Patent Description:
During installation, maintenance, repair, or other scenarios when the rotor of a wind turbine is either locked or idling, it may be desired to install an add-on device onto the blades of the wind turbine. The add-on device may relate, for example, to a vortex generator or other type of device that is intended to enhance aerodynamic performance of the blade. In a particular scenario wherein the rotor is locked or idling and is without yaw capability, it may be desired to install a temporary add-on device on the blades in the form of a vibration suppression device to prevent stall or vortex induced vibrations from occurring. These vibration suppression devices can range in design, with varying shapes and sizes, and serve to increase drag, disrupt/influence airflow over the blade surfaces, or provide vibration damping.

The current procedures for installing the add-on devices present significant challenges. For example, the conventional solutions generally require a crane, cherry picker, or repelling expertise to install or attach the add-on devices at an uptower location at or near the blade root. These procedures are expensive in terms of necessary equipment (e.g., a crane or cherry picker), time-consuming, and can present health and safety concerns for personnel.

<CIT> describes a device and associated installation method wherein a wind turbine blade oscillation preventer is formed as a closed sleeve with an aperture opening at one end thereof defined by a resilient collar. The preventer is configured for removable application over a tip of the wind turbine blade and extends longitudinally along the blade and peripherally around the blade. The preventer has a non-aerodynamic exterior surface that disrupts smooth or laminar airflow over a substantial portion of the longitudinal and peripheral extent of said sleeve when the preventer is in place on the wind turbine blade. In a particular embodiment, this exterior surface is a fishnet-type of structure. The preventer includes a smooth interior surface extending along the longitudinal extent of sleeve. In use, the smooth interior surface ensures that the blade trailing edge is shielded from contact with the rough non-aerodynamic external surface of the preventer. This ensures that the preventer can be applied to wind turbine blades having serrations at their trailing edge. In particular, the smooth internal surface prevents snagging between the rough non-aerodynamic external surface and the serrations. The smooth internal surface glides over the serrations without engaging them and without damage either to the serration or to the smooth internal fabric.

The method and device of the US '<NUM> patent has distinct disadvantages. For example, the construction of the sleeve is complex and requires an inner smooth layer and an outer fishnet or "rough" non-aerodynamic material layer. In order to keep the blade aperture open during the installation process, a separate resilient collar is required at the aperture. Installation of the sleeve requires rather exact alignment of the open end of the sleeve with the tip of the blade, which requires a particular blade orientation of the blade towards the ground and careful coordination between a technician on the ground with a first guideline and a technician in hub with a second guide line to align the sleeve with the blade tip and pull the sleeve onto the blade tip. It would be desirable to provide a device and associated method for installation of an add-on device, such as a vibration suppression device, onto the tip end of the wind turbine blade that is cost-effective, safe, performed at various orientations of the blade, and eliminates the need for a crane or other similar equipment at the wind turbine site.

A further prior art method and system are described in <CIT>.

In one aspect, the present disclosure is directed to a method for installing a pliant material add-on device onto a blade of a wind turbine, wherein the blade is mounted to a rotor at a hub that is atop a tower. The method is not limited to any particular type or purpose of the add-on device, and includes embodiments wherein the add-on device is constructed as a pliant-material wrap that drapes around the leading edge of the wind turbine blade to function as a vibration suppression device that disrupts flow across the blade in order to suppress stall or vortex induced vibrations from occurring. The method includes configuring a plurality of tag lines to the wrap, the tag lines having a length so as to extend to a ground location when the add-on device is secured on the blade. The rotor is used to position the blade to a first rotated position. The add-on device is located to a desired span-wise location on the blade such that the wrap forms an open-sleeve configuration draped around a leading edge of the blade and span-wise sides of the wrap extend along the pressure and suction sides of the blade, respectively, adjacent the trailing edge of the blade. With the tag lines handled by one or more technicians at the ground level location, the wrap is tensioned against the blade. Attachment devices (e.g., clamps, clips, etc.) are configured with the wrap and are affixed to the trailing edge of the blade via the tensioning action.

An embodiment of the method includes wrapping the tag lines around the blade in a direction towards a root end of the blade by rotating the blade with a pitch control system while advancing the tag lines from the ground location towards the root end of the blade. In this manner, the tag lines form a wrap pattern around the blade from the wrap to the root end of the blade.

The trailing edge of the blade at the desired span-wise location of the add-on device may include serrations, wherein the method includes affixing the attachment devices onto, between, or over the serrations so as not to damage the serrations.

