RU2378754C1 - Method of controlling spurious tripping of sectionalising circuit breaker in ring network line - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: invention relates to automation of electrical networks. In the method the time at the onset of the first current surge (short circuit) on transformer busbars of the main power supply, equal to time lag for switching the network station automatic transfer switch (ATS), is recorded. At its end, onset of a second current surge on back-up power source buses is monitored and if it is greater than the normal operating current, but less than the short circuit current, then successful switching of the automatic transfer switch is indicated at the moment of detecting fall of operating current at the beginning of the main power supply line to a value determined by the line load connected after the sectionalising circuit breaker, and if there is no short circuit current surge, time reading is started, equal to delay time for switching the network station automatic transfer switch. At the end of reading this time, onset of current surge at the beginning of the back-up power supply is monitored and if there is current surge with value determined by the disconnected line load of the main power supply, then spurious tripping of the sectionalising circuit breaker in the ring network line is indicated. ^ EFFECT: wider functional capabilities of the method due to obtaining information on spurious tripping of the sectionalising circuit breaker in a ring network line, powered through different substation transformer busbars. ^ 2 dwg

Description

The invention relates to the automation of electrical networks and is intended to control the false shutdown of the sectioning switch in the line of the ring network, powered by different buses of a two-transformer substation.

There is a method of monitoring the successful inclusion of the automatic transfer switch (ATS) point in a ring network powered by two-transformer substation buses, which consists in fixing two inrush currents and counting the time between them. The time is counted from the moment of the appearance of the first inrush current of the short circuit (short circuit) on the buses of the transformer of the main power supply, equal to the time delay for switching on the power point of the ATS, at the end of its countdown, the appearance of the second inrush on the buses of the backup power supply is controlled and, if more than the normal operating current, but less short-circuit current, then establish the fact of the successful inclusion of the item ABP [RF patent No. 2214667, cl. H02J 13/00].

The disadvantage of this method is the impossibility of using it to control the false tripping of the sectioning switch in the line of the ring network.

The objective of the invention is to expand the functionality of the method by obtaining information about the false disconnection of the sectioning switch in the line of the ring network, powered from different buses of a two-transformer substation.

According to the proposed method, at the time of fixing the drop in the operating current at the beginning of the main power supply line to a value determined by the load of the line connected after the sectioning switch and the absence of inrush current start the countdown of the time equal to the holding time of the on-off switch of the ATS item. At the end of the countdown of this time, the appearance of a current surge at the beginning of the backup power supply line is controlled and, if a current surge occurs with a value determined by the disconnected load of the main power supply line, then the fact of a false disconnection of the sectioning switch in the ring network line is established.

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 false shutdown of the sectioning switch in the line of the ring network (see figure 1);

The circuit (see Fig. 1) contains: a controlled sectioning switch 1, a current transformer (TT) 2, a short-circuit current sensor (DTKZ) 3, an operating current sensor (DRT) 4; element NOT 5, element NOT 6; element BAN 7; element And 8; MEMORY element 9; element DELAY 10, element REPEATER 11, element MEMORY 12, TT 13; SINGLE-VIBRATOR 14, element I 15, recording device (RU) 16, power transformer of the main power supply 17, power transformer of the backup power supply 18, substation sectional switch 19, head switch of the first line of the ring network 20, head switch of the second line of the ring network 21, sectional switch of the second line of the ring network 22, switch point ABP 23, consumer 24.

The signal diagrams at the outputs of the elements shown in Fig. 1 when the sectionalizing circuit breaker is false disconnected in the ring network line (see Fig. 1) have the form (see Fig. 2): 25 - at the output of element 2; 26 - at the output of element 3; 27 - at the output of element 4; 28 - at the output of element 5; 29 - at the output of element 6; 30 - at the output of element 7; 31 - at the output of element 8; 32 - at the output of element 9; 33 - at the output of element 10; 34 - at the output of element 11; 35 - at the output of element 12; 36 - at the output of element 13; 37 - at the output of element 14; 38 - at the output of element 15; 39 - the availability of information in element 16.

The method is as follows. In normal mode, the controlled sectionalizing switch 1 is turned on and the consumers 24 are powered from the buses of the power transformer of the main power source 17 (see figure 1). At the output of TT 2 and TT 13 there is some value of the output signal (figure 2, diagram 25 and diagram 36), due to operating currents, but insufficient for tripping of DTKZ 3, DRT 4 and SINGLE-VIBRATOR 14. The presence of the output signal from the element HE 5 to the element MEMORY 12, and from the element NOT 6, arriving at the first input of the element of the circuit And 8, do not lead to their operation. The circuit does not start.

