Mathematical modeling and analysis of brushless doubly fed reluctance generator under unbalanced grid voltage condition

• The BDFRG operation under unbalanced grid voltage condition has been studied.
• A new mathematical model for the BDFRG under this condition has been developed.
• The BDFRG torque and power equations have been derived under unbalanced condition.
• A real-time negative and positive sequence separation method has been proposed.
• The accuracy of the proposed model and equations has been validated.

The brushless doubly fed reluctance generator (BDFRG) can be an attractive choice for wind power application where mostly located at remote areas with unbalanced grid voltages, however there is not any study on the BDFRG under this condition up to now. In this paper, a mathematical model for the BDFRG under unbalanced grid voltage condition has been developed. Its equivalent circuit in dq reference frames has been extracted, and the torque and power equations have been derived, all based on the positive and negative sequence components. Also, a real-time separation method has been proposed to separate the BDFRG positive and negative sequences. The developed model and equations express the basis of the BDFRG operation under unbalanced grid voltage condition. The proposed model is simulated in MATLAB/Simulink software and the accuracy of the proposed model and equations has been validated by comparison with simulation results of an existing BDFRG model under balanced condition, which has already been experimentally verified in the literature.