SU1450040A1 - Method of switching over a capacitor bank - Google Patents

Abstract

The invention relates to electrical engineering and can be used to stepwise control the power of single-phase and three-phase capacitor banks connected to four-wire networks. The circuit of the invention — improved performance — is achieved by switching the capacitor battery f from linear to phase voltage by turning on valves 5, 6 at the time the equality of the instantaneous voltage on them to their amplitude value and the disconnection of the valves 7, fi at the moment of the subsequent of the first current crossing into them through zero. The logic circuit, assembled on two RS-triggers 12 and 13, two formers controlling the pulse pulses 15 and 16, the logical element I 10 and the formiro- clock sync pulse 9, implements the indicated method sequence. In the case of switching from a triangle to a star of a three-phase capacitor bank according to the proposed method, kc 1 mutates each phase capacitor. 2 yl. / С о с S W

Description

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The invention relates to electrical engineering and can be used for stepwise power control of single-phase and three-phase capacitor banks connected to four-wire networks.

The purpose of the invention is to increase the speed when switching a capacitor battery from linear to phase voltage.

First, turn on the phase valves at the moment of equality of the instantaneous voltage on them to their maximum

(amplitude) value, then off-15 maximum (amplitude) values;

linear valves are installed at the time of the subsequent first current crossing into them through zero.

Fig. 1 shows one of the variants of the device implementing the proposed method j in Fig. 2a, b is the timing diagrams of voltages and currents explaining the switching method,

The device (figure 1). contains con ™

thirty

A capacitor battery 1, one output co-triggers trigger 12 to another stable toro directly connected to terminal 2 for connecting one phase of the network, the other phase of the network and the neutral wire have terminals 3 and 4 respectively, phase 5, 6 and linear 7, 8 controls The valves that are connected between the other output of the capacitor battery t and terminals 3 and 4 g The output of the sync generator 9, connected between terminals 3 and 4, is connected to the second input X2 of element 10, the first XI of which is connected to terminal 11 to connect the control signal to turning on cond sensato

35

a state with a log signal, 1 at the output, which starts the shaper 15 of control pulses, giving the command to turn on the valves 5 and 6; At the same time, the signal log, I, is fed to the R input of the RS flip-flop 13, which is transferred to another stable state signal with a log. On the output, blocking the supply of control pulses to turn on the valves 7 and 8, When one of the valves 5 and 6 is turned on (moment 11), the circuit C is formed by one of the valves 7 ,. 8 - one of the veins

a state with a log signal, 1 at the output, which starts the shaper 15 of control pulses, giving the command to turn on the valves 5 and 6; At the same time, the signal log, I, is fed to the R input of the RS flip-flop 13, which is transferred to another stable state signal with a log. On the output blocking the supply of control pulses to turn on the valves 7 and 8, When one of the valves 5 and 6 is turned on (moment 11), the closing circuit C is formed - one of the valves 7 ,. 8 - one of the Venus 1 to the phase voltage. The output of the ele-40 tile 5, 6 - zero wire. And

the current conduction by the valves 7 or 8 and 5 or 6 at this moment will be opposite, the resulting circuit current AND THEN is connected to the S-terminal of the first RS-flip-flop 12, the R-input of which is connected to the S-input of the second RS-flip-flop 13 and terminal 14 for connecting a control signal for switching on a linear voltage capacitor 1, the output of the first KB trigger 12 is connected to the input of the first driver of control pulses 15 and the input of the second RS trigger 13, whose input is connected to the input of driver control transformer 16. The outputs of the formers 15 and 16 of the control impulses of the connections .. with the control inputs of the phase 5, 6 and linear 7, 8 valves, respectively.

Let the terminals 2r-4 be connected to the phase wires A, the neutral wire O of the supply mains, respectively.

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55

Neither l (FIG. 26) will have an inductance-like character and will cause a quick shut-off of the corresponding valve 7 or 8 at the moment the zero current closes ij (time t, j),

The voltage across the capacitor at this moment will be U | and Idr - Uco / 2. (by analogy with switching processes in compensating converters) Next, the voltage on the capacitor U and the corresponding phase voltage of the supply mains (moment t e) is equalized, while loop resistance f is used as the natural damping resistance

At terminal 14 a control signal is applied to the log. 1 to turn on capacitor 1 to phase voltage (terminal 11 is given a log.O signal), RS-flip-flop 13 is in a steady state with a 1m signal, 1 is output, which is fed to the input of the driver 16 for pulses to turn on linear valves 7 and 8. Condenser 1 is connected to the line voltage ids. Shaper 9 sync pulses outputs sync pulses at times of voltage U c.

5 and to terminal 11 - signal. 1 (moment to) "In l x

0

For capacitor bank switching, a signal is sent to terminal 14, O log,

The moment of the subsequent arrival of the sync pulse with the formation of the 9th synchro body and the moment (moment t)

at the output of the element And 10 appears n |

signal log.

which referrals

flies trigger 12 to another steady

a state with a log signal, 1 at the output, which starts the shaper 15 of control pulses, giving the command to turn on the valves 5 and 6; At the same time, the signal log, I, is fed to the R input of the RS flip-flop 13, which is transferred to another stable state signal with a log. On the output blocking the supply of control pulses to turn on the valves 7 and 8, When one of the valves 5 and 6 is turned on (moment 11), the closing circuit C is formed - one of the valves 7 ,. 8 - one of the valves 5, 6 - zero wire. And

Neither l (FIG. 26) will have an inductance-like character and will cause a quick shut-off of the corresponding valve 7 or 8 at the moment the zero current closes ij (time t, j),

The voltage across the capacitor at this moment will be U | and Idr - Uco / 2. (by analogy with switching processes in compensating converters) Next, the voltage on the capacitor U and the corresponding phase voltage of the supply mains (moment t e) is equalized, while the loop-phase resistance of the supply mains is used as the natural damping resistance ( resistance of wires, power supply transformer, switching resistances of switching devices ...).

The total switching time is 2 -10 ms (depends on parameters from the network).

In the case of switching from a triangle to a star in a three-phase capacitor battery according to the proposed algorithm, each phase capacitor will switch. The capacitor unit will consist of three independent units shown in FIG.

Thus, due to the proposed sequence of operations, the switching speed of the capacitor battery is improved, reducing

With the duration of the period of deficiency of reactive power, the power losses are reduced.

Claims (1)

Invention Formula The method of switching a capacitor battery from linear to phase voltage by means of controlled gates by switching them alternately from including, with, l and h and y - higher purpose neither speed, first turn on the phase valves at the moment of equality of the instantaneous voltage on them to their amplitude value, then turn off the linear valves at the time of the subsequent first current transfer to them through zero. and. WITH