Abstract: 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.

Abstract: A system (24) and method are described herein for manufacturing a wind turbine blade (22) proximate to the final installation site of a wind turbine (10). The system (24) includes a creel (72) of feeders (74) configured to apply strengthening elements (62) onto a plurality of shell core sections (26) coupled together and fed through the creel (72). The shell core sections (26) include an external surface (56) with a plurality of external grooves (58) recessed into the external surface (56) such that the strengthening elements (62) are laid into the external grooves (58). The system (24) also includes a deposition station (78) configured to apply an outer surface material layer (82) in fluid form to cover the external surface (56) and the plurality of strengthening elements (62).

Abstract: A method for controlling a multirotor wind turbine is disclosed. A first operational state of each of the energy generating units of the wind turbine is obtained. A difference in thrust acting on at least two of the energy generating units is detected. At least one constraint parameter of the set of operational constraints is adjusted in accordance with prevailing operating conditions and in accordance with the detected difference in thrust, and a new operational state for at least one of the energy generating units is derived, based on the at least one adjusted constraint parameter, the new operational state(s) counteracting the detected difference in thrust. Finally, the wind turbine is controlled in accordance with the new operational states for the energy generating units.

Abstract: A method for controlling a wind turbine is disclosed. During full load operation, a power reference value, Pref, representing a power level to be supplied to the power grid by the wind turbine, is received, and the wind turbine is controlled in order to produce an output power which is at or near the power reference value, Pref, while maintaining a constant torque on the generator. In the case that the produced output power of the wind turbine exceeds the power reference value, Pref, excess produced energy is stored in the energy storage system, and in the case that the produced output power of the wind turbine is below the power reference value, Pref, stored energy is retrieved from the energy storage system. A power level being equal to the power reference value, Pref, is supplied to the power grid.

Abstract: A first aspect of the invention provides a method of testing a yaw system (200) of a wind turbine, the wind turbine comprising a rotor; the yaw system (200) comprising a yaw gear (202) coupled to the rotor so that rotation of the yaw gear (202) causes yaw rotation of the rotor, and first and second sub-systems (204a, 204b), the first sub-system (204a) comprising a first pinion gear (206a) and a first drive motor (208a) coupled to the yaw gear (202) by the first pinion gear (206a), the second sub-system (204b) comprising a second pinion gear (206b) and a second drive motor (208b) coupled to the yaw gear (202) by the second pinion gear (206b).

Abstract: A method of charging an energy storage system, such as a battery, a capacitor, or a super capacitor, using a wind turbine is described. The method comprises establishing if turbine power production can be increased and establishing if the energy storage system is capable of taking a charge. If both conditions are met, the power generated by the wind turbine is increased above a rated power of the wind turbine and the additional power is used to charge the energy storage systems. A method of control is also disclosed.

Abstract: A first aspect of the invention provides a method of monitoring the condition of a yaw system of a wind turbine, the wind turbine comprising a rotor, the yaw system arranged to control a yaw rotation of the rotor, the method comprising: providing design data 5 representing an expected relationship between yaw moment and yaw rotation speed; measuring a pair of parameters, the pair of parameters comprising a yaw moment parameter indicative of a yaw moment applied to the yaw system, and a yaw rotation speed parameter indicative of a yaw rotation speed caused by the yaw moment; using the design data to evaluate whether the pair of parameters deviates from the expected 10 relationship; and determining a condition of the yaw system on the basis of the evaluation.

Abstract: A method of damping oscillations in a multi-rotor wind turbine and a wind turbine are provided. The wind turbine comprises a wind turbine support structure and at least a first nacelle with a first rotor and a second nacelle with a second rotor, at least one of the nacelles being located at a position away from a central longitudinal axis of the wind turbine support structure. The method comprises the steps of receiving and processing motion data, selecting a damping algorithm and generating a pitch control signal. The processing comprises determining at least one prominent oscillation mode of the wind turbine support structure and selecting a corresponding damping algorithm.

Abstract: The invention relates to a method for detecting and controlling whirling oscillations of the blades of a wind turbine. The detection of the whirling oscillations is based on measurement signal indicative of blade oscillations, and a rotation-transformation of the measurement signal from a measurement frame into at least one target frame based on the whirling oscillation frequency. The rotation-transformation comprises a backward or forward rotation transformation direction relative to a rotor rotation direction. The control is based on an oscillation component obtained from the rotation-transformed measurement signal where the oscillation component is indicative of the whirling oscillation in the backward and/or forward rotation direction.

Abstract: A method for controlling a wind turbine is disclosed. During full load operation, a power reference value, Pref, representing a power level to be supplied to the power grid by the wind turbine, is received, and the wind turbine is controlled in order to produce an output power which is at or near the power reference value, Pref, while maintaining a constant torque on the generator. In the case that the produced output power of the wind turbine exceeds the power reference value, Pref, excess produced energy is stored in the energy storage system, and in the case that the produced output power of the wind turbine is below the power reference value, Pref, stored energy is retrieved from the energy storage system. A power level being equal to the power reference value, Pref, is supplied to the power grid.

Abstract: A system (24) and method are described herein for manufacturing a wind turbine blade (22) proximate to the final installation site of a wind turbine (10). The system (24) includes a creel (72) of feeders (74) configured to apply strengthening elements (62) onto a plurality of shell core sections (26) coupled together and fed through the creel (72). The shell core sections (26) include an external surface (56) with a plurality of external grooves (58) recessed into the external surface (56) such that the strengthening elements (62) are laid into the external grooves (58). The system (24) also includes a deposition station (78) configured to apply an outer surface material layer (82) in fluid form to cover the external surface (56) and the plurality of strengthening elements (62).

Abstract: There is presented a method for controlling a rotor on a wind turbine, wherein the rotor is comprising one or more blades, and wherein the wind turbine is comprising a pitch system, the method comprising: Operating the rotor in a standstill or idling operating state, determining or receiving one or more control parameters, where the control parameters enable determining one or more yawing parameters may be described as a function of the one or more control parameters, wherein the one or more yawing parameters comprises one or more of: An angular yawing velocity of the a yawing section, an angular yawing acceleration of the yawing section, and/or a yawing moment applied by the yawing section on a remainder of the wind turbine, and pitching based on the one or more control parameters one or more blades of the rotor with the pitch system.

Abstract: A method for controlling a multirotor wind turbine is disclosed. A first operational state of each of the energy generating units of the wind turbine is obtained. A difference in thrust acting on at least two of the energy generating units is detected. At least one constraint parameter of the set of operational constraints is adjusted in accordance with prevailing operating conditions and in accordance with the detected difference in thrust, and a new operational state for at least one of the energy generating units is derived, based on the at least one adjusted constraint parameter, the new operational state(s) counteracting the detected difference in thrust. Finally, the wind turbine is controlled in accordance with the new operational states for the energy generating units.