SU1695447A1 - Device for automatic adjustment of arc-controlling coils - Google Patents

Abstract

The invention relates to means for the distribution of electrical energy, in particular, to devices for automatically controlling the compensation mode of capacitive ground-fault currents in distribution networks of 6-35 kV. The purpose of the invention is to expand the functionality of the device. For this purpose, the device is equipped with a functional voltage converter 10 proportional to the phase shift angle between the neutral bias voltage and the reference voltage to a voltage proportional to the sine of this angle, the analog signal divider 11 and the indicator 12. This device allows determining the value of uncompensated capacitive current , which allows its use in manual tuning of arc-facing, coils or when setting arc-suppressing coils with taps. 2 Il. 4mt w YO O Oh ate 4 N VI

Description

The invention relates to means for the distribution of electrical energy, in particular, to devices for automatically controlling the compensation mode for capacitive ground-fault currents in distribution networks of 6-35 kV.

The purpose of the invention is to expand the functionality of the automatic compensation adjustment device.

FIG. 1 shows a functional diagram of the device; in fig. 2 - circuit diagram in principle.

The proposed device contains a capacitor 1 connected to one of the phases of the network to create a permanent neutral displacement, an input unit 2 containing two separation transformers 3 and 4, one of which is connected to the signal winding of the arcing coil and the other to the measuring winding a voltage transformer, a phase-sensitive amplifier 5, whose input is connected to the secondary windings of the transformers of the input unit, and the output is connected to the control unit of the motor contactors, consisting of a phase-measuring circuit and comparators, to the output of which transistors are connected, in whose collector circuits the alarm control relay and the motor contactor control unit are connected, the motor contactor control unit 6, consisting of the relay 7 and 8, whose contacts are connected to the motor power circuit, and the coils are connected to the mains 220 V via the contacts of the relay of the phase-sensitive unit, the calculating unit 9, consisting of a functional voltage converter 10 proportional to the phase angle between the bias voltages and op The voltage is proportional to the sine of this angle, the input of which is connected to the output of the phase-measuring circuit of the phase-sensitive amplifier unit, the analog signal divider 11, the input of which is connected to the output of the function converter, and to the input X through a rectifier and voltage regulator The displacement of the neutral is removed from the signal winding of the arc-quenching coil and the indicator 12, which is a milliammeter connected to the output of the divider chip.

The calculation of the sign of the uncompensated capacitive auger is performed by

1ns GOLS-1ЈLP, U о

where (i - watch h and see

D C - additional capacity for creating artificial asymmetry;

11f - phase network voltage;

p0 is the phase angle between the reference voltage and the neutral displacement voltage;

Go is the displacement voltage of the neutral.

In this formula, the variables are Do and sin, therefore, the calculation of the uncompensated current value is reduced to the calculation of the variable functions U0 and sin pQ at each time instant.

The device works as follows.

The neutral bias voltage from the signal winding of the arc-quenching coil and the reference voltage from the measuring winding of the voltage transformer are fed to the primary windings of the isolation transformers 3 and 4 of the input unit of the device. From the secondary windings of isolation transformers, these voltages are fed to the input of a phase-sensitive amplifier — current-limiting resistors 13 and 14 and a stabilizing circuit assembled on diodes 15-18. Voltage is converted into square-wave pulses by means of diodes and, through operational amplifiers 19 and 20, is applied to transistors 21 and 22 operating in key mode and amplifying these signals. From the collectors of these transistors 21 and 22, the signals are fed to a phase-measuring device assembled from four elements 2I-HE 23-26, at the output of which a voltage appears proportional to the phase shift of the bias voltage of the neutral and reference voltage.

The voltage from the output of the phase-measuring unit is simultaneously fed to the input of the counting unit, to the non-inverting input of the comparator assembled at the operational amplifier 27 and to the inverting input of the comparator assembled at the operational amplifier 28. The other inputs of these amplifiers are supplied with reference voltages from voltages power supply through variable resistors 29 and 30. These resistors are used to adjust the operation of the comparators at certain values of the output voltage of the phase measuring element and, respectively, for triple actuation of automatic compensation adjustment device on the corner f.

From the output of the comparators, the signal goes through resistors 31 and 32 to the bases of transistors 33 and 34, which operate in the key

mode. Depending on the polarity of the signal, either the relay 7 is activated, which is connected to the collector circuit of transistor 33 (overcompensation mode) or the relay 8, which is connected to the collector circuit of transistor 34 (undercompensation mode). The contacts of these relays are entered into the control circuit of the contactors of the electric motor of the arcing coil and into the signaling circuit of the substation.

The control circuit of the motor contactors is typical.

The circuit contains two contactor contacts of which are located in the power supply circuit of the electric motor, and two start buttons that are bridged with the closing contacts of the starting relays that are triggered by the relay of the phase-sensitive amplifier unit.

The counting unit operates as follows.

The voltage from the output of the phase-measuring circuit of the phase-sensitive amplifier unit is fed to the input of the functional converter of the counting unit. The functional converter is assembled at the operational amplifier 35, in the positive feedback of which the parallel resistance-zener diode chains are included. A voltage proportional to the sine of the input signal is generated at the output of the function converter. Since the input voltage is proportional to the angle of phase shift, the voltage from the output of the functional converter is proportional to the sine of this angle. As shown in the formula, this conversion is necessary to calculate the uncompensated current value. From the output of the operational amplifier of a functional converter, the voltage proportional to the sine of the phase angle is fed to the input of the analog signal divider 36. The input X receives the neutral bias voltage from the signal winding of the arc coil, stabilized through a bridge 37-40 and stabilized by resistors

41, 42 and a zener diode 43. A capacitor 44 is a Filter.

The voltage from the output of divider 36. is proportional to the partial separation of the sin function by Uo. through trimmer resistor 45 is applied to milliammeter 46. Thus, the milliammeter indicates at each instant in time the value of the uncompensated capacitive current.

The economic effect of the proposed technical solution is to improve the accuracy and reliability of the compensation setting, which leads to a reduction in the accidental consequences of single-phase earth faults associated with interruptions in power supply and repair work.

Claims (1)

Invention Formula A device for automatically adjusting the arc-suppressing coils, containing a capacitance for creating a constant neutral displacement and a phase-sensitive amplifier connected in series, one input of which is connected to a reference voltage source and the other input to a neutral displacement voltage source, and an electric motor controlling the contactors. in order to extend the functionality, it is equipped with a functional voltage converter proportional to the phase angle between the voltages displacement of the neutral and the reference voltage, to a voltage proportional to the sine of this angle, an analog signal divider and an indicator, and the output of the phase-sensitive amplifier is connected to the input of the functional converter — the output of the functional converter is connected to one input of the analog divider, to another input of which the output is connected the source of the bias voltage of the neutral, the output divider analog signals connected to the indicator. Block Relay management contactors Vshep alarm (DU2 2