Fault-tolerant operation of DFIG-WT with four-switch three-phase grid-side converter by applying a simplified SVPWM technique

Abstract

This paper aims to improve the fault-tolerant ability of doubly-fed induction generator based wind turbines (DFIG-WTs) by applying a four-switch three-phase (FSTP) topology based grid side converter (GSC). Once a switch breaks down in the three-phase GSC, the corresponding phase is connected to the midpoint of the DC bus to make the wind turbine (WT) continue working properly. The operation of the GSC is explained in different operation modes of the DFIG-WT. In addition, a simplified space vector pulse width modulation (SVPWM) technique is applied to control the remaining healthy switches, and it is firstly used for DFIG-WTs. Besides, the difference between the voltages on DC-link capacitors is suppressed by adjusting the control strategy. The DC bus voltage, three-phase grid currents and power factor are analyzed to verify the technique by simulation results in Matlab/Simulink under different conditions of the wind speed. Apart from an acceptable performance of the FSTP GSC derived in DFIG-WT, the results demonstrate that the proposed fault-tolerant topology has better adaptability than the common one when wind speed changes.