SU1279029A1 - Device for controlling three-phase voltage - Google Patents

Abstract

The invention relates to the field of electrical engineering and is intended for. control of alternating three-phase voltage under load. The purpose of the invention is to reduce the nonlinear distortion coefficient of the output voltage. The device contains c. each phase controlled bidirectional keys 1 - 3, made in the form of groups of opposite-connected thyristors. Parallel to the controlled bidirectional key of each phase, the primary winding of the corresponding transformer 4-6 is turned on, the secondary winding of which is connected in parallel with the corresponding controlled remote key of the other phase. In this case, the beginning of the primary winding of one transformer is connected to the end of the secondary winding of another transformer. Load resistors 7-9 i are connected in series with controlled bidirectional switches and soy (Linena star-type circuit. Transformer windings (inductive elements) of each phase are phase-wise

Description

interconnected. Due to the fact that when changing the direction angle of the thyristor-shaped bidirectional switches, the inductive resistance of the transformer windings changes relative to each other, the instantaneous linear currents are equal and symmetrical, and

at the output of the device, the voltage will vary from the value of the mains voltage to the value determined by the inductive resistance of the transformer windings. This ensures the achievement of the goal, 2 hp, f-crystals, 2 ill.

one

The invention relates to a system for regulating electrical and magnetic quantities and is intended to control an alternating three-phase voltage under load.

The aim of the invention is to reduce the non-linear distortion factor of the output voltage.

Figs, 1 and 2 are examples of a specific implementation of the proposed device.

The device (FIG. 1) contains in each phase controllable bidirectional keys 1-3, made in the form of groups of opposite-connected tHristors. Parallel to the controllable bidirectional key of each phase, the primary winding of the corresponding single-phase transformer 4-6 is connected, the secondary winding of which is connected in parallel to the corresponding controlled bidirectional key 1 - 3 of another phase, with the beginning of the primary winding of one single-phase transformer connected to the end of the secondary winding of another single-phase transformer Ator. A load resistor 7-9 is included sequentially. directly with controlled bidirectional keys and connected according to the star,

In the device diagram (FIG. 2), the electrical connections between the windings of single-phase transformers are replaced by electromagnetic ones by combining the primary winding of one single-phase transformer with the secondary winding of another single-phase transformer and placing each formed winding 10-12 on one of the three-phase magnetic cores. The device (Fig, 1) works as follows.

If the control electrodes of the thyristors are controlled bidirectional keys 1 - 3 pulses supplied from the pulse-phase control circuit (SIFU) and the control angle is equal to zero, all current consumed by the resistors of the load 7-9 flows through the thyristors of the bidirectional control keys 1 - 3, The instantaneous linear currents are equal and symmetrical. An instantaneous line voltage is applied to the load resistors 7-9.

In the presence of control pulses and a certain angle of control of a large zero, the current consumed by the load flows through both the thyristors and the windings of the single-phase Transformers, for example, in the time interval when one of the thyristors controlled bi-directional keys. 1 is open, and the thyristors of the controlled bidirectional switches 2 and 3 are closed, the current from the phase through the thyristor of the bidirectional controlled switch 1 load resistors 7-9 of the winding of single-phase transformers 5 and 6 flows to the phases

8i C, Open thyristor shunts the primary winding of a single-phase transformer 4, as a result of which all three transformers 4-6 work in short circuit mode and, consequently, the resistance of their windings in phases B and C is almost zero. The instantaneous linear currents are equal and symmetrical. An instantaneous phase voltage is applied to the load resistors 7 9.

Claims (1)

In the absence of control thyristors, bidirectional control switches 1–3 are closed and the current consumed by the load flows through the windings of single-phase transformers, the inductive resistance of the windings of single-phase transformers limits the load current and, therefore, the voltage on the load-phase resistors 7-9. transformers are almost identical, instantaneous linear currents are equal and symmetrical. The device (figure 2) works analogously. If there are bi-directional control keys of 1–3 control pulses at the control electrodes of the thyristors and a control angle equal to zero, the instantaneous linear currents are equal and symmetrical, the instantaneous phase voltage of the network is applied to the load resistors 7–9. In the presence of control pulses of a certain control angle large zero, the included bidirectional control key shunts the corresponding winding of the transformer, in connection with which the inductive resistance of the other windings decreases. The instantaneous linear currents are equal and symmetrical. An instantaneous phase voltage of the network is applied to the load resistors. In the absence of control pulses, the bi-directional thyristors of the controlled switches 1 - 3 are closed and the current consumed by the load flows through the transformer windings 10-12 the load current and, therefore, the instantaneous voltage drop across the load resistors 7–9, Since the resistance of the windings 10–12 is almost identical, the instantaneous linear currents are equal and symmetrical. When the angle of thyristor control is changed, bidirectional controlled voltage switches at the output of both circuits (Figures 1 and 2) change from the value of the network voltage to the value determined by the inductive resistance of the transformer windings. Claims I. A device for regulating a three-phase voltage, comprising a regulator connected in phase between the input and output terminals and made in the form of controllable bidirectional keys, each of which is shunted by an inductive element: , in order to reduce the nonlinear distortion coefficient of the output voltage, the inductive elements of each of the phases are made phasewise interconnected, 2, The device according to claim 1, 1, about t l and that is used as inductive elements three single-phase transformer, the primary and secondary winding of each of | which are connected in parallel to a pair of controlled bidirectional keys of two respective adjacent phases of a regulating authority and are connected in opposite one another, 3, The device according to claim, about TL and so that windings located on the inductive elements are used adjacent magnetic cores, with the beginning of each winding connected to the input terminal of the regulator of the corresponding phase, and the end to the output terminal of the same phase. FIG. 2