Patent ID: 12215673

Single features depicted in the figures are shown relatively with regards to each other and therefore are not necessarily to scale. Similar or same elements in the figures, even if displayed in different embodiments, are represented with the same reference numbers.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, which shall not limit the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention, for instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIG.1is a perspective view of an exemplary wind turbine10. In the exemplary embodiment, the wind turbine10is a horizontal-axis wind turbine. Alternatively, the wind turbine10may be a vertical-axis wind turbine. In the exemplary embodiment, the wind turbine10includes a tower12that extends from a support system14, a nacelle16mounted on tower12, and a rotor18that is coupled to nacelle16. The rotor18includes a rotatable hub20and at least one rotor blade100coupled to and extending outward from the hub20. In the exemplary embodiment, the rotor18has three rotor blades100. In an alternative embodiment, the rotor18includes more or less than three rotor blades100. In the exemplary embodiment, the tower12is fabricated from tubular steel to define a cavity (not shown inFIG.1) between a support system14and the nacelle16. In an alternative embodiment, the tower12is any suitable type of a tower having any suitable height.

The rotor blades100are spaced about the hub20to facilitate rotating the rotor18to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. The rotor blades100are mated to the hub20by coupling a root section110to the hub20at a plurality of load transfer regions26. The load transfer regions26may have a hub load transfer region and a blade load transfer region (both not shown inFIG.1). Loads induced to the rotor blades100are transferred to the hub20via the load transfer regions26.

In one embodiment, the rotor blades100have a length ranging from about 15 meters (m) to about 91 m. Alternatively, rotor blades100may have any suitable length that enables the wind turbine10to function as described herein. For example, other non-limiting examples of blade lengths include 20 m or less, 37 m, 48.7 m, 50.2 m, 52.2 m or a length that is greater than 91 m. As wind strikes the rotor blades100from a wind direction28, the rotor18is rotated about an axis of rotation30. As the rotor blades100are rotated and subjected to centrifugal forces, the rotor blades100are also subjected to various forces and moments. As such, the rotor blades100may deflect and/or rotate from a neutral, or non-deflected, position to a deflected position.

Moreover, a pitch angle of the rotor blades100, i.e., an angle that determines a perspective of the rotor blades100with respect to the wind direction, may be changed by a pitch system32to control the load and power generated by the wind turbine10by adjusting an angular position of at least one rotor blade100relative to wind vectors. Pitch axes34of rotor blades100are shown. During operation of the wind turbine10, the pitch system32may change a pitch angle of the rotor blades100such that the rotor blades100are moved to a feathered position, such that the perspective of at least one rotor blade100relative to wind vectors provides a minimal surface area of the rotor blade100to be oriented towards the wind vectors, which facilitates reducing a rotational speed and/or facilitates a stall of the rotor18.

In the exemplary embodiment, a blade pitch of each rotor blade100is controlled individually by a wind turbine controller36or by a pitch control system80. Alternatively, the blade pitch for all rotor blades100may be controlled simultaneously by said control systems.

Further, in the exemplary embodiment, as the wind direction28changes, a yaw direction of the nacelle16may be rotated about a yaw axis38to position the rotor blades100with respect to wind direction28.

In the exemplary embodiment, the wind turbine controller36is shown as being centralized within the nacelle16, however, the wind turbine controller36may be a distributed system throughout the wind turbine10, on the support system14, within a wind farm, and/or at a remote control center. The wind turbine controller36includes a processor40configured to perform the methods and/or steps described herein. Further, many of the other components described herein include a processor. As used herein, the term “processor” is not limited to integrated circuits referred to in the art as a computer, but broadly refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. It should be understood that a processor and/or a control system can also include memory, input channels, and/or output channels.

