SU1081738A1 - Method of single-shot auto-reclosing - Google Patents

Abstract

A METHOD OF SINGLE AUTOMATIC REPEATED SWITCHING, which consists in measuring the magnitude of the first inrush of short-circuit current and controlling the position of the switch after the disappearance of the first inrush of short-circuit current, which results in starting the automatic reclosing device, characterized in that the contacts of the drive and the switch, the control is switched off, the position of the switch is carried out by the absence of current in the line after the first inrush of short-circuit current.

Description

3

g

3

Ii 1

00

i,

00 00

Fig. 1 The invention relates to electrical networks that perform a single automatic switch-on during an emergency shutdown of a power line. A known method of obtaining information on the result of the ARC sectioning apparatus, in which the first and second inrush current, short circuit and the time between inrush current currents are measured to obtain information. The disadvantage of this method is that the current between the first and second inrush current currents is not fixed that does not reliably judge the state of the partitioning apparatus. Known from the AR manual, in which the device is started up from a mismatch of the switch position when it is in the OFF state and the previous command is ON, realized by the control key and block contacts of the actuator switch 2. The disadvantage of the method lies in the dependence of AR operation From the mechanical part of the drive of the switch and its block contacts, which are used in the electric circuit, the device started up. This disadvantage is especially characteristic of the automatic reclosing of spring-cargo drives, widely used in networks of 10-35 kV. The purpose of the invention is to increase the reliability of the AR device by eliminating the mechanical drive contacts of the actuator and the switch. This goal is achieved by the fact that according to the automatic reclosing method, consisting in measuring the magnitude of the first inrush current and monitoring the switch position after the first inrush current disappears, which results in starting the automatic reclosing device, the switch off position is monitored by the absence of current lines after the first surge current short circuit. If the current between the short-circuit current inrush is zero, which corresponds to the short-circuit location, the main section where the device is installed, or behind the transformer of branches during non-selective operation of its protection, is allowed to restart. If the current is not zero, the reclosing is prohibited, since the short-circuit location is located on the adjacent section or behind the transformer of the branches during the selective operation of its protection. FIG. 1-3 shows the timing diagram of the device; in fig. 4 - primary network diagram and block diagram of a single automatic reclosing device. It is assumed that typical protections configured for selective operation are installed on the network. In the first diagram, corresponding to a stable short circuit, the value of current 1 is the operating current of the line in the normal mode, a stepwise increase in current at time ti to value I. - short circuit current; The duration of the surge current ti - ti is determined by the time of action. protection of the adjacent area. The current value 1e in the time range t - t, corresponds to the operating current at the beginning of the line after switching off under the influence of the protection of the adjacent area. Repeated inrush of short-circuit current indicates an unsuccessful reclosure at an adjacent site. With an unstable short circuit in the adjacent area (Fig. 1, second diagram), the order of current change is similar to the previous one. The difference lies in the absence of a second short circuit current surge. It should also be noted that in both cases the current after the first throw is not equal to zero, but corresponds to the operating current of the main section or the entire line. With a stable and unstable short circuit in the main section (FIG. 2, the first and second diagrams), the change in current values differs from the cases considered by the absence of a current in the time range, i.e. the presence of a dead pause. This circumstance is used as the main feature by which the reclosing is carried out. The same picture will be observed in case of a short circuit behind the transformers of the branches (Fig. 3). The first diagram shows the sequence of current changes under the non-selective action of the line protection and the transformer. In this case, when a short circuit occurs behind the transformer, the line protection is activated and turns off. Therefore, not to the diagram after the surge current surge, its value is zero. The reclosure is carried out, correcting the non-selectivity of the action of the protections. With the selective action of the protection after the inrush current (the second diagram), its