RU2335058C1 - Method of inhibiting automatic reclosure in short-circuit state at main power source busses and close short-circuit in out coming line with faulty circuit breaker - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electric circuitry automatics. The proposed method consists in recording the short-circuit current appearance at the power source input and controlling the voltage across the power source busses. Note here that the current at the power source input is controlled between the input switch and power source buses, the short-circuit current appearance between the said input switch and the power source busses is recorded and, at the same time, the line voltages across the busses on the power source side is controlled. The short-circuit current cut off by relaying, the line voltages across the busses on the power source side is controlled. If, during the short-circuit current condition, the line voltages drop below the values at which the short-circuit Users' equipment fails and if, with the short-circuit current eliminated, there exist no line voltages across the busses, it indicates the short-circuit condition at the power source busses or close short-circuit condition in out coming line and that it has been inhibited by the circuit breaker. In this case, the automatic reclosure signal is triggered off.

EFFECT: expanded performances of circuitry automatics.

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Description

The invention relates to the automation of electrical networks and is intended to prevent automatic re-activation (AR) of the circuit breaker on a short circuit on the buses of the main power source and on a short circuit in the outgoing line in the event of a circuit breaker failure.

A known method of prohibiting the automatic reclosure of an input circuit breaker to 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, in which the short circuit current is recorded at the input of the supply transformer between the input switch and the bus section of the supply transformer, in at the same time, the short circuit current in the outgoing lines is monitored, the voltage on the busbar sections of the supply transformer is monitored, and if the current is short If there is a short circuit 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 it is concluded that a short circuit has occurred on the buses of the two-transformer substation, and in this case the AR signal is disabled for the input switch [RF patent No. 2292620, cl. Н02J 9/06, 13/00, publ. 01/27/2007, Bull. Number 3].

The disadvantage of this method is that it is used only for two-transformer substations and is not applicable for the prohibition of automatic reclosure when using other power sources. In addition, this method is not applicable for the prohibition of automatic reclosure in case of a short circuit in the outgoing line in case of failure of its circuit breaker. Also, it does not allow to take into account the value of reducing the line voltages on the tires of the power source in the event of a short circuit on them or in the outgoing line, which reduces its functionality.

The objective of the invention is to expand the scope and functionality of the method by using it to prohibit the automatic reclosure on a stable two- or three-phase short circuit on the buses of the main power source and on a short circuit in the outgoing line when its circuit breaker fails, regardless of the type of power source.

To solve this problem in a known method, which consists in fixing the appearance of a short circuit current at the input of the supply transformer and in the outgoing lines, in which the short circuit current is recorded at the input of the supply transformer between the input switch and the bus section of the supply transformer, the current is monitored short circuit in the outgoing lines, 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, n is absent in the outgoing lines, and after it is turned off by the protection, there is no voltage on the busbar sections of the supply transformer, then we 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, according to the invention, the current at the input of the power supply is controlled between the input switch and the buses of the power source, detect the appearance of a short circuit current between the input switch and the buses of the power source, at the same time control the values I line voltage on the busbar from the power source, after turning off the short circuit current due to the operation of the protection, control the value of the line voltage on the busbar from the power source and, if during the passage of the short circuit current, the line voltage on the busbar is lower than the value at which the technological processes for consumers powered by a power source, and after disconnecting the short circuit current there are no line voltages on the buses, they conclude that a short a short circuit on the tires of the power source or a short circuit in the outgoing line, and its circuit breaker fails, in which case the AR signal is disabled.

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 the signal diagrams at the outputs of the elements shown in figure 1 with a short circuit at point 25 (see figure 1),

figure 3 shows a diagram of the signals at the outputs of the elements shown in figure 1 with a short circuit at point 27 (see figure 1),

figure 4 shows a diagram of the signals at the outputs of the elements shown in figure 1 with a short circuit at point 28 (see figure 1).