FIG.2is an enlarged sectional view of a portion of the wind turbine10. In the exemplary embodiment, the wind turbine10includes the nacelle16and the rotor18that is rotatably coupled to the nacelle16. More specifically, the hub20of the rotor18is rotatably coupled to an electric generator42positioned within the nacelle16by the main shaft44, a gearbox46, a high speed shaft48, and a coupling50. In the exemplary embodiment, the main shaft44is disposed at least partially coaxial to a longitudinal axis (not shown) of the nacelle16. A rotation of the main shaft44drives the gearbox46that subsequently drives the high speed shaft48by translating the relatively slow rotational movement of the rotor18and of the main shaft44into a relatively fast rotational movement of the high speed shaft48. The latter is connected to the generator42for generating electrical energy with the help of a coupling50.

The gearbox46and generator42may be supported by a main support structure frame of the nacelle16, optionally embodied as a main frame52. The gearbox46may include a gearbox housing that is connected to the main frame52by one or more torque arms. In the exemplary embodiment, the nacelle16also includes a main forward support bearing60and a main aft support bearing62. Furthermore, the generator42can be mounted to the main frame52by decoupling support means54, in particular in order to prevent vibrations of the generator42to be introduced into the main frame52and thereby causing a noise emission source.

Preferably, the main frame52is configured to carry the entire load caused by the weight of the rotor18and components of the nacelle16and by the wind and rotational loads, and furthermore, to introduce these loads into the tower12of the wind turbine10. The rotor shaft44, generator42, gearbox46, high speed shaft48, coupling50, and any associated fastening, support, and/or securing device including, but not limited to, support52, and forward support bearing60and aft support bearing62, are sometimes referred to as a drive train64.

The nacelle16also may include a yaw drive mechanism56that may be used to rotate the nacelle16and thereby also the rotor18about the yaw axis38to control the perspective of the rotor blades100with respect to the wind direction28.

For positioning the nacelle appropriately with respect to the wind direction28, the nacelle16may also include at least one meteorological mast58that may include a wind vane and anemometer (neither shown inFIG.2). The mast58provides information to the wind turbine controller36that may include wind direction and/or wind speed.

In the exemplary embodiment, the pitch system32is at least partially arranged as a pitch assembly66in the hub20. The pitch assembly66includes one or more pitch drive systems68and at least one sensor70. Each pitch drive system68is coupled to a respective rotor blade100(shown inFIG.1) for modulating the pitch angel of a rotor blade100along the pitch axis34. Only one of three pitch drive systems68is shown inFIG.2.

In the exemplary embodiment, the pitch assembly66includes at least one pitch bearing72coupled to hub20and to a respective rotor blade100(shown inFIG.1) for rotating the respective rotor blade100about the pitch axis34. The pitch drive system68includes a pitch drive motor74, a pitch drive gearbox76, and a pitch drive pinion78. The pitch drive motor74is coupled to the pitch drive gearbox76such that the pitch drive motor74imparts mechanical force to the pitch drive gearbox76. The pitch drive gearbox76is coupled to the pitch drive pinion78such that the pitch drive pinion78is rotated by the pitch drive gearbox76. The pitch bearing72is coupled to pitch drive pinion78such that the rotation of the pitch drive pinion78causes a rotation of the pitch bearing72.

Pitch drive system68is coupled to the wind turbine controller36for adjusting the pitch angle of a rotor blade100upon receipt of one or more signals from the wind turbine controller36. In the exemplary embodiment, the pitch drive motor74is any suitable motor driven by electrical power and/or a hydraulic system that enables pitch assembly66to function as described herein. Alternatively, the pitch assembly66may include any suitable structure, configuration, arrangement, and/or components such as, but not limited to, hydraulic cylinders, springs, and/or servo-mechanisms. In certain embodiments, the pitch drive motor74is driven by energy extracted from a rotational inertia of hub20and/or a stored energy source (not shown) that supplies energy to components of the wind turbine10.

