Abnormal operation of wind turbine systems

This chapter starts with the various grid fault types in the power system and the evolution progress of wind turbine systems. Aligned with modern grid codes on low-voltage ride-through, Type III and Type IV wind turbine configurations are preferred nowadays. In the case of the doubly fed induction generator-based wind turbine system, due to the direct link between the generator stator and power grid, the power faults introduce the transient stator flux, which may cause the rotor overvoltage. Consequently, the control scheme of the rotor-side converter is comprehensively addressed subject to the symmetrical and asymmetrical faults. In respect to the permanent magnet synchronous generator-based wind turbine system, as the power grid is fully decoupled from the generator, the control scheme of the grid-side converter is in focus. Different controller strategies for both symmetrical and asymmetrical faults are thoroughly studied and tested. To that end, a control method that injects asymmetrical converter current in compliance with recent grid code requirements is demonstrated.