The circuit (see Fig. 1) contains a power supply unit IP 1, an input switch Q 2 equipped with an automatic reclosure device, a current sensor DT 3, a short-circuit current sensor DTKZ 4, an element NOT 5, a voltage sensor DN 6, a voltage sensor DN 7, a sensor voltage ДН 8, voltage sensor ДНН 9, voltage sensor ДНН 10, voltage sensor ДНН 11, voltage level sensor ДУН 12, voltage level sensor ДУН 13, voltage level sensor ДУН 14, element NOT 15, element NOT 16, element NOT 17, element OR 18, element AND 19, element MEMORY 20, element AND 21, element NOT 22, element AND 23, element MEMORY 24, short circuit point 25, circuit breaker on line Q 26, short circuit point 27, short circuit point 28.

With a short circuit at point 25 (see FIG. 1), the signal diagrams at the outputs of the elements shown in FIG. 1 have the form (see FIG. 2): 29 — at the output of element 3; 30 - at the output of element 4; 31 - at the output of element 5; 32 - at the output of element 6; 33 - at the output of element 7; 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 12; 39 - at the output of element 13; 40 - at the output of element 14; 41 - at the output of element 15; 42 - at the output of element 16; 43 - at the output of element 17; 44 - at the output of element 18; 45 - at the output of element 19; 46 - at the output of element 20; 47 - at the output of element 21; 48 - at the output of element 22; 49 - at the output of element 23; 50 - at the output of element 24.

With a short circuit at point 27 (see FIG. 1), the signal diagrams at the outputs of the elements shown in FIG. 1 have the form (see FIG. 3): 51 — at the output of element 3; 52 - at the output of element 4; 53 - at the output of element 5; 54 - at the output of element 6; 55 - at the output of element 7; 56 - at the output of element 8; 57 - at the output of element 9; 58 - at the output of element 10; 59 - at the output of element 11; 60 - at the output of element 12; 61 - at the output of element 13; 62 - at the output of element 14; 63 - at the output of element 15; 64 - at the output of element 16; 65 - at the output of element 17; 66 - at the output of element 18; 67 - at the output of element 19; 68 - at the output of element 20; 69 - at the output of element 21; 70 - at the output of element 22; 71 - at the output of element 23; 72 - at the output of element 24.

With a short circuit at point 28 (see FIG. 1), the signal diagrams at the outputs of the elements shown in FIG. 1 have the form (see FIG. 4): 73 — at the output of element 3; 74 - at the output of element 4; 75 - at the output of element 5; 76 - at the output of element 6; 77 - at the output of element 7; 78 - at the output of element 8; 79 - at the output of element 9; 80 - at the output of element 10; 81 - at the output of element 11; 82 - at the output of element 12; 83 - at the output of element 13; 84 - at the output of element 14; 85 - at the output of element 15; 86 - at the output of element 16; 87 - at the output of element 17; 88 - at the output of element 18; 89 - at the output of element 19; 90 - at the output of element 20; 91 - at the output of element 21; 92 - at the output of element 22; 93 - at the output of element 23; 94 - at the output of element 24.

The scheme works as follows.

In normal operation, a working current of some magnitude is monitored by a current sensor DT 3. Since the current is not equal to or less than the minimum value of the short circuit current, there is no signal at the output of DTKZ 4, there is a signal at the output of element NOT 5, no signal at the outputs of the elements are NOT 15, NOT 16 and NOT 17, since all linear voltages on the tires are present. So, there is no signal at the output of the OR 18 element and, accordingly, the AND 19, AND 23 elements, MEMORY 24. The circuit does not start.

