The invention relates to a method for controlling a wind turbine during start up, from a non-producing operation mode to a power producing operation mode when limit cycles occur during start-up. Limit cycles are detected when a number of cut-in transitions or a number of cut-out transitions are detected. A cut-in transition is when the wind turbine fails starting up despite having the wind speed or rotor speed normally required to enter a power producing operation mode. A cut-out transition is occurring when the wind turbine is falling out of power producing operation mode after having entered the power producing operation mode.

The invention relates to a method for controlling a wind turbine during start up, from a non-producing operation mode to a power producing operation mode when limit cycles occur during start-up. Limit cycles are detected when a number of cut-in transitions or a number of cut-out transitions are detected. A cut-in transition is when the wind turbine fails starting up despite having the wind speed or rotor speed normally required to enter a power producing operation mode. A cut-out transition is occurring when the wind turbine is falling out of power producing operation mode after having entered the power producing operation mode.

An embodiment includes sensor data representative of an amount of gas in a storage tank and a speed of wind driving a wind turbine. The embodiment also includes identifying a favorable capacity condition of the storage tank by comparing the amount of gas in the storage tank to the tank's capacity. The embodiment further includes identifying a favorable wind condition by comparing the wind speed to a cut-in speed of the wind turbine. In addition, the embodiment includes receiving wind direction data indicating a direction of the wind driving the wind turbine and identifying a valve position update for a valve that controls gas flow from the tank towards the wind turbine. Finally, the embodiment includes instructing the valve according to the valve position update.

A method for operating a wind farm connected to a power grid that demands a reactive power requirement that varies with active power includes monitoring a wind speed at each of the plurality of wind turbines in the wind farm. When the wind speed is within a cut-in wind speed range, the method includes determining a reactive power margin of the wind farm based on the reactive power requirement at an active power output corresponding to the wind speed and a reactive power availability of each of the plurality of wind turbines at the wind speed. The method also includes determining a lowest possible cut-in rotor speed for each of the plurality of wind turbines that satisfies the reactive power margin. Further, the method includes commanding each of the plurality of wind turbines to cut-in and begin to produce power at the lowest possible cut-in rotor speed that satisfies the reactive power margin.

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 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 of activating and/or deactivating a safe mode of operation of a wind turbine is provided, the method including: receiving at least one measurement signal related to a weather condition; filtering of a measuring signal dependent quantity to obtain a filtered signal, wherein the filtered signal depends on whether the measuring signal dependent quantity and/or filtered signal is increasing or decreasing with time; activating and/or deactivating the safe mode of operation based on the filtered signal.

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 inventive concept provides for a method of apparatus static inertia compensation using external robots. The method includes identifying a region of at least one wind turbine experiencing actual or imminent static inertia. A wind speed at the region is identified. The identified wind speed is compared to a predetermined cut-in speed. An external force necessary to overcome the actual or imminent static inertia based on the compared identified wind speed and the predetermined cut-in speed is calculated. The calculated external force necessary to overcome the actual or imminent static inertia using at least one external robot is generated.

A system and method for predicting power output of a wind farm are disclosed. The method includes determining first and second parameter values of a power curve for a plurality of wind turbines. A second relationship is determined between the densities associated with the wind turbines and the values of the first parameter. A third relationship is determined between the densities associated with the wind turbines and the values of the second parameter. A value of the first parameter for a specified wind farm density is determined based on the second relationship. A value of the second parameter for the specified wind farm density is determined based on the third relationship. An indication of a power output for the specified wind farm density is generated by applying the determined values of the first and second parameters to the power curve.