SU296062A1 - DEVICE FOR AUTOMATIC MONITORING OF THE HIGH-VOLTAGE ISOLATION - Google Patents

Description

The invention relates to the field of electric power engineering and is intended for continuous operational monitoring of the state of high-voltage equipment by measuring the capacitance and dielectric loss of its isolation during working conditions.

When measuring with the help of known devices of similar purpose, for example, the Mosenergo KIV device, interference and various influences from the side of the spike and other equipment located under the ground are not excluded. Used for the same purpose, the known device containing three bridge circuits is also not sufficiently robust.

To improve the control accuracy by increasing noise immunity, it is proposed to make the input block of two adders producing summation of the currents of two controlled three-phase objects, and the measuring and signal blocks to include the difference of the output currents of the adders. To control two different types of three-phase objects, the adders can be equipped with adjustable tuners with regulators, by means of which the value of the output currents is set, which is inversely normal to the value of the capacitance of the objects being monitored. To eliminate measurements from current currents of influences and differences in capacitances

controlled three-phase objects each of the adders can be equipped with a regulator of the sum of the sum of the share of the phase currents for the preliminary balancing of the three-phase star of the measured currents. In addition, to determine the damaged phase and the nature of the damage, the measuring unit can be made with a phase-sensitive characteristic.

Pa figs. 1 shows the basic block diagram of the device described; in fig. 2 - a circuit diagram of the device (example of a wave). The displaced device (Fig. 1) responds to the difference in the sum of the currents of two three-phase objects. In this case, the measured currents of the phases of the object are preliminarily balanced. In the general case, when measuring the phase voltages and different inductances from the phase of the object, the magnitude of the total current is (for any of the harmonic components):

/ „Y (tl + -iB + ts) + (tl + Tsa + + tsa) i /. 4 + (tl -f 1va + ts a) + / vl, (1)

) - The average conductivity of the ISLAT phase of the object, determined by its capacitance and dielectric losses;

ST, Y-B. YC is the ratio of the conductivity of the isolate of the phase to the average conductivity for phases A, B, and CiJo, and, U.2 is the voltage of zero, direct and inverse sequences of phase mapping of the network; a, a- - factors;

/ VL - total current VLNN. If the conductivities of the phases of the object are equal (good insulation state is 1), the total current is determined by the interference current:

/ np 37gUoA + / vl (2)

If the isolation of one of the phases deteriorates

(for example, phase L) its magnitude will change

conductivity; UA 1 + AUA.

 A sigial will be obtained (out of 1)

/ HC :: Y SCJoA + DT (OD + M + 2L) 1 + / VL Y () H-4, (3)

where bf is the phase direction of the network (the first harmonic is considered).

In the proposed device for eliminating interference from currents of influences, the magnitude of the summed portion of the phase currents is controlled so that the total current, including the influence current, at the output of the summing device has an industrial frequency component close to zero.

In order to suppress the residual noise current caused by the voltage of the bullet sequence and higher harmonics, it is proposed to measure the difference of the total currents of the two objects, having previously equalized the magnitude of the measured noise currents. The resulting interference interference is then automatically stored.

The conditions for compensating for the current of interference caused by the zero-sequence voltage (out of 2);

DL, „/„ „(5 /„ „(Y-rG) 0. (4)

At the same time, the signal received in case of a defect in the insulation of one of the phases of the controlled objects will not be affected by interference. (Pz 3, when compensating for interference from influence currents):

A / not / HC - n 3U, () + AT I / f.

The phase of this current will be determined by the nature of the defect (change in capacitance or dielectric loss).

The currents flowing under the action of the working (phase) voltage through the insulation of the controlled objects are summed by adders I (see Fig. 1). in necessary cases, pre-balancing of the measured sum of currents is performed (according to the fundamental harmonic). Then, the phase of the total current of one of the objects (Ill) with the help of a phase inverter 2 rotates by 180 °, and

it is changed by controller 3 so that the compensation condition (4) is satisfied. The current on the adder 4 (A / ") will differ from zero only when there is a defect in the insulation of one of the phases of the objects being monitored. The phase-sensitive device 5 can measure the value of both the active component and the reactive component of this current phase by phase and, thus, determine

damaged object, its phase and nature of damage (change in capacitance or tg6). Signaling device 6 gives a signal that the isolation characteristics are not acceptable.

A schematic diagram of one of the possible ways to implement the proposed device cited in FIG. 2

The role of adders, phase inverter and signaling device is performed by a three-position relay 7. Shunts 8 and conventional resistances 9 allow balancing of the circuit in the presence of influence current and in case of differences in the insulation capacitance of the object from each other, and the resistance of the residual current 10 is adjusted to compensate for residual current interference .

As a phase-sensitive meter, a device of direct current with a synchronous driver 12, controlled voltage, obtained from the phase shifter 13, is used.

Subject p z about b ete e p and

Claims (4)

1. A device for automatic monitoring of the state of isolation of high-voltage equipment under operating equipment by measuring the magnitude and phase of the current through its capacitance containing input, measuring, and signal units, characterized in that, in order to improve the accuracy of control, the input unit consists of two adders, which produce the summation of the currents of two controlled three-phase objects, and the measuring and signal units are connected to the difference of the output currents of the adders. 2. A device according to claim 1, characterized in that, in order to control two non-one-type three-phase objects, the adders are provided with adjustable controllers for setting up, by means of which the output currents are determined, inversely proportional to the capacitance of the objects to be monitored. 3. The device according to paragraphs. 1 and 2, characterized in that, in order to eliminate errors measurements of the effects and differences in capacitances of the controlled three-phase objects from currents; each adder is equipped with a regulator of the sum of the sum of the phase currents for the preliminary symmetry of the three-phase star of the measured currents. 4. Device on PP. 1-3, characterized in that, in order to determine the damaged phase and the nature of the damage, the measuring unit is made with a phase-sensitive sensor if b LfcM a.