Abstract: Embodiments herein describe operating wind turbines in an offshore park to provide auxiliary power to a local AC grid or to an onshore grid during a grid malfunction. In one embodiment, the offshore park is coupled via a HVDC link to an onshore grid. When the HVDC link is down, a substation in the park includes a backup generator for creating a weak grid for powering auxiliary systems in a pilot turbine. The wind turbines in the park can switch to an auxiliary control system help power the auxiliary systems in the substation and in other turbines. In another embodiment, the offshore park is AC coupled to an onshore grid using a transformer in the substation. The wind turbines can participate in a brown or black start following a grid fault by switching to operating using the auxiliary control system.

Abstract: A jacking tool (70, 162, 174) for a wind turbine component (60) having an outer housing (62) and an internal rotatable member (64) disposed in the outer housing (62) and rotatable about a rotational axis (66) is disclosed. The jacking tool (70, 162, 174) includes a support pin (74, 164, 176) having a proximal end and a distal end that includes a bearing (112). The support pin (74, 164, 176) is configured to be selectively movable relative to the outer housing (62). The bearing (112) is configured to contact the internal rotatable member (64) to support the internal rotatable member (64) relative to the outer housing (62), and to allow the internal rotatable member (64) to rotate within the outer housing (62) while being supported by the jacking tool (70, 162, 174).

Abstract: Wind Turbine Blade (12) Leading Edge (24, 30, 88) Protection Method In a first aspect of the invention there is provided a method of applying an erosion shield (22) to a leading edge region (30) of a wind turbine blade (12). The method comprises providing a wind turbine blade (12) comprising a blade shell (26) having an aerodynamic profile and defining a leading edge region (30); providing an erosion shield (22) made of a polymer material, the erosion shield (22) having an inner surface (36) to be bonded to the leading edge region (30) of the blade shell (26), and an outer surface (38, 84, 98) to be exposed in use; activating (44) the inner surface (36) of the erosion shield (22), and cleaning (42) the inner surface (36) of the erosion shield (22) using a solvent.

Abstract: There is provided a method of avoiding edgewise vibrations during a non-operational period of a wind turbine. The method comprises defining a non-operational period for a wind turbine arranged at a specific site, determining expected wind conditions at the specific site during the non-operational period and defining a plurality of potential yaw orientations for the wind turbine. The method further comprises determining the relative probability of edgewise vibrations occurring during the non-operational period for each potential yaw orientation based upon the expected wind conditions during the non-operational period, determining one or more preferred yaw orientations, which are the yaw orientations in which the probability of edgewise vibrations occurring is lowest, and arranging the wind turbine in one of the preferred yaw orientations during the non-operational period.

Abstract: Operating a renewable energy power plant connected to a power network at a point of interconnection. The plant includes: one or more renewable energy generators connected to a collection point of the renewable energy power plant, and a connecting network connecting the collection point to the point of interconnection. One method includes: receiving one or more measurement signals indicative of measured power characteristics of the renewable energy power plant at the point of interconnection; determining a dynamic short circuit ratio (DSCR) at the point of interconnection based on the one or more measurement signals; determining an equivalent dynamic short circuit ratio (EDSCR) at the collection point based on the determined DSCR at the point of interconnection and one or more components of an impedance of the connecting network; and controlling the one or more renewable energy generators by determining and dispatching active power set points based on the determined EDSCR.

Abstract: A wind turbine rotor blade spar cap includes a stack of layers of conductive material. An intermediate layer is bonded between adjacent layers of the conductive material. The intermediate layer includes a portion of conductive material which is electrically coupled to the adjacent layers of conductive material so as to equipotentially bond the adjacent layers of the conductive material via the intermediate layer.

Abstract: This disclosure proposes procedures and systems for discharging system capacitors and de-energizing power transmission systems having Modular Multilevel Converter (MMC) topologies by intelligent control of MMC cell components including configuration of bypass and insert switches using integrated DC choppers to effectively de-energize MMC cell capacitors and/or DC-link capacitors under operating conditions such as after a normal stop, for protection against over-voltages, dumping turbine energy, and under certain hardware fault conditions.

