A Review of Research Status on LVRT Technology in Doubly-fed Wind Turbine Generator System

This paper gave a detailed introduction and analysis on the research status and industrialization situation of current LVRT Technology in doubly-fed wind turbine generator (WTG) system. Starting with the urgency of LVRT research in China, the paper introduced the requirement and test situation of LVRT in the world and China; carried out a systematical analysis on the research status of DFIG-WTG operating characteristics under voltage dip, and summarized the effect of voltage dip on DFIG-WTG operation. Subsequently, the paper systemically analyzed and compared the different strategies of LVRT in DFIG-WTG. Aiming at the realization of LVRT core components, the control strategy of turbine rotor back-to-back double PWM converter and the switching control of additional crowbar circuit, an in-depth analysis was provided. In the end, this paper presented the research status on DFIG-WTG strategy under unsymmetrical dip failure, and indicated the development direction of further research of WTG LVRT for our country.