Abstract: A method for detecting power oscillation in an electric power grid, wherein the method comprises: integrating a filtered signal on a first interval, the filtered signal being associated with the electric power grid; based on the integration of the filtered signal on the first interval, determining a positive half-period area of the filtered signal and a negative half-period area of the filtered signal, one of the positive half-period area and negative half-period area being immediately subsequent to the other one; and determining that a power oscillation in the electric power grid is detected if the following two conditions are met: a sum of the positive half-period area of the filtered signal and the negative half-period area of the filtered signal is below a first threshold; and the absolute value of one of the positive half-period area and negative half-period area is above a second threshold.

Abstract: A wind turbine blade having an electro-thermal heating element is provided. The electro-thermal heating element has a sheet of electrically resistive material, which is folded so as to provide a plurality of heat zones. Each heat zone includes one or more layers of the sheet. At least two of the heat zones have a different number of layers of the sheet.

Abstract: A method of activating an ice removal system of a wind turbine comprises: monitoring the output power of the wind turbine; monitoring an output from an ice sensor provided on the wind turbine indicative of an atmospheric icing condition; and activating the ice-removal system when the output power is below an expected output power and the output from the ice sensor indicates that an atmospheric icing condition has ended.

Abstract: A mass damper module (600) for a wind turbine installation comprises: an attachment interface (603a-d) adapted to removably attach the mass damper module to structural lifting parts (303a-d) of a nacelle (300) of the wind turbine installation; and an active tuned mass damper (601) controllable to damp vibration of the wind turbine installation when the mass damper module is so attached to the nacelle and the nacelle is attached to a tower (200) to form the wind turbine installation.

Abstract: A method for determining a relative position of wind sensors on a wind turbine comprising: obtaining wind data from each of at least two wind sensors installed on a wind turbine at a location where airflow is affected by a rotor of the wind turbine, the obtaining occurring while the rotor is rotating, identifying oscillations in the wind data from each of the wind sensors, determining a phase or amplitude difference between the oscillations, and determining a relative position of the wind sensors based on the phase or amplitude difference.

Abstract: Methods of measuring a stall condition of a rotor of a wind turbine are disclosed. In one aspect a stall parameter is obtained on the basis of the power parameter and a thrust parameter; and the stall parameter compared with a threshold to determine a stall condition of the rotor.

Abstract: A wind turbine nacelle configured for mounting on a wind turbine tower and for supporting a rotor-supporting assembly, the nacelle comprising a main unit, and at least one auxiliary unit. The auxiliary unit accommodates a at least one component, e.g. a converter or transformer. To provide efficient transportation, lower costs and easier assembly, the operative component is suspended directly on the main unit.

Abstract: A method of handling a wind turbine component (54) for assembly or maintenance, comprises coupling one or more unmanned air vehicles (20) with the wind turbine component (54) so that at least a portion of the weight of the wind turbine component (54) can be supported and lifted by the one or more unmanned air vehicles (20). The method further comprises coupling one or more cranes (50) with the wind turbine component (54) so that at least a portion of the weight of the wind turbine component (54) can be supported and lifted by the one or more cranes (50). The method further comprises controlling the one or more unmanned air vehicle (20) and crane (50) in coordination to lift the wind turbine component (54) and manoeuvre said component (54) with respect to a wind turbine (52).

Abstract: There is presented a method for damping an edgewise vibration of a rotor blade of a wind turbine, wherein the method comprises measuring at the rotor blade a motion parameter of the edgewise rotor blade vibration, generating based on said motion parameter a blade pitch angle control signal, and damping the edgewise vibration of the rotor blade by pitching the rotor blade according to the blade pitch angle control signal, wherein the blade pitch angle control signal is arranged so that a resulting force on a rotor blade pitched according to the blade pitch angle control signal, in a direction of the edgewise vibration of the rotor blade in a coordinate system, which rotates with a rotor of the wind turbine, is opposite and proportional to the edgewise rotor blade vibration velocity.

Abstract: A method of determining an orientation of a nacelle of a wind turbine, wherein the nacelle carries a Global Navigation Satellite System (GNSS) sensor, the method comprising: yawing the nacelle between a series of orientations; obtaining locus data based on a series of calibration positions measured by the GNSS sensor, wherein each calibration position is measured by the GNSS sensor when the nacelle is in a respective orientation of the series of orientations; storing the locus data; after storing the locus data, measuring a new position with the GNSS sensor; and determining the orientation of the nacelle on the basis of the stored locus data and the new position.

Abstract: A wind park with wind turbines and airborne wind energy systems where a first zone and a second zone is defined for at least one of the airborne wind energy systems such that the risk of collision between apart of that airborne wind energy systems and a part of one of the wind turbines is higher when the airborne unit of that airborne wind energy system is in the second zone than when it is in the first zone, and different control parameters are applied to the control of at least one of the wind turbine and the airborne wind energy system depending on the position of the airborne unit relative to the defined zones.

