Research On Dual-Rotor Wind Turbine Protection Control Under Extreme Wind Conditions

Wind turbine is one of the current research focuses in the field of new energy.As the size of wind turbines continues to increase,the diameter of wind turbines and the height of towers also increase.Ultra long blades pose a great challenge to the blade manufacturing industry.The huge weight increases the inertia and load of wind turbines,reducing the structural stability of the unit.The new dual-rotor wind turbine can achieve hierarchical capture of wind energy,avoid excessive blade size of the wind turbine,and solve the problem of low utilization of traditional wind energy.However,when encountering extreme wind conditions,the airborne load of dual-rotor wind turbines will still significantly increase,affecting their safety.This paper focuses on the identification and control strategy of extreme wind conditions for dual-rotor wind turbines under load shedding.The main work and achievements are as follows:(1)Based on the aerodynamic modeling theory of free vortex wake,a simulation system for the aerodynamics and control of dual-rotor wind turbines was established;The types and characteristics of extreme wind conditions are defined with reference to the IEC61400 standard;(2)Aiming at the problem of untimely control due to rapid changes in wind speed and direction caused by extreme wind conditions,a method for identifying extreme wind conditions based on short-term wind speed prediction was proposed.Firstly,a Kalman filter is used to predict wind speed;Secondly,the state equation and measurement equation required for Kalman filter are established through time series analysis theory;Finally,according to the characteristics of extreme wind conditions,the algorithm for identifying extreme wind conditions is studied and validated by simulation.Simulation results show that this method can effectively predict wind speed and identify extreme wind conditions in a timely manner;(3)Aiming at the problem that different types of extreme wind conditions cause significant increases in load at different locations,a protection and control strategy for dual-rotor wind turbines under extreme wind conditions is proposed.The strategy includes two control methods:independent pitch fuzzy control for rapid changes in wind speed and yaw fuzzy control for rapid changes in wind direction.Moreover,the effectiveness of the control strategy proposed in this paper is verified through simulation of the aerodynamic and control simulation system of a dual-rotor wind turbine.