A multiport power sharing converter topology for renewable-to-grid interface

This paper presents a new family of bidirectional multiport power sharing converters for high-power clean and renewable energy technologies with utility-scale energy storage and medium voltage grid interface. The proposed topology allows for multiple dc-voltage distributed energy resources to be individually referenced to ground and connected via high-frequency isolation to a single multilevel inverter with utility interface. Multiple system level architectures are presented, each implementing power sharing converter technology, and offering adjustable four-quadrant power flow for the system. A case study examines a 1-MW four-input system comprised of a solar array, Li-Ion battery bank flow battery, and fuel cell. Simulation confirms that the fuel cell and solar sources can charge or discharge the flow and Lithium battery banks at individual rates, while supplying a steady output voltage to a medium voltage grid interface. A reduced-scale hardware prototype verifies a broad operation range for the system´s power sharing ratio. Altogether, the proposed topology combines the benefits of MPC technology-power conditioning simplification and improved source utilization - as well as a unique bidirectional power sharing control for each individual port.