RU2292618C1 - Method for forbidding automatic enabling of reserve for short circuit on main power source buses and close short circuit in branching line on switch failure - Google Patents

Abstract

FIELD: automatics of electric networks.

SUBSTANCE: in the method current at input of main power source is controlled between input switch and main power source buses, appearance of short circuit current between input switch and buses of main power source is recorded, at the same time value of linear voltages are controlled on buses on the side of main power source, after disabling short circuit current resulting from activation of protection, values of linear voltages on buses are controlled on the side of main power source and, if during passage of current of short circuit linear voltages on buses are below the value at which technological processes of consumers are disrupted which are powered from main or reserve power sources, while after disabling of current of short circuit linear voltages in buses are absent, therefore a conclusion is drawn that short circuit occurred at main power source buses or close short circuit on branching line, and its switch has failed, and in this case forbidding signal is injected.

EFFECT: expanded area of possible use, expanded functional capabilities.

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Description

The invention relates to the automation of electrical networks and is intended to prevent the operation of the automatic transfer switch (ATS) circuit breaker on a short circuit on the buses of the main power source and on a short circuit in the outgoing line when its circuit breaker fails.

There is a method of prohibiting the automatic inclusion of a reserve for a short circuit on the buses of a two-transformer substation, in which the current at the input of the supply transformer between the input switch and the ABP switch is monitored, the appearance of a short circuit current between the input switch and the ABP switch is detected, when it is turned off due to the operation of the protection, it is controlled line voltages on the buses from the supply transformer, and if they are absent, they conclude that there was a steady short circuit clicking on the substation buses between the input switch and the ATS switch, in which case a signal is sent to prohibit the ATS. [Patent No. 2227355, cl. H 02 J 13/00, 9/06 of 02.20.02]

The disadvantage of this method is that it is used only for two-transformer substations and is not applicable for the implementation of the prohibition of ABP when using other power sources. In addition, this method is not applicable for the implementation of the prohibition of the automatic transfer switch when there is a short circuit in the outgoing line in the event of a failure of its circuit breaker. Also, it does not allow to take into account the value of reducing the linear voltage on the redundant tires 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 ABP 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 in case of failure of its switch, regardless of the type of main and backup 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, control the current at the input of the supply transformer between the input switch and the ABP switch, record the appearance of the short circuit current between the input switch and the ABP switch, when it is disconnected due to by triggering the protection, they control the line voltage on the buses from the side of the supply transformer, and if they are absent, they conclude that a resistance to a short circuit on the substation buses between the input switch and the ABP switch, in which case an ABP inhibit signal is applied, according to the invention, the current at the input of the main power supply between the input switch and the buses of the main power supply is monitored, the occurrence of a short circuit current between the input switch and the buses of the main power supply, at the same time control the values of the line voltage on the buses from the side of the main power source, after disconnecting the short circuit current, due to the protection voltage is monitored, the values of the line voltages on the buses from the side of the main power supply are monitored and, if during the passage of the short-circuit current, the line voltages on the buses are lower than the values at which the technological processes are interrupted for consumers powered by the main and backup power sources, and after if there is no short-circuit current disconnecting the line voltage on the buses, it is concluded that there was a short circuit on the buses of the main power source or a short circuit in the outgoing line, and its circuit breaker failed, in which case an ABP prohibition signal is sent.

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 26;

figure 3 shows a diagram of the signals at the outputs of the elements shown in figure 1 with a short circuit at point 28;

figure 4 shows a diagram of the signals at the outputs of the elements shown in figure 1 with a short circuit at point 29.

The circuit (see Fig. 1) contains the main power supply OIP 1, input switch Q 2, switch ABP Q 3, current sensor DT 4, short-circuit current sensor DTKZ 5, element NOT 6, voltage sensor DN 7, voltage sensor DN 8 voltage sensor DN 9, voltage sensor DNN 10, voltage sensor DNN 11, voltage sensor DNN 12, voltage sensor DN 13, voltage sensor DN 14, voltage sensor DN 15, element 16, element 17, element NOT 18, element OR 19, element AND 20, element Memory 21, element AND 22, element nt NOT 23, AND gate 24, memory element 25, the point of the short circuit 26, a Q switch 27, the line short-circuit point 28, the point of the short circuit 29.

With a short circuit at point 26 (see FIG. 1), the signal diagrams at the outputs of the elements shown in FIG. 1 have the form: 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; 51 - at the output of element 25.

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: 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; 73 - at the output of element 25.