With a two- or three-phase short circuit (in the diagram, Fig. 2, the case of a three-phase short circuit at point 25 is shown), a short circuit current appears on the busbar section of the power supply located between the input switch and the Q 26 switch, which is detected by the DTKZ 4 sensor, the output of DTKZ 4 a signal appears (see figure 2, diagram 30), which is fed to one of the inputs of the element And 19. Since a three-phase short circuit occurred on the buses, all line voltages on them become equal to zero, so the signals from the outputs of the sensors disappear voltage DN 6, DN 7 and DN 8 (see figure 2, diagrams 32, 33, 34). Accordingly, the signals from the outputs of the sensors of the nominal voltage ДНН 9, ДНН 10, ДНН 11 (see Fig. 2, diagrams 35, 36, 37), as well as voltage level sensors ДУН 12, ДУН 13, ДУН 14 (see Fig. 2, diagrams 38, 39, 40). The DUN sensors work in such a way that a signal at their output is present only when the voltage value is higher than indicated by horizontal dashed lines in diagrams 32, 33, 34 (see figure 2). That is, when the voltage drops below the value at which the technological processes are disturbed for consumers, fed from the outgoing line switched by Q 26 switch, and from other outgoing lines (not shown in FIG. 1), the signal from the outputs of the sensors ДУН 12, ДУН 13, DUN 14 disappears. This value of the voltage level is set depending on which consumers are fed from the outgoing lines. When the signals at the outputs of the sensors DUN 12, DUN 13, DUN 14 disappear, signals appear at the outputs of the elements NOT 15, NOT 16 and NOT 17 (see figure 2, diagrams 41, 42, 43). A signal appears from the output of the OR element 18 (see Fig. 2, diagram 44), which is fed to the second input of the And 19. element. Since during the short circuit current there are signals at both inputs of the And 19 element, a signal also appears at its output ( see figure 2, diagram 45), which is remembered by the element MEMORY 20 (see figure 2, diagram 46). Due to the lack of a signal at the output of the And 21 element (see FIG. 2, diagram 47), there is a signal at the output of the HE 22 element (see FIG. 2, diagram 48), this signal is fed to one of the inputs of the And 23 element. At the second input of this element, a signal is output from the output of the MEMORY 20. When the short-circuit current is turned off (Q2 switch is turned off), the signal from the output of the DTKZ 4 sensor disappears and, therefore, a signal appears at the output of the element NOT 5 (see figure 2, diagram 31). This signal is fed to the third input of the And 23 element. At the output of the And 23 element, a signal appears (see FIG. 2, diagram 49), which is stored by the MEMORY 24 element (see FIG. 2, diagram 50). The signal from the output of the element MEMORY 24 is a signal to prohibit the automatic reclosure of the input switch. The inhibit signal, as well as the signal from the output of the MEMORY 20 element, is reset when the normal mode is restored, that is, when all line voltages of the nominal value appear on the buses of the power source.

With a two-phase short circuit at point 25 (see Fig. 1), one line voltage will disappear at the time of the short circuit, the other two line voltages will drop to a certain value, that is, the signals from the elements of DNN 9, DNN 10, DNN 11 will disappear at the same time, if short circuit current. The signals from the elements of DUN 12, DUN 13, DUN 14 will change as follows: the signal from the output of one of these elements will disappear at the moment of short circuit, from the other two - at the moment of disconnection of the short circuit current. Nevertheless, a signal will be present at one of the inputs of the OR element 18, which will lead to the operation of the circuit for the rest as well as during a three-phase short circuit at point 25 (see Fig. 1).

In case of a two- or three-phase short circuit (in the diagram, Fig. 3, the case of a three-phase short circuit at point 27 is shown) in the outgoing line (see Fig. 1, point 27), close to the busbars of the power source, a short circuit current appears, which is fixed sensor DTKZ 4, at the output of DTKZ 4 a signal appears (see figure 3, diagram 52), which is fed to one of the inputs of element And 19. Since a three-phase short circuit occurred in the outgoing line, the line voltage on the buses of the power source will not equal to zero, but will decrease to a certain value. Since a short circuit occurred near the busbar of the power supply, the decrease in the line voltage on the busbar will be significant, their value will be lower than that at which the process is disturbed for consumers fed from the outgoing lines (see figure 3, diagrams 54, 55, 56 ) Accordingly, the signals from the outputs of the sensors of the nominal voltage ДНН 9, ДНН 10, ДНН 11 (see Fig. 3, diagrams 57, 58, 59), as well as voltage level sensors ДУН 12, ДУН 13, ДУН 14 (see Fig. 3, will disappear , charts 60, 61, 62). The DUN sensors work in such a way that a signal at their output is present only when the voltage level is higher than indicated by horizontal dashed lines in diagrams 54, 55, 56 (see figure 3). When the signals at the outputs of the sensors DUN 12, DUN 13, DUN 14 disappear, signals appear at the outputs of the elements NOT 15, NOT 16 and NOT 17 (see figure 3, diagrams 63, 64, 65). A signal appears from the output of the OR element 18 (see Fig. 3, diagram 66), which is fed to the second input of the And 19. element. Since during the short circuit current there are signals at both inputs of the And 19 element, a signal also appears at its output ( see figure 3, diagram 67), which is remembered by the element MEMORY 20 (see figure 3, diagram 68). Due to the absence of a signal at the output of AND element 21 (see Fig. 3, diagram 69), there is a signal at the output of element NOT 22 (see Fig. 3, diagram 70), this signal is fed to one of the inputs of And 23. At the second input of this element, a signal is output from the output of the MEMORY 20. If the Q 26 switch in the line fails, then the Q 2 switch is turned off to disconnect the short circuit current. At the same time, the signal from the output of the DTKZ 6 sensor disappears and, therefore, a signal appears at the output of the NOT 5 element (see figure 3, diagram 53). This signal is fed to the third input of the And 23 element. At the output of the And 23 element, a signal appears (see FIG. 3, diagram 71), which is stored by the MEMORY 24 element (see FIG. 3, diagram 72). The signal from the output of the element MEMORY 24 is a signal of prohibition of automatic reclosure. The inhibit signal, as well as the signal from the output of the MEMORY 20 element, is reset when the normal mode is restored, that is, when all line voltages of the nominal value appear on the buses of the power source.

