Optimal Coordinated Post-Event Voltage Control With Energy Storage Boundary Analysis for Large-Scale Wind Farms

In this paper, an optimal-coordinated post-event voltage control (OPVC) scheme with energy storage boundary analysis is proposed to enhance the fault ride-through (FRT) ability of large-scale wind farms (WFs) while reducing wind power losses during the fault conditions. The kinetic energy storage (KES) potential of the wind turbine (WT) is quantified by considering the feasible region of converter currents. A hierarchical model predictive control (MPC) model of the WF is developed to achieve optimal FRT performance. In the upper-level, the optimal power references by considering the power command are determined as input to the lower-level controller, and the terminal voltage of WT can be maintained within the feasible range specified by the grid code. In the lower-level, the d- and q-axis currents references of WTs are optimized to quickly regulate the DC bus voltage by fully utilizing the maximum KES capability. The robustness of the proposed OPVC scheme are demonstrated by considering different working conditions. The simulation results in MATLAB/Simulink show that the proposed OPVC scheme can more efficiently suppress the DC bus voltage fluctuations and maximize the KES and dynamic voltage support potential of WTs to enhance the FRT capability of WF compared with the traditional control schemes.