The pitch assembly66also includes one or more pitch control systems80for controlling the pitch drive system68according to control signals from the wind turbine controller36, in case of specific prioritized situations and/or during rotor18overspeed. In the exemplary embodiment, the pitch assembly66includes at least one pitch control system80communicatively coupled to a respective pitch drive system68for controlling pitch drive system68independently from the wind turbine controller36. In the exemplary embodiment, the pitch control system80is coupled to the pitch drive system68and to a sensor70. During normal operation of the wind turbine10, the wind turbine controller36controls the pitch drive system68to adjust a pitch angle of rotor blades100.

In one embodiment, in particular when the rotor18operates at rotor overspeed, the pitch control system80overrides the wind turbine controller36, such that the wind turbine controller36no longer controls the pitch control system80and the pitch drive system68. Thus, the pitch control system80is able to make the pitch drive system68to move the rotor blade100to a feathered position for reducing a rotational speed of the rotor18.

According to an embodiment, a power generator84, for example comprising a battery and/or electric capacitors, is arranged at or within the hub20and is coupled to the sensor70, the pitch control system80, and to the pitch drive system68to provide a source of power to these components. In the exemplary embodiment, the power generator84provides a continuing source of power to the pitch assembly66during operation of the wind turbine10. In an alternative embodiment, power generator84provides power to the pitch assembly66only during an electrical power loss event of the wind turbine10. The electrical power loss event may include power grid loss or dip, malfunctioning of an electrical system of the wind turbine10, and/or failure of the wind turbine controller36. During the electrical power loss event, the power generator84operates to provide electrical power to the pitch assembly66such that pitch assembly66can operate during the electrical power loss event.

In the exemplary embodiment, the pitch drive system68, the sensor70, the pitch control system80, cables, and the power generator84are each positioned in a cavity86defined by an inner surface88of hub20. In an alternative embodiment, said components are positioned with respect to an outer surface90of hub20and may be coupled, directly or indirectly, to outer surface90.

FIG.3is a non-limiting, schematic representation of a rotor blade100according to a specific embodiment, wherein a part of the hub20is shown by dashed lines. The entire rotor18comprising rotor blades100and the hub20is rotatable around the axis of rotation30.

According to the representation of the subject matter ofFIG.3, the pitch axis34is identical to a longitudinal axis102of the rotor blade100, wherein a longitudinal axis of a rotor blade may as well be different from the pitch axis, for example when having curved blades.

When describing the rotor blade100, a longitudinal direction104is defined according to the longitudinal axis102, and a chordwise direction108is determined according to a chord106of the rotor blade100.

The rotor blade100can be structured in a tip section120, a root section110and a middle section118connecting the root section110and the tip section120. The rotor blade100comprises a blade root112in the root section110, and a blade tip122in the tip section120. The rotor blade100further comprises a suction surface and a pressure surface formed by a skin130. The pressure surface and the suction surface are connected by a trailing edge126and a leading edge124, both forming boundaries of the rotor blade surface in chordwise direction108.

The rotor blade100comprises a lightning arrangement160for receiving lightning strikes and for conducting lightning energy into a grounding arrangement24of the wind turbine10, a shielding arrangement140and an electric heating arrangement150. The shielding arrangement140and the electric heating arrangement150are arranged in the skin130or directly at an inner or outer surface of the skin130.

The lightning arrangement160may include one or a plurality of lightning receptors162for example being arranged in the tip section120and being configured for receiving lightning bolts during a lightning situation, and furthermore comprise at least a grounding device164.

The grounding device164is configured for being capable of conducting electrical energy of a lightning strike into a grounding arrangement24of the wind turbine10, wherein an electrical connection between the grounding device164and the grounding arrangement24may be chosen according to its suitability. For example such electrical connection may be provided by conductive means166, for example comprising a suitable spark gap or arching arrangement.

