Method for controlling a wind turbine during an asymmetrical grid fault and a wind turbine

摘要

The invention is directed to a method for controlling a wind turbine connected to a three-phase electrical supply grid during an asymmetrical grid fault. The method is configured for wind turbines with a doubly-fed induction generator. The reactive current to be fed into the electrical supply grid in the negative phase-sequence system is generated by the line-side and the rotor-side converter in a coordinated manner and depends on the line voltage. The reactive current to be fed into the electrical supply grid is distributed among the rotor-side and line-side converters. As a result, even in the case of severely asymmetrical grid faults, the reactive current to be fed into the electrical supply grid can be provided and excessive loading of the rotor-side converter can be prevented using simple means. The invention is also directed to a wind turbine for performing the above method.

主权项

1. A method for controlling a wind turbine connected to a three-phase electrical supply grid during an asymmetrical grid fault, wherein the wind turbine includes a doubly-fed induction generator having a rotor connected to the electrical supply grid via a converter system and having a stator connected to the electrical supply grid, the converters system including a rotor-side converter, a line-side converter and a controller having a characteristic specifying, for an actual value of a line voltage in a negative phase-sequence system, a setpoint value for a reactive current to be fed into the three-phase electrical supply grid in the negative phase-sequence system, the method comprising the steps of:
measuring the actual values of the line voltage in at least two phases; transforming the measured actual values of the line voltage into an actual value of the line voltage in the negative phase-sequence system; determining a setpoint value for a reactive current to be fed into the electrical supply grid in the negative phase-sequence system on the basis of the characteristic and the actual value of the line voltage in the negative phase-sequence system; distributing the determined setpoint value for the reactive current to be fed into the electrical supply grid in the negative phase-sequence system among the rotor-side converter and the line-side converter by determining a setpoint value for a reactive current component to be provided by the rotor-side converter and a setpoint value for a reactive current component to be provided by the line-side converter in accordance with a distribution rule provided in the controller; and, driving the rotor-side converter and the line-side converter for feeding in reactive current corresponding to the distributed setpoint values.