With a short circuit at point 29 (see FIG. 1), the signal diagrams at the outputs of the elements shown in FIG. 1 have the form: 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; 95 - at the output of element 25.

The scheme works as follows:

In normal operation, an operating current of some magnitude flows, which is monitored by a current sensor DT 4. Since the current is not equal to or greater than the short circuit current, there is no signal at the output of DTKZ 5, there is a signal at the output of element 6, there is no signal at the outputs of the elements are NOT 16, NOT 17 and NOT 18, since all the line voltages on the tires are present. So, there is no signal at the output of the OR 19 element and, accordingly, the And 20, And 24, Memory 25 elements. The circuit does not start.

In case of a short circuit (two- or three-phase) (in the diagram, see figure 2, the case of a three-phase circuit at point 26 is shown) on the bus section of the main power source located between the input switch and the ABP switch (figure 1, point 26) appears the short circuit current, which is detected by the DTKZ 5 sensor, a signal appears at the DTKZ 5 output (Fig. 2, diagram 31), which is supplied to one of the inputs of the And 20. element. Since a three-phase short circuit occurred on the buses, all line voltages on them become equal zero, therefore si will disappear the signals from the outputs of the voltage sensors DN 7, DN 8 and DN 9 (figure 2, diagrams 33, 34, 35). Accordingly, the signals from the outputs of the sensors of the nominal voltage ДНН 10, ДНН 11, ДНН 12 (Fig. 2, diagrams 36, 37, 38), as well as voltage level sensors ДУН 13, ДУН 14, ДУН 15 (Fig. 2, diagram 39 , 40, 41). The DUN sensors work in such a way that a signal at their output is present only when the voltage value is higher than that indicated by horizontal dashed lines in diagrams 33, 34, 35, see FIG. 2. That is, when the voltage drops below the value at which the technological processes are disturbed for consumers powered by the main and backup power sources, the signal from the outputs of the sensors DUN 13, DUN 14, DUN 15 disappears. This value of the voltage level is set based on which consumers are powered from the main and backup power sources. When the signals at the outputs of the sensors DUN 13, DUN 14, DUN 15 disappear, signals appear at the outputs of the elements NOT 16, NOT 17 and NOT 18 (Fig. 2, diagrams 42, 43, 44). A signal appears from the output of the OR element 19 (Fig. 2, diagram 45), which is fed to the second input of the And element 20. Since during the short-circuit current there are signals at both inputs of the And element 20, a signal also appears at its output (Fig. 2, diagram 46), which is remembered by the element Memory 21 (FIG. 2, diagram 47). Due to the absence of a signal at the output of the AND element 22 (FIG. 2, diagram 48), there is a signal at the output of the element NOT 23 (FIG. 2, diagram 49), this signal is supplied to one of the inputs of the And 24. element. from the output of the element Memory 21. When the short circuit current is turned off (Q2 switch is turned off), the signal from the output of the DTKZ 5 sensor disappears and, therefore, a signal appears at the output of the element NOT 6 (Fig. 2, diagram 32). This signal is fed to the third input of the And 24. element. At the output of the And 24 element, a signal appears (Fig. 2, diagram 50), which is stored by the Memory element 25 (Fig. 2, diagram 51). The signal from the output of the element Memory 25 is a signal to prohibit the ATS. The inhibit signal, as well as the signal from the output of the element Memory 21, is reset when the normal mode is restored, that is, when all linear voltages of the nominal value appear on the buses of the main power source.

With a two-phase short circuit at point 26, 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 DNN 10, DNN 11 and DNN 12 will disappear simultaneously when a short circuit current occurs. The signals from the elements of DUN 13, DUN 14, DUN 15 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, there will be a signal at one of the inputs of the OR 19 element, which will lead to the operation of the circuit for the rest as well as during a three-phase short circuit at point 26.

