JPS62250815A - Current differential relay device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electric power 2ii differential relay device that detects an abnormality in a power system by comparing current values sampled simultaneously at remote locations and performs a predetermined operation. More specifically, the present invention proposes a current differential relay device with enhanced error detection function of signals being transmitted.

[Prior art]

2. Description of the Related Art A current differential relay device is known that measures current at two remote points on a power transmission line and compares the current to check whether there is an abnormality in the power transmission system.

Japanese Patent Publication No. 57-9292 shows an example of such a device. This will be explained below based on FIG.

Electrical stations A and B, such as substations, are connected to the power transmission line 1 via respective busbars 4.4. The power transmission line 1 is equipped with a terminal breaker 2.2 for disconnecting between electric stations A and B, and the current of the power transmission line 1 is connected between the terminal breaker 2.2 and the connection part of the bus bar 4.4. A current transformer 3°3 is provided to detect this.

The current transformer 3 to the electric station outputs a secondary current corresponding to the current IA flowing through that part, and this output current is converted into an electric signal [A2] at the level passed to the subsequent circuit by the manual conversion ``55''. , this electric signal rA2 is given to a sampling circuit 6 and sampled at a constant cycle, further converted into a PCM digital signal by an A/D (analog/digital) conversion circuit 7, modulated by a communication device 213, and then It is transmitted to the communication device 13 of electric station B via line 15.

The electrical signal IA2 is also input to a transmission delay delay circuit 12 which delays it by the time required for communication between the electrical stations A and 8.
Electrical signal delayed here! A1 (The current value information is I
A2) is output and the relay determination unit 14
is input to.

Electrical station B is also equipped with a device similar to that described above, and an electrical signal IB2 (i11!
The signal corresponding to the current 1B flowing through the current transformer 3 installation part at
given to. The analog output of the D/A conversion circuit 9 is filtered by the reception filter 8 to remove high frequencies associated with D/A conversion and is then provided to the relay determination section 14.The electrical signal IB2 received by the communication device 13 is also sent to the error detection circuit 11. Data error detection such as level drop detection, parity check, and cyclic code check of the transmitted digital signal is performed here. If a data error is detected, the lock signal generation circuit 10 is activated and the A lock signal is sent to the power determination unit 14 to prohibit its output.

On the electric station B side, the above-mentioned receiving side circuit also has a similar configuration. This current differential relay device is provided with a sampling synchronization control circuit (not shown) so that the sampling circuits 6, 6 of both electric stations perform sampling at the same time. Therefore, the relay determination unit 14.14 is the electric station A at the same time.

Instantaneous value of current at B■＾1. IB2 or IBI, I^2
will be input.

Note that the TRI transmits the electric signal 1B2 to the transmission delay compensation circuit 12.
This is an electrical signal delayed by .

The relay determination unit 14 compares the instantaneous values of both currents, and based on the magnitude and phase relationship, determines the protection zone, that is, the electrical station A-
It is determined whether the B gap fault is an out-of-section fault, and if it is determined to be an in-section fault, a break control output is issued to each of the terminal breakers 2 and 2 to remove the fault.

Although there are factors that cause data errors in the communication line 15 due to disturbances, etc., if a data error is detected in the error detection circuit 11, a lock signal is generated and the relay determination unit 1
4, that is, the output that should trip the terminal breakers 2, 2 is prohibited.

[Problem that the invention seeks to solve]

In the conventional current differential relay device as described above, the signal itself transmitted from another electrical station is used to detect errors such as parity checks. Therefore, even if an error is detected, it cannot be determined that the transmitted information has been disturbed in the communication line; for example, the A/D conversion circuit 7 may be defective. Therefore, if the output of the relay determining section 14 is locked based on the result of such error detection, the original protective function cannot be achieved, and there is a possibility that the failure will spread.

The present invention was made to solve these problems, and it is possible to reliably detect that current information is affected by disturbances in the communication line, thereby ensuring reliable circuit protection. The purpose of the present invention is to provide a current differential relay device that can perform current differential relaying.

[Means for solving problems]

The current differential relay device according to the present invention includes means for calculating an effective current value based on the sampled instantaneous current value,
In addition, if there is a substantial discrepancy between the circuit that calculates the effective current value from the transmitted instantaneous current value and the means that compares the calculated effective current value with the transmitted effective current value, is equipped with a relay determination section that prohibits a predetermined relay output.

