Control equipment for high voltage direct current transmission system with equipment of self-commutated converter

摘要

A high voltage dc transmission system uses equipment of self- commutated converters each of which comprises switching devices with a self-commutating (gate-turn-off) function. A first control equipment associated with the rectifier comprises a constant reactive power (var) control circuit for holding constant the reactive power on the input side of the rectifier, and a constant dc voltage control circuit for holding constant the dc system voltage on the output side thereof. A second control equipment associated with the inverter comprises a constant reactive power control circuit for holding constant the reactive power on the output side of the inverter, and a constant active power control circuit for holding constant the active power on the output side thereof. The first control equipment and the second control equipment each have a current control circuit for making independent control of each component of a two-phase current resulted from transformation of a three-phase ac current.