SU1758684A1 - Controllable three-phase reactor - Google Patents

Abstract

Usage: in industrial and special AC networks for controlling reactive power. The invention: the device contains a main three-phase winding located in the grooves of the outer and inner parts of the cylindrical magnetic conductor of electrical steel sheet, installed with one gap relative to the other, and an additional three-phase winding connected in parallel with the main winding. One of the windings is connected to a star without a neutral wire, the other is connected to a triangle. The coils of both windings are located in the slots of one part of the magnetic circuit and are shifted in space by an angle of 30 °. Each coil of both windings is provided with a group of anti-parallel thyristors. The device has an increased electroscopic effect and reduced losses due to the low level of harmonic components of the current. 2 sludge. THX

Description

The invention relates to electrical engineering, in particular, to devices for controlling reactive power in three-phase AC networks.

A three-phase controlled reactor is known that contains a cylindrical magnet duct consisting of two parts — an external and an internal, the inner part of which is enclosed by a control winding (biasing), and a three-phase winding is placed in the grooves of the outer part of the magnetic circuit; consisting of two series-connected parts.

A three-phase controlled reactor is also known, consisting of a cylindrical laminated magnetic circuit with end plates and grooves in which an equal number of coils with a larger and smaller number of turns are located.

Regulation of the inductive reactance of the reactors is achieved by changing the magnetic permeability of the magnetic core by changing the magnitude of the bias current.

The disadvantages of the known reactors are the complexity of the design and construction of the magnet pipeline; large losses during magnetic biasing due to the appearance of higher harmonics in the magnetic flux curve; big time of transition from one mode to another.

The closest to the proposed one (selected as a prototype) is a controlled reactor with a rotating magnetic field, which consists of two parts inserted one into another:

V SL 00 O 00 4

stator and internal - the rotor, On the outer part of the magnetic circuit is located the working winding of alternating current. A DC winding is wound on the inside. By changing the current in this winding, the magnetic permeability of the rotor changes, which, in turn, changes the inductance of the reactor, therefore, the current in the working winding and the reactive power consumed.

The main disadvantages of such a reactor are large inertia (the transition from one mode of operation to another takes place for tens of periods of the power supply frequency), large losses due to bias and higher harmonics in the reactor flow.

The purpose of the invention is to increase the speed, decrease the content of higher harmonics and the losses of the three-phase reactor controlled by thyristors.

The goal is achieved by the fact that in the proposed reactor, which has magnesium. The two-part cylindrical shape (internal and external), between which a non-magnetic gap is formed, instead of one, two three-phase AC windings are installed, which are located in the grooves of the internal or external part of the magnetic circuit, and to regulate the reactive power instead of the constant winding current (magnetization) are used connected in series with the windings of counter-parallel connected thyristors, with one winding with the thyristors connected in a triangle pattern, and the other in C In a star without a neutral wire, the inductance of a delta-connected winding is three times greater than the inductance of a winding connected in a star, and there is a spatial angle shift between the axes of the winding coils of the like phases (for example, between the phase AB of the triangle and the phase A). 30 °. This arrangement of the coils of the windings of the same phases provides a shift of the magnetic flux by 30 ° and compensation in them of higher harmonics, multiples of 5 and 7.

FIG. Figure 1 shows the connection diagram of a reactor controlled by thyristors; in fig. 2 - dependence of current non-sinusoidal factor on the angle of thyristor control Kn.s. f («) (where Kn.s is the non-sinusoidality coefficient; a is the angle of thyristor control).

The circuit (Fig. 1) contains six coils located in the slots of the magnetic circuit of a cylindrical structure and connected in series with anti-parallel-connected thyristors. Coils L D and tristors I are connected in a triangle pattern, and coils 1. D and tristors II in a star circuit without zero output.

Unlike magnetizable ones, the proposed reactor does not contain a bias winding, but has only AC windings. The coils of the windings are located in the slots of either the outer or the inner part of the magnetic circuit. A non-magnetic gap is formed between them.

Coil windings connected, for example, f. measures in a triangle (star) are arranged so that between them a shift in the space of 120 ° is formed.

For maximum compensation of the higher harmonics of the coil Di I, Q is calculated from the conditions of equality of the phase currents of the triangle and the star, and this condition is satisfied when

25

WA WA

 ST,

where W d - the number of turns of the winding of the triangle;

W is the number of turns of the winding star.

The proposed device works as follows.

When applying to the thyristors l (ll) control pulses through the coils D (Lfi current flows. In the case of the thyristor control angle, the magnitude of this eye can be changed, and, accordingly, the reactive power consumed by the device.

The scheme has a high speed (the transition from one mode to another takes less than one half-period) and small distortions (the non-sinusoidality coefficient does not exceed 2% (Fig. 2).

The proposed controlled three-phase reactor provides an economic effect by reducing the loss of active power and can be used in industrial and special networks of alternating power.

Current Formula of the Invention Three-phase controlled reactor containing a cylindrical magnetic conductor of electrical steel sheet, consisting of two parts, internal and external, each installed with a gap relative to the other, the main three-phase winding located in the slots of one of the parts of the magnetic circuit, characterized in that in order to increase speed and reduce losses, the reactor is equipped with thyristors and an additional three-phase winding, one of the windings is connected into a star without neutral wire, the other is connected to a triangle nickname, additional winding is connected in parallel to the main winding, coil of additional winding

shifted in space at an angle of 30 ° relative to the coils of the same phases of the main winding are located in the same part of the magnetic circuit as the coils of the main winding, and a group of anti-parallel connected thyristors is connected to each coil of both windings.

And about

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kn.s. ° f °

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2Q SO 40 50 60 70 80 90 FIG. I

Claims (2)

Claim A three-phase controlled reactor containing a cylindrical magnetic circuit made of sheet electrical steel, consisting of two parts - internal and external, installed with a gap one relative to another, the main three-phase winding located in the grooves of one of the parts of the magnetic circuit, characterized in that, in order to increase speed and loss reduction, the reactor is equipped with thyristors and an additional three-phase winding, one of the windings is connected to a star without a neutral wire, the other to a triangle, an additional winding and it is connected in parallel to the main winding, the coils of the additional winding are shifted in space by an angle of 30 ° relative to the coils of the same phases of the main winding, located in the grooves of the same part of the magnetic circuit as the coils of the main winding, and a group of counter-parallel connected thyristors is connected to each coil of both windings . Figure 1 FIG. 2.