Improved stationary reference frame for grid connected operation of single phase parallel inverters

Grid connected photovoltaic (PV) systems often consist of parallel arrangement of inverters. The control of such arrangement is crucial for maintaining the grid stability and achieving optimum power transfer. Motivated by this requirement, the intelligent control of grid-connected PV parallel inverter system in a stationary reference frame is proposed in this paper. The developed approach helps in eliminating the coordinate transformation step and reduces the control complexity to a large extent. Further, it improves the performance of the system along with reduced harmonics. To realize the development of this approach, the parallel inverter operation of two PV inverters in a single-phase grid-connected connected system is developed. The external voltage control loop of the inverter employs a fuzzy logic to minimize the PV fluctuations and enable optimal power conversion. The results provided validate the effectiveness of the proposed control scheme.