SU1480016A1 - Reactive power controller - Google Patents

Abstract

The invention relates to the power industry and can be used to increase the power factor of electric machines and static converters in industrial installations to reduce oscillations and control voltage in the power systems of arc furnaces. The goal is to simplify and improve the weight and size characteristics. The voltage is applied to two three-phase systems of primary windings of phase-turn transformers, one of which is connected in a triangle, to the vertices of which the phases of the other system are connected. The number of turns of these windings provides phase shifts of the output voltage relative to the supply (for the first transformer 0 °, for the second 80 °, for the third 160 °) due to the inclusion of controlled gates in a bridge circuit. The input alternating voltage of each phase is applied to the corresponding inputs of the bridge. By switching the valves from the linear and phase voltages, the output voltage of the frequency multiplier is generated. A positive half-cycle of the output voltage at the output of the frequency converter is formed by alternating the supply of unlocking pulses. 4 il.

Description

00

one

The invention relates to power engineering, is intended for reactive power in power grid networks and can be used to increase the power factor of electric machines and static converters in industrial installations, to reduce fluctuations and control voltage in electrical power systems for arc furnaces in electric power networks.

The purpose of the invention is to simplify and improve mass and dimensional characteristics.

On f, g. The schematic diagram of the device is presented in FIG. 2 is a vector diagram of voltages, as shown in Fig. 1, 3, curves explaining the principle of frequency multiplication; in fig. 4 - curves, explaining the principle of obtaining the output voltage of the device.

A device for adjusting reactive power (Lxg. 1) contains phase-shifting, 2 and 3 and isolating 4 transformers, a three-phase frequency multiplier, consisting of three single C

phase multipliers 5,6 and 7 frequencies, the inputs of which are connected to the secondary windings of phase-turning transformers, three-phase SHGCHK (direct frequency converter with natural switching), consisting of three 8.9 and 10 single-phase OGCHE, whose outputs are connected to the primary windings of the insulating transformer Torah. The primary windings of the phase-shifting transformers and the secondary windings of the isolation transformer are connected to the Vf, V2, V3 buses of a three-phase AC system, and the outputs of the frequency multiplier are connected to the GICHE passes.

The device works as follows.

Voltage with angular frequency w s. busbar V (, V, V3 falls on two three-phase primary windings of phase-turn transformers 1,2 and 3, one of which is connected in a triangle, to the vertices of which the corresponding phases of the primary windings of the other system are connected. The primary obdogok systems are made with a different number of turns. In this case, each phase of the system of output voltages obtained in the system of secondary windings connected into a star is synthesized by geometrically summing the voltages of the corresponding phases of the primary windings. The vector diagram of the voltages shown in Fig. 2. The number of turns of the primary phase windings of transformer transformers was selected in a sufficient manner to provide phase shifts of the output voltage relative to the power supply for the first transformer 0e, for the second transformer 80 °, for third-transformer 160e. These voltages are fed to the inputs of frequency multipliers 5.6 and 7. Each phase of the frequency multiplier consists of three identical power circuits, therefore, we consider their work using the example of power circuit 7 (Fig. one). This circuit consists of a pole nadpati controlled valves 7.1-1.7b, connected by a bridge circuit. The two alternating voltages of each phase are 1. L, 1 .B, 1 .C and their common output 1.N is applied to the corresponding hole of the bridge. Such a connection allowed to synthesize the output voltage cleverly / Mi gel frequency for the account

Q $

0 5 0, 0. -,

0

appropriate valve switching from linear and phase voltages. The principle of forming the complete curve of the output voltage of the frequency multiplier is shown in FIG. 3. In spite of the blind connection of all sixteen forming valves 7.1-7.16, a short circuit mode does not occur in the circuit, since during the formation of the output voltage, the valves are unlocked in turn so that switching takes place either between the valves belonging only to the anode or cathode valve groups, or between valves of different groups, but connected to the same phase. With this method of synthesis of the curve, the frequency of the output voltage of the multiplier is 1.5 times higher than the frequency of the input voltage. The output voltages of the multiplier power circuits are shifted relative to each other by 120 °. Such a shift occurs due to the fact that the phase shift introduced by phase shifting transformers 1, 2 and 3 increases at the output of the frequency multiplier 1.5 times and for the power circuit 5 it will be 80 ° 1.5 120 °, and for the power circuit Chain 6 will be 160 ° 1, 5 240 °. The ratio between the mains frequency and the frequency at the output of the frequency multiplier and), / 1, 5, and 2/3, which allows using the FPE 8, 9, and 10, connecting them to the outputs of the frequency multiplier, to generate a voltage with an output angular frequency of equal to the input angular frequency FPE 8, 9, and 10, as well as frequency multipliers 5,6 and 7, consist of three identical power circuits. The FPE 10 power circuit consists of twelve controlled valves 10.1-10.12, connected via a bridge system. The positive half-cycle of the output voltage is formed when alternately supplying unlocking pulses to the valves 10.1-10.6 negative when applying unlocking pulses to the valves 10.7-10.12. Alternately, the operation of the valves of these groups leads to the fact that the output of the converter 10 produces an output voltage, the principle of the formation of which is shown in FIG. 4. Outputs of the FPE 10 are connected to an isolating transformer. 4. The FPE 10 is controlled in such a way that the generated angular

output frequency uia is equal to angular i

the input frequency, the desired components of the output voltage are in phase with the corresponding system voltages. The direction and magnitude of the reactive power flux is altered by varying the amplitude of the output voltages of the napps 8, 9, and 10. Thus, HIT-IE will consume the lead current from the AC system when the amplitude of its desired output voltages is greater than system, and, conversely, it will consume the lagging current when the amplitude of its desired output voltages is less than the amplitude of the system voltages.

When comparing more traditional types of static sources of reactive power, from which you use shunt capacitors and reactors together with thyristor keys, as well as a high frequency base, the device has the advantage of being smaller and less expensive, because it lacks reactive elements. There is also no need to connect large capacitor batteries directly to the AC network and, therefore, possible issues related to the resonance of such batteries with the AC network. In addition, the output currents are slightly distorted and require

little or no filtering at all.

Claims (1)

Invention Formula five A device for regulating reactive power, containing an isolation transformer with three primary windings and a system of triangular triangles connected in a triangle, phase-shifting transformers according to the number of phases with two systems of primary windings, one of which is connected in a triangle, 15 to the vertices of which with one ends are connected the corresponding windings of the second system, which with their other ends are connected to the network, and the secondary windings of the isolating transformer, and with one system of secondary windings connected in a star with an output neutral, a frequency multiplier and a direct frequency converter, about T is 25 the fact that, in order to simplify and improve the mass-dimensional characteristics, the secondary windings of each phase-turning transformer are connected to the corresponding inputs of the multiplier Astro, the output of which is connected to the input of the direct frequency converter, the outputs of which are connected to the corresponding phases of primary-1 op. insulating transformer windings. (Reg. 2 Rig.Z Figm