SU1265907A1 - Device for protection of shunting a.c.power transmission reactor - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to relay protection, and is intended for use in protection devices of shunt reactors of high voltage networks. The aim of the invention is to increase the sensitivity of the protection to ground loops. This is achieved by turning on the second current sensor in the low-voltage input circuit of the reactor, since the current of the latter varies dramatically in magnitude and angle when the winding closes to ground. Due to the fact that the geometrical difference of currents of different inputs of one winding of the protected reactor used in the device during ground faults by absolute value is greater than the geometric difference of inputs of different windings used in the known device, the sensitivity of this device to ground fault is higher. ffi 3 Il. (L

Description

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The invention relates to electrical engineering, in particular, to relay protection, and is intended for use in protection devices of shunt reactors of high voltage networks.

The aim of the invention is to increase the sensitivity of the protection to ground loops.

The essence of the proposal is to use an abrupt change in the current of the low-voltage reactor inlet in terms of magnitude and angle when winding closes to ground.

Figure 1 shows the block diagram of the device; 2 and 3, the change in reactor currents in normal and emergency modes.

The circuit contains two current sensors 1 and 2, the outputs of which are connected to the inputs of the summing circuit 3, the voltage sensor 4, the output of which is connected to the first input of the comparison circuit 5, and the second input of the comparison circuit 5 to the output of the summing circuit 3 5, a reacting element 6 is connected. The difference of the device is that the second current sensor is connected to the second winding input circuit of the protected reactor.

The low-voltage reactor input current sensor is designed in such a way that the signal from its output is opposite in phase to the input signal, and its absolute value K2 is lower than the transfer coefficient Ki of the high-voltage input current sensor of the reactor. Consequently, in the normal mode, when the currents of the reactor inlets / in and in / nv are equal (fig. 2a), the output of the summing circuit 3 will hold the signal (fig. Zo)

(KliBB) -f () К | 1вв-К21 в.

For sensor 4, the voltage coefficient Kz is taken based on the conditions of the normal mode

IKllBB -K21nv | IK3Up |.

The connection of the reacting organ 6 with the comparison circuit 5 is made in such a way that the act of the organ lining is ensured when the signal IKilBB-K2l | IKaUpl.TaK signal. As in the considered mode, the indicated condition is not fulfilled, the device is in an unserviceable state.

In the case of a breakdown of the isolation of the reactor to earth (Fig. 26), the reactor enters an autotransformer mode with a short-circuited output, i.e., the low-voltage input current of the reactor changes dramatically both in magnitude and in phase. As a result, the signal IKiba- -KdB significantly increases (Fig.36), it becomes much larger than the signal | Кйр | and the response body is triggered.

Due to the fact that the geometrical difference of currents of different inputs of one winding of the protected equipment (reactor) used in the proposed device when ground is closed by the absolute value of the geometrical difference of inputs of different windings used in the known device, the sensitivity of the proposed device to ground-to-ground exceeds the sensitivity of the known .

When the coil closures x, the input current of the reactor increases, maintaining mutual equality and phase coincidence. In this case, the value (КЛвв-К21нв) increases and in certain conditions, when this value becomes greater than kz, the reacting organ is triggered. Under these conditions, the operation of the proposed device is similar to the action of the known.

The use of the proposed device, which has an increased sensitivity, will make it possible to detect ground loops in the windings of the shunt reactor at an earlier stage in the development of the accident, to increase the reliability of the power systems and to reduce the costs of repair and rehabilitation of the reactors.

Claims (1)

Invention Formula A device for protection of an AC shunt reactor, containing current sensors, one of which is connected to the high voltage input circuit of the reactor, a current summation circuit, the inputs of which are connected to the current sensor outputs, a voltage sensor on the reactor whose output is connected to the first input of the comparison circuit , the output of the current summation circuit is connected to the second input of the comparison circuit, the output of the comparison circuit is connected to the input of the reacting authority, characterized in that, in order to increase the sensitivity of the protection to the circuit or m upon the ground, the second current sensor is included in the low-voltage input circuit of the reactor.