Dynamic modeling of doubly fed induction machine during balanced voltage dips with control effects formulation

This paper provides the analysis of the dynamic behavior of open circuit rotor side voltage of doubly fed induction machine during three phase balanced voltage dip. The control of the rotor side converter is then formulated in a state space based model to analyze the dynamics of rotor side current, of which classical PI control method is studied. Analytical solution of the short circuit current of the rotor side converter could be obtained. It is concluded from the theoretical analysis that the rotor side converter is regulating the current against a voltage with an initial value close to the rated stator voltage, thus rotor side converter with a higher voltage rating is capable of reducing the peak value of the short circuit current. The proposed analysis also provides a way to better analyze the low voltage ride through capability. In general, the proposed method could be utilized to analyze any state space based vector control method under three phase voltage dips. The analytical solution is compared with the simulation results.