Abstract: A method of retrofitting a wind turbine (10) having a wind turbine tower (12) and a first energy generating unit (14) includes rotating at least a portion of the wind turbine tower (12). The wind turbine tower (12) is secured to a foundation (16) and has a first position on the foundation (16). The method includes rotating at least a portion of the wind turbine tower (12) from the first position to a second position. In the second position, the portion experiences less stress when the wind turbine (10) is operated in the same prevailing wind. The wind turbine tower (12) may have at least two sections (12a, 12b, 12c) and wherein rotating includes rotating one section relative to another section. One section may be secured to a foundation (16). In that case, rotating may or may not include rotating the section secured to the foundation (16).

Abstract: The present invention provides a method and controller for controlling noise emissions from individual blades (18) of a wind turbine (10), the method (60) comprising defining (720) a wind turbine model (321) describing dynamics of the wind turbine (10), the wind turbine model (321) including a description of intensity and direction of noise emissions from each individual blade (18) as a function of azimuthal angle (312); and applying (730) a model-based control algorithm (32) using the wind turbine model (321) to determine at least one control output (331), and using (740) the at least one control output (331) to control noise emissions from each individual blade (18).

Abstract: Techniques for determining the presence of ice at a wind farm with a number of wind turbines. The controller receives a current ambient temperature of the wind farm. The controller also receives a measured current wind speed from wind speed sensors of the wind turbines. The controller also receives an estimated current wind speed of each of the wind turbines that is based on measured performance parameters of the associated wind turbine. The controller determines a current wind speed difference between the measured current wind speed and the estimated current wind speed for each of the wind turbines, and determines a current delta distribution based on the current wind speed differences. The controller also determines whether an ice event has occurred, the determination being in dependence on the current ambient temperature and in dependence on the current delta distribution, and then outputs an outcome of the ice event determination.

Abstract: Controlling a wind turbine including measuring a wind speed for a location upwind of a wind turbine. Using the measured wind speed, a changed steady-state deflection of a structure of the wind turbine is predicted. The predicted changed steady-state deflection corresponds to a time when wind from the location is incident on the wind turbine. Oscillations of the structure are damped relative to the changed steady-state deflection. By damping the oscillations relative to the changed steady-state deflection, movements of the structure may be minimized when there is no predicted change in steady-state deflection, while permitting more rapid movements during transitions from one steady-state deflection to the predicted steady-state deflection, allowing more of the available power to be captured by the wind turbine.

Abstract: There is provided a method of controlling power output of a wind turbine at below-rated wind speed, the method comprising: determining an indication of blade torsion of one or more rotor blades of the wind turbine in dependence on wind speed and/or rotor speed; determining a torsion-corrected blade pitch based on the indication of blade torsion; and using the torsion-corrected blade pitch to control pitch the one or more rotor blades.

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 two auxiliary units. To increase flexibility and improve assembly and maintenance procedures of the wind turbine, the auxiliary unit comprises at least two auxiliary units each accommodating at least one wind turbine component, e.g. a converter or a transformer. The auxiliary units are attached individually to the same wall of the main unit, e.g. to a side wall or a rear wall.

Abstract: Techniques for controlling loading on a wind turbine blade in the flap-wise direction. A system model has a description of flap loading on the blade and is used to predict flap loading on the blade over a prediction horizon using the system model. A dynamic flap loading limit is determined based on predicted flap loading and a measured flap loading, and a constraint is defined to limit flap loading on the blade based on the dynamic flap loading limit. The predicted flap loading is used in a cost or performance function, and the cost function is optimized subject to the constraint to determine pitch for the blade to control flap loading on the blade. Advantageously, the dynamic limit varies based on discrepancies between predicted and measured flap loading to allow for adaptive back-off from extreme loads prior to such loads building up or being exceeded.

