CIRCULATING CURRENT CONTROL IN A MODULAR MULTILEVEL VOLTAGE SOURCE CONVERTER

摘要

A modular multilevel voltage source converter and a method and computer program product for handling circulating currents in such a modular multilevel voltage source converter are described. A control unit of the voltage source converter determines a circulating current control signal contribution (E_R1−E_R2+2V_CM) for a phase leg based on the sum of cell voltages in the upper phase arm of the phase leg, the sum of cell voltages in the lower phase arm of the phase leg and at least one modulation reference and combines the circulating control signal contribution with a modulation reference used for one of the phase arms in order to obtain a modified voltage reference for controlling the phase arm to handle a circulating current while a waveshape is formed.