Open-circuit Fault Analysis Of Doubly Fed Induction Generator

The need for renewable resources is also becoming increasingly crucial in the face of growing energy crisis and the protection of the environment.Wind power generation technology is currently the main component of power generation technology,especially doubly-fed wind power generation technology.At this stage,doubly-fed wind turbine has been used on a large scale.The converter is not as stable as the alternator and the major components.The power components contained therein are usually adversely affected by the temperature and the external environment during operation,and in some cases can not operate smoothly,which can easily lead to serious damage or suspension of operation of the wind turbine.Therefore,the status of wind power converter detection and fault diagnosis for improving the stability and effectiveness of the system is very crucial.Firstly,based on the grid-connected wind power generation system,a doubly-fed induction motor and double PWM converter model are established.Under the premise of the model and the control measures of each component,the corresponding simulation system is established by using effective Matlab / Simulink software.The final simulation results show that the system can be operated stably for a long time,and can simulate the open-circuit fault condition correctly when there are defects in the operation of the system,laying a solid foundation for the follow-up study of the converter switching problem.Secondly,in the analysis of converter fault characteristics.For the FFT transform is reflected in the frequency characteristics of the fault signal within a certain time range,and should not be used in the study of unsteady signals and performance of some abnormal signals,to determine a wavelet analysis based fault characteristics extraction.Using wavelet analysis to decompose the three-phase fault signals by wavelet decomposition,the low-frequency energy values obtained after the decomposition are taken as the eigenvectors of operation conditions,which lays the foundation for the later identification and analysis of the fault signals.The simulation results show that the method pointed out in this project reflects the excellent normal and abnormal separability,so that the rotor-side converter open-circuit problem can be distinguished effectively.Finally,this paper compares two new types of doubly-fed wind turbine rotor-side converter open-circuit fault diagnosis method.Under the condition of using the wavelet transform to obtain the open-circuit fault characteristics of rotor-side converter,the eigenvectors obtained by wavelet transform are respectively judged by the discretization,the simplified rough set and the support vector machine,compared and analyzed the advantages and disadvantages of the two methods.The research shows that based on wavelet and rough set and support vector machine,theway to diagnose the fault information of the converter can not only improve the speed of diagnosis,but also improve the accuracy of classification,which can further improve the diagnosis speed,and has very good potential for development.