Current source type phase modulator variable frequency starting commutation lead angle piecewise control method

Abstract

The invention provides a current source type phase modulator variable frequency starting commutation lead angle piecewise control method which comprises the concrete steps that a commutation lead angle of 30 degrees is used when a current source type phase modulator is started; commutation failure is judged through a detection system, the commutation lead angle of 30 degrees is maintained if the commutation failure is not detected, and the closest thyristor seamless switching time point t0 is found when the commutation failure is detected; and the commutation lead angle is switched to 60 degrees. The method is simple and convenient in practical application without redundant algorithm control; the problem of thyristor commutation failure can be effectively avoided, the starting efficiency of the phase modulator can be improved, the starting time can be shortened, the whole control process only needs one time of switching of the commutation lead angle and the redundancy of thyristor operation times can be avoided; and commutation lead angle piecewise control is used so as to have high practical engineering application value.

Description

technical field [0001] The invention belongs to the technical field of start-up of a condenser, in particular to a segmental control method of a phase-commutation lead angle for a current-source type condenser with a frequency conversion start. Background technique [0002] With the development of high-voltage direct current transmission, the problem of "strong direct current and weak AC" in the power grid has become more and more prominent. In areas where power sources are concentrated, there is a surplus of reactive power, and in areas where loads are concentrated, there is a shortage of reactive power. The problem of voltage stability has become increasingly prominent. Compared with reactive power compensation equipment such as SVC and STATCOM, as a synchronous rotating equipment, the condenser has the characteristics of strong overload capacity, wide reactive power compensation range, and strong voltage support ability. [0003] At present, the frequency converter is gen...

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Problems solved by technology

However, the rated voltage level of the currently used 300MVar condenser is 20000V, and the rated current level is 8660A. If IGBT devices are to be used in practical engineering applications, a multi-machine parallel structure must be used. However, on the one hand, the bridge arms The number of units is large, which is not conducive to the maintenance of the actual project. On the other hand, its cost is extremely high compared with thyristors

In the patent with the publication number CN101359875A, a multi-degree-of-freedom dynamic control method for the commutation lead angle of the inverter bridge started by static variable frequency is proposed, and a calculation formula for the commutation lead angle based on the motor frequency, DC current, and machine terminal voltage is proposed. The leading angle is dynamically controlled, and the calculation of this method is relatively complicated. In actual engineering, it is difficult to ensure that the inverter bridge commutation arc-extinguishing time mentioned in the patent is constant, and switching the inverter bridge commutation leading angle at any time during the start-up process will easily cause Redundant operation of thyristors at certain times

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