A Novel Four-Port Converter With All Bi-Directional Ports Having Common Ground for Photo-Voltaic Hybrid Energy Storage DC System

The rise in renewable energy generation in recent decades resulted in the proliferation of Energy Storage Systems (ESS) for reliable power delivery. The power flow in ESS can be separated into a low-frequency component due to daily interaction between average generation and consumption patterns, and a high-frequency component due to radical increase/decrease in generation/load demand. The former can be catered by utilising high energy density ESS like a battery, whereas the latter necessitate fast response ESS like a supercapacitor. This envisages the requirement of a Hybrid ESS (HESS) consisting of a battery and a supercapacitor. To address this requirement a novel Four-port Converter (FPC) to integrate solar Photo-Voltaic (PV) and HESS with DC load/grid is proposed in this paper. The resultant system is named Four-Port Solar PV-based Hybrid Energy Storage DC System (FPSHDS). Key features of the FPSHDS in comparison to existing schemes are: it’s all four ports (a) are inductively interfaced enhancing overall system reliability, (b) facilitates bidirectional power flow enhancing flexibility in interfacing PV, HESS, and DC load/grid, and (c) have a common ground eliminating leakage current concerns for solar-PV system. The design and control strategy of FPSHDS is discussed and validated using a 250 W experimental prototype.