Photovoltaic output power fluctuations smoothing methods for single and multiple PV generators

As a new measure for smoothing PV output power fluctuations and for reducing frequency deviations of isolated power utility, firstly, this paper discusses a control method based on fuzzy reasoning for single PV system. The fuzzy reasoning produces output power command for smoothing PV system's power fluctuations considering insolation and power utility conditions. Secondly, an energy storage based method is proposed. Here, PV output power fluctuations are leveled through battery charge/discharge action and the optimal size of the battery is calculated to minimize the system cost. Thirdly, a simple coordinated control method is proposed for multiple PV systems clustered in different locations. The coordinated method produces central leveling output power command by fuzzy reasoning. Local output power command is generated by multiplying individual maximum power command with tuning factor. All of the proposed methods are compared with the MPPT control and found effective in smoothing PV output power fluctuations.