Wind turbine generator vibration mitigation system and method

Abstract

A method for mitigating vibrations on a wind turbine generator (100). The method includes providing a drone (10) carrying an airflow disruption line (6) on a spool (14), securing a first portion (8) of the airflow disruption line (6) at a first attachment position on the wind turbine generator (100), deploying the airflow disruption line (6) around at least one part of the wind turbine generator (100) by flying the drone (10) around the at least one part from the first attachment position to a second attachment position on the wind turbine generator (100), and securing a second portion (9) of the airflow disruption line (6) to the second attachment position. The method enables efficient installation and removal of vibration mitigation devices on wind turbine generators (100) same with minimal manual intervention, reducing downtime and maintenance costs while effectively mitigating various types of vibrations in wind turbine structures.

Description

WIND TURBINE GENERATOR VIBRATION MITIGATION SYSTEM AND METHODTechnical Field

[0001] The present invention concerns wind turbine generator vibration mitigation systems and methods , and more particularly to means for mitigating the issue of vortex induced vibrations in parts of inactive wind turbine generators .Background

[0002] Wind turbine generators (WTGs ) are widely used for generating electricity from wind energy . A typical WTG comprises a tower and a rotor arranged on the tower . The rotor generally includes a hub , or nacelle , and multiple blades attached to the hub . When the WTG is active in an operating mode , wind flowing over the blades causes the rotor to rotate , generating torque that is transmitted through a shaft to an electrical generator within the nacelle to produce electricity .

[0003] In recent years , there has been a trend towards larger WTGs with longer blades and taller towers to capture more wind energy . However , these larger structures are more flexible and prone to vibrations . Excessive vibrations can potentially lead to damage to parts of the WTG, increasing maintenance costs and reducing their operational lifetime .

[0004] Vibrations in WTGs can occur due to various different mechanisms , and vibrations are particularly prone to being induced when the turbine is inactive . Two common types of vibrations are vortex induced vibrations (VIVs ) and stall induced vibrations ( SIVs ) . VIVs can arise when the angle of attack for a blade is around 90 degrees , while SIVs tend to occur at angles closer to stall conditions . These vibrations can stress parts of WTGs , for example the blades or tower , with vibrations being induced as the wind varies . Over time , these stresses can result in material fatigue as the parts are cycled between stressed and unstressed states . Furthermore , in some scenarios , resonance can be induced by the cycling of forces , leading to a magnification of the stresses applied . As such, both VIVs and SIVs can potentially leadto significant damage to the WTG if steps are not taken to mitigate them or their affects .

[0005] When a wind turbine is operating normally, its control systems can adj ust parameters like blade pitch and nacelle yaw to help reduce loads and counteract vibrations . However , when a turbine is parked in an inactive state , such as during maintenance or installation, these control systems may not be active , leaving the WTG more vulnerable to vibrations being induced . This creates a need for vibration mitigation methods that can be applied when the turbine is not in its normal operating state .

[0006] Various approaches have been explored to address vibrations when the WTG is inactive . However , many existing solutions have limitations in terms of ease of deployment , suitability for different turbine components , or effectiveness across the full length of a blade or tower . There remains a need for improved systems and methods to mitigate wind turbine vibrations that can be deployed efficiently and effectively on both blades and towers .

[0007] The present invention therefore seeks to address the above issues .Summary

[0008] According to a first aspect of the present invention there is provided a method for mitigating vibrations on a wind turbine generator, the method comprising : providing a drone carrying an airflow disruption line on a spool ; securing a first portion of the airflow disruption line at a first attachment position on the wind turbine generator; deploying the airflow disruption line around at least one part of the wind turbine generator by flying the drone around the at least one part ; and securing a second portion of the airflow disruption line to a second attachment position .

[0009] In this way, an airflow disruption line may be fitted wholly or partially around a part of a wind turbine generator , for examplea wind turbine tower or blade , to disrupt airflow over this part , thereby mitigating the generation of vibrations therein . Importantly, the attachment of the airflow disruption line may be achieved with minimal or no direct manual intervention by a user . As such, the need to provide personnel with access to elevated locations on the WTG is avoided, thereby allowing for faster, safer and more cost-effective deployment . The airflow disruption line may also be deployed along more than one part by a drone , for example around both a turbine tower and blade . The airflow disruption line is configured to modify the airflow flowing over the surface of the respective part of the wind turbine generator, for example by disrupting its flow direction, absorbing some of the wind speed, and / or introducing turbulence . This disruption may make the airflow around the part less linear , modifying the flow from what would otherwise be exhibited by the aerofoil profile of the parts . As such, the forces produced are lower, thereby acting to dampen oscillation, and in turn mitigating or reducing vibrations of the WTG . The reduction in vibrations may correspondingly lead to an increased lifespan of the WTG by reducing stresses and fatigue applied to components .

