Winding Inter-turn Fault Characterization Analysis Of DFIG Based On The Finite Element Model

With its advantages like wide speed range, flexible control strategy,independent power adjusting and high cost-effective, etc, doubly fed inductiongenerator (DFIG) is widely used in wind power generation. Due to poor workingconditions of the wind farm and its complex structure, it makes DFIG often fails.Stator and rotor windings failure accounted for a large proportion of DFIG fault, soit is particularly necessary for its winding inter-turn fault characterization analysis.This article build two-dimensional field-circuit coupled simulation model ofDFIG using Ansoft Maxwell software based on the finite element theory. In thispaper, internal electromagnetic field, current and electromagnetic force of thegenerator are analyzed when the generator stator winding is normal and fault indifferent degree. The rotor line current is Fourier transformed. Comparing thecurrent harmonic characteristics when the stator is normal and fault in differentdegree, we find the variation of rotor current when stator winding is fault.Rotor currents are analyzed under balance and unbalance voltage of stator whenthe generator rotor winding is fault in different degree. The simulation results canbe clearly seen that the phase and the size of the rotor current were regularlydeveloped with the fault. After spectral analysis, the fundamental negative sequencecurrent and the harmonic characteristics of the fault are studied. Comparing theharmonic content when the stator voltage is balanced and unbalanced, we obtain thecharacteristic quantity when the stator voltage imbalance.