Sizing of Energy Storage and Diesel Generators in an Isolated Microgrid Using Discrete Fourier Transform (DFT)

This paper proposes a method for coordinated sizing of energy storage (ES) and diesel generators in an isolated microgrid based on discrete Fourier transform (DFT). ES and diesel generators have different response characteristics and can complementarily compensate the generation-demand imbalance at different time scales. The DFT-based coordinated dispatch strategy allocates balance power between the two components through frequency-time domain transform. The proposed method ensures that ES and diesel generators work in their respective and most efficient, fit way. Diesel generators consecutively work at a high-level generation while ES compensates small and frequent power fluctuations. Then, the capacities of ES and diesel generators are determined based on the coordinated dispatch strategy. The proposed method can also be used in the planning of ES with other dispatchable sources such as micro-turbine or fuel-cell. Finally, the effectiveness of the proposed method and its advantages are demonstrated via a practical case study.