Hybrid stand-alone renewable energy system with high fuel-cell efficiency and unity power factor

The paper presents a hybrid standalone power conversion strategy for the integrated connection of multiple remote loads. The proposed system consists of fuel cells, PV panels, a wind turbine and batteries. The primary aims of the proposed controller are to operate the fuel cells about their maximum possible efficiency whilst maintaining unity power factor. A control technique for charging and discharging allows the renewable energy sources to i) maintain the battery charge (where possible) as well as supply to the load, or ii) maintain the battery charge and allow other sources to directly supply the load, or iii) to charge the battery when it is possible. Furthermore, the control technique has ability to control the reactive power over a wide operating range.