Abstract: The present disclosure relates to methods for operating wind turbines (10), in particular to methods for feeding wind turbine auxiliary systems when connection to the electrical grid (102) is lost. A method (100) comprises rotating a wind turbine rotor (18) at a first rotational speed by actively controlling a pitch angle of the plurality of rotor blades (22) while a safe condition is detected, and generating electric power; supplying at least part of the generated electric power to at least one wind turbine auxiliary system; detecting a specified condition; and in reply to the detection of the specified condition, rotating the wind turbine rotor (18) at a second rotational speed lower than the first rotational speed, and generating electric power.

Abstract: The present disclosure relates to methods for operating wind turbines (10) and charging one or more auxiliary power sources (84) for providing auxiliary power to one or more wind turbines (10). A method comprises pitching the wind turbine blades (22) to a predetermined idling pitch angle such that the wind turbine generator (42) produces power for charging one or more auxiliary power sources (84) above a predetermined wind speed. The method further comprises keeping the pitch angle (25) of the blades (22) at the idling pitch angle and charging the auxiliary power sources (84) when a prevailing wind speed reaches or exceeds the predetermined wind speed.

Abstract: A method of operating a wind turbine comprising a rotor, a multi winding generator having a plurality of independent sets of control windings and a plurality of independent power electronic converters for controlling each set of control windings independently, the method comprising in a normal operation mode, the plurality of power electronic converters controlling the sets of control windings in substantially the same way, whereas in a positioning mode for positioning a rotor of a wind turbine in one of one or more predetermined angular positions, one of the independent power electronic converters controlling its corresponding set of control windings in a substantially different manner than at least one other independent power electric converter. The invention further relates to a wind turbine adapted to work in at least two different operating modes.

Abstract: Systems for providing electrical power to one or more wind turbine electrical components is provided comprising an electrical grid and an auxiliary power source for providing electrical power, and one or more wind turbines. Each of the wind turbines includes a wind turbine generator, one or more electrical components, a main voltage transformer for connecting the wind turbine generator to the grid and a switchgear arranged between the main voltage transformer and a point of connection to the grid. One or more switches for alternately connecting either said electrical grid or said auxiliary power source to the switchgears of the wind turbines are provided. The switchgears comprise a switchgear voltage transformer, the switchgear voltage transformer includes primary and secondary windings, the primary windings receiving power from the electrical grid or auxiliary power source, and the secondary windings delivering electrical power to the wind turbine electrical components.

Abstract: Systems for providing electrical power to one or more wind turbine electrical components is provided comprising an electrical grid and an auxiliary power source for providing electrical power, and one or more wind turbines. Each of the wind turbines includes a wind turbine generator, one or more electrical components, a main voltage transformer for connecting the wind turbine generator to the grid and a switchgear arranged between the main voltage transformer and a point of connection to the grid. One or more switches for alternately connecting either said electrical grid or said auxiliary power source to the switchgears of the wind turbines are provided. The switchgears comprise a switchgear voltage transformer, the switchgear voltage transformer includes primary and secondary windings, the primary windings receiving power from the electrical grid or auxiliary power source, and the secondary windings delivering electrical power to the wind turbine electrical components.

Abstract: A method of operating a wind turbine comprising a rotor, a multi winding generator having a plurality of independent sets of control windings and a plurality of independent power electronic converters for controlling each set of control windings independently, the method comprising in a normal operation mode, the plurality of power electronic converters controlling the sets of control windings in substantially the same way, whereas in a positioning mode for positioning a rotor of a wind turbine in one of one or more predetermined angular positions, one of the independent power electronic converters controlling its corresponding set of control windings in a substantially different manner than at least one other independent power electric converter. The invention further relates to a wind turbine adapted to work in at least two different operating modes.