RU2421861C1 - Method for prohibiting automatic load transfer to two-phase short circuit at failure of separating automation of sectionalising circuit breaker - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: according to the above method the time between losses and occurrences of linear voltages is compared to reclosing dead time of sectionalising circuit breaker. According to invention, when the first short circuit current surge appears in line of the main power source, the time equal to actuation time of protection of the main circuit breaker of this line is read, and if short circuit current disappears at the moment when reading of this time is stopped, then fact of deactivation of the main circuit breaker is established; reading of time equal to waiting time of automatic reclosing (AR) of deactivated circuit breaker is started when the first short circuit current surge is interrupted, and when reading of this time is stopped, occurrence of the second short circuit current surge and occurrence of voltage on one of phases of ALT is controlled, and if short circuit current and voltage appears at the specified moment of time on one of ALT phases, then fact of separating automation failure of sectionalising circuit breaker is established, and ALT prohibition is introduced. ^ EFFECT: enlarging functional capabilities of the method by ALT prohibition introduction at stable two-phase short circuit in the main power source line, which occurred in the line section which is not adjacent to ALT and at failure of separating automation of sectionalising circuit breaker of this line. ^ 2 dwg

Description

The invention relates to the automation of electrical networks and is intended to prohibit the automatic inclusion of a reserve (ATS) for a two-phase short circuit (short circuit) in the event of a failure of dividing automatics (YES) of the sectioning switch in the ring network line.

There is a method of prohibiting network ATS on two-phase short circuits, which consists in comparing the time between disappearances and occurrences of line voltages with the time of a dead time pause for the automatic restart of the sectioning switch. For this purpose, the presence of all three linear voltages is monitored, the disappearance of one of them is recorded, and when the other two disappear, a countdown is started, which is set equal to a dead time pause for the automatic restarting of the sectioning switch and, if the occurrence of these two voltages is detected at the end of the countdown, they give a signal to ban ABP [RF patent No. 2181920, Cl. 7 H02J 9/06, 04/27/2002 Bull. No. 12].

The disadvantage of this method is the impossibility of using it to prohibit ATS with a stable two-phase short-circuit fault that did not occur on an adjacent section of the line with the ATS point, but on a section of the line located behind the adjacent section of the line with respect to the ATS point in the main source line power failure YES sectioning line circuit breaker.

The objective of the invention is to expand the functionality of the method by introducing a ban on the automatic transfer switch with a stable two-phase short circuit in the line of the main power source that occurred on a section of the line that is not adjacent to the ABP point, and the failure of dividing automation of the sectioning switch of this line.

According to the proposed method from the moment of the appearance of the first inrush short circuit the time equal to the response time of the protection of the head switch of this line is counted in the line of the main power source. If at the end of the countdown of this time the short-circuit current disappears, then establish the fact of disconnecting the head switch. From the moment of disconnection of the first inrush short circuit start the countdown of time equal to the exposure time of the reclosure of the circuit breaker. At the end of the countdown of this time, the appearance of a second short-circuit current fault is controlled. and the appearance of voltage on one of the phases of the ABP point, and if at the indicated moment in time a short-circuit current appears and the voltage at one of the phases of the ATS point, then establish the failure of the YES sectioning switch and prohibit the ATS.

The essence of the invention is illustrated by drawings, where:

figure 1 presents a structural diagram containing elements for implementing the method;

figure 2 is a diagram of the signals at the outputs of the elements shown in figure 1, when short at point 23 (see figure 1).

The circuit (see Fig. 1) contains a power transformer for main power 1, a power transformer for backup power 2, an input switch for the main power supply 3, an input switch for the backup power supply 4, a substation section switch 5, a head switch for the main power supply 6, a head switch for the backup a power source 7, a sectioning switch of the main power source 8, a sectioning switch of a backup power source 9, an ABP 10 switch, a current transformer (CT) 11, a current sensor briefly short circuit (DTKZ) 12, the element MEMORY 13, the element NOT 14, the element DELAY 15, the element AND 16, the element MEMORY 17, the element DELAY 18, the SINGLE VIBRATOR 19, the element I 20, the voltage sensor (DN) 21, the element I 22, the point short 23.

