Operation of a five-level current source converter based PV power plant as a STATCOM

In this paper, two control strategies based on space vector modulation (SVM) technique are developed for a five-level current source converter (CSC) based STATCOM. In case of control strategy-1, DC-link currents are kept constant, and the reactive power is varied by changing the modulation index. On the other hand, in case of control strategy-2, DC-link currents are varied in accordance with reactive power requirement, keeping the modulation index constant. Therefore, in case of control strategy-2, losses reduce when the converter feeds smaller amount of the reactive power. Whereas, the control strategy-1 exhibits faster dynamic response to the changing reactive power commands compared to that in control strategy-2.