RU2292105C1 - Method for reducing time delay at automatic load transfer in case of two-phase fault in one of backup line sections - Google Patents

Abstract

FIELD: power mains automation.

SUBSTANCE: proposed method for reducing time delay at automatic load transfer in case of two-phase fault in one of backup line sections includes monitoring of voltage across backup line as well as reverse-sequence voltage across the latter, location of one line-voltage failure at the same time noting reverse-sequence voltage across backup line, conclusion being made about phase failure in one of backup line sections, whereupon failure of all line voltages across backup lines is located, and reading of maximal time delay in automatic load transfer is started at the same time checking for repeated reverse-sequence voltage across backup line due to failure of automatic load transfer to respond to two-phase fault in one of sectionalizing circuit breakers installed in backup line, its occurrence is noted, and conclusion is made upon its disappearance, Provided there are no line voltages across backup line, that one of sectionalizing circuit breakers installed in backup line has opened as result of failure of automatic load transfer in response to two-phase fault in one of mentioned line sections; when this is the case, signal is supplied for operating mains automatic load transfer facility without waiting for termination of its maximal time delay reading.

EFFECT: enlarged field of application and functional capabilities due to use of proposed method.

1 cl, 2 dwg

Description

The invention relates to the automation of electrical networks and is intended to reduce the exposure time of the network automatic switch on reserve (ATS) during a two-phase short circuit in one of the sections of the reserved line.

There is a method of prohibiting ATS in case of asymmetric short circuits on a partitioned line with two-sided power supply, which consists in comparing the time between surges of the reverse sequence voltage with the time of a currentless pause of automatic restart (AR) of the sectioning switch [Auth. St. No. 412655, cl. H 02 J 9/06 from 08/26/1974].

The disadvantage of this method is the narrow scope of its application, since this method is applicable only to prohibit ATS in case of asymmetric short circuits on a partitioned line with two-way power supply and does not allow reducing the response time of a network ATS in case of a two-phase short circuit in one of the sections of the redundant line.

The objective of the invention is to expand the scope and functionality of the method by using it to reduce the exposure time of the network automatic switch on the reserve during a two-phase short circuit in one of the sections of the reserved line.

To solve this problem, in a known method, the time between surges of the negative sequence voltage is compared with the time of an uninterrupted pause of the automatic reclosure circuit-breaker, according to the invention, the line voltages in the redundant line are monitored, as well as the negative sequence voltages in it, the disappearance of one line voltage is recorded, at the same time, the appearance of the voltage of the negative sequence in the redundant line, conclude that on one of the sections of the redundant line short-circuit short circuit, then the disappearance of all line voltages in the redundant line is recorded, after which the maximum exposure time of the network ABP is started, at the same time, the reverse sequence voltage appears in the redundant line due to the unsuccessful reclosure for a two-phase short circuit of one of the sectional circuit breakers installed in the redundant line, record its appearance even after its disappearance, if all linear voltages in the torn line, conclude that as a result of an unsuccessful automatic reclosure on a two-phase short circuit that occurred in one of the sections of the redundant line, one of the sectionalizing circuit breakers installed in the redundant line tripped, and in this case they signal the operation of the network automatic transfer switch, without waiting for the countdown to end maximum exposure time of its operation.

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 21.

The circuit (see Fig. 1) contains: a sectioning switch Q1 in the redundant line, a sectioning switch Q2 in the redundant line, a sectioning switch Q3 in the redundant line, a circuit breaker ABP Q4, a voltage sensor DN 5, a voltage presence sensor DNN 6, an element NOT 7 , element Delay 8, element Memory 9, element OR 10, element Delay 11, negative sequence voltage filter FNOP 12, negative sequence voltage sensor DNOP 13, pulse shaper FI 14, element Memory 15, element I 16, element Memory 17, element And 18, element Memory 19, line voltage sensor DLN 20 short circuit point 21, short circuit point 22.

