SU1397896A1 - Device for controlling capacitor banks - Google Patents

Abstract

The invention relates to electric power industry and can be used in devices for power control of capacitive capacitor devices. The purpose of the invention is to increase speed and accuracy. The goal is achieved by the fact that a capacitor bank control device containing a voltage transformer 2. a current transformer 1 connected to a differentiation unit 5, a regulator 15, N of thyristor switches 16.1-16.N, which switch N capacitor banks 17 .1- 17. H, a precision rectifier 3, a device for sampling and storage 4, a comparator 6 zero current derivative values, a multiplier 7, a comparator 8 for extracting a negative portion of the instantaneous power, a sum counter 9. a pulse generator 10, a code converter 11, Kocksharer 14 current zero, multiplying the digital-to-analog converter 13 with the function of storing digital information. The device allows to determine the value of the reactive component of the load current over a quarter of the period of the supply voltage, which will significantly increase the speed of control of capacitor banks. 3 il. - (L

Description

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The invention relates to power engineering and can be used in devices for power control to compensate for 1x capacitor devices.

The purpose of the invention is to increase speed and accuracy.

FIG. 1 is a block diagram

The devices in FIG. 2 and 3 are temporary loads of P (Fig. 2). which

diagrams explaining his work with the active-inductive and active-capacitive nature of the load, respectively.

The device contains a current transformer 1, a voltage transformer 2, a preamplifier 3, a sampling and storage device 4 (VHR), a differentiation unit 5, a comparator 6 zero current derivatives, a multiplier 7, a comparator for extracting a negative portion of the instantaneous power, summing counter 9, pulse generator 10, code converter 11, HE logic element 12, multiplying digital-to-analog converter 13 (DAC) with digital information storage function, comparator 14 current zero values, controller 15, thyristor r Switches 16.1- 16.N and capacitor batteries 17.1- 17.N (KB).

The device works as follows.

Signal and output transformer

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1, proportional to the load current i, is fed to the input of a precision rectifier 3, at the output of which an unipolar ultrasonic voltage is formed (Fig. 2). corresponding to the instantaneous value of the load current i. This voltage is applied to the information input of the VHR 4.

The output signal from the current transformer 1 is also fed to the input of the differentiation unit 5, from the output of which the derivative of the current U is fed to the input of the selector 6 of the zero values of the derivative. At the moment of passing the derivative of current Ui through the zero value of t, (Fig. 2), a short pulse Ug is generated at the output of the comparator 6, which is the control signal of the water level control unit 4 and the zero counter of the counter command 9. At the moment of arrival of the pulse t at the control input VH4 4 fixes the value of the load current U ,, equal to its amplitude

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then enters the input of the comparator 8 in the division of negative portions of the instantaneous power. At the output of the comparator 8, a pulse Ug is formed, the leading front of which coincides with the beginning of the negative segment of instantaneous power t, and the rear front with the end of this segment t.j. The impulse Ug arrives at the control input of summing counter 9, and from the time t, the summing counter starts counting the pulses from the generator 10 pulses. At the output of the counter 9, a digital code is formed, which is proportional to the number of pulses received at its input for the time interval t t, and corresponds to the phase shift H between the supply voltage and load current i. This digital code is fed to the converter 11 codes, built on the basis of a logical programmable matrix, the output of which is generated digitally code.

at time t ,, corresponding to the falling edge of the pulse Ug, the counting of pulses by the summing counter 9 stops and the state of the logical element HE 12 changes, the output of which is a signal of logical 1. This signal is the control for the multiplying DAC 13. When this signal arrives at the register control input of the multiplying DAC 13, the digital code from the converter of 11 codes multiplies and the analog signal U ,, coming from the VHD 4 at the input of the reference voltage of the DAC 13 and equal to the maximum The values of the load current. The result of the multiplication is the value of the reactive component of the load current. The digital code received in the DAC 13 from the output of the converter 11 is stored in its register until the next multiplication tg, and the result of the multiplication is stored on the liAn 13 output until the multiplication time ts

there

The first and second inputs of multiplier 7 receive signals from current transformer 1 and voltage transformer 2 U proportional to instantaneous values of load current i and network voltage U. At the output of multiplier 7, a voltage is generated and proportional to instantaneous power 5

