A Unified Model of DFIG for Simulating Acceleration with Rotor Injection and Harmonics in Wind Energy Conversion Systems

The synchronous reference frame is widely used in DFIG modeling. It is usually assumed that slip control is in place at the rotor-side converters to make sure that the injected rotor voltage at slip frequency gives a nominal-stator frequency (60 Hz or 50 Hz). In the analysis, the injected rotor voltages are directly expressed in the synchronous reference frame. In the cases where slip control is not available, the above modeling will not work. In this paper, a unified DFIG model is proposed to take into consideration various scenarios of the injected rotor voltage, such as no slip control in place and non-sinusoidal rotor injection. The frequency of the injected rotor voltage is an explicit input in the model. Matlab/Simulink is used to perform the simulations of two case studies (acceleration via rotor injection and harmonic simulation) which demonstrate the effectiveness of the model. An experiment confirms the simulation results.