[Effect]

While determining the failure of the power system by comparing the instantaneous current value transmitted from the other end with the instantaneous current value detected at the corner of the eye, the effective current value is calculated using the instantaneous current value transmitted. This calculated current effective value is compared with the transmitted current effective value. If there is a disturbance in the communication line and a data error occurs, there is virtually no possibility that the two effective values will match. Therefore, if a mismatch between the two effective values is detected, it is assumed that there is a disturbance in the communication line, and the output of the relay determining section is locked. On the other hand, if the two effective values match, there is no possibility of a data error due to disturbance in the communication line, so the output of the relay determination section is not locked.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 1 is a block diagram of a current differential relay device according to the present invention. Electrical stations A and B are connected to the power transmission line 1 via respective busbars 4 and 4, and the power transmission line 1 is equipped with a terminal breaker 2.2 for disconnecting electric stations A and B. vessel 2,2
A current transformer '53'3 for detecting the current of the power transmission line 1 is provided between the busbars 4 and the connecting portion of the busbars 4, 4.

The current transformer 3 of the electric station A outputs a secondary current corresponding to the current 14 flowing through that part, and this output current is converted by the input converter 5 into an electrical signal IA2 of a level passed to the subsequent circuit, This electrical signal IA2 is applied to a sampling circuit 6, where it is sampled at a constant period, and further converted into a digital signal of I'CM by an A/D (analog/digital) conversion circuit 7, and then applied to a synthesis circuit 17. On the other hand A/
The output of the D conversion circuit 7 is input to the effective value calculation circuit 16,
Here, the effective value IA2 of the detection current IA is determined by the method described later.
R is calculated. The calculated current effective value IA2R is manually inputted to the synthesis circuit 17, where it is converted into an instantaneous current value IA2 and a current effective value T.
The A2H digital signals are synthesized in an appropriate format and sent to the communication device 13, where they are modulated and transmitted to the communication device 13 of electric station B via the communication line 15. Such a configuration is the same on the electric station B side, and the instantaneous current value TB2 of the current IB detected by the current transformer 3 and the effective value IB2R of the current IB calculated from this IB2 are sent to the communication device I3 to the electric station. The configuration to be sent is as follows.

FIG. 2 is an explanatory diagram of the effective value calculation method. The instantaneous current value is sampled every 30 electrical degrees, and the time series data is expressed as i ftl, i (t-1), i (L-2
), i (t~3)..., then the effective current value i is
The current sampling value i (i=&ii[t))2+(t-3)12 is obtained using tl and the sampling value i (t~3) three times before.

The electrical signal IA2 is also input to a transmission delay delay circuit 12 that delays the time required for communication between electrical stations A and B, and becomes a delayed electrical signal IAI (its current value information is the same as rA2). relay determination unit 1
4.

From electric station B, instantaneous value 1 of detected current IB of current transformer 3
B2 and the effective value IB2R are transmitted. Communication device 1
3 receives and demodulates the signal, and sends the demodulated signal to a D/A conversion circuit 9. It is given to the effective value calculation circuit 18 and the effective value extraction circuit 19.

The D/A conversion circuit 9 converts only the instantaneous value rB2 into an analog signal and supplies this to the relay determination section 14 via the reception filter 8.

The effective value calculation circuit 18 calculates the effective value fB2R from the instantaneous value rB2 using a method similar to that described above, and provides this to the error detection circuit 20. The effective value extraction circuit 19 extracts only the latter from the inputted instantaneous value IB2 and effective value IB2R, and supplies this to the error detection circuit 20.

The error detection circuit 20 compares the input IB2R1 and IB2R, and if they match, it does not output anything, and if they do not match, it issues a predetermined output to the relay determining section 14.

The relay determination unit 14 determines the protection zone, that is, the electrical station A-B, based on the magnitude one-phase relationship of the input instantaneous values IAI and IB2.
It is determined whether it is an inter-gap fault or an inter-interval fault, and if it is determined that it is an intra-interval fault, a cut-off control output is issued to each of the terminal cut-offs 12.2 to eliminate the fault, but the error detection circuit 20 issues the output. If this occurs, it is assumed that there is a disturbance in the communication line 15 and the output is prohibited.

The receiving circuit on the electric station B side also has the same configuration, and is marked 1 in the figure.
81 is a current instantaneous value signal obtained by delaying 1B2 by the transmission delay compensation circuit 12, and lA2R1 is calculated by the effective value calculation circuit 18 of electric station B based on the instantaneous current value IA2 transmitted from electric station A. It is an effective value.

Although not shown, a sampling cycle side control circuit is provided for synchronizing the sampling cycles of the sampling circuits 6.6 of both electrical stations. Further, the present invention does not preclude the use of a conventional error detection circuit that performs a parity check.

Figure 3.4.5 shows the error detection circuit 20 and the relay determination unit 14.
FIG. 3 is a block diagram showing three examples of configurations. In FIG. 3, reference numeral 141 is a differential arithmetic circuit using IAI and In2 as two inputs, and the differential output thereof is inputted to a level detector 143 via a zero control circuit 142. If there is no output from the error detection circuit 20, the differential output is input as is to the level detection circuit 143, where it is compared with a predetermined dark value, and if it exceeds the threshold value, it is determined that there is an abnormality in the power transmission line l, and the terminal breaker 2.2 level detection circuit 1
43 output. The error detection circuit 20 output is given to the zero control circuit 142, and the error detection circuit 20 is
When a mismatch between B2R and lB2R1 is detected and output, the zero control circuit 142 outputs zero regardless of the differential output of the differential calculation circuit 141, and as a result, the level detection a143 generates a signal that should operate the circuit breaker 2.2. is not output.

