RU1781765C - Two-stage capacitor installation - Google Patents

Abstract

Usage: for stepwise regulation of the power of a three-phase capacitor bank. SUMMARY OF THE INVENTION: In order to increase the speed when switching capacitors from a triangle to a star using switches, the discharge of capacitors is carried out using the switch of the discharge to the phase voltage amplitude. Then, the star switch of the capacitor bank is switched on without impact, connecting the star capacitors. The operation of all switches is ensured by a logic circuit consisting of a control unit, elements, and a single vibrator. 2 ill. .

Description

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The invention relates to electrical engineering and can be used to stepwise control the power of a three-phase capacitor bank.

A device is known for controlling the power of a three-phase battery, comprising star and delta switching switches for the capacitor bank, a control unit, three discharge resistors, three thyristor switches connected in series with the discharge resistors, two AND elements, an OR-NOT element, a trigger, a one-shot, delay element, electronic key.

The disadvantages of the known device are its low reliability due to the complexity of the circuit, the discharge of capacitors when switching from star to triangle.

Known discrete capacitor installation containing switches for switching on a capacitor battery star and

triangle, discharge switch, three bit resistances, control unit, two AND elements, one-shot, delay element, electronic key.

A disadvantage of the known device is its low speed, since permission to turn on capacitors by a star is only given after they are fully discharged.

The purpose of the invention is to increase speed.

This goal is achieved by the fact that in a two-stage capacitor installation comprising a star switch on the capacitor bank, a triangle switch on the capacitor bank, and a discharge switch of the capacitor unit, made in the form of thyristor switches, a control unit with inputs for connecting an adjustable parameter to the sensor, three times data of resistance included by vj

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VJ about with

therefore, with the thyristor keys of the capacitor bank discharge switch, a one-shot, the input of which is connected to the output of the capacitor bank control unit by a triangle, a direct output with the discharge switch input, two AND elements, one of whose inputs are connected to the corresponding outputs of the control unit, the other inputs are with an inverted output of a single vibrator, and the outputs with the outputs of the respective switches for switching on the capacitor bank, a delay element in series with an electronic key included e in the control circuit of the discharge switch, each channel of the star and delta switch on the capacitor bank is additionally equipped with an And element and a null indicator, and in the control circuit of each channel of the discharge switch, the element is FORBID and sequentially United delay element and electronic key, and the output of the element And each channel of the switch for switching on the capacitor bank with a star and a triangle is connected to the control input of the thyristor switch, the outputs of which are connected to the inputs of the zero indicator the outputs of which are connected to the first input of the element And the channel of the switch on, the second input of which is the input of the corresponding switch on, the electronic key output of each channel of the discharge switch is connected to the control input of the corresponding thyristor key, the input of the delay element is connected to the output of the FORBID element, my input of which is the input of the discharge switch, and the inverse input is connected to the output of the null indicator of the corresponding channel of the switching capacitor bank switch Golnik.

Figure 1 presents a functional diagram of the proposed capacitor unit (KU): figure 2 is a voltage diagram on the capacitors when switching from a triangle to a star.

The device (Fig. 1) comprises a three-channel switch 1 for switching on a capacitor bank (KB) drawn from capacitors 2-4 by a triangle, a two-channel switch 5 for switching on capacitors 2-4 by a star. Each channel of the KB switching switches 1 and 5 with a star and a triangle contains (using channel 1.1 as an example) a power triac b. 1, element And 7.1, the output of which is connected to the control input of triac 6.1. The inputs of the null indicator 8.1 are connected to the outputs of the triac 6.1, and the output is connected to the input X2 of the And 7.1 element, the input X1 of which is connected to the input Y1 (Y2) of the switch 1 (5).

In parallel to capacitors 2-4, bit

resistance 10-12. Each channel of the switch 9 of the discharge of capacitors 2-4 contains (for the example of channel 9.1) a bit triac 13.1, the control input of which is connected to the output of the electronic key

0 14.1, The output of the electronic key 14.1 is connected to the output of the delay element 15.1, the input of which is connected to the output of the element BAN 16.1. The direct input of the element BAN 16.1 is connected to the input Y3 of the switch 9

5 bits, and inverse - with the output of the zero indicator 8.1 of the corresponding channel 1.1 of switch 1.

The input of the control unit 17 is connected to terminal X for connecting an adjustable parameter to the sensor, and the outputs are connected to inputs X1 of elements 18 and 19, the outputs of which are connected to the corresponding inputs Y1 and Y2 of the switching switches 1 and 5 by a triangle and a star. Inputs X2 of elements And 18 and 19 are connected to the inverse output of a single-shot 20, the direct input of which is connected to input Y3 of the 9th switch, and the input is connected to input X1 of element And 18.

0 The device operates as follows.

Depending on the value of the monitored parameter X, a signal appears at one of the inputs of the control unit 17.

