Decentralized control strategy for fuel cell/PV/BESS based microgrid using modified fractional order PI controller

The concept of renewable energy based microgrid (MG) and its control has been evolved as key area of research in energy sector. In this paper, a decentralized control strategy based on modified fractional order PI (MFO-PI) and two-degree of freedom PI (2DOF-PI) controllers is proposed for efficient operation of an autonomous MG. The autonomous MG consists of solid oxide fuel cell (SOFC) & photovoltaic (PV) system as distributed generation (DG), battery energy storage system (BESS) as a storage unit and various AC & DC loads. The MFO-PI controller is utilized for controlling voltage source inverters (VSI) and 2DOF-PI is utilized for controlling various DGs and BESS. An evaporation rate-based water cycle algorithm (ERWCA) is employed to optimally tune the proposed controllers. To show the effectiveness of the proposed decentralized control strategy, a comparison of various performance indices such as overshoot, settling time and integral absolute error is made with PI and fractional order PI controllers. The results show that proposed control strategy is efficient in improving the steady state as well as dynamic performance of the system under all operating conditions by effectively regulating the real and reactive power flows among the DGs.