RU2214666C2 - Method for checking inhibition of automatic load transfer center closure to short circuit in rung mains - Google Patents

Abstract

FIELD: automatic control of power networks. SUBSTANCE: method intended to check automatic load transfer center incorporating device inhibiting closure to short circuit in ring mains supplied with power from double-transformer substation buses by receiving information about inhibiting closure of automatic load transfer center includes recording of inrush currents and measurement of time intervals between them; initial time reading is taken at instant of occurrence of short-circuit inrush current at transformer buses of main power supply equal to on-time delay of circuit breaker in automatic load transfer center; instant of its final reading is checked by occurrence of working inrush current exceeding rated value or short-circuit current at transformer buses of stand-by power supply, or, if the latter is not available, fact of inhibiting circuit breaker closure at automatic load transfer center to short circuit in ring mains is stated. EFFECT: enlarged functional capabilities. 1 cl, 2 dwg

Description

 The invention relates to the automation of electrical networks and is intended to control the prohibition of the circuit breaker of the automatic transfer switch (ATS), equipped with a device for prohibiting the inclusion of a short circuit in a ring network, powered by different buses of a two-transformer substation.

A known method of obtaining information about the result of the automatic restart of the sectioning apparatus, which consists in fixing the inrush current of the short circuit, measuring the time after it disappears before the appearance of the second inrush current and monitoring the on position of the switch at the beginning of the line after the disappearance of the first inrush current of the short circuit, with subsequent measurement of second inrush current, and if it is greater than the normal operating current, but less than the short circuit current, a successful automatic reclosing, if it is equal to or greater than the short circuit current - unsuccessful. [1]
The disadvantage of this method is the impossibility of using it to control the operation of the ABP point in the ring network.

 The objective of the invention is to expand the functionality of the method by obtaining information about the prohibition of the inclusion of the item ABP in the ring network, powered by buses of a two-transformer substation. At the same time, the ATS item is equipped with a device for prohibiting its inclusion in a short circuit.

 According to the proposed method, the appearance of an inrush caused by a short circuit in the line powered by this transformer is detected on the tires of the transformer of the main power source. When the appearance of an inrush short-circuit current begins to count down the time equal to the time delay point ABP. At the end of the countdown, the inrush current is monitored (the current can increase to a value more than a normal working one, but less than a short circuit current or to a short circuit current) on the buses of the second (backup) transformer. If at the end of the countdown there is no inrush on the tires of the backup source, this indicates that there was a ban on the inclusion of the ABP item.

The essence of the invention is illustrated using the drawings, where:
figure 1 shows 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 short circuit at point 21 (see figure 1).

 The circuit (see Fig. 1) contains: ABP switch 1, current transformer 2, short-circuit current sensor 3, element MEMORY 4, element DELAY 5, one-shot 6, element I 7, recording device (RU) 8, current transformer 9, short-circuit current sensor 10, single-shot 11, element OR 12, element NOT 13 head switch of the main power supply line 14, sectionalizer of the line 15, head switch of the backup power supply line 16, sectionalizer of the line 17 switch, main power supply transformer 18, transformer with lovoy backup power supply 19, the substation sectionalizing switch 20, the short-circuit point 21, 22 and 23 users.

 The signal diagrams at the outputs of the elements shown in figure 1 with a short circuit at point 21 (see figure 1) have the form (see figure 2): 24 - at the output of element 2; 25 - at the output of element 3; 26 - at the output of element 4; 27 - at the output of element 5; 28 - at the output of element 6; 29 - at the output of element 9; 30 - at the output of element 10; 31 - at the output of element 11; 32 - at the output of element 12; 33 - at the output of element 13; 34 - at the output of element 7; 35 - the availability of information in element 8.

 In normal mode, the switch point ABP 1 is turned off and the consumers 22 and 23 are fed through the head switch 14 and the sectioning switch 15 from the main power transformer 18. At the outputs of the current transformers 2 and 9 there is some value of the output signals (figure 2, diagrams 24, 29) due to operating currents, but insufficient for the operation of the short-circuit current sensors 3 and 10, and the single-element element 11, so there are no signals at the inputs of the remaining circuit elements and the circuit does not start.

 In case of a short circuit at point 21 (see Fig. 1), the output signal of current transformer 2 is sufficient to trigger the short-circuit current sensor 3 (Fig. 2, diagram 24), at the output of which a signal appears (Fig. 2, diagram 25). This signal is stored by the element MEMORY 4 (figure 2, diagram 26) and is fed to the input of the element DELAY 5, from the output of which the signal will appear after a time equal to the delay time of the on-off switch ABP (figure 2 diagram 27). The signal from element 5 will go to the input of a single-shot 6, this element will give a single pulse (Fig. 2 diagram 28), which will “reset” the element MEMORY 4 and will go to one of the inputs of element And 7. If a short circuit occurs in the section adjacent to the ABP point, then the ATS inhibit device will give a signal to prohibit operation of the item. Therefore, the switch of the ATS item will not turn on. So, the signal does not change at the output of current transformer 9 (Fig. 2, diagram 29), there will be no surges of the operating current more than normal and short circuit current. Therefore, there are no signals at the outputs of the elements of the one-shot 11 and the short-circuit current sensor 10 (figure 2 diagram 31, 30). Accordingly, there is no signal at the inputs of the OR element 12 and at its output (Fig. 2 diagram 32). At the output of the element NOT 13 there is a signal (Fig. 2 diagram 33), which is fed to the second input of the element And 7. Therefore, a signal appears at its output (Fig. 2 diagram 34). This signal includes the RU 8 recording device. The RU 8 recording device contains information (Fig. 2 diagram 35) on the prohibition of turning on the ABP item for a short circuit in a ring network powered by different buses of a two-transformer substation.

 If, however, a short circuit occurs in another area, or for some reason the prohibition device does not work, then, accordingly, the ATS prohibition will not be issued. This means that the switch of the ABP 1 item will turn on, at the output of the current transformer 9 there will be a signal sufficient to trigger the short-circuit current sensor 10, or the one-shot element 11. At the same time, the one-shot element 11 will work if there is a surge of operating current more than normal. The signal from them will go to the input of the OR element 12, which means that the signal from the output of the HE 13 element will disappear. There will be no signal at the second input of the AND 7 element. Therefore, information will not be received in the RU 8 recording device.

 If you prohibit the inclusion of the item ABP information about this on the basis of the proposed method will go to the maintenance staff.

 Thus, the proposed method allows to provide timely information about the prohibition of turning on the switch of the network ABP item. This will undoubtedly lead to an increase in the reliability of power supply to consumers through the adoption, on the basis of the information received, by the operational staff of the necessary decisions.

Sourse of information
1. Auth. St. 851644, cl. H 02 J 13/00 - prototype.

Claims (1)

 A method for controlling the prohibition of turning on the circuit breaker of an automatic transfer switch (ATS) point for a short circuit in a ring network powered by two-transformer substation buses, which consists in fixing the inrush currents and in measuring the time between them, characterized in that they count the time from the moment the inrush of the short circuit occurs on the tires of the transformer of the main power source, equal to the time delay for turning on the switch of the ABP point, at the moment of the end of its countdown, the appearance of an inrush of the operating current is controlled T he longer normal, or short-circuit current of the transformer to the backup power supply tires and if it is not, then set the fact of banning the inclusion of paragraph ATS switch for a short circuit in the ring.

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