Abstract: A method of installing rotor blades on an offshore wind turbine includes arranging a tower of the wind turbine at an offshore installation site. Then a first end of a tensioner is fastened to at least one of the tower, the nacelle, and the hub at a distance above sea level. A second end of the tensioner is fastened to a holding device floating in the sea at a distance from the tower. Then a pulling force is applied to the tensioner from the holding device at least part of the time while the rotor blades are being mounted to the hub, so that oscillations of the tower due to external forces are dampened during installation of the rotor blades.

Abstract: A wind turbine has a bearing housing, a rolling element bearing within the bearing housing and a space within the bearing housing for containing grease for lubricating the rolling element bearing. A shaft is rotatably supported by the rolling element bearing. A pressure sensor in fluid communication with the space measures the pressure of grease in the space within the bearing housing.

Abstract: In a first aspect of the invention there is provided a wind turbine blade comprising a blade shell that extends in a spanwise direction from a root end to a tip end, and in a chordwise direction from a leading edge to a trailing edge. The blade shell comprises a spar cap formed from a plurality of substantially planar strips of reinforcing material, the strips being arranged in a plurality of stacks extending longitudinally in the spanwise direction and arranged side-by-side in the chordwise direction. In each stack an uppermost strip defines an upper surface of the stack, a lowermost strip defines a lower surface of the stack, and longitudinal edges of the stacked strips define side surfaces of the stack. The blade further comprises a retaining clip comprising a plurality of side-by-side substantially U-shaped sections. The U-shaped sections each comprise a pair of mutually-spaced side portions defining a stack-receiving region therebetween, and the side portions are joined by a bridging portion.

Abstract: A method of forming a wind turbine foundation includes providing an anchor cage in an excavation pit, the anchor cage including an upper flange, a lower flange, and a plurality of anchor bolts extending therebetween. A first cementitious material is directed into the excavation pit so that the anchor cage becomes at least partially embedded in the material, which is allowed to cure to form a rigid body. A connecting element is selectively engaged with the upper flange and an actuating element is positioned in operative relation with the connecting element, the connecting and actuating elements positioned in non-contact relation with the anchor bolts. The actuating element is actuated relative to the connecting element to raise the upper flange from the rigid body into a leveled position. A second cementitious material is directed into a space beneath the raised upper flange and is allowed to cure to form a support layer.

Abstract: A method for erecting a wind turbine tower is disclosed. A tower section (8) comprising a lower flange (9) and an upper flange (10), and a plurality of stud bolts (6) and nuts (7) are provided. The tower section (8) is oriented in an upright position with the lower flange (9) below the upper flange (10), and stud bolts (6) are positioned in bolt holes (12) in the lower flange (9) with nuts (7) arranged on an upper side of the lower flange (9). The tower section (8) is lifted to a mounting position on top of another tower section (13), and a flange combination is formed by aligning the bolt holes (12) formed in the lower flange (9) of the tower section (8) with bolt holes (15) formed in an upper flange (14) of the other tower section (13), while advancing the stud bolts (6) through the bolt holes (12, 15). The invention further provides a socket tool (16) for screwing nuts (7) onto stud bolts (6) in a manner which positions the stud bolts (6) correctly with respect to a flange (9).

Abstract: A tool (600) for aligning tubular structures (200, 300) of a wind turbine comprises: a plurality of hanger members (601) configured to be pivotably attached to an end region of a first tubular structure (300) so as to extend axially outward therefrom, each of the hanger members comprising a guide part (605) adapted to engage an interior wall (203) of a second tubular structure (200); at least one cable (615) connecting the hanger members (601) together; and a tension mechanism arranged to adjust a tension of the at least one cable (615). The tension mechanism is operable to adjust said tension to pivot the guide parts (605) into engagement with the interior wall (203) of the second tubular structure (200) when the first tubular structure (300) is moved axially toward the second tubular structure (200), thereby to guide the first tubular structure (300) into axial alignment with the second tubular structure (200).