RU2292620C1 - Method for forbidding automatic repeated enabling of input switch for short circuit in buses of two-transformer sub-station - Google Patents

Abstract

FIELD: automatics of electric networks.

SUBSTANCE: in the method, short circuit current is recorded at input of powering transformer between input switch and section of powering transformer buses, at the same time short circuit current in branching lines is controlled, voltage on section of buses of powering transformer is controlled and, if short circuit current is present at input of powering transformer, but is absent in branching lines, and after its disabling by protection voltage is absent in section of buses of powering transformer, then conclusion is drawn that short circuit occurred on buses of two-transformer sub-station and in this case forbidding signal for automatic repeated enabling of input switch is injected.

EFFECT: expanded area of possible use and functional capabilities.

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Description

The invention relates to the automation of electrical networks and is intended to prevent the automatic reconnection (AR) of the input circuit breaker to short circuit on the buses of a two-transformer substation.

A known method of prohibiting automatic inclusion of a reserve (ATS) for a short circuit on the buses of a two-transformer substation, in which a short circuit current is recorded at the input of the supply transformer between the input switch and the switch, control the short circuit current in the outgoing lines, control the voltage on the bus sections of the supply transformer and, if a short-circuit current is present at the input of the supply transformer, but is not present in the outgoing lines, then after the short-circuit current is disabled by the protection if there is no voltage on the busbar sections of the supply transformer, a signal is issued to prohibit the ABP [Patent No. 2251193, cl. H 02 J 9/06 of 10.16.03]

The disadvantage of this method is its lack of reliability and functionality, since it is applicable only to prohibit ATS on a two-transformer substation.

The objective of the invention is to expand the scope and functionality of the method by using it to prohibit the automatic reclosure of the input switch to a stable two- or three-phase short circuit on the buses of a two-transformer substation.

To solve this problem, in the known method, which consists in fixing the short circuit current at the input of the supply transformer and in the outgoing lines, the short circuit current at the input of the supply transformer between the input switch and the ABP switch is fixed, the short circuit current in the outgoing lines is fixed, the voltage at the sections is controlled busbars of the supply transformer and, if a short-circuit current is present at the input of the supply transformer, but is absent in the outgoing lines, then after the current is turned off by the protection a short circuit, if there is no voltage on the busbar sections of the supply transformer, a signal is issued to prohibit the ABP, according to the invention, a short circuit current is recorded at the input of the supply transformer between the input switch and the bus section of the supply transformer, at the same time, the short circuit current in the outgoing lines is monitored, control the voltage on the busbar sections of the supply transformer and, if a short circuit current is present at the input of the supply transformer, but is absent in the outgoing lines, and the last If it is not turned off by the protection, there is no voltage on the busbar sections of the supply transformer, then they conclude that a short circuit occurred on the buses of the two-transformer substation, and in this case the AR signal prohibit the input switch.

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

figure 1 shows a structural diagram of a device that implements the method;

figure 2 shows a diagram of the signals at the outputs of the elements shown in figure 1, with a short circuit at point 20;

figure 3 shows a diagram of the signals at the outputs of the elements shown in figure 1, with a short circuit at point 21.

The circuit (see Fig. 1) contains a supply transformer T1, an input switch Q2 on the high voltage side, an input switch Q3 on the low voltage side, an ABP switch Q4, a switch in the outgoing line Q5, a switch in the outgoing line Q6, a switch in the outgoing line Q7 , short-circuit current sensor DTKZ 8, short-circuit current sensor DTKZ 9, short-circuit current sensor DTKZ 10, short-circuit current sensor DTKZ 11, element OR-HE12, element I 13, voltage presence sensor DNN 14, element HE15, element Memory 16 , element HE17, element And 18, the element Memory 19, the point of short circuit 20, the point of short circuit 21.

With a short circuit (short circuit) at point 20 (see FIG. 1), the signal diagrams at the outputs of the elements shown in FIG. 2 have the form: 22 — at the output of element 8; 23 - at the output of element 9; 24 - at the output of element 10; 25 - at the output of element 11; 26 - at the output of element 14; 27 - at the output of element 12; 28 - at the output of element 13; 29 - at the output of element 15; 30 - at the output of element 17; 31 - at the output of element 16; 32 - at the output of element 18; 33 - at the output of element 19.