With a two-phase short circuit at point 27 (see Fig. 1), one line voltage will significantly decrease at the time of the short circuit, the other two line voltages will also decrease, although to a lesser extent, that is, signals from the elements DIN 9, DNN 10, DNN 11 disappear at the same time when a short circuit current occurs. The signals from the elements of DUN 12, DUN 13, DUN 14 will change as follows: the signal from the output of one of these elements will disappear at the moment of short circuit, from the other two - at the moment of disconnection of the short circuit current. Nevertheless, a signal will be present at one of the inputs of the OR element 18, which, if the Q 26 switch fails in the line, will lead to the operation of the circuit in the same way as with a three-phase short circuit at point 27 (see Fig. 1) .

If a short circuit occurs at point 27 (see figure 1) and the Q 26 circuit breaker does not fail in the line, then the short circuit current is disconnected using this switch. In this case, immediately after switching off the short-circuit current, the line voltages on the buses of the main power supply will become nominal and, thus, at that moment a signal will appear at the output of the And 21 element, which will “reset” the MEMORY 20 element and lead to the disappearance of the signal at the output of the element NOT 22. As a result of this, there will be no signals at the corresponding inputs of the And 23 element, the signal will not appear at its output and, therefore, the AR inhibit signal will not be issued. The circuit will return to its original state.

When a two- or three-phase short circuit (in the diagram, Fig. 4, shows the case of a three-phase short circuit at point 28) in the outgoing line (see Fig. 1, point 28), at a considerable distance from the power supply buses, a short circuit current appears, which is detected by the DTKZ 4 sensor, a signal appears at the DTKZ 4 output (see Fig. 4, diagram 74), which is supplied to one of the inputs of element 19. As a three-phase short circuit occurred in the outgoing line, the line voltages on the buses of the power supply will not be equal to zero, but will decrease to a definite actual value. Since the short circuit occurred at a considerable distance from the power source, the decrease in the line voltage on the buses will not be large, that is, the line voltage values will be higher than the level at which the process is disturbed for consumers fed from outgoing lines (see Fig. 4, diagrams 76, 77, 78). The signals from the outputs of the sensors of the nominal voltage DNN 9, DNN 10, DNN 11 will disappear (see figure 4, diagrams 79, 80, 81), since the voltage reduction still occurred. The signals from the outputs of the voltage level sensors ДУН 12, ДУН 13, ДУН 14 (see Fig. 4, diagrams 82, 83, 84) will not disappear, since the signal at their output is present at a voltage level above a value at which a violation of technological processes occurs consumers, that is, above the level indicated by horizontal dashed lines in diagrams 76, 77, 78 (see figure 4). Since there will be no disappearance of signals from the outputs of the elements DUN 12, DUN 13 and DUN 14 during the passage of the short circuit current, at this time the signals do not appear on the outputs of the elements NOT 15, NOT 16 and NOT 17 (see figure 4, diagrams 85, 86, 87), the signal from the output of the OR element 18 does not appear at this time (see Fig. 4, diagram 88). The signal to the second input of the And 19 element (while the signal from the DTKZ 4 element is present at its first input) will not be sent. Since during the passage of the short circuit current there is no signal at one of the inputs of the And 19 element, there is also no signal at its output (see Fig. 4, diagram 89), there is no signal at the input of the MEMORY 20 element and, therefore, at its output (see Fig. 4, diagram 90). Due to the lack of a signal at the output of element And 21 (see figure 4, diagram 91) there is a signal at the output of element NOT 22 (see figure 4, diagram 92), this signal is fed to one of the inputs of element And 23. But at the second there is no signal from the output of the MEMORY element to the input of this element 20. If the Q 26 switch in the line fails, then the Q 2 switch is turned off to disconnect the short circuit current. At the same time, the signal from the output of the DTKZ 4 sensor disappears and, therefore, the signal at the output of the element DOES NOT 5 (see FIG. 4, diagram 75). This signal is fed to the third input of the And 23 element. But, since there is no signal at one of the inputs of this element, the signal does not appear at its output (see Fig. 4, diagram 93). There is no signal, respectively, and at the output of the element MEMORY 24 (see figure 4, diagram 94). That is, the AR inhibit signal is not issued in this case. The reclosure then turns on.

