuration diagram of a current differential protection relay device according to a second embodiment of the present invention.

FIG. 9 is a flowchart on the transmitting side of the current differential protection relay device according to the second embodiment of the present invention.

FIG. 10 is a flowchart on the receiving side of the current differential protection relay device according to the second embodiment of the present invention.

FIG. 11 is a configuration diagram of a current differential protection relay device according to a third embodiment of the present invention.

FIG. 12 is a flowchart on the receiving side of the current differential protection relay device according to the third embodiment of the present invention.

FIG. 13 is a configuration diagram of a current differential protection relay device according to a fourth embodiment of the present invention.

FIG. 14 is a flowchart on the receiving side of the current differential protection relay device according to the fourth embodiment of the present invention.

FIG. 15 is a configuration diagram of a conventional current differential protection relay device.

FIG. 16 is a diagram illustrating current data sampled by a conventional current differential protection relay device.

FIG. 17 is a configuration diagram of transmission data of a conventional current differential protection relay device.

FIG. 18 is a diagram showing a sampling state of a conventional current differential protection relay device.

[Explanation of symbols]

1A, 1B busbars, 2 power transmission lines, 3A, 3B circuit breakers, 4A, 4B instrument current meters, 5A, 5B subtractors,
6A, 6B Meter transformer, 7A, 7B Charging current calculation circuit, 8A, 8B Modulation communication device, 9A, 9B Demodulation communication device, 10 Communication line, 11A, 11B Differential judgment unit, 12A, 12B Instantaneous value flag Detector, 13A,
13B reference value flag detection unit, 14A, 14B instantaneous value detection unit, 15A, 15B reference value detection unit, 17A, 17
B deviation calculation circuit, 18A, 18B instantaneous value calculation circuit.

Claims (5)

[Claims] 1. A current differential protection relay device, which detects a power transmission current flowing at each of two points of a power transmission line and detects an abnormality of a power transmission system according to a comparison of the power transmission currents. A means for sequentially transmitting the time-series change amount of the instantaneous value of the power transmission current at the point to the other point side, and transmitting the instantaneous value of the power transmission current to the other point side at regular intervals or when a transmission abnormality occurs. A means for restoring an instantaneous value from the transmitted instantaneous value and the time-series change amount, and an abnormality in the power transmission system according to the comparison between the restored instantaneous value and the instantaneous value of the transmission current at the other point. A current differential protection relay device comprising a detecting means. 2. A current differential protection relay device for detecting a transmission current flowing at each of two points of a transmission line and detecting an abnormality of a transmission system according to a comparison of the transmission currents. A means for transmitting the time-series change amount of the instantaneous value of the transmission current at a point to the other point side in sequence, and transmitting the current reference value to the other point side at regular intervals or when a transmission abnormality occurs. Means for restoring an instantaneous value from the current reference value and the time-series variation amount, and detecting an abnormality in the power transmission system according to the comparison between the restored instantaneous value and the instantaneous value of the transmission current at the other point And a current differential protection relay device. 3. A current differential protection relay device, which detects a power transmission current flowing at each of two points of a power transmission line and detects an abnormality of a power transmission system according to a comparison of the power transmission currents. The time-series variation of the instantaneous value of the transmission current at one point is transmitted to the other point side in sequence, and if there is a request to transmit the instantaneous value from the other point side, the instantaneous value of the transmission current at one point is transferred to the other point side. And means for restoring the instantaneous value from the transmitted instantaneous value and the time-series change amount, and transmitting power according to a comparison between the restored instantaneous value and the instantaneous value of the transmission current at the other point. A current differential protection relay device comprising means for detecting a system abnormality. 4. A current differential protection relay device, which detects a transmission current flowing at each of two points of a transmission line and detects an abnormality of a transmission system according to a comparison of the transmission currents. The time series variation of the instantaneous value of the transmission current at a point is sequentially transmitted to the other point side, and when there is a request for transmission of the reference value from the other point side, the current reference value from one point side to the other point side. Means for transmitting an instantaneous value from the transmitted current reference value and the time-series change amount, and a means for transmitting the restored instantaneous value and an instantaneous value of the transmission current at the other point according to the comparison. A current differential protection relay device comprising: means for detecting an abnormality in a power transmission system. 5. The current differential protection relay device according to any one of claims 1 to 4, wherein the instantaneous value of the transmission current is an instantaneous value obtained by correcting the charging current of the transmission system to be protected. Current differential protection relay device.