With a short circuit (short circuit) at point 21 (see FIG. 1), the signal diagrams at the outputs of the elements shown in FIG. 2 have the form: 23 — at the output of element 6; 24 - at the output of element 20; 25 - at the output of element 7; 26 - at the output of element 8; 27 - at the output of element 9; 28 - at the output of element 10 when operating with a maximum time delay of the network ABP; 29 - at the output of element 11 when working with the maximum time delay of the network ABP; 30 - at the output of element 19 during operation with a maximum time delay of the network ABP; 31 - at the output of element 12; 32 - at the output of element 13; 33 - at the output of element 14; 34 - at the output of element 15; 35 - at the output of element 16; 36 - at the output of element 17; 37 - at the output of element 18; 38 - at the output of element 10 when working with a reduced time delay network ABP; 39 - at the output of element 11 when working with a reduced time delay network ABP; 40 - at the output of element 19 when working with a reduced time delay network ABP.

The scheme works as follows.

In normal operation, on the redundant line there are all line voltages and there is no negative sequence voltage, therefore there are no signals at the outputs of elements NOT 7, FNOP 12; at the output of the element DLN 20 there is a signal that is sent to reset the elements Memory 9, Memory 15, Memory 17 and Memory 19. The circuit does not start.

The operation of the ATS with maximum time delay when the voltage on the redundant line disappears is ensured as follows.

At the time of the appearance of the two-phase short circuit at point 21 or 22, one of the linear voltages disappears, which leads to the disappearance of the signal from the output of the DL element 20 (Fig. 2, diagram 24). Thus, the reset signal disappears from the elements Memory 9, Memory 15, Memory 17 and Memory 19. Since at this moment two other line voltages are present, there is a signal in the redundant line at the output of the element 6 (figure 2, diagram 23). After disconnecting short circuit sectioning switch Q2 (figure 1) in the case of short circuit at point 21 (figure 1) or switch Q1 in the case of short circuit at point 22 (Fig. 1), the signal from the output of the element ДНН 6 disappears (Fig. 2, diagram 23), a signal appears at the output of the element NOT 7 (Fig. 2, diagram 25) and is fed to the input of the element Delay 8, the output of which the signal appears after a time equal to the maximum delay time of the network ABP (Fig. 2, diagram 26). This time takes into account the longest uninterrupted pause time of the automatic reclosure of sectioning switches installed in the redundant line (in this case, the uninterrupted pause time of the automatic reclosure switch Q3). The signal from the output of the element Delay 8 is fed to the input of the element Memory 9, at its output there is a signal received at the input of the element OR 10 (figure 2, diagram 27). The signal from the OR element 10 is fed to the input of the Delay 11 element, which provides the time delay necessary for switching off the Q3 circuit breaker by the fission automatics (Fig. 1). From the Delay 11 element, a signal is fed to the input of the Memory 19 element (Fig. 2, diagram 29), a signal appears on the output of this element, which turns on the network ABP (Fig. 2, diagram 30). If during the time specified in the Delay 8 element a successful automatic reclosure of one of the circuit breakers (Q2 or Q1) occurs, then all the line voltages in the redundant line will be restored, respectively, a signal will appear from the output of the DLN 20 element, which will be sent to reset the Memory 9 and Memory 19. Thus, the inputs of the OR elements 10 and, accordingly, the Delay 11 and the signal will not be given, as a result of which the ATS will not happen.

Reducing the response time of the network ABP using the circuit (figure 1) is as follows.

