Limiting the fault current of a wind turbine driven doubly fed induction generator system using fuzzy resistance limiter

Abstract

A doubly fed induction generator (DFIG) is preferred over other wind generators because of its capacity to adapt to variable wind speeds and economic converter. DFIG is sensitive to grid faults as its stator is directly connected to the grid. To fulfill the grid code requirement, DFIG is required to be connected to the grid during the fault. Converter control is not sufficient to maintain grid stability. Ladder resistive fault current limiter (LRFCL) and fuzzy logic control-based series dynamic braking resistor (FLC-SDBR) are proposed for low voltage ride-through (LVRT) enhancement. The series resistor consumes the surplus active power during the grid voltage dip. A control system has been developed to control the step resistance in the LRFCL, whose operation changes with the deviation in grid voltage. A fuzzy logic-based control system has been developed to precisely control the power being consumed in the SDBR. The LVRT capability of the DFIG has been investigated for different levels of fault in bus terminals. The performance of the proposed model is compared with that of a resistive superconducting fault current limiter (R-SFCL) and a conventionally controlled SDBR. Simulation results performed in MATLAB show that the proposed model has the capacity to enhance LVRT for different levels of bus voltage sag. FLC-SDBR is superior in performance with a quick restoration of the system stability.