A method of starting a wind turbine in a cold climate environment includes providing a wind turbine in the cold climate environment in a stand-still or near stand-still condition; allowing the rotation speed of the rotor to increase during start up of the wind turbine; optimizing heat generation within the gear box; and generating power using the wind turbine, wherein heat generation within the gear box is optimized prior to providing the generated electrical power to an electrical grid. Optimizing heat generation within the gear box may include maximizing internal power losses in the gear box during start up. This may allow the start up to be achieved without using external heaters. Aspects of this method may be used during periods of low wind conditions in cold climate environments so that once sufficient wind conditions are reestablished, the wind turbine is ready for immediate power production.

A wind turbine comprises a permanent magnet synchronous generator, a main converter, a main converter controller, a wind turbine master controller and an electrical power supply stage comprising an electrical energy storing device. A startup of the wind turbine can be performed using electrical energy from the electrical energy storing device independent from a power supplying grid and/or a combustion engine. After startup, the wind turbine can be operated in an island mode by controlling an intermediate voltage of the main converter by the main converter controller and retrieving power from the synchronous generator independent from the electrical energy storing device.

A method for controlling a wind turbine system including an electrical generator, a power converter system, a DC-link, and at least a grid-side breaker arrangement controllable between open and closed states, wherein the method comprises monitoring for the presence of a shutdown event and, in response to identifying the presence of a shutdown event, controlling the wind turbine into a production-ready state, comprising: i) controlling the grid-side breaker arrangement in the closed state; ii) disabling one or more drive signals to the power converter system; and iii) controlling the DC-link of the power converter system in a charged state. Advantageously, this approach reduces the frequency of use of the grid-side breaker arrangement which extends serviceable life considerably, and also allows the wind turbine system to be transitioned rapidly between an operating state and a production-ready state.

A start control method for wind turbines (102), comprising: a master control determines whether its real-time wind speed reaches a preset start wind speed when a wind speed of at least one wind turbine (102) or anemometer tower in a wind farm reaches or exceeds the preset start wind speed; the master controller updates a corresponding number simulative start times when determining that its real-time wind speed reaches or exceeds the preset start wind speed, and starts the wind turbine (102) when the number of simulative start times reaches a preset count value. The present invention also relates to a master controller, a system, and a central controller for wind turbines (102).

A method for controlling a wind turbine having rotor blades with an adjustable blade angle, comprising the steps operating the wind turbine in a partial load mode for wind velocities up to a nominal wind velocity, wherein in the partial load mode, a fixed partial load angle is provided for the blade angle, operating the wind turbine in a full load mode for wind velocities above the nominal wind velocity, wherein in the full load mode the blade angle is enlarged with increasing wind velocity and has values above the partial load angle, and wherein in the partial load mode, starting from a predetermined operating state, the blade angle is reduced as compared with the partial load angle.

A method of controlling a floating-body wind turbine power generating apparatus including a wind turbine generator disposed on a floating body includes a pitch-angle increasing step of increasing a pitch angle of a blade of the wind turbine generator when the wind turbine generator is stopped, so that an aerodynamic braking force is applied to a rotor of the wind turbine generator. In the pitch-angle increasing step, a first change rate of the pitch angle of the blade in a first period during which the wind turbine generator is in an inclining motion toward an upwind side from a vertical direction due to sway of the floating body, is smaller than a second change rate of the pitch angle of the blade in a second period during which the wind turbine generator is in an inclining motion toward a downwind side from the vertical direction due to the sway of the floating body.

A method for detecting an electrical fault in the stator of an electric machine is provided, wherein the stator includes multiple groups of windings, wherein the windings of each group are assigned to a respective phase of the electric machine, including the steps of: determining a respective current firstly between a subgroup of one of the groups of windings and a distinct further subgroup of the same group of windings and/or secondly between a subgroup of one of the groups of windings and a neutral point, and/or thirdly between a neutral point and either a further neutral point or to a common neutral point connected to at least the neutral point and the further neutral point, evaluating a fault condition, wherein the fulfilment of the fault condition depends on the respective determined current, and outputting a fault signal to personal and/or a device when the fault condition is fulfilled.

A method of transitioning a wind turbine from a sleep state is provided in which a wind speed at the wind turbine is measured, and the measured wind speed is compared to a wake-up threshold. If the wind speed exceeds the wake-up threshold, the wind turbine is transitioned to an active state. Before comparing, either the measured wind speed or the wake-up threshold is adjusted based on an outcome of at least one previous transition from the sleep state of the wind turbine.

A method for transitioning a wind turbine into an energy harvesting mode in which the wind turbine generates electrical power from wind energy is provided. An energy storage system supplies electrical power to an auxiliary system when the wind turbine is not generating or receiving electrical power sufficient for supplying the auxiliary system. The method includes operating the wind turbine in a first operating mode in which an electrical power supply is ceased; obtaining environmental data including at least one of wind data and meteorological data; and determining if the obtained environmental data meets a predefined condition. If the predefined condition is met, a transition of the operation of the wind turbine into the energy harvesting mode is caused, wherein transitioning the operation into the energy harvesting mode comprises supplying electrical power from the energy storage system to the one or more auxiliary power consumers of the first group.

The present disclosure relates to methods (300) to determine a duration of a period for warming up of a power converter (20) of a wind turbine (1). The method (300) comprises determining (301) a first indicator that is indicative of a time that the power converter (20) has been inactive. Further, the method (300) comprises determining (302) the period for warming up at least partially based on the first indicator. A power converter assembly is also disclosed.