In a particular embodiment, the attachment devices are connected to the wrap via elastic members (e.g., an elastic cord or line) and the tag lines are connected to the attachment devices, wherein the tensioning process comprises pulling on the tag lines from the ground location to stretch the elastic members (and tension the wrap against the blade) until the attachment devices engage and affix to the trailing edge of the blade. The wrap may have a rectangular shape and one of the tag lines and attachment devices may be attached to each corner of the wrap.

The first rotated position of the blade may be, for example a relative position between <NUM> o'clock and <NUM> o'clock or between <NUM> o'clock and <NUM> o'clock.

In a particular embodiment, the add-on device is located at the desired span-wise location on the blade by: with a technician at the rotor hub, positioning the wrap around the leading edge of the blade and dropping the tag lines to the ground location; and with technicians at the ground location, using the tag lines to move the wrap span-wise along the blade to the desired span-wise location. With this embodiment, the technician at the rotor hub may pay out a guideline attached to a chord-wise side of the wrap to stabilize the wrap as the wrap moves along the blade to the desired span-wise location.

In another embodiment, the add-on device is located at the desired span-wise location on the blade by: with one or more technicians at the ground location below the desired span-wise location on the blade, propelling one or more of the tag lines up and over the leading edge of the blade; with the technicians at the ground location, pulling the propelled tag lines to raise the wrap up an over the leading edge of the blade to form the open-sleeve configuration draped around the leading edge; and with the technicians at the ground location, pulling on the tag lines to tension the wrap against the blade and affix the attachment devices to the trailing edge of the blade. With this embodiment, the tag lines and attachment devices may be attached to each of four corners of the wrap, wherein the tag lines attached to the corners at one span-wise side of the wrap are propelled over the blade.

The present invention also encompasses various method embodiments of removing the add-on device from a wind turbine blade in essentially the reverse order in which the add-on device was installed.

The present invention also encompasses an add-on device for a wind turbine, the add-on device including a pliant-material wrap having a size and dimensions so as to form an open-sleeve configuration that drapes around a leading edge of the wind turbine blade at a desired span-wise location along the wind turbine blade, wherein span-wise sides of the wrap extend along pressure and suction sides of the blade, respectively, adjacent a trailing edge of the blade. A plurality of tag lines are attached to the wrap, the tag lines having a length so as to extend from the desired location of the add-on device on the wind turbine blade to a ground location so that technicians at the ground location can handle the tag lines to locate the add-on device at the desired location on the blade. Attachment devices are connected to the wrap, the attachment devices configured to secure the wrap to a trailing edge of the blade.

The trailing edge of the blade at the desired span-wise location of the add-on device may include serrations, wherein the attachment devices are configured to attach onto, between, or over the serrations without damaging the serrations.

In a particular embodiment, the attachment devices include a body with one or more protrusions on a side thereof that fit between the serrations along the trailing edge. The body may be a relatively flat, planar member wherein the protrusions are defined on an underside thereof.

In another embodiment, the attachment device may include a generally U-shaped body member with internal molded surfaces conforming to the shape of the serrations, wherein the serrations slide into the body upon fixing the attachment device to the trailing edge of the blade.

In a certain embodiment, the attachment devices are attached to the wrap via elastic members and the tag lines are attached to the attachment devices, the elastic members having a length so as to tension the wrap against the blade when the attachment devise are affixed to the trailing edge. In this embodiment, the elastic members may extend completely along and beyond the chord-wise sides of the wrap.

The wrap may have a generally rectangular shape, wherein one of the tag lines and clamp devices is attached to each corner of the wrap.

A particular embodiment of the add-on device includes a guideline attached to a chord-wise side of the wrap, the guideline having a length to allow a technician at a rotor hub of the wind turbine to handle the guideline as the add-on device is moved span-wise to the desired location on the blade.

In a unique embodiment, the wrap is formed from an open weave construction or material, for example a fishnet material.

The present invention also encompasses the wind turbine blades having one or more of the add-on devices installed thereon.

The invention will be further supported and described with reference to the following description and appended claims.

