Reliability improvement of wind power frequency modulation based on look-ahead control strategy and stage of charge optimization of energy storage

Aiming at the continuous frequency modulation (FM) dynamic process of the current wind turbine (WT), FM reliability is affected by wind speed fluctuation and prediction error. This study proposes an advanced energy storage (ES) control strategy based on wind speed prediction. First, according to the wind speed fluctuation in a future forecast period, the model predictive control (MPC) method is used to modify the current charging and discharging behavior in advance to improve the FM reliability of WT in the forecast period. Second, considering the ES capacity limitation, an adaptive ES dynamic state of charge (SOC) two-layer optimization model is proposed. In the outer layer of the model, an optimization function is designed to automatically adjust the initial SOC value with the change in wind speed to maintain the optimal FM capability of the wind-storage system at different wind speeds. In the inner layer, the ES charge-discharge speed model is constructed to avoid the loss of ES life caused by overcharge and over-discharge in the continuous FM process. The simulation results show that in the continuous perturbation, maximum frequency deviation is improved by 0.035 Hz in the first perturbation and 0.036 Hz in the second perturbation compared with the non-optimization model. Besides, the deviation degree of system frequency decreased by 0.082 Hz under continuous load disturbance. The strategy and dynamic SOC optimization model can effectively improve the FM reliability.