A Novel Modeling of DFIG Appropriate for Wind- Energy Generation Systems Analysis

Power generation from wind using doubly-fed induction generators (DFIG) has become an attractive option in terms of a multi-megawatt controlled generation. Moreover, accurate modeling of the DFIG is a significant factor to design an appropriate rotor-connected converter (RCC) and grid- connected converter (GCC) controller for the DFIG to control the active power output when employed for renewable power generation applications purposes. The existing modeling of the DFIG does not consider the energy loss factor of the machine. Therefore, the existing controllers that are designed and developed based on the existing DFIG modeling are either operating the machine inefficiently or the control mechanism is erroneous. An accurate mathematical model for the DFIG considering both the core-loss and copper-loss of the machine has been developed and presented. In this paper, it has been revealed that the iron loss in the variable speed DFIG is a variable loss and not constant. It varies not only due to terminal voltage variation but also due to speed or slip variations. The developed two-axis (d-q) model was validated mathematically, and simulated on the MATLAB-Simulink platform, which produces satisfactory results.