With a two-phase short circuit at point 21 or point 22 (FIG. 1), at the moment of its appearance, one of the linear voltages disappears, which leads to the disappearance of the signal from the output of the DL element 20 (FIG. 2, diagram 24). Thus, the reset signal disappears from the elements Memory 9, Memory 15, Memory 17 and Memory 19. At the same time, the voltage of the negative sequence appears in the reserved line, therefore, the signal appears at the output of the FNOP 12 (Fig. 2, diagram 31), which leads to the triggering of the element DNOP 13, the output of which the signal is fed to the inputs of the elements FI 14, And 16 (figure 2, diagram 32). The FI element 14 generates a signal when the signal disappears at its input, that is, at the output of the FI element 14, the signal (Fig. 2, diagram 33) appears at the moment the signal disappears from the output of the DNOP element 13 (Fig. 2, diagram 32). This occurs when one of the sectioning switches Q2 or Q1 trips due to short circuit. at point 21 or 22, respectively. The signal from the output of the element FI 14 is stored by the element Memory 15, the output of which the signal is fed to one of the inputs of the element And 16 (figure 2, chart 34). At the second input of the And 16 element at this time, there is no signal, since there is no signal from the output of the DNOP 13 element (Fig. 2, diagram 32). After a certain time of a current-free pause, the automatic reclosure of one of the sectioning switches Q2 or Q1 occurs (with a short circuit at point 21 or 22, respectively), as a result of which, if a two-phase short circuit is stable, the negative sequence voltage appears again in the redundant line (automatic reclosure is unsuccessful). There are signals at the outputs of the elements FNOP 12 and DNOP 13 (figure 2, diagram 31, diagram 32, respectively). The signal from the output of DNOP 13 is fed to the second input of the element And 16 (figure 2, diagram 32), at the first input of which at this time there is a signal from the element Memory 15 (figure 2, diagram 34). At the output of element And 16, a signal appears (figure 2, diagram 35), is stored by the element Memory 17 (figure 2, diagram 36) and is fed to one of the inputs of element And 18, at the second input of which the signal appears from element NOT 7 when it disappears voltage in the redundant line after disconnecting one of the sectioning switches Q2 or Q1 (with short circuit at point 21 or 22, respectively) (Fig. 2, diagram 25).

At the output of AND element 18, a signal appears (Fig. 2, diagram 37), which is fed to the input of OR 10 element. This signal arrives at one of the inputs of OR element 10 before its second input receives a signal from Memory element 9 (operating in circuit of the maximum delay time of the operation of the network ABP), since the time of an uninterrupted pause of the automatic reclosure of the sectioning switches Q2 and Q1 is less than the uninterrupted pause of the automatic reclosure of the switch Q3. From the output of the OR element 10, the signal is fed to the input of the Delay 11 element (Fig. 2, diagram 38), from the output of which the signal is supplied after a time sufficient for the Q3 circuit breaker to turn off the circuit breaker (Fig. 1). From the Delay 11 element, a signal is supplied to the input of the Memory 19 element (Fig. 2, diagram 39), a signal appears on the output of this element, which turns on the network ABP (Fig. 2, diagram 40). In this case, the network ABP is turned on earlier than during the operation of the circuit with the maximum delay of its operation, as follows from a comparison of diagrams 30 and 40 (Fig. 2) for the time Δt (Fig. 2).

If a two-phase short circuit at point 21 or point 22 it will be unstable and self-eliminating during a dead time pause of switch Q2 or Q1, respectively, in this case, automatic reclosure of one of the indicated sectionalizing switches will occur. In this case, all linear voltages in the redundant line will be restored, accordingly, a signal from the output element of the DLN 20 will appear, which will be sent to the reset of the elements Memory 9, Memory 15, Memory 17 and Memory 19. Thus, the inputs of the elements OR 10 and, accordingly, Delay 11 will not be signaled, as a result of which the ATS will not turn on.

Thus, there is a decrease in the response time of the network ABP during a two-phase short circuit in one of the sections of the redundant line. This extends the scope and functionality of the method, which increases the efficiency of power supply to consumers by reducing the time of interruptions in their supply of electrical energy.

Claims (1)

A method of reducing the response time of the network automatic transfer switch (ATS) during a two-phase short circuit in one of the sections of the redundant line, which consists in monitoring the negative sequence voltage in the redundant line, characterized in that the linear voltage in the redundant line is monitored, as well as the voltage of the negative sequence it, they fix the disappearance of one line voltage, at the same moment they fix the appearance of the voltage of the negative sequence in the redundant of the first line, conclude that a two-phase short circuit occurred on one of the sections of the redundant line, then the disappearance of all line voltages in the redundant line is recorded, after which the maximum delay time of the network ABP is started, at the same time, the repeated occurrence of the negative sequence voltage in redundant line due to unsuccessful automatic reclosing (AR) on a two-phase short circuit of one of the sectionalizing switches installed in a redundant line, record its appearance and after its disappearance, if all the line voltages in the redundant line are absent, conclude that as a result of an unsuccessful automatic reclosure on a two-phase short circuit that occurred in one of the sections of the redundant line, one of the sectional switches installed in the redundant lines, and in this case they signal the operation of the network ABP, without waiting for the end of the countdown of the maximum exposure time of its operation.

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