[0010] Using an airflow disruption line enables the same deployment methodology to be implemented for each respective part of the wind turbine generator . For example , an airflow disruption line may be deployed around a turbine blade and / or a turbine tower . Furthermore , in contrast to other methodologies employing netting or "socks" , the airflow disruption line can be more easily detached from wind turbine blades without becoming ensnared in blade serrations , such as aero addons , which have become more prevalent on the edges of modern wind turbine blades . Instead, in embodiments , the airflow disruption line may be fitted between blades serrations , thereby making use of them as a means for securing the line in place . Moreover, as the airflow disruption line may be quickly and efficiently spooled out and respooled, it allows for rapid deployment , and corresponding retrieval , on part or parts of a wind turbine generator . Fast deployment may allow for rapid installation for limiting the exposure of WTG to harmfulvibrations . Further, rapid deployment and retrieval may reduce the downtime of a wind turbine generator .

[0011] In embodiments , the at least one part is a wind turbine blade or a wind turbine tower . In this way, the airflow disruption line may be applied to one or more of a wind turbine blade or a wind turbine tower to enable the mitigation or reduction of vibrations and further extend the lifetime of the wind turbine generator .

[0012] In embodiments , the airflow disruption line is a foam rope or an inflatable hose . In this way, the airflow disruption line may be provided as a lightweight and compressible line , thereby allowing a relatively long line with a small gauge to be provided on the spool , and which can then expand to a larger cross section after deployment . The construction of the airflow disruption line as a narrow length of elongate material provides for a lightweight body which thereby minimises the payload of a drone carrying it , thereby providing energy savings and extending the battery life of a drone . A compressible airflow disruption line enables a longer length to be carried on the spool of the drone . Expansion to a larger cross section after deployment allows for an increased efficacy of vibration mitigation and reduction . The ability to expand after deployment means that a large length of airflow disruption line may be carried in a compressed state , with a relatively large cross section after deployment , offering the combined benefits of compressibility and improved vibration reduction / mitigation after deployment .

[0013] In embodiments , the airflow disruption line is an inflatable hose and the method further comprises inflating the inflatable hose . Such inflation may be after the airflow disruption line has been secured to the second attachment position of the wind turbine generator . Additionally or alternatively, such inflation may begin after the drone has begun to spool out the airflow disruption line . In this way, the airflow disruption line may be significantly expanded after and / or during deployment . Thisenables a large length of inflatable hose to be carried on a spool in a compressed state , while also offering a substantial reduction / mitigation in vibrations once inflated to its expanded state due to a larger cross section disrupting airflow on the wind turbine generator . The inflation may be through the use of compressed gas , a pump , or other means . Further , inflation may be effected by air flowing into openings along the airflow disruption line due to , for example , wind pushing air into the openings and / or the movement of the drone through the air causing air to enter the openings . Openings may be designed to be one-way ( e . g . a valve ) .

[0014] In embodiments , the first and / or second attachment positions comprise a position towards at least one of a root of a wind turbine blade , a tip of a wind turbine blade , a base of a wind turbine tower , and a top of a wind turbine tower . In this way, the airflow disruption line may be deployed around one or more parts of the wind turbine generator either partially, or wholly .

[0015] In embodiments , the step of providing a drone comprises providing a plurality of drones , each carrying an airflow disruption line for deployment around at least one part of the wind turbine generator .

[0016] In embodiments , securing the airflow disruption line to the second attachment position of the wind turbine generator comprises parking the drone at the second attachment position of the wind turbine generator . In this way, the drone may attach itself to the wind turbine generator , for example using a clamp, magnets or a vacuum, and in so doing secure the airflow disruption line at the second attachment position . This removes the need for detaching the airflow disruption line from the spool , which may reduce complexity in securing the airflow disruption line at the second attachment point . Similarly, this means that detaching the airflow disruption line from the second attachment position may involve unparking the drone by reversing its attachment to the wind turbine generator . As such, reduced complexity can also beachieved during the retrieval operation .

