RU2394331C1 - Method to control cut-off of line main circuit breaker at cut-off fault of sectionalising circuit breaker in its repeated cut-in at stable short circuit in circular circuit - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: after appearance of first short-circuit current surge at transformer buses, count down of time is started that is equal to that of sectionalising switch (SS) protection operation. Note that moment of short-circuit current surge cut-off is recorded and, if said moment complies with the moment of short-circuit current surge cut-off, then first, SS cut-off state is registered and, further, after moment of short-circuit current surge cut-off, total time equal to delay time of automatic repeated cut-in of given circuit breaker and time of operation of circuit breaker protection operation with acceleration, then second short-circuit current surge origination and time of its protection operation with acceleration is controlled. Then if after its origination, at the moment of termination of total time count down no cut-off of second short-circuit current surge cut-off occurs, then SS repeated cut-off failure is registered. If the moment of termination of the main switch protection operation complies with the moment of second short-circuit current surge cut-off, then line main switch is considered cut-off in its repeated cut-in at stable short-circuit condition in circular circuit.

EFFECT: expanded performances.

2 dwg

Description

The invention relates to the automation of electrical networks and is intended to control the shutdown of the line head switch in case of failure of the sectioning switch disconnection when it is again turned on for a stable short circuit (short circuit) in the ring network powered by the buses of a two-transformer substation. Moreover, a sectional switch is installed in the line, equipped with a single-acting automatic reclosing device (AR).

There is a method of controlling the tripping and unsuccessful reclosure of a sectionalizing circuit breaker in a ring network line powered by two-transformer substation buses, which consists in the fact that since the appearance of the first inrush current short circuit on the tires of the transformer supplying the line, a countdown starts, equal to the response time of the protection of the sectionalizing circuit breaker, and the moment of switching off the first inrush short-circuit current is monitored, and if the end time of the countdown coincides with the moment of disconnecting the first inrush short-circuit current, then first establish the fact of disconnecting the sectioning switch, and then from the moment of disconnection of the first inrush short-circuit start the countdown of the total time equal to the reclosure time of this switch and the response time of its protection with acceleration, while controlling the appearance of a second inrush current short circuit and, if after its appearance, at the end of the countdown of the total time, the second short-circuit current inrush trips, then after that the fact of the unsuccessful reclosure of the sectioning switch installed in the ring network line is established [RF Patent No. 2304338, cl. H02J 13/00, publ. 08/10/2007, bull. No. 22].

The disadvantage of this method is the impossibility of using it to control the tripping of the head circuit breaker in case of failure to disconnect the sectioning switch when it is turned on again at a stable short circuit in a ring network powered by buses of a two-transformer substation.

The objective of the invention is to expand the functionality of the method by obtaining information about the tripping of the head line circuit breaker in case of failure to disconnect the sectioning switch when it is turned on again at a stable short circuit in a ring network powered by buses of a two-transformer substation.

According to the proposed method from the moment of the appearance of the first inrush short circuit on the tires of the transformer supplying the line, a countdown starts, equal to the response time of the protection of the sectionalizing circuit breaker, and the moment of switching off the first inrush short-circuit current is monitored, and if the end time of the countdown coincides with the moment of disconnecting the first inrush short-circuit current, then first establish the fact of disconnecting the sectioning switch. From the moment of disconnection of the first inrush short circuit start the countdown of the total time equal to the AR time delay of this switch and the response time of its protection with acceleration, while controlling the appearance of a second inrush current short circuit Then, from the moment of the appearance of the second inrush current short circuit start the countdown of the response time of the protection of the head switch, and if after its appearance, at the end of the countdown of the total time, the second short-circuit current surge does not trip, then the fact of the failure of the repeated disconnection of the sectioning switch is turned off. And then, if the end time of the operation of the protection of the head switch coincides with the moment of disconnection of the second inrush current short circuit, then establish the fact of disconnecting the head circuit breaker in case of failure to disconnect the sectioning switch when it is turned on again at a stable short circuit in the ring network.

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 with a stable short circuit at point 30 (see figure 1).

The circuit (see Fig. 1) contains a controlled head circuit breaker of the ring network line 1; sectional switch of the first line of the ring network 2; power transformer 3; power transformer 4; substation sectional switch 5; the head switch of the second line of the ring network 6; sectional switch of the second line of the ring network 7; switch of the point of automatic inclusion of reserve 8; MEMORY element 9; item NOT 10; element BAN 11; element BAN 12; current transformer (TT) 14; short circuit current sensor (DTKZ) 13; MEMORY element 15; DELAY element 16; REPEATER element 17; MEMORY element 18; DELAY 19 element; REPEATER element 20; element NOT 21; element And 22; MEMORY element 23; DELAY 24 element; REPEATER element 25; element And 26; MEMORY element 27; element And 28; recording device (RU) 29; point of sustainable short-circuit thirty.

