On the Reduction of the Rated Power of Energy Storage System in Wind Farms

This paper proposes a novel control approach to reduce the rated power of energy storage system (ESS) in the smoothing of wind power output. Wind power generation causes frequency fluctuations in power systems. Therefore, ESSs are used to absorb the fluctuating power of wind generators. Generally, the controller in an ESS is composed of a first-order low-pass filter (FLF) with a large time constant. However, the FLF incurs a high cost because its phase-lag induces an unnecessary increase in the rated power of ESS. This study addresses the reduction in the rated power of ESS without using a complex controller. First, the requirement of the controller is analyzed and its structure is proposed. Then, the absorption of the short-period wind power output is reduced by tuning a gain in the controller until the grid code is violated. The effectiveness of the proposed controller is verified by comparing it to the conventional controllers via scenario simulations using real wind data.