Method for Suppressing Circulating Current in Modular Multilevel Converter for High Voltage Direct-Current Transmission

摘要

Provided is a method for suppressing a circulating current in a modular multi-level converter for a high voltage direction-current (HVDC) transmission system. The HVDC transmission system converts an alternating current (AC) into a direct current (DC) and vice versa, transmits energy using a DC cable, and including a modular multilevel converter generating a high voltage source by stacking a plurality of sub-modules in series. In the circulating current suppression method, a circulating current (i_diffj; j=a,b,c) of a,b,c phase in an abc 3-phase stationary reference frame, a DC current (i_dc) flowing in a DC cable, a current reference value (i*_dc) of a DC component that needs to flow in the DC cable are inputted. The circulating current (i_diffj) of the a,b,c phase is controlled to become zero. A compensation value (V*_diffj) for suppressing a harmonic component of the circulating current is outputted.