Digital control of three-phase series converter for DFIG wind turbine low voltage ride-through solution

This paper introduces a new solution for Doubly-Fed Induction Generators (DFIG) to stay connected to the grid during short circuit condition. The main idea is to increase the stator voltage to a level that creates the required flux to keep the rotor side converter current below its transient rating. To accomplish this goal, a series compensator is added to inject voltage, during the short circuit, in series to the stator side line. Digital deadbeat controller is designed, implemented, and applied to a three-phase series converter. The proposed controller adjusts the series converter voltage with four sampling periods. Since the turbine and converter stay connected, the synchronization of operation remains established during and after the fault and normal operation can be resumed immediately after the fault is cleared. Simulation and experimental results are presented, which show the feasibility of the proposed controller for this topology.