In case of a short circuit (two- or three-phase) (in the diagram, see figure 3, the case of a three-phase circuit at point 28 is shown) in the outgoing line (figure 1, point 28), a short circuit current appears near the buses of the main power source, which is detected by the DTKZ 5 sensor, a signal appears at the DTKZ 5 output (Fig. 3, diagram 53), which is fed to one of the inputs of element 20. As a three-phase short circuit occurred in the outgoing line, the line voltage on the buses of the main power source is not become equal to zero, but decrease to a certain nnogo value. Since a short circuit occurred near the tires of the main power source, the decrease in the line voltage on the tires will be significant, their values will be lower than that at which the process is disturbed for consumers powered by the main and backup power sources (Fig. 3, diagrams 55, 56, 57). Accordingly, the signals from the outputs of the sensors of the nominal voltage DNN 10, DNN 11, DNN 12 (Fig. 3, diagrams 58.59, 60), as well as voltage level sensors ДУН 13, ДУН 14, ДУН 15 (Fig. 3, diagrams 61, 62, 63). The DUN sensors work in such a way that a signal at their output is present only at a voltage level above that indicated by horizontal dashed lines in diagrams 55, 56, 57, see FIG. 3. When the signals at the outputs of the sensors DUN 13, DUN 14, DUN 15 disappear, signals appear at the outputs of the elements NOT 16, NOT 17 and NOT 18 (Fig. 3, diagrams 64, 65, 66). There is a signal from the output of the OR element 19 (Fig. 3, diagram 67), which is fed to the second input of the And element 20. Since during the short-circuit current there are signals at both inputs of the And element 20, a signal also appears at its output (Fig. 3, diagram 68), which is remembered by the element Memory 21 (FIG. 3, diagram 69). Due to the lack of a signal at the output of AND element 22 (FIG. 3, diagram 70), there is a signal at the output of element NOT 23 (FIG. 3, diagram 71), this signal is fed to one of the inputs of AND element 24. A signal is supplied to the second input of this element from the output of the Memory 21 element. If the Q27 switch fails in the line, then the Q2 switch is turned off to disconnect the short circuit current. This disappears the signal from the output of the sensor DTKZ 5 and, therefore, a signal appears at the output of the element NOT 6 (figure 3, diagram 54). This signal is fed to the third input of the And 24. element. At the output of the And 24 element, a signal appears (Fig. 3, diagram 72), which is stored by the Memory element 25 (Fig. 3, diagram 73). The signal from the output of the element Memory 25 is a signal to prohibit the ATS. The inhibit signal, as well as the signal from the output of the element Memory 21, is reset when the normal mode is restored, that is, when all linear voltages of the nominal value appear on the buses of the main power source.

In the case of a two-phase short circuit at point 28, 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, the signals from the elements ДНН 10, ДНН 11 and ДНН 12 will disappear simultaneously, when current occurs short circuit. The signals from the elements of DUN 13, DUN 14, DUN 15 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. However, there will be a signal at one of the inputs of the OR 19 element, provided that the Q 27 switch in the line fails. It will lead to the operation of the circuit for the rest, as well as for a three-phase short circuit at point 28.

If a short circuit occurs at point 28 (Fig. 1) and the Q 27 circuit breaker does not fail in the line, then the short circuit current is disconnected using this switch. At the same time, 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 22 element, which will “reset” the Memory 21 element and lead to the disappearance of the output signal element NOT 23. As a result, there will be no signals at the corresponding inputs of element AND 24, the signal will not appear at its output, and, therefore, the ATS prohibition signal will not be issued. The circuit will return to its original state.

In case of a short circuit (two- or three-phase) (in the diagram, see Fig. 4, the case of a three-phase short circuit at point 29 is shown) in the outgoing line (Fig. 1, point 29), a short current appears at a considerable distance from the main power supply buses circuit, which is recorded by the sensor DTKZ 5, at the output of DTKZ 5, a signal appears (Fig. 4, diagram 75), which is fed to one of the inputs of element 20. As a three-phase short circuit occurred in the outgoing line, the line voltages on the buses of the main source power will not become zero, but sn zyatsya to a certain value. Since the short circuit occurred at a considerable distance from the main 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 powered by the main and backup power sources (Fig. .4, diagrams 77, 78, 79). The signals from the outputs of the sensors of the nominal voltage DNN 10, DNN 11, DNN 12 will disappear (Fig. 4, diagrams 80, 81, 82), since the voltage reduction still occurred. The signals from the outputs of the voltage level sensors ДУН 13, ДУН 14, ДУН 15 (Fig. 4, diagrams 83, 84, 85) 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 for consumers (above the level indicated by horizontal dashed lines in diagrams 77, 78, 79, see figure 4). Since there will be no disappearance of signals from the outputs of the elements of DUN 13, DUN 14 and DUN 15 during the passage of the short circuit current, at this time the signals at the outputs of the elements NOT 16, NOT 17 and NOT 18 do not appear (Fig. 4, diagrams 86, 87, 88), the signal from the output of the OR element 19 does not appear at this time (Fig. 4, diagram 89). The signal to the second input of the And 20 element (while the signal from the DTKZ 5 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 20 element, there is also no signal at its output (Fig. 4, diagram 90), there is no signal at the input of the Memory 21 element and, therefore, at its output (Fig. 4 , diagram 91). Due to the lack of a signal at the output of the AND element 22 (Fig. 4, diagram 92), there is a signal at the output of the element NOT 23 (Fig. 4, diagram 93), this signal is fed to one of the inputs of the And element 24. But at the second input of this element is missing the signal from the output of the element Memory 21. If the Q27 switch fails in the line, then the Q2 switch is turned off to disconnect the short circuit current. In this case, the signal from the output of the DTKZ 5 sensor disappears and, therefore, a signal appears at the output of the element NOT 6 (Fig. 4, diagram 76). This signal is supplied to the third input of the And 24. element. But since there is no signal at one of the inputs of this element, the signal does not appear at its output (Fig. 4, diagram 94). There is no signal, respectively, and at the output of the Memory element 25 (Fig. 4, diagram 95). That is, the ATS prohibition signal in this case is not issued. ATS in this case turns on.

