Performance comparison of LVRT techniques for DFIG wind turbine under asymmetrical voltage sags

The low voltage ride through(LVRT) requirements are usually defined by the grid codes at the point of common coupling(PCC). The voltage dip types experienced at the doubly-fed induction generator(DFIG) terminals are different from the conditions at the PCC due to the characteristics and limitations of the network. This paper first analyzes the fault characteristics experienced at the terminal of the wind turbine. Second, the performance of the crowbar circuit under severe asymmetrical grid faults are analyzed. Meanwhile, the operation behaviors of several LVRT control strategies under mild asymmetrical grid faults are given by simulation with the Matlab/Simulink. Then the performance of the approach by using stator damping resistor(SDR) are further analyzed based on the simulation results. This paper aims to give help on choosing or redesign reasonable LVRT control strategies under asymmetrical grid faults.