Abstract: The present invention relates to a power system having a plurality wind turbine generators and a power plant controller arranged to communicate with the plurality of wind turbines generators, where each of the plurality of wind turbine generator being related to a wind turbine controller, the wind turbine controller being arranged to control an active power output in its related wind turbine generator according to an active power set point received from the wind power plant controller; a first subset of wind turbine generators operating at an active power output unrestricted of the active power set point; and a second subset of wind turbine generators operating according to an active power set point; and wherein the wind power plant controller communicates the active power set point, in accordance with the active power output of the first subset of the plurality of wind turbines generators, so as to reduce active power fluctuation of the aggregated active power output of the first and second subset of the plu

Abstract: A method of making a wind turbine blade is described. The wind turbine blade comprises first and second half shells joined together and a shear web bonded between inner surfaces of the respective half shells. The blade is made in a one-stage join up process, which involves supporting the half shells in respective mould halves, and arranging one of the half shells on top of the other half shell with the shear web arranged between the two half shells. Adhesive is provided between the shear web and the inner surfaces of the respective half shells. During the join-up process, the shear web is supported by stabilisers. The use of stabilisers avoids the need for a jig to support the shear web. Stabilisers attached to an inboard end of the shear web may remain accessible after the join-up and can be removed.

Abstract: An alignment tool (1) for aligning a bore (13) extending through a first structural member (14) with a bore (19) extending through a second structural member (15) is disclosed. The alignment tool (1) comprises two shaft portions (2, 3) having a cylindrical or cylindrical like configuration. The second shaft portion (3) is arranged adjacent to the first shaft portion (2). A portion of the second surface forms a continuation of a portion of the first surface. A first bushing (8) is arranged along the first shaft portion (2) and substantially covering the first surface, and a second bushing (9) is arranged along the second shaft portion (3) and substantially covering the second surface. Mutual rotational movements are allowed between the first shaft portion (2) and the first bushing (8) and between the second shaft portion (3) and the second bushing (9).

Abstract: A method for estimating a wind speed at a wind turbine is disclosed, said wind turbine comprising a rotor carrying a set of wind turbine blades, each wind turbine blade having a variable pitch angle. A blade torsion contribution, representing torsion introduced in the wind turbine blades, is derived, based on an obtained rotational speed, ?, of the rotor, and an obtaining a pitch angle, ?, of the wind turbine blades. An adjusted pitch angle, ??, is calculated as a sum of the obtained pitch angle, ?, and the derived blade torsion contribution, and a wind speed, vest, is estimated, based on the obtained rotational speed, ?, and the calculated adjusted pitch angle, ??. An accurate and reliable estimate for the wind speed is thereby obtained. The wind turbine may be controlled in accordance with the estimated wind speed, vest.

Abstract: There is provided a method of operating a renewable power plant that is connected to a wider power network by a bus. The method comprises: identifying a predetermined voltage condition of the renewable power plant or of the bus; controlling the renewable power plant to maintain zero reactive power exchange at the bus for a first period; calculating an average voltage level of the bus that was achieved during the first period; and controlling the renewable power plant to maintain the voltage output at a set voltage level for a second period, the set voltage level being substantially equal to the calculated average voltage level. The method ensures that voltage oscillations due to a push-pull phenomenon between a power plant controller and the power network do not upset the stability of the grid.

Abstract: A method for operating at least two floating offshore wind turbines (1) is disclosed. The wind turbines (1) are operated at respective first operating positions (7), and a previous and/or a future expected wear impact on each wind turbine (1) is estimated. At least one wind turbine (1) to be relocated to a respective second operating position (9) is identified, based on the estimated wear impact. The identified wind turbines (1) are moved to respective second operating position (9) and operated there.

