A Battery Energy Storage System Dual-Layer Control Strategy for Mitigating Wind Farm Fluctuations

The intermittent power output of a wind farm is the main challenge behind increasing wind power penetration of power systems. This paper proposes a battery energy storage system (BESS) dual-layer control strategy-consisting of a fluctuation mitigation control layer and a power allocation control layer-to mitigate wind farm power output fluctuations. The fluctuation mitigation control layer calculates the power instructions for the BESS so that the combined wind farm and BESS power output meets fluctuation mitigation requirement (FMR). The layer implements a flexible first-order low-pass filter (FLF), updating the time constant of the FLF through use of a particle swarm optimization (PSO) algorithm. The power allocation control layer optimizes power instructions allocation among the battery energy storage units of the BESS. The layer's energy management of the BESS uses a mixed-integer quadratic programming (MIQP) model, which improves reliability. Moreover, the paper compares two types of charge/discharge switching constraints to reduce the number of charge/discharge cycles, which can prolong the operational lifetime of the BESS. Finally, the effectiveness of the proposed dual-layer control strategy is verified through case studies.