[0017] In embodiments , deploying the airflow disruption line around at least one part of the wind turbine generator by flying the drone around the at least one part comprises flying the drone from the first attachment position to a second attachment position on the wind turbine generator . In this way, the drone may quickly and efficiently deploy the airflow disruption line around the wind turbine generator . In embodiments , the step of flying comprises flying the drone in a helical flight path .

[0018] According to a second aspect of the invention there is provided a method of retrieving the airflow disruption line deployed according to the method of any preceding claim, further comprising : detaching the second portion of the airflow disruption line from the second attachment position; retrieving the airflow disruption line by flying the drone in a reverse flight around the at least one part , whilst respooling the airflow disruption line onto the spool of the drone ; and detaching the first portion of the airflow disruption line from the first attachment position . In this way, the airflow disruption line may be easily removed from a wind turbine generator with minimal manual intervention . This is achieved by flying the drone in a flight around the part in an opposing direction to deployment , for example if the airflow disruption line was deployed by a drone flying clockwise around a part , a reverse flight would be a drone flying counterclockwise around the part . Moreover , the airflow disruption line may be reused for the same or another wind turbine generator .

[0019] According to a third aspect of the present invention there is provided a system for mitigating vibrations on a wind turbine generator, the system comprising : an airflow disruption line for deploying around at least one part of the wind turbine generator, the airflow disruption line having a first portion for securing at a first attachment position on the wind turbine generator and a second portion configured to be secured at a second attachment position on the wind turbine generator; and a drone comprising : aspool , for carrying the airflow disruption line and for deploying the airflow disruption line onto the at least one part when the first end is secured at the first attachment position and while the drone flies around the at least one part .

[0020] In this way, a system is provided that may deploy an airflow disruption line wholly or partially around a part of a wind turbine tower , for example a wind turbine tower or blade , with minimal manual intervention .

[0021] In embodiments , the airflow disruption line is a foam rope or an inflatable hose .

[0022] In embodiments , the airflow disruption line is an inflatable hose , and the system further comprises a mechanism for inflating the inflatable hose after deployment . The mechanism may be compressed gas , a pump or any other suitable means .

[0023] In embodiments , the drone further comprises a coupling being operable to secure the drone to the part of the wind turbine generator . In embodiments , the coupling comprises a mechanical clamp, a hook, a magnet or a vacuum seal for securing itself to the second attachment position on the wind turbine generator . In this way, the drone is able to secure itself to the second attachment position without detaching the airflow disruption line from the spool , and in so doing reduce complexity in securing the airflow disruption line to the second attachment position . Further, the coupling provides a reversible method of securing the drone to the WTG . For example , a magnet may be an electromagnet allowing the magnet to be magnetised or demagnetised to easily disengage from the wind turbine generator . Similarly, the suction cup mount may operable such that can be reversibly engaged to generate a vacuum suction force for releasably securing the drone .

[0024] In embodiments , the drone further comprises an arm for deploying the airflow disruption line . In this way, the arm may provide a proj ection for distancing the airflow disruption linefrom the drone ' s propellers as it is spooled out or respooled . This may thereby prevent the blades of the drone becoming entangled in the airflow disruption line and thereby facilitates efficient deployment .

[0025] In embodiments , the system comprises a plurality of drones each configured to install an airflow disruption line on a respective plurality of parts of wind turbine generators . In this way, multiple drones may be used to expedite the deployment of multiple airflow disruption lines . For example , one drone may deploy an airflow disruption line on a first blade of a wind turbine generator , while a second drone deploys an airflow disruption line on one or more further blades and / or a tower of a wind turbine generator .

[0026] In embodiments , the system further comprises a controller configured to cause the drone to : secure a first portion of the airflow disruption line at a first attachment position on the wind turbine generator; deploy the airflow disruption line around at least one part of the wind turbine generator by flying the drone around the at least one part , from the first attachment position to a second attachment position on the wind turbine generator ; and secure a second portion of the airflow disruption line to the second attachment position .

[0027] In a fourth aspect of the present invention there is provided a drone for mitigating vibrations on a wind turbine generator , the drone comprising : a spool configured to carry an airflow disruption line .

[0028] In this way, a drone is provided that eliminates or reduces the need for manual installation of an airflow disruption line . Such a drone may provide the advantages described in relation to the first aspect of the invention .

[0029] In embodiments , the drone further comprises a magnet or suction cup for securing the drone to the wind turbine generatorand the controller is further configured to secure the airflow disruption line to the second attachment position by parking the drone using the magnet or suction cup .