Abstract: The present invention relates to an Electro-Thermal Heating element for a wind turbine blade comprising an electrically conductive resistive material; two active busbars for supplying electrical power to the electrically conductive resistive material; and at least one dummy busbar at a predetermined spacing between the two active busbars on the electrically conductive resistive material. The present invention is also directed to a method of repair of the Electro-Thermal Heating Element.

Abstract: In a first aspect of the invention there is provided a method of making a wind turbine component, the method comprising supporting a layup (14) of fibrous reinforcing material in a mould (12); providing a supply of resin (16); providing a supply of hardener (20) comprising at least a first hardener (20a) and a second hardener (20b), the second hardener being faster than the first hardener; mixing resin with the first and/or second hardener to create a resin mixture (24); supplying the resin mixture (24) to the layup (14) during an infusion process; monitoring one or more process parameters of the infusion process; and controlling the speed of the hardener (20) by varying the relative proportions of the first and second hardeners (20a, 20b) in the resin mixture (24) during the course of the infusion process in dependence upon the one or more process parameters.

Abstract: The invention relates to a method for controlling a wind turbine as virtual synchronous machine by determining the synchronous machine rotational speed rotational speed and the synchronous machine angle. The virtual synchronous machine rotational speed is determined based on a combination of a feedback of a damping power, a power reference for a desired power output of the wind turbine, a grid power supplied by the wind turbine to a power grid and a chopper power dissipated by the chopper and an inertial integration model, the synchronous machine angle is determined based on an integration of the synchronous machine rotational speed, and the damping power is determined based on the virtual synchronous machine rotational speed.

Abstract: A method for controlling wind turbines of a wind farm is disclosed. The wind farm is positioned at a site which includes one or more turbulence generating structures, such as hills, valleys, trees or buildings. A wind direction at the site of the wind farm is detected, and one or more upstream wind turbines and one or more downstream wind turbines are identified, based on the detected wind direction, where each of the upstream wind turbines is arranged in front of one or more of the downstream wind turbines, as seen in the wind direction. If it is detected that turbulent wind conditions are occurring, based on measurements performed by the wind turbines of the wind farm, then at least one of the upstream wind turbines is controlled based on measurements performed by at least one wind turbine which is a downstream wind turbine relative to the upstream wind turbine.

Abstract: Control of a wind turbine in a stop process where a stop controller is used to pitch the blades at a number of pre-set pitch rates including a first pitch rate and a second pitch rate. The stop controller is arranged to access desired pitch angles of the stopping process and add an envelope band to the desired pitch angles. In the stop process, pitching at a selected pitch rate among the number of pre-set pitch rates is performed, and the pitch rate is changed according to criteria to keep the pitch value within the envelope band.

Abstract: A method of determining an orientation of a nacelle of a wind turbine, wherein the nacelle carries a Global Navigation Satellite System (GNSS) sensor, the method comprising: yawing the nacelle between a series of orientations; obtaining locus data based on a series of calibration positions measured by the GNSS sensor, wherein each calibration position is measured by the GNSS sensor when the nacelle is in a respective orientation of the series of orientations; storing the locus data; after storing the locus data, measuring a new position with the GNSS sensor; and determining the orientation of the nacelle on the basis of the stored locus data and the new position.

Abstract: The invention provides a wind turbine blade body manufacturing method, the method comprising the steps of: providing a mould (40) having an elongated mould surface (43), placing a movable insert (50) on the mould surface, in a first position, forming, with the insert in the first position, a first blade body having a first length (L1), placing the insert (50) on the mould surface, in a second position, and forming, with the insert in the second position, a second blade body having a second length (L2) which is different from the first length.

Abstract: Aspects of the present invention relate to a method of voltage control for at least one wind turbine generator configured to absorb and supply reactive power on demand, the method comprises: receiving a dispatch signal from a power plant controller indicating a reactive power set point; determining a terminal voltage level of the at least one wind turbine generator; generating a reactive power correction value based on a deviation of the terminal voltage level from a voltage set point; adjusting the reactive power set point by the reactive power correction value; and controlling the at least one wind turbine generator according to the adjusted reactive power set point.

Abstract: A method for operating a cluster of a plurality of wind turbines is disclosed. For each of the wind turbines, one or more parameter values of a parameter being indicative for a condition occurring at the wind turbine are derived, based the measurements obtained by the wind turbine. In the case that a derived parameter value for a specific wind turbine exceeds a trigger value, measures for mitigating an effect of the condition at the specific wind turbine are initiated. The derived parameter values for the wind turbines of the cluster of wind turbines are compared to an expected distribution of the parameter values. In the case that a distribution of the derived parameter values differs from the expected distribution of the parameter values, the trigger value is adjusted, and the adjusted trigger value is subsequently applied when comparing the derived parameter values to the trigger value.