An Optimum Design of Hybrid Energy Storage for PV Power Fluctuation Smoothing Based on Frequency Analysis

Proper design of an energy storage system can effectively and economically smooth out the PV power fluctuation and improve the power quality. A frequency analysis based hybrid energy storage devices (ESDs) selection method as well as typical PV data selection method are proposed to determine an optimum energy storage combination to meet the requirement of a power grid. A Fast Fourier Transform (FFT) method is applied to analyze PV output power fluctuations. FFT is also applied to determine the most representative PV output data for the design cycle. The proposed algorithm divided the entire PV output power frequency spectrum into low and high ranges. The divisions are based on the characteristics of individual ESD's as well as their cycle life and capacity loss. Through the proposed method, the lowest-cost ESD solution can be determined to meet the requirements to smooth out PV output fluctuation under the most representative weather pattern.