[0030] In embodiments , the drone further comprises an arm for deploying the airflow disruption line .

[0031] In embodiments , the controller is further configured to cause the drone to : detach the second portion of the airflow disruption line from the second attachment position; retrieve the airflow disruption line by flying the drone in a reverse flight around the at least one part from the second attachment position to the first attachment position, whilst respooling the airflow disruption line onto the spool of the drone ; and detach the first portion of the airflow disruption line from the first attachment position .

[0032] In embodiments , the controller is further configured to cause the drone to deploy the airflow disruption line around at least one part of the wind turbine generator by flying the drone around the at least one part , from the first attachment position to a second attachment position on the wind turbine generator in a helical flight path .Description of Drawings

[0033] Illustrative embodiments of the present invention will now be described with reference to the accompanying drawings in which :FIGs . la and lb shows an illustrative wind turbine generator and blade , respectively;FIGs . 2a-2b illustrate side and top views of a drone according to a first embodiment ;FIGs . 3a-3c show a second embodiment in which a drone deploys an airflow disruption line around parts of a WTG;FIGs . 4a-4 c show a third embodiment in which a drone deploys an airflow disruption line around parts of a WTG by securing the airflow disruption line at a second attachment position by parking itself ;FIG . 5 shows a close-up view of the drone shown in Fig .4c securing an airflow disruption line at a second attachment position by parking itself on the turbine blade ;FIGs . 6a-6c show a fourth embodiment in which multiple drones each deploy a respective airflow disruption line around respective parts of the wind turbine generator ; andFIGs . 7a-7c show a fifth embodiment in which multiple drones deploy an airflow disruption line around a part of the wind turbine generator by securing the airflow disruption line at the first and second attachment position by parking themselves .Detailed Description

[0034] The following description sets forth illustrative embodiments of the invention .

[0035] Referring to FIG . la , a wind turbine generator 100 is illustrated comprising a tower 4 and a nacelle 2 mounted to the top of the tower 4 . The nacelle 2 supports a rotor 1 , to which is mounted a plurality of blades 3a-3c . In use , the rotor 1 is caused to rotate under the influence of the flow of wind over the blades 3a-3c . Said rotation generates a torque that is transmitted through a rotor shaft to a generator located within the nacelle 2 . In this way, the generator produces electricity which can be supplied to the electrical grid . In this illustrated example , three blades Sale are shown, though in some implementations , the number of blades may vary .

[0036] Fig lb illustrates an enlarged view of one of the turbine blades 3a shown in Fig . la , mounted to the rotor 1 . The blade 3a includes blade serrations 20on its trailing edge , which function as aero addons . Such serrations 20 may additionally or alternatively be present on the blade' s leading edge . Blade serrations 20 may be present in the illustrative examples described below, albeit that they have been omitted for simplicity .

[0037] FIGs 2a and 2b show, respectively, a side view and top view of a drone 10 according to a first embodiment . The drone 10 comprises a body 15 , onto which are mounted propellers 12 , each comprising and propeller blades 11 . As is known in the art , bycontrolling the propellers 12 , the flight of the drone 10 can be controlled in operation . In this respect , the drone 10 comprises a controller 18 , configured to control the propellers 12 . The controller 18 may receive instructions from a remote control being operated by a user or remote system. In other embodiments , the controller may control the drone 10 autonomously or using a preloaded flight plan . The drone 10 further comprises a spool 14 onto which is wound an airflow disruption line 6 and from which the airflow disruption line 6 can be deployed to be attached to parts of the WTG 100 by flying the drone 10 around the parts , as is described in further detail below . In this embodiment , the drone 10 comprises an arm 13 for feeding the airflow disruption line 6 from the spool 14 . The arm 13 acts to hold the deployed part of the airflow disruption line 6 a distance from the propellers . In this embodiment , the drone 10 also comprises a coupling 16 operable to secure the drone 10 to a part of the WTG 100 . The drone 10 may further comprise a camera 17 .

[0038] In other embodiments , the drone 10 may comprise more than one spool 14 , to enable multiple airflow disruption lines 6 to be deployed . Additionally, or alternatively, the spool 14 may be detachable such that a further spooled airflow disruption line may be easily re-attached and deployed after deployment of a first airflow disruption line 6 . In such arrangement , the drone 10 may comprise a spool receptacle into which new spools of airflow disruption lines 6 may be loaded for deployment .