Turning on the ABP during a remote short circuit in the outgoing line does not cause such negative consequences as switching on a short circuit on the buses of the main power supply or a short circuit in the outgoing line, since this does not reduce the voltage on the buses of the main power source and on the backup buses power supply to a value at which the technological process is disrupted for consumers powered by the main and backup power sources. In addition, when the ATS 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 27 circuit breaker to open in the line. In this case, the power of consumers fed through other outgoing lines will be restored using a backup power source. If, when the ATS is turned on, in the event of a stable short circuit at point 29 (see Fig. 1), the Q 27 switch does not open again, then the ATS switch will open by means of protection.

With a two-phase short circuit at point 29, 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 DNN 10, DNN 11 and DNN 12 will disappear at the same time when a short circuit current occurs. The signals from the elements of DUN 13, DUN 14, DUN 15 will not disappear, because the linear voltage will not drop to a value at which the process is disturbed for consumers powered by the main and backup power sources. Therefore, there will be no signals at all inputs of the OR element 19 and a signal at its output. The circuit will not start. ATS prohibition signal will not be issued.

If a short circuit occurs at point 28 (Fig. 1) and the Q 27 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 ATS prohibition 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 5 element, the circuit will not start, therefore, the ATS inhibit signal will not be issued .

The implementation of the ATS ban according to the proposed method does not depend on the availability of an automatic reclosing device (AR) of the input switch Q 2, since if a short circuit occurred on the buses (point 26, figure 1) or in the outgoing line (point 28, figure 1) , and its circuit breaker fails (Q 27, Fig. 1), then the ATS inhibit signal will be issued at the first appearance of the short circuit current. If the reclosure is successful, after its operation, the rated line voltage will appear on the buses of the main power source. This will cause the circuit to return to its original state. If the automatic reclosure is unsuccessful, the inhibit signal will not be reset, since the busbar will not have nominal line voltage. ATS ban will be implemented.

In case of a short circuit at point 29 (Fig. 1) and the automatic reclosure of the input switch (in case of failure of the Q 27 switch in the line), the ATS inhibit signal will not be issued, since in this case the signals from the outputs of the sensors ДУН 13, ДУН 14, DUN 15 during the flow of short circuit current. The circuit will not start.

Thus, the ATS prohibition signal is issued only in the event of a short circuit on the main power supply busbars and a short circuit in the outgoing line, in case of failure of its circuit breaker, regardless of the type of short circuit (two- or three-phase) and the presence or absence of an automatic reclosure device for an input switch . This extends the scope and functionality of the method, which increases the service life of the ATS switch, reduces the cost of its repair and maintenance.

Claims (1)

The method of prohibiting automatic turn-on of the reserve (WUA) to a short circuit on the buses of the main power source and a short circuit in the outgoing line when its switch fails, which consists in fixing the appearance of a short circuit current at the input of the main power source and monitoring the voltage on the buses from the main power source characterized in that they control the current at the input of the main power source between the input switch and the buses of the main power source, record the appearance of the short circuit current relations between the input switch and the buses of the main power source, at the same time control the values of the line voltage on the bus side of the main power source, after disconnecting the short circuit current caused by the protection, control the value of the line voltage on the bus side of the main power source, and if during the passage of the short circuit current, the linear voltage on the tires is lower than the value at which the technological processes are disturbed for consumers powered by the main and the cut power sources, and after disconnecting the short circuit current there are no line voltages on the buses, they conclude that there was a short circuit on the buses of the main power source or a short circuit in the outgoing line, and its circuit breaker failed, in which case an ABP inhibit signal is issued .

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