Research On Inter-turn Short Circuit Fault Of Doubly-fed Wind Power Generators

Doubly fed induction generator(DFIG) is the most widely used in wind power generation system.It has the characteristics of variable speed constant frequency, is the core equipment of wind power generation system. In order to ensure the safe and stable operation of the wind turbine, the common faults of the doubly fed induction generator should be monitored and diagnosed. For doubly fed induction generator, the winding inter-turn short circuit is a typical electrical fault, and the rotor eccentricity is a typical mechanical fault. The main work of this paper is as follows:(1)The finite element simulation model of the DFIG is built by the Ansoft Maxwell 2D simulation software based on the electromagnetic field finite element theory with the specific parameters. Through the design and modification the simulation model and the external circuit, the simulation model is more close to the actual situation. It can simulate the stator winding inter-turn short circuit, the inherent unbalance of the stator winding, the rotor eccentricity and the rotor winding inter turn short circuit. It can simulate a single fault or complex fault simulation.(2) Analyses the harmonic of rotor current caused by stator winding inherent imbalance. The DFIG may exist inherent imbalance in actual. Pointed out it could diagnosis stator inter-turn short circuit fault with stator inherent imbalance. Proposed a method which can avoid the false diagnosis.(3) Analysis of the fault characteristics of stator winding inter-turn short circuit and rotor eccentricity fault, the simulation model of the stator winding inter turn short circuit and the rotor static eccentricity fault is analyzed. And the stator and rotor current harmonics are analyzed. The method of monitoring the complex fault is proposed.(4)The rotor inherent mixed eccentricity of doubly-fed induction generator(DFIG) which caused by the rotor is not centred completely is analyzed.The effect of the inherent mixed eccentricity of the rotor on the fault diagnosis of the rotor winding inter turn short circuit is studied.One of the simulation models is a DFIG with ideal conditions and the other is a DFIG with rotor inherent mixed eccentricity.It studied the spectrum of stator current,rotor current and electromagnetic torque of two models.Proposed a method which could avoid the false diagnosis.