[0039] As mentioned above , the arm 13 is configured to maintain separation between the drone 10 and the airflow disruption line 6 during deployment or retrieval . In this way, the potential for the airflow disruption line 6 to become entangled in the propellers 11 of the drone 10 is reduced . In embodiments , the arm 13 may be retractable to allow the drone 10 to be more compactly stowed or to occupy a smaller footprint when parked . The arm 13 may also be controllably articulated to aid in attaching and detaching the airflow disruption line 6 .

[0040] In embodiments , the coupling 16 is operable to releasablysecure the drone 10 to the WTG 100. The coupling 16 may be any reversible means for securing the drone 10 to the part of the WTG 100, such as a passive or active vacuum seal (e.g. a suction cup) , a magnet, a hook, a clamp, an adhesive surface etc.

[0041] The camera 17 is connected to the controller 18 for use, for instance, in providing a video feed to a remote operator or system, or in feedback control implemented by the controller itself. For example, the camera 17 may allow the controller 18 to control the drone 10 to autonomously carry out deployment of the airflow disruption line 6, or to relay video to be used by an operator remotely controlling the drone 10. A combination of autonomous and remote control of the drone 10 is also contemplated.

[0042] The airflow disruption line 6 is provided as an elongate flexible rope-like body which can be wrapped around a part or parts of a WTG 100, as described below. For example, the airflow disruption line 6 may comprise a lightweight, compressible material such as a foam or an inflatable structure e.g. an inflatable hose or foam rope.

[0043] FIGs 3a-3c illustrate the drone 10 shown in FIGs 2a-2b used to deploying the airflow disruption line 6. Specifically, the drone 10 is deploying the airflow disruption line 6 around a turbine tower 4 and a turbine blade 3a. In FIG 3a, a first portion 8 of the airflow disruption line 6 is secured to the base of the turbine tower 4, at a first attachment position. This securing may be achieved manually by a user, or autonomously by the drone 10. For instance, the drone 10 may be operable to attach the airflow disruption line 6 to a tether mounted on the WTG 100. The drone 10 then begins to fly around the turbine tower 4, deploying the airflow disruption line 6 from the spool 14 thus wrapping the airflow disruption line 6 around the turbine tower 4. In this respect, a user may control the flight of the drone 10 using a remote controller. It will be understood that in other embodiments the flight of the drone 10 is controlled autonomously.

[0044] As shown in FIG 3b, the drone 10 may then continue to deploy the airflow disruption line 6 around a turbine blade 3a.Once the drone 10 reaches the tip of the turbine blade 3a , the drone 10 secures a second portion 9 of the airflow disruption line 6 at a second attachment position on the tip of the turbine blade 3a . The airflow disruption line 6 is thus deployed and secured around both a turbine tower 4 and a turbine blade 3a . The process may be repeated for the remaining turbine blades 3b and 3c . The airflow disruption line 6 may be secured at the first / second attachment positions by any suitable means , for example hooks , clamps , adhesive surfaces , or other suitable fastening mechanisms . Knots may additionally be used, as described in more detail below with reference to FIG 5 . Once deployed, the airflow disruption line 6 acts to disrupt airflow over the respective part of the WTG 100 , thereby mitigating the formation of vibrations .

[0045] To remove the airflow disruption line 6 , the drone 10 may be operated to reverse the above-described process . Specifically, by detaching the second portion 9 of the airflow disruption line 6 from the second attachment position . Then retrieving the airflow disruption line 6 by flying in a reverse flight around the part ( s ) of the WTG 100 from the second attachment position to the first attachment position, whilst respooling the airflow disruption line 6 onto the spool 14 of the drone 10 . Finally, by detaching the first portion 8 of the airflow disruption line 6 from the first attachment position .

[0046] It will be appreciated that in some embodiments the drone 10 deploys the airflow disruption line 6 around both the turbine tower 4 and the turbine blade 3a using only a first and second attachment position . For example , where the first attachment position is at the base of the turbine tower 4 and the second attachment position is at the tip of the turbine blade 3a .

[0047] The drone 10 may alternatively deploy an airflow disruption line 6 first around the turbine tower 4 and then around the turbine blade 3a in separate operations . For example , this may be achieved by securing the first portion 8 of the airflow disruption line 6 at a first attachment position at the base of the turbine tower 4 , flying the drone around the turbine tower 4 from the base to the top, then securing the second portion 9 ofthe airflow disruption line 6 at a second attachment position at the top of the turbine tower 4 . The drone 10 may then repeat this process for the turbine blade 3a, where in this case the first attachment position is the root of the turbine blade 3a and the second attachment positions is the tip of the turbine blade 3a . To do this , the drone 10 may carry more than one spool 14 , or may comprise a detachable spool 14 so that a new spooled airflow disruption line may be fitted after deployment of the first airflow disruption line 6 .

