RU2504061C1 - Method to monitor disconnection of input circuit breaker of buses and false disconnection of input circuit breaker of substation transformer - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: from the moment of short circuit current surge on buses of the substation they start counting time equal to the time of delay of actuation of the input bus circuit breaker protection, and they monitor the moment of short circuit current disconnection, and if at the moment of time count completion the short circuit current disappears, a conclusion is made on disconnection of the input bus circuit breaker, from the moment of short circuit current disconnection they continue time count to the moment of completion of the time of delay of actuation of the transformer circuit breaker protection, at the same time they monitor the time of voltage disappearance from the side of the secondary winding of the transformer, and if it disappears at the moment of completion of the time of delay of actuation of the input transformer circuit breaker protection, a conclusion is made on false disconnection of the input transformer circuit breaker in the substation. The proposed method makes it possible to produce information on disconnection of the input circuit breaker of buses and false disconnection of the input circuit breaker of the substation transformer.

EFFECT: expansion of functional capabilities by production of information on disconnection of an input bus circuit breaker and false disconnection of an input substation transformer circuit breaker.

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Description

The invention relates to the automation of electrical networks and is intended to control the opening of the input bus switch and the false disconnection of the input switch of the substation transformer.

There is a method of controlling the false tripping of a sectionalizing circuit breaker in a ring network line powered by different buses of a two-transformer substation, which consists in fixing the inrush currents and in measuring the time between them. For this, at the time of fixing the drop in the operating current at the beginning of the main power supply line to a value determined by the load of the line connected after the sectioning switch and the absence of inrush short-circuit current (short circuit), the time is set equal to the shutter-off time of the circuit breaker of the automatic transfer switch. At the end of the countdown of this time, the appearance of a current surge at the beginning of the backup power supply line is controlled and, if a current surge occurs with a value determined by the disconnected load of the main power supply line, then the fact of a false disconnection of the sectioning switch in the ring network line is established [patent RU No. 2378754, cl . H02J 13/00, publ. 10/10/2010, bull. No. 1].

The disadvantage of this method is the impossibility of using it to obtain information about the tripping of the input bus switch and the false disconnection of the input switch of the substation transformer.

The objective of the invention is to expand the functionality of the method by obtaining information about turning off the input bus switch and false disconnecting the input switch of the substation transformer.

According to the proposed method, from the moment of the appearance of a short-circuit current surge on the substation's tires, a time count starts equal to the response time of the protection of the bus input breaker and the moment of short-circuit current tripping is monitored, and if the short-circuit current disappears at the end of the countdown, then a conclusion is made that the bus breaker is turned off , from the moment the short-circuit current is cut off, the countdown is continued until the end of the response time of the protection of the input transformer breaker, while the moment of voltage failure is monitored I am on the side of the secondary winding of the transformer and, if it disappears at the end of the holding time of the protection of the input switch of the transformer, then they conclude that the input switch of the transformer of the substation is false disconnected.

The essence of the invention is illustrated by drawings, where:

figure 1 - presents a structural diagram containing elements for implementing the method;

figure 2 - diagrams of the signals at the outputs of the elements shown in figure 1.

The circuit (see Fig. 1) contains: an input switch of the transformer 1, a power transformer 2, an input switch of the tires 3, lines extending from the buses of the substation 4, 6, 7 and 8, a short-circuit point 5, a short-circuit current sensor (DTKZ) 9 , elements: MEMORY 10, NOT 11, DELAY 12, SINGLE-VIBRATOR 13, AND 14, MEMORY 15, DELAY 16, SINGLE-VIBRATOR 17, voltage sensor (DN) 18, elements NOT 19 and 20, recording device (RU) 21.

The signal diagrams at the outputs of the elements shown in Fig. 1 with a stable fault at point 5 have the form (see Fig. 2): 22 - at the output of element 9, 23 - at the output of element 10, 24 - at the output of element 11, 25 - at the output of element 12, 26 - at the output of element 13, 27 - at the output of element 14, 28 - at the output of element 15, 29 - at the output of element 16, 30 - at the output of element 17, 31 - at the output of element 18, 32 - the output member 19, 33 - at the output of element 20, 34 -to RU 21. in the diagrams of the output signals as shown in scheme: t ₁ is the moment of time of occurrence of stable CG, t ₂ - time of tripping time input th switch tire 3, t ₃ - run-off time of the transformer circuit breaker 1.

The method is as follows.

In normal operation of the network, switches 1 and 3 are turned on, there is no signal at the output of DTKZ 9, so the circuit is in control mode.

When a stable fault occurs at point 5, a signal will appear at the output of DTKZ 9 (Fig. 2, Diagram 22, time t ₁ ), which will be received at the input of element NOT 10, and the signal will disappear from its output (Fig. 2, Diagram 23 ), and also the signal will go to the input of the MEMORY 11 element, where it will be remembered (Fig. 2, Fig. 24) and will go to the input of the element DELAY 12. From the output of this element, the signal will appear after a time equal to the response time of the protection of the input bus switch 3 (Fig. .2, diag. 25) and will go to the input of the SINGLE-VIBRATOR element 13. It will produce one oscillation (Fig. 2, diag. 2 6) and with this signal, it “discards” the memory from element 11 (Fig. 2, Diagram 24) and arrives at the second input of element And 14. At this point in time, the bus input switch 3 will turn off. The short-circuit current will disappear and at the output of the element NOT 10 a signal will again appear (Fig. 2, Diagram 23) which will go to the first input of And 14. It will work (Fig. 2, Diagram 27) and its output signal will arrive at RU 21 and provide the appearance there of information on opening the opening switch 3 (Fig. 2, Diagram 34). Also, the output signal from the And element 14 will go to the input of the MEMORY element 15, where it will be remembered (Fig. 2, Diagram 28) and will go to the input of the DELAY element 16. From the output of this element, the signal will appear after a time equal to the difference between the response time of the input protection switch 1 of the transformer and the exposure time of the protection of the input switch 3 tires (figure 2, Fig. 29). After the specified period of time, the signal will go to the input of the SINGLE-VIBRATOR element 17. It will make one oscillation (Fig. 2, Diagram 30) and with its signal “discard” the memory from Element 15 (Fig. 2, Diagram 28) and go to the first input element And 20. At this point in time, due to any malfunction, the input switch 1 will deviate and the voltage on the transformer 2 will disappear. The output signal from DN 18 will disappear (Fig. 2, Diagram 31) and the output signal will appear on the element NOT 19 (Fig. 2, Diagram 32), which will go to the second input of AND element 20. It is with works, its output signal will appear (Fig. 2, Diagram 33), which, having entered RU21, will provide information there on the false shutdown of the input switch 1 of the transformer substation.

Thus, the proposed method allows to obtain information about turning off the input switch of the tires and false disconnecting the input switch of the transformer substation.

Claims (1)

A method of controlling the opening of the input bus switch and the false switching of the input switch of the substation transformer, which consists in fixing the inrush currents of short circuit (short circuit) and in counting the time between them, characterized in that from the moment the inrush of the short circuit current appears on the substation tires, a time count starts equal to time the shutter speed of the busbar breaker protection, and control the short-circuit current trip time, and if the short-circuit current disappears at the end of the countdown, then make a conclusion about the shutdown of the bus breaker in, from the moment of switching off the short-circuit current, they continue to count the time until the end of the response time of the protection of the transformer's input circuit breaker, while monitoring the moment the voltage disappears from the secondary side of the transformer, and if it disappears at the end of the exposure time of the protection of the transformer input circuit-breaker, then conclusion about the false shutdown of the input switch of the substation transformer.

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