Ride-through capability improvement of 30kW DFIG-based wind turbine under unsymmetrical voltage dip

This paper addresses the use of resonant control to improve the grid ride-through capability of Doubly Fed Induction Generators (DFIG) under unbalanced grid conditions. DFIG is very sensitive to grid disturbances as its stator circuit is directly connected to the grid. Voltage sags can be harmful to the wind energy conversion systems (WECS) as they induce high voltages and high currents in the rotor circuit. It is important that wind energy systems continue operating during grid disturbances in order to guarantee grid stability. Electric system operators worldwide are introducing minimum requirements for the connection of wind energy systems to the grid. In this regard, this paper presents the insertion of resonant control to the classical PI control strategy in order to improve the ride-through capability during unbalanced voltage dips. The study was carried out in a 30kW WECS laboratory bench. Simulation results using MATLAB/Simulink and experimental results show the control performance.