The signal diagram at the outputs of the elements shown in figure 1 with a short circuit at point 23 (see figure 1), have the form (see figure 2): 24 - at the output of element 11, 25 - at the output of element 12, 26 - at the output of element 13, 27 - at the output of element 14, 28 - at the output of element 15, 29 - at the output of element 16, 30 - at the output of element 17, 31 - at the output of element 18, 32 - at the output of element 19, 33 - at the output of element 20, 34 - at the output of element 21, 35 - at the output of element 22.

The method is as follows. In normal mode, at the beginning of a partitioned line, short-circuit current control is carried out. and voltage phases ABP. At the output of the TT 11 there is a certain value of the output signal due to the operating current (Fig. 2, diagram 26, time t ₁ ), but not sufficient for tripping of the DTKZ 12 (Fig. 2, diagram 27), and there is also an output signal ДН 21 (figure 2, diagram 34) the circuit is in control mode.

With a stable short circuit at point 23 (see FIG. 1), the value of the output signal TT 11 (FIG. 2, diagram 24) will be sufficient for triggering DTKZ 12 (FIG. 2, diagram 25, time t ₁ ), therefore, a signal will appear at its output, which will go to the input of elements NOT 14, from the output of which the signal will disappear (Fig. 2, diagram 27), and MEMORY 13, where it will be remembered, and will go to the input of the DELAY 15 element, from the output of which the signal will appear after a time equal to the exposure time of the automatic reclosure head switch 6. After this time, the signal from the element DELAY 15 will go to one of the two inputs of the element AND 16. At this point in time, with good automation and the correct action of the protection, switch 6 will turn off the short-circuit current. (figure 2, diagram 24), therefore, with DTKZ 12 the output signal will disappear. In this case, the output signal from the element HE 14 (figure 2, diagram 27, time t ₂ ) will appear, which will go to the second input of the element And 16.

The presence of two input signals at the input of the And 16 element will lead to the appearance of its output signal, which will go to the input of the MEMORY 17. The signal received from the And 16 element will be remembered by the MEMORY 17 element and will go to the input of the DELAY 18 element, from the output of which the signal will appear through time equal to the AR time of the head switch 6. After this time, the signal from the DELAY 18 element (Fig. 2, diagram 31, time t ₃ ) will be input to the SINGLE-SELECTOR 19, it will give a single pulse that will clear the memory from element 17 and eleme nta 13, and also will go to one of the inputs of the And 20 elements. At this point in time, with the correct and correct operation of automation equipment, the head switch 6 must be turned on for a stable short circuit, which will ensure the presence of an output signal from DTKZ 12, which will go to the second input of the And 20 element. The presence of all input signals will trigger the And 20 element and a signal will appear at its output that will go to one of the inputs of the And 22 element. Also, when the head switch 6 is turned on again, the voltage on the AB phases is monitored. P and if it appears at least on one of the phases with DN 21, a signal will arrive at the second input of the And 22. element. The presence of two signals And 20 and DN 21 will provide an output signal from the And element 22, introducing a ban on the ATS.

Thus, the proposed method excludes the inclusion of the ABP switch on a stable short circuit in case of failure of the YES of the sectioning switch, which increases the service life of the switch, reduces the cost of its repair and maintenance.

Claims (1)

A method of prohibiting automatic switching on of a reserve (ATS) to a two-phase short circuit (short circuit) in the event of a failure of dividing automatics (YES) of a sectioning switch, which consists in comparing the time between disappearances and occurrences of line voltages with a no-break pause for automatic restart (AR) of a sectioning switch, characterized in that since the appearance of the first inrush short-circuit the time equal to the response time of the protection of the head switch of this line and if the short-circuit current is counted in the line of the main power source if it disappears, then the fact of switching off the main switch is established, and from the moment of switching off the first inrush current short circuit, the countdown starts equal to the holding time of the automatic reclosure circuit breaker, and at the end of the countdown this time control the appearance of the second inrush current short circuit and the appearance of voltage on one of the phases of the ABP point, and if at the indicated moment in time a short-circuit current appears and voltage at one of the phases of the ATS point, then establish the fact of failure of the YES sectioning switch, and prohibit the ATS.

Images