The wind turbine (WT) terminal overvoltage during grid voltage swell events may result in tripping the WT and consequently threaten the secure operation of large-scale wind farms (WFs). In this paper, an optimal coordination of droop control and adaptive model predictive control (MPC) scheme is proposed to enhance the high-voltage ride-through (HVRT) and post-event recovery of large-scale WFs. During the HVRT, the reactive power reference is generated in each WT controller by following an optimal droop coefficient to realize a fast voltage reduction at the WT terminal. The droop coefficients are precalculated by taking the WF collection system topology and voltage swell magnitude into consideration. At the post-event recovery stage, an adaptive MPC-based voltage recovery control scheme is proposed to improve post-event voltage dynamic restoration performance. The droop coefficients of the WT controllers are optimized based on the voltage sensitivity coefficients and voltage swell magnitude. With the proposed control scheme, all the WT terminal voltage can be maintained within their feasible range and the response time of post-event voltage recovery is significantly shortened. The proposed control scheme is validated and tested under various operating scenarios.
- Wind farm
- High-voltage ride-through (HVRT)
- Post-event recovery
- Model predictive control
- Droop control