Referring now to the drawings, <FIG> illustrates a perspective view of an embodiment of a wind turbine <NUM> with one of its blades <NUM> configured with an add-on device <NUM> according to the present disclosure. As shown, the wind turbine <NUM> generally includes a tower <NUM> with a ground-level base <NUM>, a nacelle <NUM> mounted on the tower <NUM>, and a rotor <NUM> coupled to the nacelle <NUM>. The rotor <NUM> includes a rotatable hub <NUM> and rotor blades <NUM> coupled to and extending outwardly from the hub <NUM>. Each rotor blade <NUM> may be spaced about the hub <NUM> to facilitate rotating the rotor <NUM> to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub <NUM> may be rotationally coupled to an electric generator positioned within the nacelle <NUM> to permit electrical energy to be produced.

For purposes of the present disclosure, the term "nacelle" is used herein to include machine head components (e.g., drive train components, generator, etc.) located within the nacelle housing and the hub <NUM> components.

The add-on device <NUM> depicted on one of the blades in <FIG> may serve different purposes and have varying designs. For example, the add-one device <NUM> may be designed as a device intended to remain on the blade during operation to enhance aerodynamic performance of the blade. Alternatively, the add-on device may be designed as a temporary device intended to minimize vibrations in the blade during a non-operational condition of the wind turbine, for example when the rotor <NUM> is in a locked or idling state, or when the rotor cannot be yawed. It should be appreciated that the present invention is not limited to the type or purpose of the add-on device <NUM>. For purposes of explanation only, the add-on device <NUM> is depicted and described herein as a vibration suppression device intended to suppress or damp vibrations in the blades <NUM>.

The present disclosure is directed to various method embodiments for installing the add-on device <NUM> onto one or more blades <NUM> of the wind turbine <NUM> generally adjacent to the blade tip <NUM>. The method may also be used for installing the add-on device along any span-wise portion of the blade <NUM>.

The shape, size, and configuration of the add-on device can vary within the scope of the invention. A particular embodiment of an add-on device <NUM> in depicted in <FIG> and includes a pliant-material wrap <NUM> that drapes around the leading edge <NUM> of the wind turbine blade <NUM> to function as a vibration suppression device that disrupts flow across the blade <NUM> in order to suppress stall or vortex induced vibrations from occurring. In this regard, the wrap <NUM> may have a surface texture that is designed to disrupt airflow across the blade <NUM>. In a unique embodiment, the wrap <NUM> is formed from an open weave construction or material, for example a fishnet material, as depicted in the figures in general. The wrap <NUM> may have a generally rectangular shape, as depicted in <FIG>.

The wrap <NUM> has a size and dimensions so as to form an open-sleeve configuration that drapes around the leading edge <NUM> of the wind turbine blade (<FIG>) at a desired span-wise location along the wind turbine blade <NUM>. Span-wise sides <NUM> of the wrap <NUM> extend along pressure <NUM> and suction <NUM> sides of the blade <NUM>, respectively, adjacent the trailing edge <NUM> of the blade <NUM>.

The add-on device <NUM> includes a plurality of tag lines <NUM> attached to the wrap <NUM>, for example at each corner of the wrap <NUM> (<FIG>). The tag lines <NUM> may be any type of rope, cord, cable, etc., and have a length so as to extend from the desired location of the add-on device <NUM> on the wind turbine blade <NUM> to a ground-level location <NUM>, as explained in more detail below with respect to <FIG>.

The add-on device <NUM> includes a plurality of attachment devices <NUM> connected to the wrap <NUM>. These devices <NUM> may be variously configured and serve to secure the wrap <NUM> to the trailing edge <NUM> of the blade. The attachment device <NUM> may be any manner of mechanical clamp, clip, or the like, that releasably affixes to the trailing edge <NUM>. In the various embodiments depicted in the figures, the attachment devices <NUM> are attached to the wrap <NUM> via elastic members <NUM> (e.g., an elastic cord or rope, bungee, or the like), wherein the tag lines <NUM> are, in turn, attached to the attachment devices <NUM>. The elastic members <NUM> have a length so as to tension the wrap <NUM> against the blade surfaces, <NUM>, <NUM> when the attachment devise <NUM> are affixed to the trailing edge <NUM>. Referring to <FIG>, in a particular embodiment, the elastic members <NUM> may extend completely along and beyond the chord-wise sides <NUM> of the wrap <NUM>.

