Blade mass imbalance identification and estimation for three-bladed wind turbine rotor based on modal analysis

Abstract

Early detection of rotor imbalance is one promising approach to address wind turbine durability. This work proposes a novel blade mass imbalance identification and estimation method for the wind turbine rotor. The method is capable of identifying the presence of a wind turbine rotor mass imbalance. In addition, if a mass imbalance exists in the wind turbine rotor, this method can identify which blade is imbalanced, and then quantify the imbalance severity. The remediation to balance the wind turbine rotor is also provided. The advantages of this method include that only a handful of data is required as input variables (which are the frequencies and modes shapes of all first-order modes) and the method can be applied to a stationary (non-rotating) rotor prior to the first operation. The decision-making process of this method is fast and reliable. The performance of the method is illustrated with the help of both numerical simulation and experimental tests. Model to test correlation and direct blade physical measurements are also conducted to validate the ability of the method to both identify mass imbalance and quantify the degree of mass imbalance. This method was demonstrated to be a high-fidelity tool for identifying the imbalance of the wind turbine rotor and it is also applicable to the wind turbines operating in the field. In addition, this method also shows strong potential to be extended to other wind turbine configurations and even other rotating machinery such as propellors and symmetric, repeated structures.