Furthermore, a power source180and determination device190are provided, wherein the power source180and determination device190are electrically connected to the heating arrangement150and the shielding arrangement140. The power source180and determination device190can be combined in one single technical component, wherein a controller186may be provided in order to control the power source180and/or the determination device190. According to an embodiment, the determination device190can be a measurement device, which can be embodied as a specific component, which can be integrated in the power source180and/or in the controller36of the wind turbine.

The controller186, the power source180and/or determination device190can be connected to at least one temperature sensor194by sensor connective means192(e.g. a cable), wherein the temperature sensor194can be arranged in the skin180and an area comprising the electric heating arrangement150or to an area not having the electric heating arrangement150.

FIG.4is a schematic sectional illustration through the skin130of the rotor blade100showing a possible but not limiting configuration of layers of the skin130. The inner surface of the skin130is at least partially formed by an inner layer136. When moving towards the outer surface of the skin130, the inner layer136are followed by a first heating layer152and a second heating layer154of the electric heating arrangement150. The shielding arrangement140comprising a shielding layer142is electrically insulated with respect to the first heating layer152and the second heating layer154of the electric heating arrangement150by the help of the insulation arrangement146comprising at least one insulation layer148. The outer surface of the skin130is formed by an outer layer134preferably sealed with respect to the environment by a gel coat132.

The heating arrangement150is connected to the power source180by the heating conductor156. For safety reasons is the heating arrangement150also connected to conductive means166of the lightning arrangement160, wherein a surge protection device158is electrically provided between the conductive means166of the lightning arrangement160and the electric heating arrangement150. Thus, in case an overvoltage situation is present in the electric heating arrangement150, the surplus electric energy can be conducted via the surge protection device158into the lightning arrangement160in order to protect the power source180and/or the determination device190.

In addition, the shielding arrangement140is electrically connected to the power source180and/or to the determination device190by the shielding conductor144.

The power source180is configured for applying a predetermined amount of electric test- and/or maintenance-energy182such that the electric test- and/or maintenance-energy182is effectively present between the shielding arrangement140and the electric heating arrangement150. For example, the electric test- and/or maintenance-energy182is provided to the shielding arrangement140and to the electric heating arrangement150such that as a consequence a shield-heating-voltage is applied effectively between the shielding arrangement140and the electric heating arrangement150.

Furthermore, —if the skin130is in a suitable condition—, as a consequence of the provision of the electric test- and/or maintenance-energy182, a shield-heating-current flows between the shielding arrangement140and the electric heating arrangement150, or vice versa. Hence, the shield-heating-voltage and the shield-heating-current are caused by the provision of the predetermined electric test- and/or maintenance-energy182.

The determination device190are electrically connected to the shielding arrangement140and to the electric heating arrangement150in a way that the shield-heating-voltage and/or the shield-heating-current being present between the shielding arrangement140and the electric heating arrangement150can be determined.

FIG.5is a schematic flow chart of the method for checking the functionality of the insulation arrangement146applying the test cycle and furthermore of the method for restoring the functionality of the insulation arrangement146applying the repair cycle300.

The process may generally start by defining202a first shield-heating-current threshold, wherein the shield-heating-current threshold represents an accepted current leakage between the shielding arrangement140in the electric heating arrangement150during, in particular exclusively during, the execution of the test cycle. The test cycle can be performed in various iterations (loops). In particular, the shield-heating-current threshold is decreasing from each iteration to the subsequent iteration, for example starting with 10 mA, applying subsequently 5 mA, wherein after 1 mA is used as acceptable shield-heating-current threshold. According to an optional alternative, the shield-heating-current threshold is increasing from each iteration to the subsequent iteration, for example starting with 1 mA, applying subsequently 5 mA, wherein after 10 mA is used as acceptable shield-heating-current threshold.