[0048] In FIGs 3a-3c , the drone 10 is shown to secure the airflow disruption line 6 directly to parts of the turbine generator at the first and second attachment positions through a fastening mechanism. However , the drone 10 may secure the airflow disruption line 6 at the second attachment positions by parking itself on the respective part of the WTG 100 . This is discussed is more detail with reference to FIGs 4a-4c and 5 below .

[0049] FIGs 4a-4 c illustrate a drone 10 deploying an airflow disruption line 6 by flying it around at least one part of a WTG 100 and parking itself at a second attachment position , Specifically, the drone 10 is deploying the airflow disruption line 6 around a turbine tower 4 and a turbine blade 3a and parking itself by attaching to the tip of a turbine blade 3a .

[0050] The method of deployment of the airflow disruption line 6 may be achieved in a manner substantially similar to that described with reference to FIGs 3a-3c . However , as can be seen in FIG 4 c, second end of the line 6 is secured by the drone 10 landing and coupling to the second attachment position . This is shown in a close-up view in FIG 5 . Also shown in FIG 5 are the blade serrations 20 , along with knots 21 along the length of the airflow disruption line 6 . The knots 21 may be formed along the length airflow disruption line 6 such that they interact with the blade serrations 20 to secure the line 6 in place . As such, the knots 21 may be used to secure the first / second portions 8 , 9 of the airflow disruption line 6 at their respective first or second attachment positions . The knots 21 may be used in addition to other fastening mechanisms present at the first and second portions 8 , 9 , to bettersecure the airflow disruption line 6 in place along its length . In this way blade serrations 20 may work in tandem with the knots 21 to better secure the airflow disruption line 6 in place , whilst still being easily removed . This is in contrast to other solutions that use netting , which may become ensnared in blade serrations 20 , thus hindering their removal .

[0051] The drone 10 is configured to park by securing itself to the part of the WTG 100 using coupling 16 . This may act to secure the airflow disruption line 6 . This parking capability may allow the drone 10 to maintain a stable position while securing the airflow disruption line 6 at a second attachment position .

[0052] The coupling 16 in this embodiment is provided as a clamp although, in other embodiments , the drone may employ other attachment mechanisms . For example , in embodiments the drone may utilize a vacuum seal suction cup mechanism. This system may create a suction force between the drone and the surface of the part of WTGs 100 , allowing the drone to adhere securely even in windy conditions . Alternatively, the drone may incorporate magnetic attachment capabilities . Magnetic attachment may be particularly useful for securing the drone to metallic portions of the wind turbine structure . Both these attachment mechanisms are reversible , and therefore facilitate easily reversing the attachment such that the deployment process may be reversed, as described above with reference to FIGs 3a-3c .

[0053] As with FIGs 3a-3c, the drone 10 may deploy the airflow disruption line 6 around both the turbine tower 4 and the turbine blade 3a with only a first and second attachment position . However, the drone 10 may also apply individual airflow disruption lines to parts of the WTG 100 separately . To do this the drone 10 may directly secure an airflow disruption line 6 to a first part of the WTG 100 and deploy a second airflow disruption line around a second part of the WTG 100 by parking itself at a further second attachment position .

[0054] FIGs 6a- 6c illustrate an embodiment in which a plurality of drones lOa-lOc are each configured to deploy a respectiveairflow disruption line 6a-6c around a respective part of a WTG 100 . In particular , drone 10b deploys airflow disruption line 6b around turbine tower 4 ; drone 10a deploys airflow disruption line 6a around turbine blade 3a; and drone 10c deploys airflow disruption line 6c around turbine blade 3c . The method of deployment of the airflow disruption lines 6a-6c is substantially similar to that described above , with respect to FIGs 3a-3c and 4a-4 c . As can be seen in FIG 6c, some drones 10a , 10c may be configured to directly secure the second portion 9b, 9c of their respective airflow disruption lines 6b , 6c at the second attachment position, while other drones 10a may be configured to secure their airflow disruption lines 6a by parking themselves at a second attachment position .

