Coordinated Control of Grid-Forming Wind Turbines and Grid-Forming Energy Storage Systems for Power System Restoration

Grid-forming wind turbines (GFM-WTs) provide a promising solution for the restoration of wind-integrated power systems owing to their fast restart and grid support capabilities. However, individual GFM-WTs rely on external GFM sources for self-start, and their GFM support capability may be hindered by wind power shortages, potentially causing restoration failures. To address these challenges, this paper combines GFM-WTs and GFM energy storage systems (ESSs) to construct a black-start source for power system restoration. The GFM-ESS can provide self-start conditions for the GFM-WT while also improving its GFM support capability to withstand wind power shortages and load restoration transients. To ensure the stability of the restored system, a coordinated control strategy is proposed. First, a pre-synchronization control is designed to enable the GFM-WT to seamlessly connect with the GFM-ESS. Second, a power system stabilizer is developed to mitigate the power oscillation between the parallel GFM-WT and GFM-ESS. Third, to coordinate their power outputs during the load restoration, a model predictive secondary frequency control considering the stability of the WT rotor speed and system frequency is presented. The simulation results demonstrate that the proposed strategy can improve the stability and security of the system restoration process under wind power shortages.