RU2231156C1 - Differential-phase relay - Google Patents

Abstract

FIELD: electrical engineering, differential-phase protection while locating point of short-circuit on basis of comparison of current phase across ends of protected line.

SUBSTANCE: differential-phase relay incorporates four comparators, two actuators, clock pulse generator, one-shot multivibrator, short-pulse former, subtracter, adder, two-way limiter, no recursive filter, six AND gates, three OR gates, delay element, reversible counter.

EFFECT: increased noise immunity under conditions of high-frequency interference, capability to locate point of short-circuit in monitored line.

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Description

The invention relates to electrical engineering and can be used in systems of differential-phase protection when determining the location of a short circuit based on a comparison of the phases of the current at the ends of the protected line.

A device is known that contains a series-connected clock generator, a binary counter, a decoder, a pulse shaper and an actuator made in the form of a transistor [1].

The disadvantage of this device is the relatively narrow functionality that does not allow using it as a differential-phase relay.

The closest in technical essence to the proposed device is a device containing a series-connected measuring transducer, a first differentiation unit, a second differentiation unit, an adder, the second and third inputs of which are connected to the outputs of the measuring transducer and the first differentiating unit, a comparator and an actuator [2].

The disadvantage of the closest technical solution is the relatively narrow functionality, since the device allows you to determine the degree of desync of the input signals, but does not allow you to determine the location of the short circuit, as well as the relatively low noise immunity in conditions of high-frequency interference.

The technical result of the invention is the expansion of functionality and increased noise immunity.

This technical result is achieved in that a second comparator, a third comparator, the output of which is connected to the input of the first actuator, a non-recursive filter connected in series, and a fourth comparator, the input of which is connected to the input of the third comparator, are introduced into the device containing the first actuator and the first comparator and the second actuator, the first element And, the first and second inputs of which are connected to the output “more” of the first and with the output “less” of the second comparators respectively but, the second element And, the first and second inputs of which are connected to the output “less” of the first and with the output “more” of the second comparators, respectively, the third element And, the first and second inputs of which are connected to the outputs “more” of the first and second comparators, respectively, the fourth the AND element, the first and second inputs of which are connected to the outputs “less” of the first and second comparators, respectively, the first OR element, the first and second inputs of which are connected to the outputs of the first and second elements And, the second element And LI, the first and second inputs of which are connected to the outputs of the third and fourth elements AND, the fifth element And, the first input of which is connected to the output of the first OR element, the sixth element And, the first input of which is connected to the output of the second OR element, reversible counter, subtraction inputs and summing which is connected to the outputs of the fifth and sixth elements And, respectively, serially connected one-shot and a clock generator, the output of which is connected to the second inputs of the fifth and sixth elements And, pos interconnected short-pulse shaper, the input of which is connected to the output “greater” than the first comparator, and the output is connected to the control input of the non-recursive filter, a delay element, and a third OR element, the second input of which is connected to the output of the single-vibrator and to the installation input to zero non-recursive filter, and the output is connected to the installation input at zero of the reverse counter, as well as a series-connected subtraction unit, the first input of which is connected to the output of the reverse counter, a two-way limiter and an adder, the output of which is connected to the information input of the non-recursive filter, the output of which is connected to the second inputs of the subtraction unit and the adder, while the inputs of the first and second comparators are current inputs at the first and second ends of the monitored line, respectively.

Figure 1 presents the electrical structural diagram of a differential-phase relay, figure 2 - non-recursive filter.

The differential phase relay (Fig. 1) contains a first actuator 1, a first comparator 2, a second comparator 3, a third comparator 4, the output of which is connected to the input of the first actuator 1, a non-recursive filter 5 connected in series, a fourth comparator 6, the input of which is connected with the input of the third comparator 4, and the second actuator 7, the first element And 8, the first and second inputs of which are connected to the output “more” of the first 2 and with the output “less” of the second 3 comparators, respectively, the second element And 9, per the second and second inputs of which are connected to the output “less” of the first 2 and with the output “more” of the second 3 comparators, respectively, the third element And 10, the first and second inputs of which are connected to the outputs “more” of the first 2 and second 3 comparators, respectively, the fourth element And 11, the first and second inputs of which are connected to the outputs “less” of the first 2 and second 3 comparators, respectively, the first OR element 12, the first and second inputs of which are connected to the outputs of the first 8 and second 9 elements AND, the second element OR 13, first and the second inputs of which are connected to the outputs of the third 10 and fourth 11 elements And, the fifth element And 14, the first input of which is connected to the output of the first element OR 12, the sixth element And 15, the first input of which is connected to the output of the second element OR 13, a reverse counter 16, the subtraction and summing inputs of which are connected to the outputs of the fifth 14 and sixth 15 elements And, accordingly, the one-shot 17 and the clock generator 18 are connected in series, the output of which is connected to the second inputs of the fifth 14 and sixth 15 elements ntents And, in series connected to the short pulse former 19, the input of which is connected to the output “greater” than the first comparator 2, and the output is connected to the control input of the non-recursive filter 5, the delay element 20 and the third element OR 21, the second input of which is connected to the output of the one-shot 17 and with the installation input at zero of the non-recursive filter 5, and the output connected to the installation input at the zero of the reverse counter 16, as well as a series-connected subtraction unit 22, the first input of which is connected to the output of the reverse counter 16, two a side limiter 23 and an adder 24, the output of which is connected to the information input of the non-recursive filter 5, the output of which is connected to the second inputs of the subtracting unit 22 and the adder 24, while the inputs of the first 2 and second 3 comparators are current inputs at the first and second ends of the monitored line, respectively .

