A Cost-Efficient Virtual Synchronous Generator System Based on Coordinated Photovoltaic and Supercapacitor

Virtual synchronous generator (VSG) control is widely adopted in grid-connected inverters owing to its ability of inertia support and primary frequency regulation. However, these benefits are achieved at the increased cost of energy storage (ES). Therefore, a cost-efficient grid-forming VSG system based on coordinated photovoltaic (PV) and supercapacitor (SC) is proposed in this article. Considering the different features of reserved PV power and SC, we propose a coordinating control to make the SC tackles short-term high power whereas the reserved PV power provides long-term low power. A novel cost-efficient transient energy sharing between short-term and long-term energy provision is proposed, along with its parameter design procedure, to optimize the cost of curtailed PV energy and SC investment. Moreover, we propose an improved PV-SC-VSG control scheme to further reduce the ES both in the dc-link and the SC. Experimental results validate the effectiveness of the proposed control strategy.