Numerical and experimental analysis of blade-tower clearance for large-scale wind turbines

With the increase of the rotor diameter and the flexibility of the blade, the efficient blade-tower clearance control becomes increasingly important. As a widely used strategy in the wind power industry to increase the bladetower clearance, the fine pitch strategy still has the problem of power de-rating under typical operating conditions. Therefore, a novel coupled blade-tower clearance control strategy is proposed, combining the fine pitch strategy with a revised LiDAR monitoring system. Incorporating the LiDAR's characteristics and the operation modes of wind turbines, the LiDAR is designed to be installed at the front of the nacelle to monitor the real-time blade-tower clearance and feed back to adjust the pitch angle, allowing for safe operation of the wind turbine and maximizing output power. The reliability of the proposed strategy and the influence of weather on the strategy are verified through 22-day all-weather field tests on numerous wind turbines in a wind farm in China, nearly 100% of the efficiency can be achieved if conditions permit. Additionally, the strategy's two trigger modes-the clearance threshold and data validity protection mechanism-are exemplified, demonstrating the efficiency of the proposed coupled blade-tower clearance control strategy.