Unbalanced Voltage Compensation Control Strategy of Photovoltaic Considering Spare Capacity of Converters

With the rapid development of the photovoltaic (PV), making full use of the spare capacity of PV converters to remedy the unbalanced voltage problem is becoming a promising idea. In this paper, a dual-module based asymmetrical voltage compensation strategy is developed for PV converters to utilize the spare converter capacity as needed. By means of the positive/negative-sequence dual-module design, the proposed control strategy can mitigate the negative voltage and provide the reactive power to improve the overall PCC voltage. A power constraint factor based on the instantaneous power theory is introduced to flexibly adjust the converter power within the converter capacity. Effectiveness of the proposed strategy is verified by simulations on PSCAD/EMTDC platform.