SU1674092A1 - Device for controlling a capacitor unit - Google Patents

Abstract

The invention can be used in discrete power control devices of capacitor units with semiconductor switches. The purpose of the invention is to simplify the device and increase its reliability. For this, the device is equipped with a recharge unit consisting of an inverter 4, a member of the BANCH 5, a frequency divider 7, a single vibrator 8, which allows you to simultaneously recharge and recharge the capacitor battery 11. The permission to turn on the switch 1 is controlled by a null indicator 2 by means of which the switching of the battery is carried out at the time of equality of the supply voltage and the residual voltage of the capacitor, i.e. with minimal current spikes. Resampling capacitors is carried out to increase their reliability. 1 il.

Description

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The invention relates to electrical engineering and can be used in devices for discrete control of reactive power of capacitor plants with semiconductor switches.

The purpose of the invention is to simplify the device and increase reliability.

FIG. 1 shows a functional diagram of the proposed device; in fig. 2 - timing diagrams of signals at the outputs of individual units of the device.

The device contains a switch 1 on bipolarly connected thyristors and a zero indicator 2, the outputs of which are connected to the power inputs of switch 1. The output of the zero indicator 2 is connected to the second input X2 of the FM element and the input of the inverter 4, whose output is connected to the forward input of the element 5 ban. The inverse input of the prohibition element 5 is connected to the first input X1 of the IZ element and to the terminal b for connecting a source of control voltage. The input of the frequency divider 7 is connected to the output of the prohibition element 5, and the output is connected to the input of the one-shot 8. One input of the element OR 9 is connected to the output of the element AND 3, and the other to the output of the one-shot 8.

The input of pulse generator 10 is connected to the output of the element OR 9, and the output is connected to the control input of switch 1. Switch 1 is connected in series with a capacitor battery 11 The supply voltage is connected to terminals 12, 13.

The device works as follows.

Suppose that the control voltage Uy is connected to the terminal b, to the terminals 12-13 - the supply voltage, the thyristor switch 1 is turned on. Then the voltage on the capacitors is equal to the sinusoidal voltage of the power supply network (Fig. 2a), the output of the null indicator retains the signal 1 (Fig. 2d).

When the control voltage Uy is removed at time ti (Fig. 2c), the output of element 3 and element 9 (figure 2c) is set to 1, which prohibits the impulse control from pulse generator 10 to switch thyristors 1 at the moment of transition the current in switch 1 is zero (time t2), the thyristors of switch 1 are closed and O appears at the output of the null indicator, which is inverted by inverter 4 and fed to the direct input of prohibition element 5. Since at the inverse input of prohibition element 5, the control voltage Uy corresponds to O, then at the output of prohibition element 5 a signal appears

1. whose duration is determined by the moments of supplying the control voltage Uy and the occurrence of pulses at the output of the null indicator 2.

FIG. Figure 2 shows the case where the recharge of the capacitor battery 11 takes place after two periods of supply voltage. In this case, the frequency divider 7 divides the pulse frequency from the output of the prohibition element 5 into n 2.

At the moment of occurrence of the (n - 1) -th (in this case, n - 1 1) pulse at the output of the null indicator 2 (time rh), the front of the pulse is formed at the output of the frequency divider 7, the falling edge of which is formed at the time of the appearance of th pulse at the output of the zero-indicator 2 (time m). A pulse from the output of the frequency divider 7 is fed to the input of the one-shot 8. which is triggered on the falling edge of the specified pulse (time t4). At the output of the one-vibrator 8 a pulse is formed (Fig. 2 g), the duration of which is not less than the time required to turn on the thyristors of the switch 1 Under the action of a pulse from the one-vibrator 8, a similar pulse appears at the output of the OR 9 element (Fig. 2h), allowing short-term supply of control pulses for switching on the thyristors of switch 1. Switch 1 turns on and connects the capacitor battery 11 to the power supply for half a period of supply voltage. At the moment the current in the switch 1 passes through zero, the switch disconnects the capacitor battery 11 from the network (time ts) with a change in the polarity of the voltage across it. Further, the circuit operation is repeated (at the moment te) the subsequent recharging of the capacitor battery is performed.

With the subsequent occurrence of voltage Uy at the output of prohibition element 5 is set O (time t, fig. 2e), suspending the operation of the recharge circuit at the output of the element IZ at the time of appearance of the pulse at the output of the zero indicator (time ta. ) set 1, which is supplied to the element OR 9, (FIG. 2, h) allowing the pulse shaper 10 to work. The thyristors of the switch 1 are turned on by performing a non-impact connection of the capacitor battery 11 to the network.

The number n by which the frequency divider 7 divides the pulse frequency from the null indicator 2 is determined by the allowable reload period T p. Tc, where Tc is the period of supply voltage. At the time of reloading, it is simultaneously carried out.

change in the polarity of the residual voltage on the capacitor and its charge to the amplitude value of the supply voltage. Due to the null-indicator 2, the capacitor battery 11 always switches when the supply voltage and the residual voltage on the capacitor are equal, i.e. with minimal current surges.

Thus, the proposed device, which is simpler known, allows for unstressed connection of capacitors and a periodic change in the polarity of the voltage on the disconnected capacitors, which increases the reliability of the capacitor plant.

Claims (1)

Apparatus of the Invention A device for controlling a capacitor unit, comprising a pulse shaper, the output of which  five connected to the control input of the switch, and the input to the output of the element ILI, one input of the element OR connected to the output of the element I. The first input of which is connected to the terminal for connecting the source of the control voltage and the inverse input of the inhibit element, in order to simplify and increase reliability, a null-indicator is introduced into it. an inverter, a frequency divider and a one-shot, the output of which is connected to another input of the OR element, and the input is connected to the output of a frequency splitter, the input of a frequency splitter is connected to the output of an inhibiting element, whose direct input is connected to the output of the inverter, the input of the inverter and the second input of the And element with the output of a null indicator, the inputs of which are connected to the power inputs of the switch. t7t8 Phage.2