Abstract: Embodiments herein described provide systems and techniques for performing black start operations. For example, one embodiment provides a method for performing black start operations. The method generally includes operating a wind turbine in a wind park in a first mode to provide power to an alternating-current (AC) grid using a control system. The control system may include a reactive power control leg and an active power control leg. The method also includes switching operation of the wind turbine from the first mode to a second mode based on an indication to perform a black start of an electrical grid and by activating a controller with an integral action to thereby increase output power of the wind turbine, the controller being coupled between the reactive power control leg and the active power control leg, and providing power to the electrical grid while operating in the second mode.

Abstract: A method of installing a rotor on a nacelle (44) on a wind turbine generally includes providing a rotor hub counterweight assembly (10, 10?) which are rotated and lifted from a downtower location to an uptower location at which wind turbine blades (50, 52, 54) are progressively attached and the counterweights (14, 16), (14?, 16?) are progressively removed. The rotor hub and counterweight assembly (10, 10?) for use when installing a rotor on a wind turbine (46) generally includes a rotor hub (12) having first, second and third flanges (18, 20, 22), a first counterweight (14, 14?), a second counterweight (16, 16?), and a lifting apparatus connecting member (26, 26?). A lifting apparatus connecting member (26) is configured with at least two connection points (60, 62) being configured for allowing at least two of three operations including installation, rotating and lifting the rotor hub (12), and removal of the lifting apparatus connecting member (26?).

Abstract: A renewable power plant configured to deliver electrical power to an electrical grid in accordance with a reference is disclosed. The renewable power plant comprises at least one energy generating system of a first type, at least one energy generating system of a second type, and a control system including a central power plant controller (CPPC) which generates setpoints for controlling the energy generating systems in accordance with the reference. The energy generating systems provide feedback signals to the CPPC. The control system is configured to generate a modified feedback signal based on the feedback signal received from the energy generating systems of the second type, and using a model representing operational behavior of the energy generating systems of the second type. The CPPC is configured to apply the modified feedback signal to a feedback control loop for controlling the energy generating systems.

Abstract: A method of making a wind turbine blade is described. The blade comprises first (12) and second (14) half shells bonded together and a shear web (16) bonded inside the shells. Prior to joining the shells together, the shear web is positioned in one of the shells. A plurality of bars (70) are attached to the shear web and engaged with a plurality of mounts (80) in order to support and stabilise the shear web relative to that shell. The shells are then arranged one above the other whilst the bars remain attached to the shear web. The bars continue to support the shear web whilst the shear web is aligned with the other shell. The bars are then detached from the shear web and the shells are brought together to bond the shells to each other and to bond the shear web between the shells.

Abstract: A method of controlling a hybrid power plant connected to a power network, the hybrid power plant having a first renewable energy generator and a second renewable energy generator, the first renewable energy generator being configured to generate power using a different source of renewable energy to the second renewable energy generator. The method comprises: determining a target plant power output for the hybrid power plant; determining a target generator power output for each of the first and second generators based on the target plant power output; determining a respective ramp rate for each of the first and second renewable energy generators based, at least in part, on an attribute of the respective renewable energy generator; and operating each of the first and second renewable energy generators to change its power output to the power network at the determined ramp rate to achieve the target generator power output.

Abstract: Generating a control schedule for a wind turbine, the control schedule indicating how the turbine maximum power level varies over time. Generating the control schedule includes determining a value indicative of the current remaining fatigue lifetime of the turbine, or one or more turbine components, based on measured wind turbine site and/or operating data; applying an optimisation function that varies an initial control schedule to determine an optimised control schedule by varying the trade off between energy capture and fatigue life consumed by the turbine or the one or more turbine components until an optimised control schedule is determined.

Abstract: The present invention relates to a method for controlling a wind power plant, WPP, comprising a plurality of wind turbine generators, WTGs, connected to an electrical grid, the method comprising: setting a plant power reference (Ptotal) according to an electrical value of the electrical grid; determining an inertia delta power reference (IRdeltaP) required for the WPP to meet a power demand in response to a change in the electrical value; adding the inertia delta power reference and the plant power reference (Ptotal) to form a power reference (Ptotalref); deriving an overboost reference (PrefOB) as the difference between the power reference (Ptotalref) and an available power value; dispatching the power reference (Ptotalref) to each wind turbine generator; dispatching the overboost reference (PrefOB) to each wind turbine generator. The invention also relates to a wind power plant control system and a wind power plant comprising a control system.

