The safe operation of grid connected power converters during abnormal condition is a key issue in order to guarantee its operation and to avoid undesired trips. In this paper different control strategies for the operation of a D-STATCOM are introduced, where the reference currents are determined in such a way that not only none of the phase currents goes over the limits, but also the DC voltage fluctuations remain in safe operation limit. Fluctuating active power interchange, during unbalanced condition leads to DC voltage oscillation. Severe unbalanced condition and small DC capacitor selection (to meet the size and cost constraints) intensify the DC voltage oscillation. Therefore, the contribution of this paper lays on the combination of the DC voltage oscillations and the current limit control. The effectiveness of three proposed control strategies are verified by simulating a D-STATCOM tied to an industrial distribution network. Moreover a scaled scenario has been reproduced experimentally which shows that the results cope well with the analytical equations and the simulation results.

Peer Reviewed