Referring to <FIG>, certain designs of wind turbine blades <NUM> include serrations <NUM> along a span-wise portion of the blade trailing edge <NUM>. These serrations <NUM> provide an enhanced aerodynamic performance from the blade <NUM>. The serrations <NUM> are typically located along the trailing edge <NUM> closer to the blade tip <NUM>, which may also coincide with the desired span-wise location of the add-on device <NUM> on the blade <NUM>. In this case, the attachment devices <NUM> may be specifically configured to attach onto, between, or over the serrations <NUM> without damaging the serrations. For example, referring to <FIG>, in a particular embodiment, the attachment devices <NUM> may be designed as a clamp having a body <NUM>, which may be a relatively flat, planar, member with one or more protrusions <NUM> on an underside thereof, the protrusions <NUM> having a shape and size so as to between the serrations <NUM> along the trailing edge <NUM>. With this embodiment, due to the elasticity of the elastic member <NUM>, the attachment device <NUM> is initially pulled (via the tag line <NUM>) beyond the trailing edge <NUM> so that the protrusions <NUM> can enter between the serrations <NUM>. Upon release of tension on the tag line <NUM>, the elastic member <NUM> pulls the body <NUM> back towards the wrap <NUM> causing the protrusions <NUM> to engage between the serrations <NUM> while the body lies generally flat against the serrations <NUM> across the trailing edge <NUM> and onto the pressure or suction side of the blade <NUM>.

In another embodiment depicted in <FIG>, the attachment device <NUM> may include a generally U-shaped body member <NUM> with internal molded surfaces defining a recess or cavity <NUM> that conforms to the shape of the serrations <NUM>. The cavity <NUM> may be a generally open space in which the serrations <NUM> reside or, in the depicted embodiment, individual cavities <NUM> are formed to conform to the shape of individual serrations <NUM>. The attachment device <NUM> is engaged with the trailing edge <NUM> in the same manner discussed above with respect to the embodiment of <FIG> and <NUM>. The body <NUM> is initially pulled beyond the trailing edge <NUM> at least to the extent that the entrance to the cavity <NUM> is past the serrations <NUM>. Upon release of the tag line <NUM>, the elastic member <NUM> pulls the body <NUM> back towards the wrap <NUM> causing the serrations <NUM> to slide into the cavity <NUM>.

As depicted in <FIG>, a particular embodiment of the add-on device <NUM> may include a guideline <NUM> attached to a chord-wise side <NUM> of the wrap <NUM>. As explained below in greater detail, the guideline <NUM> has a length to allow a technician at the <NUM> rotor hub of the wind turbine to handle the guideline <NUM> as the add-on device <NUM> is moved span-wise to the desired location on the blade <NUM>.

Aspects of the method for locating and securing the add-on device <NUM> onto a blade <NUM> of a wind turbine <NUM> are discussed with reference to <FIG>.

The method includes configuring a plurality of the tag lines <NUM> to the wrap <NUM>. This step may be done by a technician <NUM> positioned at the rotor hub <NUM>, wherein the tag lines <NUM> can then be dropped from the hub <NUM> to other technicians <NUM> at the ground location <NUM>. As mentioned, the tag lines 50have a length so as to extend to a ground location <NUM> when the add-on device <NUM> is being positioned and secured on the blade <NUM>.

The method includes rotating the rotor <NUM> (and thus, the hub <NUM>) to locate the blade <NUM> to a first position desired for the installation process. In <FIG>, for example, the blade <NUM> is positioned essentially horizontal to ground (i.e., at the <NUM> o'clock or <NUM> o'clock position). In other embodiments, this first rotated position of the blade may be between <NUM> o'clock and <NUM> o'clock or between <NUM> o'clock and <NUM> o'clock.

The add-on device <NUM> is then located to the desired span-wise location on the blade <NUM> such that the wrap <NUM> forms an open-sleeve configuration draped around the leading edge <NUM> of the blade <NUM> and the span-wise sides <NUM> of the wrap <NUM> extend along the pressure <NUM> and suction <NUM> sides of the blade, respectively, adjacent the trailing edge <NUM> of the blade (<FIG>). The wrap <NUM> is initially positioned around leading edge <NUM> by the technician 41at the rotor hub <NUM>, wherein the technician <NUM> then drops the tag lines <NUM> to the ground location <NUM>. The technicians <NUM> at the ground location <NUM> grab and use the tag lines <NUM> to walk the wrap <NUM> span-wise along the blade <NUM> to the desired span-wise location, as depicted in <FIG>. With this embodiment, the technician 41at the rotor hub <NUM> may pay out the guideline <NUM> attached to a chord-wise side <NUM> of the wrap <NUM> to stabilize the wrap <NUM> as it moves along the blade <NUM> to the desired span-wise location.

