A fuzzy based control method for isolated power utility connected PV-diesel hybrid system to reduce frequency deviation

A Photovoltaic (PV) system's power output is not constant and fluctuates depending on weather conditions. Fluctuating power causes frequency deviations in the power utilities when PV power penetration is large. Using a battery is the common practice to smooth PV output power fluctuations. In this paper, we propose a new and simple fuzzy based control method for PV-diesel hybrid system to reduce frequency deviations without smoothing PV output power fluctuations. By means of the proposed method, output power control of PV system considering the conditions of power utilities and maximizing energy capture are achieved. Here, fuzzy reasoning is used to generate the PV output power command. This fuzzy reasoning has three inputs of average insolation, change of insolation, and frequency deviation. The proposed method is compared with the method where extracted maximum power is given to the utility. The simulation results show that proposed method is effective to reduce the frequency deviation of isolated power utility and delivers power near maximum PV power.