Reconfiguration strategies for Doubly Fed Induction Generators based wind system

Wind energy is nowadays widespread and the increasing number of wind turbine installations leads to more and more severe grid code requirements for grid connection. Control and grid synchronization algorithm must ensure these requirements on the whole range of operating mode, from starting to nominal power generation mode. In this paper, authors present reconfiguration control strategies, in order to meet standards for interconnecting to the utility network. At first, reconfigurations are investigated under healthy grid conditions, in two cases: when current sensor fault occurs, and then when transition from no load mode to grid connected mode. Secondly, large grid faults are considered: reconfiguration is performed by activation of a protective crowbar circuit. This remedial solution allows the turbine to stay connected and helps grid recovery through reactive power injection. A 4kw DFIG-based wind system emulator is described and some experimental results are presented to validate simulations results and to emphasize the effectiveness of proposed reconfiguration methods.