Frequency regulation optimization for wind storage based on frequency regulation reliability and state of charge in isolated island off‐grid

Abstract

Abstract To further improve the frequency regulation stability of wind farm, and optimize the state of charge (SOC) basepoint, charge and discharge rate and recovery capacity of energy storage. In an isolated, off‐grid state, a two‐layer optimization method is proposed, taking into account the frequency regulation reliability and SOC adaptive adjustment of the wind storage. In the upper layer, the model predictive control theory is adopted to optimize the energy‐storage frequency regulation output power with the goal of minimizing the wind storage frequency regulation power deviation. While solving the problem of low‐frequency regulation reliability of wind farm, the SOC recovery basepoint and frequency regulation power of energy storage are optimized. At the SOC optimization layer, based on the upper SOC recovery basis point, we propose a dynamic recovery method for energy‐storage SOC that considers both the SOC recovery demand and grid‐bearing capacity, to determine the energy‐storage recovery power. By determining the frequency regulation or recovery power, we propose a calculation method to optimize the energy‐storage charge and discharge coefficients as per the SOC for avoiding excessive charging and discharging. The simulation results show that, under continuous disturbance, the root‐mean‐square deviations of the proposed method is 80.13% and 62.63% lower than those of the fixed K and SOC methods, respectively. Furthermore, the proposed method exhibits the best SOC maintenance effect.

Keywords

• energy storage
• frequency regulation
• model predictive control
• recovery of SOC
• wind farm