Solar power smoothing using battery energy storage system through fuzzy filtration technique

This chapter presents a novel fuzzy-based control technique to smooth the transient solar output power generation by designing a varying low pass filter. Solar and wind-based renewable energy sources have variable power profiles due to their intermittent nature. In the case of solar photovoltaic systems, this fluctuation is proportional to the amount of irradiance falling on the photovoltaic panels, while in the case of wind farms, this fluctuation is due to wind speed. Dispatching the generated power from such an intermittent power supply negatively affects the power grid by deteriorating the stability performance, creating power quality issues, and voltage fluctuations. Smoothing the generated power before dispatching it into the grid is needed to alleviate the intermittency consequences. Conventionally, a low pass filter (LPF) is utilized to get smooth the output power fluctuations and maintain simplicity through a battery energy storage system (BESS). However, with the increment in the filtering time constant the delay issue becomes more severe. To obviate overworking of the BESS in the process of injecting/absorbing power in the absence of clouds, that is, minimal or no fluctuations, the ramp rate of the solar power generation system is used to formulate the value of the filtering time constant. The proposed controller improves on the conventional low pass filter technique to appropriately obviate system power variability as well as reduce overworking of the battery. The obtained results based on numerous distinctive irradiance profiles prove the superiority of the proposed fuzzy controller framework in comparison to conventional LPF with better response, permissible ramp rates, and improved battery performance.