Control system for power conversion system

摘要

A control system for a power conversion system composed of a plurality of power converters, each of which is connected between one of a plurality of AC power systems and a DC line to exchange an electric power between them, respectively. The control system is composed of a plurality of control units, each of which includes units for detecting an AC current flowing between the AC power system and the power converter, an AC voltage of the AC power system, and a DC voltage of the power converter, and a unit for detecting an active power and a reactive power exchanged between the power converter and the AC power system. Each of the control units further includes an active power control unit for generating an active current command so that the DC voltage drops with the increase of one of the active power and a DC current, a unit for setting a reactive power reference, a reactive power control unit for comparing the reactive power reference and the reactive power to obtain a reactive power difference and for generating a reactive current command so as to bring the reactive power difference close to zero, a current control unit for generating a plurality of output voltage commands so as to coincide the AC current to the active and reactive current commands, and a gate control unit for switching the semiconductor switching devices in the power converter based on the output voltage commands.