Design and Control of Renewable DC Microgrid using Current Sharing based Dual Loop Proportional Integral Control Technique

Microgrids are gaining popularity due to their higher reliability, clean energy, localized energy management and capability for standalone operation. This paper proposes the design and control of a Standalone Renewable DC Microgrid consisting of a Photovoltaic (PV) array and Hydrogen Fuel-Cell renewable sources, and a supercapacitor as an energy storage unit. Along with the Maximum power point tracking (MPPT) of a PV source, the DC Link voltage has been regulated at the load center. A current sharing rule-based dual loop Proportional-Integral (PI) controller has been presented to achieve voltage regulation and for optimal sharing of load between sources and the supercapacitor storage unit. The proposed current sharing algorithm generates references for inner current control loops proportional to the State of Charge (SoC) of supercapacitor and the hydrogen availability. Proposed system efficacy has been tested in terms of reference tracking, response time and stability, under varying DC bus power conditions such as variation of solar irradiance, low fuel, load variations, etc. A detailed analysis and simulation study are provided to verify the proposal.