With a short circuit at point 21 (see FIG. 1), the signal diagrams at the outputs of the elements shown in FIG. 3 have the form: 34 — at the output of element 8; 35 - at the output of element 9; 36 - at the output of element 10; 37 - at the output of element 11; 38 - at the output of element 14; 39 - at the output of element 12; 40 - at the output of element 13; 41 - at the output of element 15; 42 - at the output of element 17; 43 - at the output of element 16; 44 - at the output of element 18; 45 - at the output of element 19.

The scheme works as follows:

In normal operation, the operating current flows in the outgoing lines and at the input of the transformer T1. Since the currents in the lines and at the input are not equal to the short circuit current, there are no signals at the outputs of DTKZ 8, DTKZ 9, DTKZ 10. Accordingly, there is a signal at the output of the OR-NOT 12 element, but since there is no signal from the DTKZ 11 element, then there is no signal at the output of AND element 13. All the line voltages on the buses are present, therefore, there is a signal from the element ДНН 14, which is sent to reset the element Memory 16. The circuit does not start.

In the event of a short circuit (two- or three-phase) on the substation bus section located between the input switch and the bus section of the supply transformer (Fig. 1. point 20), a short circuit current appears at the input of transformer T1, which is detected by the DTKZ 11 sensor, at the output of DTKZ 11, a signal appears (FIG. 2, diagram 25). Since the circuit occurred on the tires, then at the outputs of the sensors DTKZ 8, DTKZ 9 and DTKZ 10 there is no signal (Fig. 2, diagrams 22, 23, 24). As a result, the signal from the OR-NOT 12 element is supplied to one of the inputs of the And 13 element, at the second input of which there is a signal from DTKZ 11. At the I13 output, a signal appears and is supplied to the Memory 16 input (Fig. 2, diagram 31), which supplies the input signal of the element And 18 (figure 2, chart 32). At the second input of the I18 element, the signal appears after the short circuit is turned off. switch Q3. In this case, the input signal is supplied from the element NOT 15 (figure 2, diagram 29). At the 3 input of the I18 element, there is a signal from the output of the HE17 element (Fig. 2, diagram 30), which appears due to the disappearance of voltage on the buses at the time of short circuit Due to the presence of 3 signals at the input of the I18 element and the absence of a reset signal, a signal will appear at the output of the NAM 14, which, through the Memory 19 element, will give a signal to ban the reclosure of the input switch (Fig. 2, diagram 33). When normal mode is restored, the voltage will appear on the substation tires, which will be detected by the DNN 14 sensor, the signal from which will reset the Memory 16 and Memory 19 elements, the circuit will return to its original state.

In case of a short circuit (two- or three-phase) in the outgoing line (Fig. 1, point 21), its appearance is detected by short-circuit current sensors. in the line and at the input T1, it is DTKZ 8 and DTKZ 11, a signal appears at their outputs (Fig. 3, diagrams 34 and 37, respectively). As a result, the signal disappears from the OR-NOT 12 element, and therefore the signal disappears at one of the inputs of the And 13 element (Fig. 3, diagram 40), at the second input of which there is a signal from DTKZ 11. At the And 13 output, the signal does not appear and, therefore , will not be fed to the input Memory 16 (figure 3, diagram 43). So, there is no signal at the input of Memory 19 (Fig. 3, diagram 45). Accordingly, the AR warning prohibition signal will not be issued. After disconnecting the short circuit current switch Q 5 the signals from the sensors DTKZ 8 and DTKZ 11 will disappear (Fig.3, diagrams 34 and 37, respectively), the circuit will return to its original state.

Thus, the AR inhibit signal is issued only in case of a short circuit on the buses of a two-transformer substation between the input switch and the section switch, regardless of the type of short circuit (two- or three-phase). This extends the scope and functionality of the method, which increases the service life of the circuit breaker, reduces the cost of its repair and maintenance.

Claims (1)

A method of prohibiting automatic reconnection (AR) of the input circuit breaker on a short circuit on the buses of a two-transformer substation, which consists in fixing the appearance of a short circuit current at the input of the supply transformer and in the outgoing lines, characterized in that they fix the short circuit current at the input of the supply transformer between the input switch and section of the busbar of the supply transformer, at the same time, control the short circuit current in the outgoing lines, control the voltage on the section of the bus power transformer, and if a short circuit current is present at the input of the supply transformer, but is absent in the outgoing lines, and after it is turned off by the protection, there is no voltage on the bus sections of the supply transformer, then we conclude that a short circuit occurred on the buses of the two-transformer substation, in this case signal prohibit the reclosure of the input switch.

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