SU1339828A1 - Method of controlling switching device of three-phase capacitor stack - Google Patents

Abstract

The invention relates to a converter technique and can be used in converters. The aim of the invention is to improve the energy performance of the supply network. According to the proposed method, a sequence of pulses shifted by 90 el is formed to control the thyristors of each phase. hail with respect to the main sequence, synchronize it with the moments of transition of the phase voltage of the advanced phase through zero and are applied to the thyristors, and the triggering signal to turn on the corresponding thyristor in each phase of the mains after which the control pulses of both of the above sequences are allowed to pass to the thyristors. Thus, the installed capacity of a three-phase capacitor battery is most fully utilized. 3 il. V (L 00 SAE QD 00 to 00

Description

113

The invention relates to a converter technique, namely, to controlling thyristor switches of three-phase capacitor banks used to compensate for reactive power in industrial networks or to provide artificial switching in sources of reactive power for autonomous current inverters.

The purpose of the invention is to increase the energy performance of the mains through the full use of the installed capacity of a three-phase capacitor battery,

FIG. 1 shows a functional diagram of the device that implements the proposed method; in fig. 2 - power supply line voltage diagrams; in fig. Figure 3 shows the currents through the battery capacitor and the high voltages across the elements of the control device.

The switch consists of a form

synchrophase voltage bodies 1, sub-25 are connected respectively to an inverted-connected to the supply mains phases with direct and inverse outputs, to which shaper 2 linear voltage sync pulses are also connected

 iK direct and inverse form for- I

with direct and inverse outputs, world unit 2 linear sync pulse 3 commands, first elements AND 4-9, elements OR 10-12, blocks 13-15 delays, elements EXCLUSIVE OR 16-18, which are included at the output of elements OR 10 -12, AND-HE elements 19-21, second AND elements 22-24, triggers 25-27, shapers 28-30 control pulses, opposite-turn thyristors 31-36 in each phase, capacitor banks 37-39.

A capacitor battery consists of capacitors 37-39 connected between the phases of the mains supply through anti-parallel connected thyristors 31-36, the driver of the phase voltage sync pulses connected to the phases of the power supply network to which the driver of the linear voltage two sync pulses is also connected. Block 3 commands sets the mode of operation of the switch (on / off). The control unit contains three similar channels for the formation of control pulses of anti-parallel-connected thyristors for thyristors 31 and 32, 33 and 34 and 35 and 36

For example, in the channel for controlling the thyristors 31 and 32, the driver 28 is connected to the control unit.

equaling electrodes of the corresponding thyristors, the input element 28 is connected to the output of the first element I 22, the first input of which is connected to the output of the element EXCLUSIVE OR 16, the second input to the forward output of the D flip-flop 25, and the third input to the output of the block 3 teams. The output of the command block 3 is also connected to the D-input of the trigger 25, the C-input of the trigger is connected to the output of the element AND-NO 19. The first input of the element IS-NOT 19 is connected to the output of the element EXCLUSIVE OR 16, and the second 5 input - to the output of the block 13 delays. The output of the element OR 10 is connected respectively to the second input of the element EXCLUSIVE OR 16 and the input of the block 13 of the delay. The output of the delay unit 13 is connected to the first input of the EXCLUSIVE OR 16 element, the first and second inputs of the OR element 10 are connected to the outputs of the AND 4 element and the AND 5 element, respectively, the first inputs of which

0

and the direct outputs of the advance phase of the generator of 1 phase sync pulses, and the second inputs of these elements iK to the direct and inverse outputs of the i

Worlds 2 linear sync pulses for linear voltage of a given pair of thyristors of the switch.

A device implementing the method works as follows (at the generation of thyristor control signals 33 and 34).

At the outputs of the elements 6 and 7, two sequences of pulses (90 al. Grades) of the supply network period are formed, which are fed to the inputs of the element OR 11 (Fig. 1 and 2). From the output of element 11LI 11, a sequence of pulses is removed (90 degrees), i.e. a square wave that is fed to the inputs of the delay unit 14 and the EXCLUSIVE OR element 17. On. the output of the element EXCLUSIVE OR 17 is formed a sequence of narrow pulses with a period of 90 e. power supply hail, the duration of which can be adjusted using the block 14 delay. The received sequence of pulses goes to one of the outputs of the element AND 23. The following of these pulses to the executive thyristors of the switch is determined by the signal from the block of 3 commands, and the element IS-HE 20 forms a sequence of pulses, synchronization 5

0

five

Linear voltage zero crossover, which determines the switching on time of the switch thyristor in the presence of a turn on signal from the 3 command block. The supply of the first control pulse to one of the two anti-parallel switches on the thyristors of the switch always occurs at the moment the linear voltage passes through zero when the voltage is positively applied to the switch thyristor.

Then, the signal from trigger 26 allows the passage of a sequence of pulses from an EXCLUSIVE OR 17 element to the switch thyristors. The signal from the block of 3 commands and the signal from the trigger 26 to turn off the element And 23 is blocked, with the result that the control pulses are removed from the switch thyristors and the current through the battery capacitors is stopped. Thereafter, D-flip-flops at the R and S-inputs are reset.

From the diagrams of current through capacitors 37-39 of a three-phase capacitor battery and control pulses for thyristors 31-36 (Fig, 3) it can be seen that the operation of capacitors takes place at the moments of voltage transfer (in this case AB, BC, CA) through zero values, which is determined by the corresponding trigger signals 25-27 (Fig. 1).

The introduction of an additional sequence of pulses shifted by

190 ela, degrees relative to the main sequence of sync pulses, allows to obtain a continuous current through capacitors 37-39. At the same time, in order to eliminate surges of free currents when a capacitor bank is turned on, it is necessary to first apply control of the switch thyristors

the main sequence synchronized with the point of voltage crossing through zero.

Thus, the method of controlling the thyristor switch three-phase

capacitor bank allows you to ensure the full use of the installed capacity of the capacitor battery during operation,

Claims (1)

Invention Formula The method of controlling a thyristor switch of a three-phase capacitor battery, which consists in forming the main sequence of pulses synchronized with the moments of zero crossing of the linear voltages of the power supply networks and supplies them to the thyristors of each phase, characterized in that, in order to improve the energy performance of the supply network, form an additional sequence of pulses shifted by 90 el, degrees relative to the main sequence of pulses and feed them to the thyristors of each phase added after the main feed. ((Uf (Uc : ± j j Bl: i-T five r " 681.1 BSjt. 7Lg / 6ita. 7L //. "/ Plainr.h"  G "L n P P P n n P P n n Jll IT n Л П n n n n n n n. JITL n fl n n  tf // U n n IT- JITL n fl n n and Ul.Z Upr.Z. At 33 33.З.335 Ulr.36 fpU2.3