Diagrams of the signals at the outputs of the elements shown in figure 1 with a stable short circuit at point 30 (see figure 1), have the form (see figure 2): 31 - at the output of element 9; 32 - at the output of element 10; 33 - at the output of element 11; 34 - at the output of element 12; 35 - at the output of element 13; 36 - at the output of element 14; 37 - at the output of element 15; 38 - at the output of element 16; 39 - at the output of element 17; 40 - at the output of element 18; 41 - at the output of element 19; 42 - at the output of element 20; 43 - at the output of element 21; 44 - at the output of element 22; 45 - at the output of element 23; 46 - at the output of element 24; 47 - at the output of element 25; 48 - at the output of element 26; 49 - at the output of element 27; 50 - at the output of element 28; 51 - the availability of information in element 29; t _{sec sec} - response time of the protection of the sectioning switch 2; t _s.z. - response time of the protection of the head switch 1; t _{ARV sec.} - time delay reclosure sectioning switch 2; t _{sec sec} - response time of the protection of the sectioning switch 2 with acceleration.

The method is as follows. In normal mode, the monitored head switch 1 and the partition switch 2 are turned on (FIG. 2, time t ₀ ). From the output of the element NOT 10, the signal goes to the inhibitory input of the element FORBID 11. At the output of the TT 14 there is a certain value of the output signal (figure 2, diagram 36), due to the operating current, but insufficient for the operation of the DTKZ 13, so the presence of the output signal from the element is NOT 21 at one of the inputs of the elements of the circuit And 22 and And 28 is not enough for their operation. The circuit does not start.

When short at point 30 (see Fig. 1), the value of the output signal TT 14 (Fig. 2, diagram 36, time t ₁ ) will be sufficient for triggering DTKZ 13, so a signal appears at its output (Fig. 2, diagram 35), which will go to the inputs of the elements BAN 11, BAN 12, NOT 21 and AND 26 (see figure 1). At the output of the element BAN 12 (figure 2, chart 34), a signal will appear and will go to the input of the element MEMORY 15. From the output of the element NOT 21, the signal will disappear (figure 2, chart 43). At the output of the element BAN 11, the signal does not appear (figure 2, diagram 33), because from the element NOT 10, the signal enters its inhibitory input. The presence of a signal with DTKZ 13 at one of the inputs of the elements of the circuit And 26 is not enough for its operation (figure 2, chart 48). The signal from the element PROHIBIT 12 is stored by the element MEMORY 15 (Fig. 2, diagram 37) and is fed to the input of the element DELAY 16, from the output of which the signal appears after a time equal to the response time of the protection of the sectioning switch 2 (Fig. 2, diagram 38, time t ₂ ). From the output of element 16, the signal will go to the input of the REPEATER element 17, this element will give a single pulse (figure 2, diagram 39), which will go to the input of the elements MEMORY 9, AND 22 and "reset" the element MEMORY 15. This signal will be remembered by the element MEMORY 9 and from its output there will be a signal (figure 2, diagram 31) to the input of the element NOT 10 and the inhibitory input of the element BAN 12. From the output of the element NOT 10 the signal (figure 2, diagram 32) arriving at the inhibitory input of the element BLOCK 11 will disappear. If at the same moment, under the influence of the maximum current protection, the sectional off yuchatel 2 (see FIG. 1) will disable the short-circuit current, then DTKZ output signal 13 disappears (see FIG. 2, diagram 35). In this case, the output signal from the element HE 21 (figure 2, diagram 43) will appear, which will go to the inputs of the elements And 22 and And 28. The presence of two input signals at the input of the element And 22 leads to the appearance of its output signal (figure 2, chart 44), which will go to the input of the element MEMORY 23 and in RU 29 (see figure 1). At the same time, information will appear in RU 29 that a sectioning switch 2 has been disconnected in the ring network line. The signal from the And 22 element is stored by the MEMORY 23 element (Fig. 2, diagram 45) and is fed to the input of the DELAY 24 element, from the output of which the signal appears after the total time equal to the time delay of the automatic reclosure of the sectioning switch and the response time of its protection with acceleration (Fig. 2, diagram 46, point in time 14).