With a false shutdown of the sectioning switch 1 at the beginning of the line there will be a drop in the operating current (figure 2, time t ₁ ). At the output of TT 2 (Fig. 2, diagram 25), the output signal will decrease by a value determined by the load of the line connected after the sectioning switch 1, which is fed to the input DTKZ 3 and DRT 4. The value of the output signal of the TT 2 will be insufficient for tripping DTKZ 3 therefore, a signal does not appear at its output (Fig. 2, diagram 26), which would be input to the element NOT 6 (see Fig. 1). From the output of the element NOT 6, the signal does not disappear (figure 2, diagram 29). At the output of the DRT 4, which is triggered when the worker falls, to a value determined by the load of the line connected after the sectioning switch, a signal will appear (figure 2, diagram 27), which will be input to the element BAN 7 and the element NOT 5. From the output of the element NOT 5 the signal will disappear (figure 2, chart 28). At the output of the element FORBID 7, a signal will appear (figure 2, diagram 30) and will go to the second input of the element And 8. The simultaneous presence of two input signals at the input of the element And 8 will lead to the appearance of its output signal (figure 2, diagram 31), which will go to the input of the MEMORY 9. This signal will be remembered by the MEMORY 9 element (Fig. 2, diagram 32) and will be fed to the input of the DELAY 10 element. From the output of element 14, the signal will appear after a time equal to the holding time of the on / off switch of the ABP item (see Fig. 2, the time interval t ₁ -t ₂ ). After counting the delay time for turning on the switch of the ABP item, the signal from the output of element 10 (Fig. 2, diagram 33) will be input to the REPEATER element 11. Element 11 will give a single pulse (Fig. 2, diagram 32), which will be input to the element MEMORY 12, to the input of AND element 15 and "RESET" the element MEMORY 9. This signal will be remembered by the element MEMORY 12, from the output of which the signal (Fig. 2, diagram 35) will go to the inhibitory input of the element BAN 7. At the output of the element BAN 7, the signal will disappear (Fig. 2, diagram 30), arriving at the second input of the element And 8. At the same time the output of the element And 8 the signal will also disappear (figure 2, diagram 31). If at the same moment the switch of the ABP 23 switch is turned on, then the output of the TT 13 will have a signal (Fig. 2, diagram 36), increased by a value determined by the load of consumers 24. The magnitude of this signal is sufficient for operation of the SINGLE-VIBRATOR 14. The output signal from the SINGLE-VIBRATOR will go to the second input of AND element 15. The presence of two input signals to And 15 will lead to the appearance of a signal at its output (figure 2, diagram 38). The output signal from And 15, having entered the RU 16, will provide information in it about the false shutdown of the sectioning switch.

When restoring normal operation (Fig.2, time t ₃ ), the controlled sectionalizing switch 1 will turn on and consumers 24 will be powered by the buses of the power transformer of the main power source 17 (see Fig. 1). At the output of TT 2 and TT 13 there will be a certain value of the output signal (Fig. 2, diagram 25 and diagram 36), due to operating currents, but insufficient for tripping of DTKZ 3 and SINGLE-VIBRATOR 14. At the output of DRT 4, which is triggered when the worker drops to a value, determined by the load of the line connected after the sectioning switch, the signal will disappear (figure 2, diagram 27), which was input to the element BAN 7 and element NOT 5. The output NOT 5 will display a signal (figure 2, diagram 28), which "will reset "MEMORY element 12. The circuit will return to its original state control.

Thus, the method allows to obtain timely information about the false shutdown of the sectioning switch in the line of the ring network, powered by the 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 monitoring a false shutdown of a sectionalizing circuit breaker in a ring network line powered by different buses of a two-transformer substation, which consists in fixing the inrush currents and in measuring the time between them, characterized in that at the moment of fixing the drop in the operating current at the beginning of the main power supply line to a value determined the load of the line connected after the sectioning switch and the absence of an inrush current of the short circuit start to count down the time equal to the switch-on delay time automatic transfer switch, and in the end of the countdown emergence control inrush current at the start line and the backup power source if there is cast a current value determined by the load off the main power source line, the set of false fact partitioned off switch in the ring network line.

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