[0055] By using a plurality of drones lOa-lOc to each deploy a respective airflow disruption line 6a-6c around a respective part of a WTG 100 , the efficiency of the deployment process may be increased . This , in turn, reduces the down time of a WTG 100 because less time can be spent deploying and retrieving airflow disruption lines 6a- 6c .

[0056] FIGs 7 a-7 c show an alternate embodiment where two drones 10a, 10b deploy an airflow disruption line 6 around at least one part of a WTG 100 . In this embodiment , one or both drones 10a , 10b may comprise a spool for deploying the airflow disruption line 6 .

[0057] FIG 7a shows drones 10a , 10b carrying an airflow disruption line 6 between them and approaching a turbine blade 3a of a WTG 100 . As shown in FIG 7b , the first drone 10a secures itself , and hence the first portion 8 of airflow disruption line 6 , at the first attachment position at the root of the turbine blade 3a by parking itself in a manner analogous to that described above with respect to FIGs 4a-4 c and 5 . The second drone 10b flies around the turbine blade 3a from the root towards the tip deploying the airflow disruption line from its spool . As depicted in FIG 7c , the second drone 10b then parks itself at the second attachment position to secure the second portion 9 of the airflow disruption line in place , in this case the second attachment position is the tip of the turbine blade 3a .

[0058] Alternatively, the drones 10a , 10b may both start their flight in the middle of the part of the WTG 100 , in this case the turbine blade 3a . The drones may then fly around the turbine blade 3a in opposite directions towards their respective attachment positions . That is , in this case starting from the middle one drone 10b may fly around the turbine blade 3a towards the tip, whilst the other drone 10a flies around the turbine blade 3a towards the root . The drones 10a , 10b may then secure themselves at the first and second attachment positions , which in this case are the root and tip of the turbine blade 3a , hence securing the first 8 and second 9 portions of the airflow disruption line 6 . Therefore , in this embodiment , the deploying the airflow disruption line 6 around the at least one part of the WTG 100 is performed before securing the airflow disruption line 6 at the first and second attachment positions . In this way, the speed of deployment of the airflow disruption line 6 may be increased .

[0059] The drones 10a, 10b may reverse the deployment of the airflow disruption line 6 by detaching themselves from the first and second attachment positions and reversing the direction of their flight around the wind turbine blade 3a .

[0060] Although the pair of drones 10a , 10b has been shown deploying a single airflow disruption line 6 along a single part of a WTG 100 , the turbine blade 3a, the drones 10a , 10b may deploy the airflow disruption line 6 around more than one part . For example , a wind turbine tower 4 and a wind turbine blade 3a , as described in relation to FIG 3a-3c .

[0061] Furthermore , in some embodiments a plurality of pairs of drones 10a , 10b may be used to deploy a respective plurality of airflow disruption lines 6 around a respective plurality of parts of WTGs 100 . Such deployment may be using the process described with respect to FIGs 7a-7c in a manner similar to that described with respect to FIGs 6a- 6c . For example , four pairs of drones may be used to deploy four airflow disruption lines , one around each turbine blade 3a-3c and one around the turbine tower 4 . Alternatively, two pairs of drones could deploy two airflowdisruption lines , one around the turbine tower 4 and turbine blade 3a , the other around the remaining turbine blades 3a, 3c . Other combinations are contemplated .

[0062] In the embodiments described, the first and second attachment positions have been described at the extremities of parts of WTGs 100 , for example the top / base of a turbine tower 4 or the root / tip of a turbine blade 3a . However, it will be appreciated that the first and second attachment position could be anywhere along the length of a part or parts of a WTG 100 . In this way, it is possible to deploy an airflow disruption line 6 partially or wholly along the length of a part of a WTG 100 . In an example of partial deployment , a drone 10 could deploy an airflow disruption line 6 around a portion towards the end of a part of a WTG 100 , for instance around a portion towards the tip of a wind turbine blade 3a . Other partial deployments of an airflow disruption line are contemplated .

[0063] Further, drones 10 may deploy the airflow disruption lines 6 by flying in either direction around a part of a WTG 100 and may reverse the first and second attachment positions . That is , for example , a drone 10 may fly from the base of a turbine tower 4 to the top of a turbine tower 4 , or from the top to the base either clockwise or anti clockwise around the tower 4 . Further, a drone 10 may fly from the root of a turbine blade 3a to the tip, or from the tip to the root either clockwise or anti-clockwise . It may be particularly advantageous for a drone to fly from the tip of the blade to the root . In this way, the drone 10 may secure the first portion 8 of the airflow disruption line 6 at a first attachment position at or towards the tip of the turbine blade 3a, for example by engaging a knot 21 between blade serrations 20 . The drone 10 may then deploy the airflow disruption line around the turbine blade 3a by flying around it towards the root . Once at the root , a user may manually secure the second portion 9 of the airflow disruption line 6 at the second attachment position . A user may aid similarly in securing the airflow disruption line 6 at the second attachment position when the drone 10 deploys the airflow disruption line 6 by flying from the base to the top of a turbinetower 4 .

