A Fuzzy Based Coordinated Control Method for Isolated Power Utility Connected Multiple PV Systems to Reduce Frequency Deviations

A PV system output is not constant and varies depending on climate conditions. Varying PV power causes frequency deviations and decrease in reliability of the isolated power utility when large PV power from multiple PV systems is fed in the utility. In this paper, to overcome this problem, a simple coordinated control method based on fuzzy reasoning is proposed to reduce the frequency deviations. Here, the power command is formed in two steps: central and local. Fuzzy control is applied to produce the central power command considering average insolation, change of insolation, and frequency deviations. In the local step, a simple coordination is kept between the central power command and the local power commands by producing a common tuning factor. The proposed method is compared with the method where extracted maximum power is supplied to the utility without coordination. Simulation results show that the proposed method is feasible to reduce the frequency deviations of the isolated power utility and delivers PV power near the maximum PV power. Usually, to reduce frequency deviations, PV power is smoothed; however, propose method reduces the frequency deviation without smoothing of the PV power variations.