Abstract: The invention relates to a method for controlling a wind turbine which comprises a transformer has a variable turns ratio such as an on load tap changer transformer. The adjustment of the turns ratio is possible when a primary side current or a secondary side current of the transformer is less than a switching current threshold. The method comprises operating the wind turbine so that the primary or secondary side current is above the switching current threshold. In response to obtaining a condition for changing the turns ratio of the transformer, the wind turbine is operated so that the primary or secondary side current is reduced below the switching current threshold so that the turns ratio can be changed during the temporary current reduction.

Abstract: The present invention relates to a rotor control system for actuating pitch of pitch adjustable rotor blades in order to reduce vibrations of a wind turbine element, e.g. tower vibrations. A pitch modification signal is determined which is based on an m-blade coordinate transformation, such as the Coleman transformation. The m-blade coordinate transformation taking as input a first signal and a second signal. The second signal is determined by filtering the first signal with a signal filter with a quadrature phase shift filter phase response.

Abstract: A wind turbine blade is provided comprising a main blade portion and a light detection and ranging (LIDAR) element. The main blade portion has a shell defining an outer aerodynamic surface of the blade. The LIDAR element is disposed within a volume bounded by the outer aerodynamic surface and comprises at least one LIDAR system configured to transmit light beams away from the blade and to detect reflected light beams incident upon the blade.

Abstract: The present invention relates to a power system having a plurality wind turbine generators and a power plant controller arranged to communicate with the plurality of wind turbines generators, where each of the plurality of wind turbine generator being related to a wind turbine controller, the wind turbine controller being arranged to control an active power output in its related wind turbine generator according to an active power set point received from the wind power plant controller; a first subset of wind turbine generators operating at an active power output unrestricted of the active power set point; and a second subset of wind turbine generators operating according to an active power set point; and wherein the wind power plant controller communicates the active power set point, in accordance with the active power output of the first subset of the plurality of wind turbines generators, so as to reduce active power fluctuation of the aggregated active power output of the first and second subset of the plu

Abstract: A retrofitted wind turbine installation for replacing a prior wind turbine installation includes the foundation of the prior wind turbine installation and a replacement wind turbine supported by the foundation, wherein the tower of the retrofitted wind turbine installation is a cable-stayed tower to reduce the bending loads imposed on the foundation. A method of retrofitting an existing wind turbine installation with a replacement wind turbine includes disassembling at least a portion of the existing wind turbine, assembling a replacement tower to a remaining portion of the existing wind turbine installation, attaching a plurality of stay cables between the tower of the retrofitted wind turbine installation and stay cable foundations, and attaching the replacement energy generating unit to the replacement tower.

Abstract: A control system and method of control are disclosed. A model predictive control, MPC, unit is configured to determine a control signal for controlling an operation of the wind turbine based at least in part on a cost function comprising a wear cost relating to one or more types of wear of the winding turbine, and a corresponding cost weighting, which defines a relative weighting of the wear cost in the cost function. A weighting determination unit is configured to receive a reference signal comprising a target wear, receive a feedback signal comprising a wear measure of the wind turbine, and determine, based at least in part on a difference between the target wear and the wear measure, a weighting adjustment for at least part of the cost weighting of the cost function. The MPC unit then sets the cost weighting based at least in part on the weighting adjustment.

Abstract: The present invention relates to a method of controlling a doubly fed induction generator wind turbine converter system in case of a sub-synchronous resonance event, the method comprising the steps of detecting the sub-synchronous resonance event, and switching from a first control mode to a second control mode in response to detecting the predetermined event, wherein the second control mode comprises the step of setting at least one rotor current controller parameter on the basis of a generator speed of the doubly fed induction generator. The predetermined event may also be a fault ride through event. The present invention further relates to a doubly fed induction generator wind turbine converter system being capable of handling such events.