Referring to <FIG>, once the wrap <NUM> has been located on the blade <NUM>, the technicians <NUM> pull the tag lines <NUM> to tension the wrap <NUM> against the blade and to pull the attachment devices into engagement with the trailing edge <NUM> of the blade <NUM> as discussed above.

Referring to <FIG>, once the wrap <NUM> has been affixed to the blade via the attachment devices <NUM>, the method may include wrapping the tag lines <NUM> around the blade <NUM> in a direction towards a root end <NUM> of the blade <NUM> by rotating the blade <NUM> with a pitch control system (indicated by the rotating arrows in <FIG>) while the ground technicians <NUM> advance (e.g., walk) the tag lines <NUM> towards the root end <NUM> of the blade <NUM>. This action causes the tag lines <NUM> to wrap around the blade <NUM> in a first wrap pattern <NUM>. After completion of the first wrap pattern <NUM> at the tip end <NUM> of the blade <NUM>, it may be desired to form one or more chord-wise wraps <NUM> at or near the root end <NUM> of the blade <NUM>. This may be done by orienting the tag lines <NUM> generally perpendicular to a span-wise axis of the blade <NUM> while rotating the blade with the pitch control system to create the chord-wise wraps <NUM>.

Referring to <FIG>, various embodiments of the method may include attaching a lead or extension line <NUM> to and end of the tag lines <NUM> via any suitable releasable connection device <NUM>, such as a quick-release mechanical device. These lines have a length so as to be paid out from the ground level position <NUM> while the tag lines <NUM> wrap around the blade <NUM>. The extension lines <NUM> may be controlled by the technicians <NUM> at the ground level position <NUM> proximate to the tower base <NUM> until the entire length of the tag lines are wrapped around and secured to the blade <NUM>. The extension lines <NUM> can be disconnected from the ends of the tag lines <NUM> by the technician <NUM> at the rotor hub <NUM> and allowed to fall to ground.

The present invention also encompasses various methods for uninstalling the add0in device <NUM> (the wrap <NUM> and tag lines <NUM>) from the blade <NUM> in an essentially reverse procedure. For removing the add-on device <NUM>, the extension lines <NUM> can be reattached to the ends of the tag lines <NUM> by the technician <NUM> at the hub <NUM>, and the add-on device <NUM> can be removed by reversing the process described above.

<FIG> depict an alternate embodiment for locating the add-on device <NUM> at the desired span-wise location on the blade <NUM>. The one or more technicians <NUM> are located at the ground location <NUM> below the desired span-wise location on the blade20. The technicians <NUM> propel (e.g., throw, shoot, etc.) the taglines <NUM> up and over the leading edge of the blade <NUM>. Extension lines <NUM> may be attached to each of the tag lines <NUM>, as discussed above. The technicians <NUM> pull the propelled tag lines <NUM> (or extension lines <NUM>) to raise the wrap <NUM> up an over the leading edge of the blade <NUM> to form the open-sleeve configuration draped around the leading edge. The technicians <NUM> then pull on all of the tag lines <NUM> to tension the wrap <NUM> against the blade <NUM> and affix the attachment devices <NUM> to the trailing edge <NUM> of the blade <NUM>, as discussed above. With this embodiment (as well as the embodiment of <FIG>), the tag lines <NUM> and attachment devices <NUM> may be attached to each of four corners of the wrap <NUM>, wherein the tag lines50 attached to the corners at one span-wise side <NUM> of the wrap <NUM> are propelled over the blade <NUM>.

The present invention also encompasses the individual wind turbine blades <NUM> blades having one or more of the add-on devices <NUM> wrapped therearound, as described herein.

Claim 1:
A method for installing an add-on device (<NUM>) onto a blade of a wind turbine,
wherein the blade is mounted to a rotor at a hub that is atop a tower, the add-on device including a pliant-material wrap that drapes around a leading edge of the blade, the method comprising:
configuring a plurality of tag lines to the wrap, the tag lines having a length so as to extend to a ground location when the add-on device is positioned on the blade;
with the rotor, positioning the blade to a first rotated position;
locating the add-on device at a desired span-wise location on the blade such that the wrap forms an open-sleeve configuration draped around the leading edge of the blade and span-wise sides of the wrap extend along pressure and suction sides of the blade, respectively, adjacent a trailing edge of the blade;
with the tag lines, tensioning the wrap against the blade; and
affixing attachment devices configured with the wrap to the trailing edge of the blade.