Fault Diagnosis Technology Of Direct-Driven Wind Turbine With Permanent Magnet Machine

With the energy crisis and environmental pollution becoming more and more severe, wind power is attracting more and more attention. The variable speed constant frequency wind turbine is very popular in the field of wind power; especially direct-driven wind turbine with permanent magnet generator (D-PMG) grows rapidly in recent years. During the operation of wind turbines, a lot of faults are easily appeared due to aerodynamic force and harsh environment, reducing the safety and reliability of wind turbines. In order to solve this problem, it is extremely important to implement fault diagnosis of wind turbines. In this thesis, fault diagnosis of D-PMG system, including blade imbalance fault, stator winding asymmetry, inter-turn and open phase faults of permanent magnet machine and converter fault, is systematically investigated. Some fault diagnosis methods based on the electrical signals of the generator are proposed to improve the reliability of wind turbines. Both the simulation and experimental results are given to verify the theoretical analysis. This work lays an important technology foundation for the further improvement of reliability of wind turbines and promotion of development of wind power industry.The research results of this thesis are as follows:1. The structure of D-PMG is introduced and its mathematical model is given, mainly including turbine, drive train and permanent magnet (PM) machine. The simulation platform of wind turbine is established based on MATLAB/Simulink, laying a foundation for simulation research on fault diagnosis of wind turbine.2. Three methods are proposed for fault diagnosis of blade imbalance of wind turbine, which are based on stator current, stator current Park vector’s modulus square and vector control strategy. Both the simulation and experimental results prove the validity of the proposed fault diagnosis methods.3. Fault diagnosis method for three-phase PM machine is investigated. The methods based on zero sequence voltage component and zero sequence current component are proposed for wye-connected and delta-connected PM machine, respectively, which are used for the diagnosis of stator winding asymmetry, inter-turn and open phase faults. All the relative conclusions are verified by the simulation and experiment.4. A frequency tracking algorithm is proposed based on orthogonal reference coordinate, where amplitude and initial phase angle of AC signal can be calculated in time domain, thus reducing calculation burden.5. The method based on line voltage error is proposed to diagnose the converter fault, where the open switch can be diagnosed and located. To improve the reliability of the fault diagnosis method, a double standard based on amplitude and time is adopted in the proposed method. The effectiveness of the proposed fault diagnosis method is validated by the simulation and experimental results.6. Fault diagnosis method of multi-phase flux-switching permanent magnet (FSPM) machine is investigated. Based on the analysis of the neutral-point connection mode of nine-phase FSPM machine, the method is proposed for fault diagnosis of the nine-phase FSPM machine.7. Based on the real-time dSPACE, a digital drive hardware and control experimental platform of D-PMG are built, which lay a foundation for verifying the effectiveness of the proposed fault diagnosis methods.