A New Power Management Scheme for Parallel-Connected PV Systems in Microgrids

The problem of control of parallel-connected photovoltaic (PV) based distributed generation units in an ac distribution system is studied in this paper. First, a new robust backstepping sliding mode based maximum power point tracking strategy is designed for each PV system. Then, a new control scheme is presented for power management of parallel-connected inverters of PV systems. The proposed control technique is an improvement to the instantaneous average current sharing control scheme (IACS) and uses adaptive fuzzy controllers to adjust the gains of the controllers of each inverter module. The fuzzy inference system is optimized using the H-infinity optimal theory to reduce the error in the fuzzy system. This adaptive fuzzy gain scheduling is then introduced to the IACS controller to improve the current and power sharing for a condition in which the system parameters change. Simulation results are presented to show the effectiveness of the proposed control strategy in improving the load sharing among parallel-connected PV systems.