Improved LVRT Techniques for Grid-Connected DFIG Wind Turbines: A Technical Review

Abstract

Wind energy currently represents a very important source of renewable energy sources (RESs). As a result, the impact of various grid faults on grid-connected wind turbines (WTs) raises many nuisance streamers for wind energy producers. Extra costs and technical interventions are needed to comply with the new grid code requirements. Among critical grid requirements is the low voltage ride-through (LVRT) of doubly fed induction generator (DFIG)-based wind turbines (DFIG-WTs). Conceptually, DFIG-WTs must stay connected to the grid during transient grid faults. In addition, they should provide active and reactive powers promptly during and after fault clearance, to support system recovery in a variety of transient grid fault scenarios. In the literature, a lot of good works has been done to improve DFIG's LVRT capability. So, this paper explores, with critical analysis, the recently emerged LVRT techniques for DFIG-WTs to help wind energy producers/operators to select the appropriate technique. According to a wide range of articles, LVRT techniques can be classified into two groups: exterior and interior techniques; each group has its merits and demerits. A thorough discussion has been made to assess the performance and alignment of these LVRT techniques with prominent grid codes. Different case studies have been carried out using MATLAB/SIMULINK to show the performance of the selected techniques. The effectiveness of each technique during grid faults is demonstrated. Finally, this paper suggests guidelines and recommended technical designs for the LVRT techniques for DFIG-WTs to cope with local grid codes.