5 Assume that the control signal (log 1) is forwarded to the upper (according to the circuit) output of the control unit 17. The one-shot 20 is triggered by the cutoff of the pulse, therefore, a signal is stored at its inverse output

0 log. 1, which is supplied to the outputs X2 of the elements And 18 and 19, allowing the passage of the control signal to turn on the triacs of the switch 1. At the moment of zero voltage on the triac 6

5, the corresponding zero indicators 8 give a signal of log.1 to the inputs X1 of the I7 elements, allowing shock-free phase-by-phase switching of the switch 1. At the same time, the capacitors 2-4 are connected to the network according to the triangular circuit.

In the case when the controlled parameter has changed so much that it is necessary to switch the KB from a triangle to a star, at the lower (according to the scheme) output of block 17

5, a signal log.1 (moment to) appears, and at the top (according to the circuit) output, a signal log.O. According to the difference 1-0 of the signal at the upper (according to the scheme) output of the control unit 17, a single-shot 20 is launched, which generates a pulse at the direct output

with log level 1, and on the inverse level with log level O, which prohibits the passage of control signals through the elements 18 and 19 to the on-off switches 1 and 5. The pulse duration of the one-shot 20 is chosen equal to the time required for the discharge of the capacitors 2-4 s amplitude linear voltage to 0.85-0.95 amplitude phase voltage.

The signal log. 1 from the direct output of the single-shot 20 is fed to the direct input of the channel elements PROHIBIT 16 of the switch 9 bits KB. At the times ti, ta, ts (Fig. 2), the triacs b of the switch 1 are turned on one by one at the outputs of the corresponding zero indicators 8, the logic signals O appear, which are fed to the inverse inputs of the elements BAN 16 of the switch 9 of the category. As a result, at the output of the elements BAN 16, a signal is set to log.1, which, with a small time delay necessary for guaranteed locking of the triac 6 of the on-switch 1 and provided by the delay elements 15, is transmitted through electronic keys 14 to the control inputs of the corresponding triac 13 of the switch 9 of category . The triacs 13 of the switch 9 at the times ta, t4, he (Fig. 2) are turned on, providing a fast discharge of the capacitors 2-4. At time t, when the residual voltage across the capacitors becomes phase, a log.O signal is set at the direct output of the single-vibrator 20. It removes the control signal from the triacs of the switch 9 of the bit, and a signal log.1 is enabled at its inverse output, allowing passage the control signal from the control unit 17 to turn on the switch 5, At times t8 and tg the voltage is zero on the triacs of the two-channel switch 5 to turn on the KB star, the outputs of the corresponding zero-indicators are log.1 signals, which through the elements And the post Payuta to the control electrodes of the switch 5. These triacs triacs at instants te and tg (Figure 2) incorporated unstressed, when connected to the network KB wye. In this case, the triacs 13 of the switch 9 of the category are naturally locked at the moment the current flows through them through zero.

In the case when the controlled parameter X has changed so much that it is necessary to switch the KB from the star circuit to the triangle circuit, the signal log.1 is set at the top (according to the circuit) output of the control unit 17, and the log is set at the lower (according to the circuit) O. The one-shot 20 does not start in this case. As a result of the installation of the signal O. at the input Y2 of the switch 5, and the log O. at the input Y1 of the switch 1, the triacs of the switch 5 are sequentially locked at the moment the current passes through them to zero and

5 alternately turn on the triacs of the switch 1 at the moment of voltage transition across them through zero (the switching process is described above). As a result, capacitors 2-4 are shocklessly connected to the network according to the triangle triangle pattern.

Thus, the proposed device allows to increase (3-4 times the speed of switching capacitors from a triangle to a star, as a result

5, the time interval of abnormal reactive power is minimized, and the quality of the voltage in the network is improved. It is possible to use KU to combat fluctuations in reactive power and voltages, i.e., the functionality of a capacitor unit is expanded.

Claims (1)

The claims 5 Two-stage capacitor unit, comprising a star switch on the capacitor bank, a delta switch on the capacitor bank and a capacitor bank discharge switch, made in the form of thyristor switches, a control unit with inputs for connecting an adjustable parameter to the sensor, three bit resistances connected in series with 5 thyristor keys, switch, capacitor bank discharge, one-shot, the input of which is connected to the output of the control unit for switching on the capacitor battery, a triangle, a direct output –– from the input of the discharge switch, two AND elements, one of whose inputs are connected to the corresponding outputs of the control unit , the other inputs are with the inverted output of a single-shot, and the outputs are with the inputs of the corresponding switches for switching on the capacitor bank, a delay element and an electronic key connected in series to the circuit systematic way discharge switch, wherein 0 in that, in order to improve performance, each channel of the switch for switching on the capacitor bank with a star and a triangle is additionally equipped with an And element and a zero indicator, and in the circuit 5, for each channel of the discharge switch, a BAN element and a progressively connected delay element and an electronic key are introduced, the output of the element And of each channel of the switch on the capacitor bank turning on with a star and a treusolnik connected to the control input of the thyristor switch, the outputs of which are connected to the inputs of the zero indicator, the outputs which are connected to the first input of the element And the channel of the switch on, the second input of which is the input of the corresponding thyristor key, the input the delay element is connected to the output of the BAN element, the direct input of which is the input of the discharge switch, and the inverse input is connected to the zero indicator output of the corresponding channel of the switch for switching on the capacitor bank with a triangle. and Jc