After the time delay of the automatic reclosure of the sectioning switch 2 (see figure 1), it will turn on, and it will turn on at a stable short circuit at point 30 (see figure 1). Because the magnitude of the output signal TT 14 (figure 2, diagram 23) will be sufficient for triggering DTKZ 13, then the signal again appears on its output (figure 2, diagram 35, time t ₃ ), which will go to the inputs of the elements BAN 11 , FORBIDDEN 12, NOT 21 and AND 26 (see figure 1). At the output of the element BAN 11 (figure 2, diagram 33), a signal will appear that will be input to the element MEMORY 18. The signal from the element BAN 11 is remembered by the element MEMORY 18 (figure 2, diagram 40) and received at the input of the element DELAY 19, s the output of which the signal appears after a time equal to the response time of the protection of the head switch 1 (Fig. 2, diagram 41, time t ₅ ). From the output of the element NOT 21, the signal will disappear (figure 2, diagram 43). At the output of the element BAN 12, the signal does not appear (figure 2, diagram 34, time t ₃ ), because from the element MEMORY 9, the signal enters its prohibitory input. The presence of a signal with DTKZ 13 at one of the inputs of the elements of the circuit And 26 is not enough for its operation (figure 2, chart 48). But if after the automatic reclosure of the sectioning switch 2 to a stable short circuit if it does not turn off with acceleration for any reason, then at this point in time the signal from the DELAY 24 element after counting the total time (see above) will go to the input of the REPEATER 25 element, this element will give a single pulse (figure 2, diagram 47 ), which will "reset" the element MEMORY 23 (figure 2, diagram 45) and will go to the second input of the element And 26 (see figure 1). The presence of two input signals at the input of element And 26 will lead to the appearance of its output signal (figure 2, chart 48, time t ₄ ), which will be received in RU 29 (see figure 1) and to the input of the element MEMORY 27. IN RU 29 information will appear that a failure has occurred in tripping of the sectioning switch when it is turned on again (FIG. 2, diagram 51). The signal from the And 26 element is remembered by the MEMORY 27 element (Fig. 2 diagram 49) and is input to the And 28 element. After the countdown of the protection time of the controlled head switch 1 from the output of the DELAY 19 element (Fig. 2, diagram 41, time t ₅ ) a signal will appear that will go to the input of AND element 28, which will “reset” the MEMORY element 18. If at the same moment, under the influence of overcurrent protection, the monitored head switch 1 (see Fig. 1) disconnects the short-circuit current, then DTKZ 13 the output signal will disappear (see figure 2 diagram 35). In this case, the output signal from the element HE 21 (Fig. 2, diagram 43) will appear, which will go to the inputs of the elements AND 22 and I 28. The presence of three input signals at the input of the element AND 28, from the elements MEMORY 27, REPEATER 20 and NOT 21 leads to the appearance of its output signal (Fig. 2 diagram 50), which will go to RU 29 and "reset" the MEMORY 27 and MEMORY 9. elements. In this case, information will appear in RU 29 that the head switch of line 1 has been disconnected if the sectioning switch failed circuit breaker 2 when it is turned on again at a stable short circuit in the ring network. The circuit will return to the initial state of control.

Thus, the method allows you to receive timely information about the trip of the head circuit breaker in case of failure to disconnect the sectioning switch when it is turned on again at a stable short circuit in a ring network powered by buses of a two-transformer substation. This will lead to an increase in the reliability of power supply to consumers through the adoption of necessary decisions based on the information received by operational personnel.

Claims (1)

A method for controlling the disconnection of the line head switch in case of failure of the sectioning switch shutdown when it is again turned on for a stable short circuit (short circuit) in the ring network powered by the buses of the two-transformer substation, which consists in the fact that since the first inrush current the short circuit on the tires of the transformer supplying the line, a countdown starts, equal to the response time of the protection of the sectionalizing circuit breaker, and the moment of switching off the first inrush short-circuit current is monitored, and if the end time of the countdown coincides with the moment of disconnecting the first inrush short-circuit current, then first establish the fact of disconnecting the sectioning switch, and then from the moment of disconnection of the first inrush short-circuit start the countdown of the total time equal to the time delay for the automatic restart of this switch and the response time of its protection with acceleration, while controlling the appearance of a second inrush current short circuit, characterized in that from the moment the second inrush current short-circuit start counting the response time of the protection of the head switch and if, after its occurrence, at the end of the countdown of the total time, the second short-circuit current fault does not trip, then the fact of the failure of the repeated disconnection of the sectioning switch is established, and if the end time of the response of the protection of the head switch coincides with the moment of disconnection of the second short-circuit inrush current, then the fact of disconnecting the line head switch in case of failure to disconnect the sectioning switch when it is repeated th switched on sustainable sc in the ring network.

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