Research On Diagnosis Methods Of DFIG Rotor Winding Inter-turn Short Circuit Fault

Double-fed induction generator is the earliest variable speed constant frequency wind power gercuit fault is a common fault in double-fed induction generator.Once the fault occurs,it will cause local of the winding overheat and aggravate mechanical vibration,which will further affect the insulation and further deteriorate the fault.Therefore,research on the fault diagnosis methods of doubly-fed induction generator rotor winding inter-turn short circuit fault,which is of great significance to guarantee the nerator,but also is one of the mainstream model of the wind farm.Rotor winding inter-turn short cisafe operation of wind turbine and improve the operation efficiency of wind power system.Slip will change with the wind speed when the double-fed induction generator works in the actual operation process.When the slip is small,the characterist ic component(1 + 2ks)f of the rotor inter-turn short-circuit fault in the traditional stator current spectrum is always difficult to highlight and is easily drowned by the fundamental component.In view of this situation,four fault diagnosis methods are proposed: fault diagnosis method of rotor inter-turn short circuit based on spectral characteristic analysis of Clarke vector-mode transform;fault diagnosis method of rotor inter-turn short-circuit fault based on spectrum analysis of Hilbert mode transform;fault diagnosis method of rotor inter-turn short circuit based on spectrum characteristic analysis of average instantaneous power;fault diagnosis method of rotor inter-turn short circuit based on spectrum characteristic analysis of instantaneous power under the Hilbert transform.The above four methods have been rigorously mathematically deduced,and the simulation results are in agreement with the theoretical analysis.The results show that the proposed method has potential application in rotor inter-turn short circuit fault of doubly-fed induction generator.Simultaneously,according to the multi-loop theory,a mathematical model of ideal double-fed induction generator is established with M-function in the three-phase coordinate system,which in the normal situation and the occurrence of rotor winding inter-turn short circuit fault situation.The voltage and current waveform of the stator and rotor are obtained by the simulation of the model,then the electrical quantities are transformed and spectrum an alyzed through the above four methods.The simulation results combined with the theoretical analysis show that the four proposed methods,compared with the traditional diagnosis method of stator current spectrum,can avoid the problem that the characterist ic component of thefault is submerged because of too close to the fundamental component under the condition of low slip.The methods effectively improve the accuracy of detection,so as to realize the early diagnosis of DFIG rotor winding inter-turn short circuit fault.