In FIG. 4, the output of a differential arithmetic circuit 141 similar to that described above is directly input to a level detector 143, and its output is input to an ANlog gate 144. On the other hand, the output of the error detection circuit 20 (which becomes high level when a mismatch is detected) is applied to the low active input terminal of the AND gate 144.

Therefore, when the error detection circuit 20 detects a mismatch between IB2rl and In2R1 and issues a high-level signal, the level detector 143 output does not pass through the gate 144, and the signal output to the circuit breaker 2.2 is prohibited. .

In the example of FIG. 5, the comparator as described above is used as the error detection circuit 2o! Instead, it uses a differential calculation circuit.

That is, this error detection circuit detects the digital effective value signal IB2.
It calculates the difference between R and In2R1 and converts it into an analog value, and this analog output lB2R2 is input to the differential calculation circuit 145 powered by three people. Differential calculation circuit 145
is the above-mentioned current ■^1 outside this input. IB2 is input, and the analog output IB2R2 is ＼＾1. It is used to suppress the differential output of IB2. The output of the differential calculation circuit 145 is input to the level detector 143, and compared with the same dark value as before to determine the operation of the circuit breaker 2.2.
Output a signal. In this example, the output of the error detection circuit 20 is 2.
When the difference between the human power IB2R and IB2R1 becomes large, the output of the differential arithmetic circuit 145 is made small, and as a result, the operational output of the circuit breaker 2.2 is prohibited.

In the above embodiments, the effective value calculation circuit 16.1B, the effective value extraction circuit 19, etc. are described as being constituted by separate circuits, but the part that processes digital signals may be performed by a microprocessor. Of course.

〔effect〕

In the case of the device of the present invention as described above, data error detection is performed by comparing the effective current value calculated based on the instantaneous value of the current transmitted from the other end with the effective current value also transmitted from the other end. As a result, it is possible to reliably detect when the transmission signal is affected by disturbances in the communication line, thereby preventing the failure of the current circuit from accidentally locking the circuit breaker when it should be activated, causing a serious malfunction. There will be nothing to do.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the apparatus of the present invention, FIG. 2 is an explanatory diagram of the actual J value calculation method, and FIG. 4. FIG. 5 is a block diagram showing the configuration of an error detection circuit and a relay determining section, and FIG. 6 is a block diagram of a conventional device. 1... Transmission line 2... Terminal X disconnector 3... Current transformer 4... Bus bar 6... Sampling circuit 13...
Communication device 14...Relay determination unit 15...Communication line
16.18...Effective value calculation circuit 17...Composition circuit 19...Effective value extraction circuit 20...Error detection circuit Note that the same reference numerals in the drawings indicate the same or corresponding parts. Patent Applicant Mitsubishi Electric Corporation Agent Patent Attorney Masuo Oiwa and 2 others 12=i'
(+)・:'(t-3) 2nd, 2 /da/ #2 1tjFigure 3

Claims (1)

[Claims] 1. Convert instantaneous current values sampled synchronously at multiple current detection ends of the power system into digital signals and transmit them to the other end, and compare the transmitted instantaneous current values at the other end with the In a current differential relay device that compares the current instantaneous value at the end and detects an abnormality in the power system based on the comparison result and operates in a specified manner,
means for calculating an effective current value based on the sampled instantaneous current value; means for transmitting the sampled instantaneous current value and the calculated effective current value to the other end; and means for calculating the effective current value based on the instantaneous current value transmitted from the other end. means for calculating an effective current value; error detection means for comparing the effective current value calculated by the means with the effective current value transmitted from the other end; A current differential relay device comprising: a relay determination unit that prohibits the predetermined operation when a mismatch is detected. 2. The relay determination unit includes a differential arithmetic circuit that inputs the instantaneous current values of the own end and the other end, and an error detection means that sets the output of the differential arithmetic circuit to zero when the error detection means detects a substantial mismatch between the two effective current values. The current differential relay device according to claim 1, further comprising means for making the current differential relay device. 3. The relay determination unit includes a differential calculation circuit that inputs instantaneous current values at one end and the other end, determination means for determining whether there is an abnormality in the power system based on the output of the differential calculation circuit, and error detection means. 2. The current differential relay device according to claim 1, further comprising a circuit that inhibits output from said determination circuit when said current effective value detects a substantial discrepancy between the two effective current values. 4. The error detection means includes a difference calculation circuit that calculates the difference between the effective values of both currents, and supplies an amount of electricity corresponding to this difference to the relay determination unit as a signal involved in the determination. The current differential relay device according to item 1.