The non-recursive filter 5 (FIG. 2) contains a memory register of 25-1 ... 25-k cells connected in series, the input of the first cell is the information input of the filter 5. The cell outputs through the corresponding 26-1 ... 26-k multiplier by 1 / k, where k is the number of cells in the filter memory register, connected to the corresponding inputs of the adder 27, the output of which forms the average value of the received samples. The output of the adder 27 is the output of the filter 5. The inputs to the zero and the memory register are the inputs to the zero and the control inputs of the non-recursive filter 5.

The first 1 and second 7 actuators can be made in the form of relay windings with corresponding contacts, which are connected through an amplifier or directly to the outputs of the third 4 and fourth 6 comparators, respectively. Shaper 19 generates a short pulse along the leading edge of its input signal, i.e. when the input signal drops from the level of logical zero to the level of a logical unit. The remaining units of the device are standard units of electrical engineering. The power supply circuits of the blocks in the drawing are omitted as non-essential in the framework of this application.

The differential phase relay operates as follows.

When the relay is turned on, the signal 18 starts the generator 18, and the reverse counter 16 and the memory register of the non-recursive filter 5 are set to zero. The inputs of the first 2 and second 3 comparators receive signals proportional to the instantaneous values of the currents at the ends of the monitored line. With external short-circuit currents have different signs and, therefore, are shifted by 180 degrees. When short circuit on the protected line currents coincide in phase. At the output of the first element OR 12, a signal of a logical unit is formed when the signs of the instantaneous values of the currents do not coincide, and at the output of the second element OR 13, when the signs coincide. In the corresponding time intervals, the subtracting and summing inputs of the reverse counter 16 receive counting pulses from the generator 18. As a result, for the period of current changes in the reverse counter 16, a value is generated proportional to the difference in time intervals for the period of current changes in the line during which the signs of the currents coincided and did not match. At the signal of the former 19, the contents of the reverse counter 16 are written into the memory register of the non-recursive filter 5, passing through the subtraction unit 22, the two-way limiter 23 and the adder 24, after which the contents of the reverse counter 16 are reset. The smoothed signal from the output of the non-recursive filter 5 is compared in the third comparator 4 with the upper threshold level, the excess of which corresponds to the short circuit on the monitored line and the operation of the first actuator 1. At the same time, the signal of the non-recursive filter 5 is compared in the fourth comparator 6 with the lower threshold level, which corresponds to the fact Short circuit outside the controlled line and the actuation of the second actuator 7.

The signal from the output of the reversible counter 16 before entering the input of the non-recursive filter 5 is subjected to the following transformations. First, in block 22, subtracting from the output signal of the reverse counter 16, the output signal of the non-recursive filter 5 is subtracted, which under normal conditions is added to the same signal in the adder 24. Therefore, in the absence of high-frequency interference, the output signal of the reverse counter 16 is only averaged in the non-recursive filter 5, which leads to reduce the effect of low-frequency interference. If there is high-frequency interference at the output of the subtraction unit 22, a relatively large absolute deviation signal from the output of the non-recursive filter 5 will be observed. A two-way limiter 23 limits the deviation signal, which reduces the effect of anomalous distortions of the input parameters caused, for example, by high-frequency interference.

Thus, the proposed technical solution expands the functionality and the device allows you to determine the location of a short circuit, and also increases the noise immunity of the relay by reducing the influence of high-frequency interference.

Sources of information

1. Electrical reference book, in 4 volumes, t.2. Electrical products and devices. Under the general editorship of V.G. Gerasimova et al. - M.: Publishing House MPEI, 1998, p. 390, Fig. 35.10.

2. Andreev V.A. Relay protection and automation of power supply systems. - M.: Higher School, 1991, p. 352, Fig. 12.13 (prototype).

Claims (1)

Differential-phase synchronization relay containing a first actuator and a first comparator, characterized in that a second comparator, a third comparator, in which the signal is compared with the upper threshold level, the output of which is connected to the input of the first actuator, are connected in series with a non-recursive filter, the fourth comparator , in which the signal is compared with a lower threshold level, the input of which is connected to the input of the third comparator, and the second actuator, the first element And, first the second and second inputs of which are connected with the output “More” of the first and with the output “Less” of the second comparators, respectively, the second element And, the first and second inputs of which are connected with the output “Less” of the first and with the output “More” of the second comparators, respectively, the third element And, the first and second inputs of which are connected to the outputs “More” of the first and second comparators, respectively, the fourth element And, the first and second inputs of which are connected to the outputs “Less” of the first and second comparators, respectively, the first element t OR, the first and second inputs of which are connected to the outputs of the first and second AND elements, respectively, the second OR element, the first and second inputs of which are connected to the outputs of the third and fourth AND elements, respectively, the fifth AND element, the first input of which is connected to the output of the first OR element , the sixth AND element, the first input of which is connected to the output of the second OR element, a reversible counter, the subtraction and summing inputs of which are connected to the outputs of the fifth and sixth AND elements, respectively, connected in series a bottom vibrator and a clock pulse generator, the output of which is connected to the second inputs of the fifth and sixth elements And, a shorter pulse generator is connected in series along the leading edge, the input of which is connected to the “More” output of the first comparator, and the output is connected to the control input of the non-recursive filter, the delay element and the third OR element, the second input of which is connected to the output of the one-shot and to the installation input at “0” of the non-recursive filter, and the output is connected to the installation input to “0” of the reverse counter, and also therefore, a connected subtraction unit, the first input of which is connected to the output of the reversible counter, a two-way limiter and an adder, the output of which is connected to the information input of a non-recursive filter, the output of which is connected to the second inputs of the subtraction unit and the adder, while the inputs of the first and second comparators are current inputs to the first and second ends of the monitored line, respectively, and the input of the one-shot is the input of the start of the differential-phase relay.

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