Coordinated Fuzzy Logic Control Strategy for Hybrid PV Array with Fuel-Cell and Ultra-Capacitor in a Microgrid

摘要

This paper presents a coordinated control strategy to achieve power management in a microgrid which consists of a photovoltaic (PV) array, a solid-oxide fuel cell (SOFC) and an ultra-capacitor (UC). A power management is implemented by fuzzy logic control to coordinate the operations of SOFC and UC. The output power of a PV array is intermittent due to the variations in irradiation and temperature and causes a power imbalance in the power system, while SOFC not only generates power to its own local load also compensates the power imbalance caused by intermittency of PV array. To maximize the lifetime of SOFC, the fuel utilization rate should be in the safe operation range. Therefore, ultra-capacitor works as a supplementary energy source for SOFC to improve the transient response. The state-of-charge of UC should be considered in the normal range to enhance the lifetime of UC. The proposed operating strategy always operates the PV array at the maximum power point and the SOFC in high efficiency and safe performance range, hence, to enhance the system stability and improve the performance of system operation.