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then enters the input of the comparator 8 in the division of negative portions of the instantaneous power. At the output of the comparator 8, a pulse Ug is formed, the leading front of which coincides with the beginning of the negative portion of the instantaneous power t, and the back front with the end of this portion t.j. The pulse Ug is fed to the control input of summing counter 9 and from time t, the summing counter starts counting the pulses from the pulse generator 10. At the output of the counter 9, a digital code is formed, which is proportional to the number of pulses received at its input for the time interval t t, and the corresponding phase shift H between the supply voltage and load current i. This digital code is fed to the converter 11 codes, built on the basis of a logical programmable matrix, the output of which generates a digital code.

at time t, corresponding to the leading edge of the pulse Ug, the counting of pulses by summing counter 9 stops and the state of the logical element 12 changes, the output of which is a signal of logical 1. This signal is the control for multiplying DAC 13. When When this signal arrives at the input of the register control of the multiplying DAC 13, the digital code is multiplied from the converter 11 of the codes and the analog signal U from the WCH 4 to the input of the reference voltage of the DAC 13 and is equal to the value of the load current. The result of the multiplication is the value of the reactive component of the load current. The digital code entered in the DAC 13 from the output of the converter 11 is stored in its register until the next multiplication tg, and the result of the multiplication is stored on the liAn 13 output until the multiplication ts

or until the load current changes.

To obtain at the output of the DAC 13 a bipolar signal, the polarity of which corresponds to the inductive or capacitive nature of the reactive component of the current, the highest bit of the DAC 13, which is a significant bit, is given a pulse U g from the output of the comparator 14 zero current values. The inductive load (Fig. 2) at the time of multiplying tj by the sign bit of the D / A converter 13 is fed logical 1, and with the active-capacitive nature of the load (Fig. 3), logical O is received at the time of multiplication.

The output signal of the multiplying DAC 13 is fed to the input of the controller 15, which controls the thyristor switches 16.1-16.N, which carry out the switching of CB 17.1-17.N.

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The use of the proposed device makes it possible to determine the value of the reactive component of the load current for a quarter of the period of the supply voltage, which will improve the speed of control of capacitor banks. In addition, the use of a digital method for measuring the reactive component of the current will allow an increase in the accuracy of the adjustment compared to the known measuring means.

Claims (1)

Invention Formula A device for controlling capacitor banks. . voltage transformer, current transformer connected to a differentiation unit, a controller for controlling five-thyristor keys in capacitor battery circuits, characterized in that, in order to improve speed and accuracy, a precision straightener, a sampling and storage device are added to it , comparator of zero values of the current derivative, multiplier, comparator for the selection of the negative section of the instantaneous power, summing counter, pulse generator, code converter, logical element t is NOT a zero-current comparator multiplying a digital-to-analog converter with a digital information storage function, the current transformer being connected to the input of a precision rectifier, g input of the differentiation unit, the first input of the multiplier, the second input of which is connected to the voltage transformer, the comparator input of the current zero values, the output of the high-precision slider is connected to the information input of the sampling and storage device, the output of which is connected to the base voltage of the multiplying digital-analog converter, 5, the output of the differentiation unit is connected to the comparator input of the zero derivative of the current derivative, the output of which is connected to the zeroing distance of the summing counter and the control input of the sampling and storage device, the multiplier output is connected to the comparator for extracting negative portions of the instantaneous power connected to the summing bus of the summing meter, and through logical  the element is NOT with the register control input of the storage of the multiplying digital-analog converter, the pulse generator is connected to the counting the input of the summing counter, and output 0 A summing counter is connected via a code converter to the input of a multiplying digital-to-analog converter, with the most significant bit of a digital-to-analog converter connected to the output of a zero current value comparator, the output of digits of taxes from the converter is connected to a regulator.