PROJECT TITLE :

Arm Balancing Control and Experimental Validation of a Grid Connected MMC with Pulsed DC load - 2017

ABSTRACT:

This paper focuses on the operation of a grid-connected modular multilevel converter (MMC) supplying a pulsed dc load. The goal is to attain minimum ac power fluctuation despite the high power fluctuation present on the dc aspect. The MMC has been selected for its inherent ability to decouple ac and dc current controllers. However, if no additional provisions are taken, the pulsed load causes imbalance of cell capacitor voltages between higher and lower arms in every section. This paper presents the theoretical analysis of the imbalance problem and proposes a straightforward arm-balancing controller to enable the operation of the converter below pulsed dc load. The effectiveness of the controller has been successfully verified on a 7 kW MMC experimental prototype with a three kA pulsed dc load.