value is not zero and the automatic reclosure is not carried out. Consider how, based on these features, the automatic reclosing operation is performed. The primary network includes substation 1, switches 2, main line section 3, branch transformers 4, adjacent section 5 .. Secondary circuits include circuit 6 for connecting current transformers, intermediate transformer 7, short circuit current sensor 8, zero current sensor 9, logic elements 10 and 11, implementing the operation "Memory, logic elements 12 and 13, implementing the operation" And, elements 14 and 15 DELAY, logic element 16 INVERSION, signal amplifier 17, executive element 18. In the event of a short circuit in the adjacent area 5 through the gap ny transformer 7, which is included in the circuit 6 of the current transformers compound feed relaying device, information is simultaneously supplied to the short-circuit current sensors 8 and 9, the zero current. The short-circuit current sensor 8 reacts to the short-circuit current surges, therefore, a signal appears at its output, since the short-circuit current surge is equal to the protection time, therefore the signal from the short-circuit current sensor 8 supplies for memory to the logic element 10 MEMORY, and then to the input element And 12. The zero current sensor is a logical element that implements the operation "NOT, therefore at its output When the current is injected, there will be no signal, as there is a signal at the input. There will be no signal at the output of this element even after the inrush of the short-circuit current, so that the line will not be equal to zero. Thus, the input element And 12 will be served only one signal, which is not enough to receive a signal at the output and carry out AR. During a short circuit, a current inrush occurs at the main section, at which the output of the current 8 sensor 8 turns on the signal that is fed to the logic element 10 MEMORY, then to element 12. After disconnecting the short circuit from the relay protection, the current in the line becomes zero, disappears the signal at the input of the zero-current sensor 9, respectively, at the output is a signal that is applied to the element And 12. Last, the signal triggers and sends an input to the 14 DELAY element, setting the dead time delay, and then to the signal amplifier 17 and the performer A new body 18, which closes the power supply circuit of the electromagnet of the on / off switch. In normal mode, the start-up circuit is de-energized. Power is supplied to it from the element 10 MEMORY when a signal appears on the input of the short-circuit current sensor 8. 108 8 One-time start-up of the automatic reclosing is provided by the logic elements 13 AND 11 of the MEMORY. The input element And 13 signals from the sensor 8 current short-circuit (short-term) and the amplifier 17 signals through the element 11 MEMORY. With a successful reclosure, there will be only one signal at the input, which is removed when de-energizing the start-up circuit. In case of unsuccessful reclosure, a second inrush of the short-circuit current to the input occurs, in addition to the signal from element 11 of the MEMORY, a short-term signal from the output of the 8 TOK sensor is given. Then, at the output of the AND 13 unit, a short-term signal that will reset the element 10 of the MEMORY and the circuit will return to the initial state. In order for the output element And 12 did not exist signal at inrush current. not connected with a short circuit in the main section, the MEMORY element 10 is reset by means of the elements 16 NOT and 15 DELAY. A signal to reset the memory with a short time delay is applied to the element 10 MEMORY, if there is no signal at the output of the element I 12. According to the analysis of the reliability of automatic reclosing devices based on spring-loading drives, carried out in three electrical networks, from all cases of automatic reclosing more on the cause of the malfunction block contacts. Frequent adjustments of the contacts are required to keep the automatic reclosing device in good condition, and in some cases such adjustments do not give proper results, especially in winter. The positive effect of the proposed AR method is to reduce operating costs, increase the reliability of the AR device and significantly reduce the interruptions in power supply to consumers.

fr

6

j

FIG g

il

iz tfc

Jv.

i tz J

e.J

Claims (1)

METHOD FOR ONE-TIME AUTOMATIC REPEATING ON, consisting in measuring the value of the first inrush current and monitoring the position of the circuit breaker after the disappearance of the first inrush current, according to the results of which the automatic reclosure device is started, characterized in that in order to increase the reliability of the automatic reclosure device by refusing mechanical block contacts drive and circuit breaker, control off. the position of the switch is carried out by the absence of current in the line after the first inrush of a short circuit current. Figure 1