Grid-forming (GFM) battery energy storage systems (BESSs) offer a promising solution for improving the dynamic performance and robustness of wind power generation systems. Unfortunately, the inherent coupling between active and reactive power in GFM control degrades the system controllability, making accurate power regulation challenging. This paper systematically investigates the power coupling issue of GFM-BESS in wind farm and introduces a power decoupling control strategy based on feedback linearization. First, a power dynamic response model is established to reveal the power coupling phenomenon. Based on this model, a novel power decoupling control strategy is proposed by compensating the voltage vector reference of the GFM, and its physical essence is further visually explained using phasor diagrams. Then, the power performances of the GFM-BESS for wind farm are investigated by a small-signal model with the proposed decoupling controller. Finally, the validity of the proposed scheme is verified through time-domain simulations.

Grid-forming voltage source converters (VSCs) are regarded as a promising solution for future converter-dominated power systems, but they still demand advanced control schemes to realize their full potential for robust grid operation. This paper presents a decentralized composite control for grid-forming VSC-dominated power systems. The proposed control scheme integrates model predictive control (MPC)-based voltage control with droop-based synchronization, achieving fast voltage regulation and decentralized power sharing. An augmented MPC for voltage control is developed to enable rapid voltage tracking, while mitigating the impact of power/voltage loop coupling and enhancing power regulation. Furthermore, a disturbance observer is incorporated to estimate external unmeasured values and model parameters uncertainties, effectively compensating for disturbances and ensuring accurate control based on local information. The mechanism underlying the performance improvement brought by the proposed controller is investigated through detailed analysis. The validity of the proposed scheme is verified through MATLAB/Simulink and hardware-in-the-loop real-time simulations in both single-and multi-VSC systems.