Turning on the automatic reclosure during remote short circuit in the outgoing line does not cause such negative consequences as switching on a short circuit on the busbars of the power supply or a short circuit in the outgoing line, since this does not reduce the voltage on the busbars of the power supply and on the buses of the backup power supply to the value at which the consumer’s process is disrupted. In addition, when the reclosure is turned on, if the short circuit in the outgoing line is stable, the repeated flow of the short circuit current can cause the Q 26 circuit breaker to trip in the line. In this case, the power of consumers fed through other outgoing lines will be restored by turning on the Q 2 switch. If, when the reclosure is turned on, in case of a steady short circuit at point 28 (see Fig. 1), the Q 26 switch does not turn off again, then switch Q 2 will open.

With a two-phase short circuit at point 28 (see FIG. 1), one line voltage will slightly decrease at the time of the short circuit, the other two line voltages will also decrease, although to a lesser extent. That is, the signals from the elements of the DNN 9, DNN 10 and DNN 11 will disappear simultaneously when a short circuit current occurs. The signals from the elements of DUN 12, DUN 13, DUN 14 will not disappear, because the linear voltage will not drop to a value at which the process is disturbed for consumers fed from outgoing lines. Therefore, there will be no signals at all inputs of the OR element 18 and a signal at its output. The circuit will not start. Alert bar will not be issued.

If a short circuit occurs at point 27 (see figure 1) and the Q 26 circuit breaker does not fail in the line, then the short circuit current is disconnected using this switch. In this case, immediately after switching off the short-circuit current, the line voltages on the buses of the main power supply will become nominal. The circuit will not start, the AR inhibit signal will not be issued.

If the line voltages on the buses of the main power source disappear due to other reasons (for example, operational switching, failure of the main power source, etc.), then there will be no signal from the DTKZ 4 element, the circuit will not start, therefore, it will not be issued auto-ban signal.

Thus, the AR inhibit signal is issued only in the event of a short circuit on the power supply buses and a short circuit in the outgoing line, if its circuit breaker fails, 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 input switch equipped with an automatic reclosure device, reduces the cost of its repair and maintenance.

Claims (1)

The method of prohibiting automatic restart (AR) on a short circuit on the tires of the power source and a short circuit in the outgoing line in case of failure of its switch, which consists in fixing the appearance of a short circuit current at the input of the power source and monitoring the voltage on the tires of the power source, characterized in that control the current at the input of the power source between the input switch and the buses of the power source, record the appearance of a short circuit current between the input switch and the buses of the power source, at the same time, the line voltage values are monitored on the bus side of the power supply, after the short-circuit current is switched off due to the operation of the protection, the line voltage values are monitored on the bus side of the power source, and if the line voltage on the buses is lower than the value during the short-circuit current flow , in which technological processes are violated by consumers powered by a power source, and after disconnecting the short-circuit current, there are no linear voltage on the buses, then They conclude that there was a short circuit on the tires of the power source or a short circuit in the outgoing line, and its circuit breaker failed, in which case an AR warning signal is issued.

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