SU758109A1 - Device for regulating three-phase ac voltage and direct current - Google Patents

Description

The invention relates to electrical engineering, in particular to converter equipment, and can be used, for example, in devices for regulating and stabilizing the voltage or current on the load, the value of which is variable.

A device for regulating three-phase alternating voltage and current is known, containing for each phase a load and a C-string from a linear choke and a capacitor, tuned in resonance and connected-. _ GOVERNMENTAL with the input terminals ^e thyristor device through the corresponding key, and conclusions kondensatorovIS -chain are connected to output terminals devices [1], £ 2] and [3]. 20

The main disadvantage of the known device is the presence of higher harmonics of voltage and current, of the order of three, in the input and output circuits of the device, which can only be eliminated by means of filters of higher harmonics in each phase.

The aim of the invention is to improve the energy performance of the device by improving the harmonic ... m

the composition of the current and voltage consumed without introducing additional filters of higher harmonics.

This goal is achieved by the fact that the EC-chains are connected in triangle, the vertices of which are formed by common points of connection of the linear choke and capacitor of this and adjacent phases, respectively, and are connected in phase with the input terminals of the device via thyristor switches.

At the same time, to obtain a sinusoidal shape of the load current with a wide range of its regulation, the output terminals of the device of each phase are connected to the terminals of the capacitors of the corresponding EC-chain via an additional linear choke, the phase windings of which are connected according to each other.

The drawing shows the electric circuit of the device, where 1, 2, 3 thyristor keys; 4, 5, 6 and 7, 8,

9 - linear chokes and capacitors

EU chains, respectively; 10, 11, 12 - loads of phases A, B, C, respectively; 13, 14, 15 - phase windings

additional linear choke;

3

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four

16, 17, 18 - input terminals of the device.

The principle of operation ^ device consists of (as follows.

When the switching angle of the thyristor switches 1, 2.3 is changed, the effective value of the line voltages applied to the EU-connected chains, consisting of Line chokes 4, 5, 6 and capacitors 7, 8, 9, changes, respectively.

As a result, voltage or current is controlled in loads 10, 11, 12 connected in parallel to the respective capacitors.

7, 8, 9.

If the above EU chains are set to resonate at the frequency of the mains supply, then the effective value of the load current in each phase at the switching angles of the thyristor switches 1, 2,

3, slightly different from zero, remains almost constant, and then decreases with an increase in the specified angle and, with the thyristor switches turned off completely, is equal to zero.

If the CA is a chain. Tuned to resonance at frequencies higher than the frequency of the mains supply, then with an increase in the opening angle of the thyristor switches 1 ,.

2, 3 output voltage, first increases to a certain maximum value, and then decreases and equals zero when the thyristor switches are turned off.

In both modes of operation of the device, the EC-chains play the role of higher harmonic filters arising from the phase-pulse regulation.

At the same time, thanks to the inclusion of the EU chains in a triangle, there is a closed loop for a higher order, a multiple of three, which ensures a sufficiently effective filtering of the latter in the load chains 10, 11,

12 bypass capacitors 7,

8, 9, and also leads to the absence in the circuits of these loads of the component voltages from zero-sequence currents.

The device can be structurally performed in various ways, including to reduce the number of reactive elements and improve the weight-dimensional indicators linear chokes 4, 5, 6 are performed on one three-rod symmetric core and windings 4, 5, 6, at the same time. located on its different rods, include according to each other.

If necessary, a wide range of current regulation loads and maintain its sinusoidal shape in series with loads 10,

ten

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thirty

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11, 12, each phase can be connected to the winding 13 (14, 15) of an additional linear choke (as shown in the drawing), all the windings of which 13, 14, 15 include according to each other.

Claims (3)

Claim A device for controlling three-phase AC voltage and current, containing for each phase of the load (. From the chain of a linear choke and capacitor tuned to resonance and connected to the input terminals of the device through an appropriate thyristor switch, and the terminals of the EU capacitors are phase-connected to the output terminals device, characterized in that, in order to improve energy performance by improving the harmonic composition of the consumed current and voltage, the EU-chains are connected in a triangle, the tops of the cat They are formed by common points of connection of a linear choke and a capacitor of this and adjacent phases, respectively, and are connected in phase to the input terminals of the device via thyristor switches. 2. The device according to claim 1, characterized in that the windings of the linear chokes of each phase are placed on a common three-core symmetric core and are connected according to each other. 3. The device according to claim 1, characterized in that, in order to obtain a sinusoidal waveform of the load current with a wide range of its regulation, the output of the device of each phase is connected to the terminals of the capacitors of the corresponding BS-chain through an additional linear choke, the phase windings of which are included according to each other.