RU2280934C1 - Method for reactive power correction device - Google Patents

Abstract

FIELD: power engineering; reactive power correction.

SUBSTANCE: proposed method for controlling reactive power correction device incorporating thyristor-reactor group, higher-harmonic capacitor-bank filters, and reactive-power static condenser built around fully controllable diodes includes measurement of voltage U across ac buses, its comparison with U_max and U_min settings, generation of control signals, and generation of harmonics in static condenser current in phase opposition to current harmonics of thyristor-reactor group detected during analysis.

EFFECT: twice as low power of thyristor-reactor group, enhanced efficiency of input reactive power control and higher harmonic filtration.

1 cl, 1 dwg

Description

Technical field

The invention relates to the electric power industry and can be used in reactive power compensation devices with a thyristor-reactor group (TEG).

State of the art

A known method of controlling a static reactive power compensator [1], which includes comparing the AC voltage with two settings corresponding to the maximum and minimum acceptable value of the mains voltage, and the formation of the reactive power level of the compensator depending on the comparison result.

A reactive power compensation system [2] is also known, which uses a static reactive power compensator based on fully controlled valves with pulse-width (PWM) modulation, the so-called STATCOM, and a capacitor bank controlled by thyristor switches.

There is a known method and device for compensating reactive power consumed by an industrial load [3], in which the TEG is controlled, in parallel with which higher-harmonic filter capacitor banks are connected. Method [3] adopted as a prototype.

The disadvantage of the prototype is the inability to turn off the condenser battery filters of higher harmonics in all modes of operation of the TWG due to a sharp deterioration in the quality of voltage after turning off the filters of higher harmonics. In this regard, the power of the TWG should be twice as high as the power of the higher harmonic condenser filter batteries with the same nominal value of the output and consumed reactive power.

SUMMARY OF THE INVENTION

The objective of the invention is to halve the power of the TWG and increase the efficiency of regulation of consumed reactive power and filtering higher harmonics.

The subject of the invention is a method for controlling a reactive power compensation device comprising a thyristor-reactor group, high-harmonic capacitor banks-filter capacitors and a static reactive power compensator on fully controllable valves (STATCOM), which measure voltage u at AC buses, compare the voltage u with the settings U _max and U _min , generate control signals, and when the voltage u exceeds the settings U _max disconnect the conden filter batteries of higher harmonics measure the values and phases of current harmonics in the thyristor-reactor group circuit and form harmonics proportional and antiphase to the measured harmonics in the current of the static compensator, and when the voltage u falls below the U _min setting, the thyristor-reactor group is _turned off and the capacitor Harmonic filter batteries.

This set of features allows to solve the problem of the invention.

The implementation of the invention

The proposed method implements a diagram of a device for reactive power compensation, shown in the drawing. The circuit contains substation AC buses 1, powered by AC network 2. Bus 1 is connected to the load 3 and through the transformer 4 feed bus 5 of the device for reactive power compensation. To buses 5 are connected: ТРГ 6, filters 7 of the highest harmonics with switch 8 and static compensator 9 of type STATCOM. A voltage transformer 10 is connected to the buses 1, the signal from which is supplied to the comparison unit 11. The output signals of block 11 are supplied to the control system 12 of the compensator 9 and to the control system 13 of the TRG 6. Systems 13 and 12 also receive signals proportional to the currents of the compensator 9 and TRG 6, respectively, from the current transformers 14 and 15.

Since the role of the compensator 9 is, in addition to the output (or consumption) of reactive power, also in compensating the harmonics of the current of the TRG 6, due to the corresponding influence on the control system 12 of the compensator 9, harmonics are created in its current that are out of phase to the harmonics of the current of the TRG 6. The number of these harmonics can be greater than the number of harmonics suppressed by the filters 7. The power of the compensator 9 can be determined mainly from the need to suppress harmonics and expand the range of regulation of reactive power.

The method is as follows.

When finding the voltage level u, issued by the transformer 10, within the range U _min <u <U _max, all devices 6, 7, 8 and 9 are turned on and operate in the mode of maintaining voltage u. If the voltage level u becomes higher than U _max , then a signal to turn off the switch 8 is supplied from the comparison unit 11 and, at the same time, a signal is sent to the control system 12 of the compensator 9. Upon receipt of this signal from the unit 11, the system 12 analyzes the phase and magnitude of the harmonics contained in the output the signal of the transformer 14, proportional to the current of the TRG 6, and, acting on the compensator 9, forms harmonics in its current that are out of phase to the harmonics of the current of the TRG detected in the analysis.

When the voltage level u drops below the U _min setting, from the comparison unit 11 a signal is issued to the control system 13 to turn off the TG and a signal to turn on the switch 8, which connects high harmonic filters 7 to the buses 5.

When the voltage u reaches a level exceeding U _min , a signal is sent from the block 11 to the control system 13 to activate the TWG.

Since when implementing the method, it becomes possible to turn off the filters 7 of the higher harmonics, the power of the TRG 6 can be reduced by half.

Information sources

1. USSR Copyright Certificate No. 1654918 A1.

2. Patent DE 3863951 D, 1991.

3. Patent EP 1318588, 2003.

Claims (1)

A method of controlling a reactive power compensation device containing a thyristor-reactor group connected in parallel to AC buses, capacitor banks - filters of higher harmonics and a static reactive power compensator on fully controllable valves, which measure the voltage u on the AC buses, compare the voltage u with the settings U _max and U _min , generate control signals, and when the voltage exceeds u the settings U _max disconnect the capacitor banks - filters of higher harmonics IR, measure the values and phases of the current harmonics in the thyristor-reactor group circuit and form harmonics proportional and antiphase to the measured harmonics in the current of the static compensator, and when the voltage u drops below the U _min setting, turn off the thyristor-reactor group and turn on capacitor banks - filters of higher harmonics .