In step212it is defined with what kind of test voltage (voltage ramp for the test voltage for loops of test cycles, for example increasing each loop from 0 (0.5) kV to 5 kV in steps of 100 V) and the first test voltage is applied. As a consequence of the application of the test voltage in step212a shield-heating-current between the shielding arrangement140and the electric heating arrangement150is established and determined by determination device190. In step206it is analyzed if the shield-heating-current resulting of the application of the test voltage (first test voltage) does exceed the (first) shield-heating-current threshold as determined in step202. If this is not the case the first loop of the test cycle has been passed successfully by the rotor blade (system).

Subsequently, the test voltage is increased208to its next higher value (second test voltage) and the test is conducted repeatedly in step216. If the plurality of test voltages has been applied up to the maximum value of the test voltage and the test cycle has been passed successfully, the shield-heating-current threshold is increased to the second shield-heating-current threshold and the test cycle is conducted repeatedly applying the plurality of test voltages. Eventually, the test cycle has been passed successfully by the rotor blade if the determined shield-heating-current resulting from the highest test voltage is lower than acceptable shielding-heating-current threshold.

The repair cycle300can be applied is applied if the test cycle is not passed. For example, if it is determined in step206that the shield-heating-current exceeds the respective shield-heating-current threshold example it is determined by the controller186that an unacceptable conductivity184must be present between the shielding arrangement140and the electric heating arrangement150. Therefore, the heating arrangement150and further components of the rotor blade100would not be sufficiently protected against overvoltage during a lightning strike. Therefore, the insulation functionality of the insulation arrangement146is to be improved, for example, by applying the repair cycle300(second operational embodiment).

During step302of the repair cycle300a specific amount and quality of a shield-heating-current (electric repair current) is provided between the shielding arrangement140and the electric heating arrangement150in order to pass through the conductivity184. As a consequence, the conductivity184is heating up due to the electric repair current, which eventually may result in a deterioration of the conductivity184. Said deterioration of the conductivity results in an increased insulating functionality for example due to a melting of the material of the rotor blade, an/or due to burning up the conductivity184. Subsequently, the test cycle can be performed repeatedly in order to determine if the insulation arrangement146is working as required.

The skilled person is aware, that test cycle and repair cycle can be performed repeatedly and iteratively, for example, the electric repair current can be increased from a first electric repair current to a higher subsequent electric repair current if the test cycle200is not passed when having applied only a lower first electric repair current during the repair cycle300.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art, for example that heating layer is152,154and insulation layers148can be arranged differently than shown inFIG.3. Such other examples are intended to be within the scope of the claims if they include elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

REFERENCE NUMBERS10wind turbine12tower14support system16nacelle18rotor20rotatable hub22hub transformer portion24grounding arrangement26load transfer regions28wind direction30axis of rotation32pitch system34pitch axes36controller of the wind turbine38yaw axis40processor42electric generator44main shaft46gearbox48high speed shaft50coupling52main frame54decoupling support means56yaw drive mechanism58meteorological mast60forward support bearing62aft support bearing64drive train66pitch assembly68pitch drive system70sensor72pitch bearing74pitch drive motor76pitch drive gearbox78pitch drive pinion80pitch control system84power generator100rotor blade102longitudinal axis104longitudinal direction106chord108chordwise direction110root section112blade root114root flange118middle section120tip section122blade tip124leading edge126trailing edge128fiber reinforced portion130skin132gel coat134outer layer136inner layer138thickness direction140shielding arrangement142shielding layer (copper mesh)144shielding conductor146insulation arrangement148insulation layer150electric heating arrangement152first heating layer154second heating layer156heating conductor158surge protection device160lightning arrangement162lightning receptor164grounding device166conductive means180power source182electric test- and/or maintenance-energy184conductivity186controller190determination device192sensor connective means194temperature sensor200test cycle202defining a shield-heating-current threshold204determining shield-heating-current206comparing determined shield-heating-currentwith shield-heating-current threshold208increasing test voltage210increasing shield-heating-current threshold212applying shield-heating-voltage214defining a test voltage threshold216final voltage test300reduction of conductivity (repair cycle)302establishing maintenance current