An Adaptive Series-Dynamic-Resistor-Based Protection Scheme for Brushless Doubly- Fed Induction Generator Under Asymmetrical Fault Conditions

Low-voltage ride-through (LVRT) is one of the most important criteria for integrating wind energy into the power grid. Based on grid connection codes, wind generators must remain connected during fault conditions. However, this requires a careful protection scheme design for addressing the successful ride through of the brushless doubly fed induction generator (BDFIG) during severe voltage dips. This paper proposes a comprehensive solution for enhancing the BDFIG ride through during asymmetrical faults. Furthermore, since the proposed solution is dependent on the type and severity of voltage dips, an updated harmonic resilient scheme is developed to detect the dip level and type of faults. Performance of the proposed protection scheme is investigated for further improvement of the brushless DFIG LVRT capability based on series dynamic resistor (SDR) circuit design in order to limit post-fault oscillations. With the proposed solution, the BDFIG can satisfy ride through requirements for severe voltage dip scenarios. The proposed framework which includes a voltage detection method, appropriate SDR value determination procedure, and SDR control circuit was implemented and validated with a coupled circuit model in MATLAB/Simulink for a BDFIG prototype.