Fault Diagnosis Of The Impeller In A Doubly-Fed Wind Turbine Based On Stator Current By Finite Element Model

Wind power generation is one of the main ways of using new energy,and it has developed rapidly in recent years.With the rapid increase in the capacity of global wind turbine assembly machines,wind turbine technology has become more mature and commercialized.It is especially important to monitor the operation status of wind turbines to ensure the normal and stable operation of the units.The blades are the key component of wind turbines.It is located outside the nacelle,directly facing the wind source.It plays an important role in energy conversion.The safety and reliability of the blade and it's energy conversion efficiency have a very important impact on the entire wind turbine.Its performance also directly affects the operation and stability of the whole machine,so it is necessary to monitor and diagnose the health of the blade.In this paper,the aerodynamics theory of wind turbine and the variable-speed constant-frequency operation mode of doubly-fed motor are analyzed.The stator flux linkage vector control model of doubly-fed electric machine is derived.The mass block is used to simplify the transmission chain model,which provides the basis for subsequent theoretical derivation.Then the expression of the stator current of the doubly-fed motor under the impeller mass imbalance and the aerodynamic asymmetry fault is deduced in detail,and the corresponding fault characteristic frequency is obtained,which provides a theory for the impeller unbalance fault diagnosis method based on the stator current signal characteristic analysis.The wind turbine model under normal and unbalanced conditions was built by GH Bladed software,and the motor speed signal of the unit was obtained by inputting a stable wind speed in the speed regulation stage.Finally,the motor speed signal is imported into the finite element model of the doubly-fed motor built by ANSYS Maxwell to obtain the stator current signal with fault characteristics.Finally,the MATLAB is used for spectrum analysis.The simulation results verify the feasibility of the stator current detection method for fault diagnosis of impeller imbalance fault.