Abstract：Doubly-fed induction generators (DFIG) are widely used in wind power generation systems. The common mode voltage caused by the converter can induce bearing voltage through the coupling capacitance and result in the bearing currents, which seriously affect the efficiency and safety of wind power generation. It’s very important to construct a precise bearing currents model. This paper established a completed bearing currents equivalent model, which considered both stator common mode voltage and rotor common mode voltage. The capacitances of the DFIG could be calculated through finite element method and the measurement method on capacitances of DFIG was provided. Then a 1.5 MW DFIG was analyzed. The result showed that bearing voltage induced by stator common mode voltage was very small, and the effects of the stator part can be neglected. The simplified model which only considered the rotor common mode voltage is suitable for analyzing the bearing current problem of DFIG. The sensitivity analysis on capacitors was carried out. The capacitor Crwr is a key parameter to suppress the bearing voltage and bearing current.
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2018, Vol. 33 