[0064] A number of implementations have been described . Nevertheless , it will be understood that various modifications may be made without departing from the scope of the claims .

[0065] With the above arrangements , a drone may be used to deploy or install the airflow disruption line , providing for minimal manual invention, for example no manual intervention, and enhancing the rapid deployment and retrieval of the airflow disruption line discussed above . Furthermore , minimising manual installation of an airflow disruption line reduces or eliminates the need for engineers to work in dangerous environments , for example at the heights and extreme wind conditions associated with WTGs 100 . Using a drone for deployment or installation of a wind disruption line further eliminates the need to rotate the blades of a WTGs 100 to a predetermined position for such deployment or installation, for example to a six O' clock position such that the blade is closer to the ground . Pitching the blade , again for placing it in a more suitable position for deployment , may also be avoided . Therefore , even if the rotor 1 or pitching system of a WTG 100 is blocked or damaged a wind disruption line may still be deployed .

Claims

CLAIMS1 . A method for mitigating vibrations on a wind turbine generator, the method comprising : providing a drone carrying an airflow disruption line on a spool ; securing a first portion of the airflow disruption line at a first attachment position on the wind turbine generator ; deploying the airflow disruption line around at least one part of the wind turbine generator by flying the drone around the at least one part ; and securing a second portion of the airflow disruption line to a second attachment position .2 . The method of claim 1 , wherein the at least one part is a wind turbine blade or a wind turbine tower .3 . The method of claim 1 or 2 , wherein the airflow disruption line is a foam rope or an inflatable hose .4 . The method of claim 3 , wherein the airflow disruption line is an inflatable hose and the method further comprises inflating the inflatable hose .5 . The method of any preceding claim, wherein the first and / or second attachment positions comprise a position towards at least one of a root of a wind turbine blade , a tip of a wind turbine blade , a base of a wind turbine tower, and a top of a wind turbine tower .6 . The method of any preceding claim, wherein the step of providing a drone comprises providing a plurality of drones , each carrying an airflow disruption line for deployment around at least one part of the wind turbine generator .7 . The method of any preceding claim, wherein securing the airflow disruption line to the second attachment position of the wind turbine generator comprises parking the drone at the secondattachment position of the wind turbine generator .8 . The method of any preceding claim, wherein deploying the airflow disruption line around at least one part of the wind turbine generator by flying the drone around the at least one part comprises flying the drone from the first attachment position to the second attachment position on the wind turbine generator .9 . A method of retrieving the airflow disruption line deployed according to the method of any preceding claim, further comprising : detaching the second portion of the airflow disruption line from the second attachment position; retrieving the airflow disruption line by flying the drone in a reverse flight around the at least one part , whilst respooling the airflow disruption line onto the spool of the drone ; and detaching the first portion of the airflow disruption line from the first attachment position .10 . A system for mitigating vibrations on a wind turbine generator, the system comprising : an airflow disruption line for deploying around at least one part of the wind turbine generator , the airflow disruption line having a first portion for securing at a first attachment position on the wind turbine generator and a second portion configured to be secured at a second attachment position on the wind turbine generator ; and a drone comprising : a spool , for carrying the airflow disruption line and for deploying the airflow disruption line onto the at least one part when the first portion is secured at the first attachment position and while the drone flies around the at least one part .11 . The system of claim 10 , wherein the airflow disruption line is a foam rope or an inflatable hose .12 . The system of claim 11 , wherein the airflow disruptionline is an inflatable hose , and the system further comprises a mechanism for inflating the inflatable hose after deployment .13 . The system of any of claims 10 to 12 , wherein the drone further comprises a coupling being operable to secure the drone to the part of the wind turbine generator .14 . The system of any of claims 10 to 13 , wherein the drone further comprises an arm for deploying the airflow disruption line .15 . The system of any of claims 10 to 14 , comprising a plurality of drones each configured to install an airflow disruption line on a respective part of a wind turbine generator .

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