SU907692A1 - Device for smooth regulation of reactive power - Google Patents

Description

The invention relates to a conversion technique and is intended to control reactive power in compensating systems.

A device for compensating reactive power, containing two controlled valves connected in parallel, a capacitor connected in series with these valves, and a pulse regulating device connected in parallel with capacitors and providing fast re-charge of the capacitor with a short current pulse of high power [1].

The disadvantage of this device is the high power of the current pulses at the output of the regulating device, due to the amplitude value of the mains voltage, the capacitance of the capacitors and the rate of change of voltage when charging the capacitors, which creates large energy losses.

The purpose of the invention is the reduction of energy loss.

This goal is achieved in that a device for smooth regulation of reactive power, containing a main capacitor, psdConnected to the network through oppositely connected thyristors, and a pulse generator, is equipped with 5 transformers, a reactor and an additional capacitor, the secondary winding of the transformer is connected between the first output of the anti-parallel connected thyristors and the first output of the main capacitor, a reactor is connected in parallel with it, and a generator is connected to the primary winding of the transformer pulse generator, and an additional capacitor is connected with one terminal to the second terminal .15 of the main capacitor, and the second, an additional capacitor terminal is connected to the second terminal of the in-parallel connected thyristors. At the same time, to lock the thyristors of the controller, it is enough to have current pulses with a power equal to

Ptoa ^{= and} kr · ¹ nt, calf = 2 Ц> г Л ы where where U ^ y, is the “voltage amplitude of the network” w is the network frequency; ^? thyristor shutdown time;

I _NT - the amplitude value of the current 30 load of the regulator.

In FIG. 1 shows a schematic diagram of the proposed device; in FIG. 2 - diagrams of voltages and currents.

A device for regulating reactive power contains thyristors 5 1 and 2 interconnected counter-parallel, a capacitor 3, a transformer 4 and a generator 5 of short rectangular voltage pulses. In this case, the secondary winding 4 of the transformer is connected in series to the circuit of thyristors 1 and 2 and is shunted by the reactor 7, and the primary winding is connected to the output of the generator 5 of rectangular voltage pulses 115. The input terminals of the controller are shunted by the capacitor 6, Reactor 7 eliminates the saturation of the core-transformer when current pulses flow through the thyristors. '20 In the initial state, the capacitor is discharged, and capacitor b is under voltage. At a point in time, a current pulse is supplied to the control electrode circuit of thyristor 25. 1. The triggering moment of thyristor 1 is selected in order to limit the inrush currents so that the voltage difference across capacitors 3 and 6 is minimal. At start-up, this is possible βθ at the moment when the mains voltage U _c has a value greater than zero. Then the unlocking of the thyristor 1 will cause the current i to appear in the circuit i _{with an} amplitude determined by the capacitance of the capacitor and the rate of change of the mains voltage at the moment the control current pulse is applied, and the capacitor 3 will charge to a voltage close to the mains voltage.

At the time point from the output 40 of the generator 5, a voltage pulse U _{K of a} rectangular shape of a positive sign is supplied through a transformer 4. In this case, the voltage on the thyristor 1 becomes negative and 45 it turns off. Moreover, for even locking of the thyristors, it is necessary that the voltage pulse duration U _K be longer than the turn-off time of thyristor 1, and its amplitude exceed jq exceed the critical value.

At time 1 _{3, the} control pulse iy ^ is supplied to the circuit yn> of the equalizing electrode of thyristor 2. The moment of supply of the current pulse to control thyristor 2 should be selected so that the voltage at its anode has a small positive value. When the thyristor 2 is unlocked, the processes in the controller proceed similarly to the processes during operation of the thyristor 1. At the time moment from the output of the generator 5, a voltage pulse of a rectangular shape with a negative sign is supplied through the transformer 4. In this case, the voltage at the anode of thyristor 2 becomes negative and it turns off.

The proposed implementation of the device for smooth regulation of reactive power provides a decrease in the power of the current pulse at the output of the control device ^{in wt} e, bti < ^pa3

Claims (2)

FIG. 1 is a schematic diagram of the proposed device; in fig. 2 - voltage and current diagrams. A device for controlling reactive power contains thyristors 1 and 2 interconnected anti-parallel, capacitor 3 transformer 4 and generator 5 short rectangular voltage pulses. In this case, the secondary winding 4 of the transformer is connected in series to the circuit of thyristors 1 and 2 and is shunted by reactor 7, and the primary winding is connected to the output of the generator 5 of rectangular voltage pulses. The input terminals of the regulator are bridged by capacitor 6, Reactor 7 eliminates saturation of the transformer core during the flow of current pulses through the thyristors. In the initial state, capacitor 3 is discharged, and capacitor b is under network voltage. At time t, a current pulse i is supplied to the control electrode circuit of the thyristor 1. The moment of unlocking the thyristor 1 to limit current surges is chosen so that the voltage difference across the capacitors 3 and b is minimal. During start-up this is possible at the moment when the mains voltage has a value greater than zero. Then unlocking the thyristor 1 will cause the amplitude determined by the capacitance of the capacitor 3 and the rate of change of the mains voltage at the moment of supplying the control current pulse capacitor 3 to a voltage close to the magnitude of the network. At time tj. From the output of the generator 5, a voltage pulse U of a rectangular positive sign is applied through the transformer 4. In this case, the voltage on the thyristor 1 becomes negative and it turns off. In this case, for even shutdown of the thyristors, it is necessary that the voltage pulse duration be longer and the thyristor 1 is turned off, and its amplitude exceeds a critical value. At time t, the pulse rofta of control i is supplied to the circuit of the control electrode of the thyristor 2. The moment of applying the current control pulse of the thyristor 2 must be chosen in such a way that the voltage at its anode has a small positive value. When the thyristor 2 is unlocked, the processes in the controller proceed similarly to the processes during the operation of the thyristor 1. At the time t from the output of the generator 5, a voltage pulse Ui is applied through the transformer 4. rectangular negative sign shape. In this case, the voltage at the anode of the thyristor 2 becomes negative and it turns off. The proposed implementation of a device for smooth adjustment of reactive power provides a reduction in the power of the current pulse at the output of the regulating device in wt yKp33. Apparatus of the invention for smoothly adjusting reactive power, containing a main capacitor connected to a network via anti-parallel connected thyristors and a pulse generator, characterized in that, in order to reduce energy losses, it is equipped with a transformer, a reactor and an additional capacitor, the secondary winding of the transformer connected between the first terminal of the anti-parallel connected thyristors and the first terminal of the main capacitor, the reactor is connected in parallel with it, to the primary ke transformer connected pulse generator, and an additional capacitor connected by one terminal to the second terminal of the main capacitor, a second terminal connected to an additional capacitor second terminal of the anti-parallel connected thyristors. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 230959, cl. H 02 J 3/18, 1963.  fe N p 1 to l L-jl