Robust Universal Droop Control for Multi-paralleled VSCs in High PV Penetrated DC Microgrids

With the proliferation of PV generation, dc microgrid has attracted extensive attention because of its high flexibility and efficiency. For high PV penetrated dc microgrids, the instability issues caused by the external impedance become the key bottleneck for efficiently integrating and utilizing PV generations. In this paper, a detailed and systematic model of universal droop control-based voltage source converters (VSCs) considering instantaneous power of ac- and dc-side is derived, especially in high frequency range. The formulated model can effectively guide the design and implementation of subsequent control strategies to cope with the instability issues caused by external impedances. The stability of the formulated model is theoretically analyzed and demonstrated. The accuracy of the formulated model and the effectiveness of the corresponding robust control strategy are validated in time-domain PSCAD/EMTDC platform.