Patent ID: 7332827
Filing Date: 2008-02-19
Classification: F03D,H02P,Y02E

Abstract:
1. A method for controlling a power grid connected to wind turbine generator during grid faults, the generator comprising a rotor driven by a wind turbine and a stator normally connected to the grid, and the stator, during normal operation being connected to deliver power to the power grid, and the generator comprising a double-fed asynchronous generator, the rotor including windings normally connected to the grid through a back-to-back converter so as to transfer energy between the rotor windings and the grid in a controlled manner, said method comprising the steps of: a) disconnecting the stator windings from the power grid when a grid fault condition is detected, b) connecting the stator windings to impedances for dissipating between 0 and 100% of the power generated by the wind turbine during a grid fault condition, c) maintaining a certain magnetization of the generator during a grid fault condition, and d) after removal of the grid fault condition, synchronizing the generator with the power grid and disconnecting the impedances and reconnecting the stator windings to the power grid, the method further comprising the step of maintaining the connection of the back-to-back converter to the grid during a grid fault condition and controlling the back-to-back converter so as to deliver a controlled short-circuit contribution to the grid during a grid fault condition.