Method for retrofitting wind turbine blade on wind turbine

Abstract

A method of retrofitting a wind turbine blade (26a, 26b, 26c) on a wind turbine (10) is disclosed. The wind turbine blades (26a, 26b, 26c) each comprise a plurality of sections. The inner blade section (36a, 36b, 36c) is coupled to the rotor hub (24). The outer blade section (38a, 38b, 38c) is coupled to the inner blade section (36a, 36b, 36c) at the interface bracket (34a, 34b, 34c). The blades (26a, 26b, 26c) are selected. For a selected blade (26a, 26b, 26c), the method includes (i) coupling a lifting tool (42, 62, 72) to an interface bracket (34a, 34b, 34c). The lifting tool (42, 62, 72) includes a lift (50) and a lifting cable (52, 66, 88) operably coupled to the lift (50). The method further comprises (ii) coupling the lifting cable (52, 66, 88) to the outer blade section (38a, 38b, 38c), iii) disconnecting the outer blade section (38a, 38b, 38c) from the inner blade section (36a, 36b, 36c) such that the inner blade section (36a, 36b, 36c) remains coupled to the rotor hub (24) and the outer blade section (38a, 38b, 38c) is supported by the lifting tool (42, 62, 72), and iv) lowering the outer blade section (38a, 38b, 38c) to a support surface adjacent to the wind turbine (10) using the lifting tool (42, 62, 72).

Description

Technical Field

[0001] This invention generally relates to wind turbines, and more specifically to methods for modifying the blades of wind turbines. Background Technology

[0002] Wind turbines are used to generate electricity using renewable resources without burning fossil fuels. A wind turbine converts wind kinetic energy into mechanical energy, and then subsequently into electrical energy. A common type of wind turbine is the single-rotor upwind horizontal axis wind turbine (HAWT). An exemplary single-rotor HAWT includes a tower, a nacelle located at the apex of the tower, and a single rotor having a central hub and one or more blades (e.g., three blades) mounted to and extending radially from the hub. The rotor is supported by the nacelle and positioned at the front of the nacelle such that the rotor faces the wind upstream of its supporting tower. The rotor may be directly or indirectly coupled to a generator housed within the nacelle and is configured to convert the mechanical rotation of the rotor into electrical energy.

[0003] Wind turbine manufacturers continuously strive to design and manufacture wind turbines with improved electricity production. The design of a wind turbine plays a crucial role in the power output generated from the wind. For example, the energy extracted from the wind is proportional to the swept area of ​​the wind turbine blades. For a single-rotor HAWT (Half-Range Wind Turbine), the swept area can be increased by using longer wind turbine blades. The longer the blade, the larger the area traced by the blade tip. This translates to extracting more energy from the wind. However, the length, maximum chord length, and root diameter of the wind turbine blades used in a particular wind turbine are limited by several design factors.

[0004] As illustrative constraints, blade weight and root diameter increase with blade length. Each of these physical characteristics presents significant design challenges. First, reliably supporting the increasingly heavy wind turbine blades at their attachment point to the rotor becomes a limiting factor. The increased load at the root amplifies fatigue at that location during rotor rotation and yaw motion during wind turbine operation. Transporting blades from the manufacturing location to site installation is a known challenge, and the increased blade length, root diameter, and weight make transportation even more challenging.

[0005] One design solution that allows for increased blade length is to support the wind turbine blades with cables during wind turbine operation. Cable-supported blades can be relatively longer than unsupported blades. Wind turbines utilizing cable-supported rotors can be called "cable-supported rotors" or "cable-stayed rotors." Specifically, the webbing of the cables extends to adjacent blades and between adjacent blades. With the aid of cables, blades can be proportionally longer while addressing the aforementioned design challenges. In this way, cable-supported rotors can be used to increase the swept area of ​​the blades to generate more energy from the wind. Longer blades can be components of multiple sections or segments along the length direction. When a blade consists of two segments along the length direction, it is often referred to as a "two-part blade" or "split blade." The total length of a split blade can include the sum of the lengths of the main blade segment or inner blade segment and the terminal blade segment or outer blade segment.

[0006] During wind turbine operation, blades suffer damage over time. This damage eventually necessitates periodic blade replacement to maintain effective power generation. One technique for blade replacement involves using a crane to lift the blade from the center hub and then hoist the new blade into place on the hub. The height of the wind turbine tower, along with the weight and size of the blades, necessitates the use of specialized cranes. As an example, the boom height on the crane must exceed the height of the wind turbine tower. Due to their unique nature, using cranes to replace wind turbine blades is expensive. Other blade replacement techniques exist, but these are also costly and difficult to implement. For these reasons, while necessary for long-term energy efficiency, blade retrofitting still incurs significant costs for operators.

[0007] Therefore, wind turbine manufacturers and operators are seeking to improve energy production while overcoming current design limitations, including solutions for retrofitting blades at minimal cost. Summary of the Invention

[0008] To further achieve these objectives, a method for retrofitting a wind turbine is disclosed. The wind turbine is preferably a single-rotor HAWT. In one embodiment, a method exists for retrofitting a wind turbine having multiple wind turbine blades coupled to a rotor hub. Each of the multiple wind turbine blades is a split blade. An inner blade section is coupled to the rotor hub, and an outer blade section is coupled to the inner blade section at an interface support. The method includes selecting a blade from the multiple wind turbine blades. For the selected blade, the method further includes (i) coupling a lifting tool to the interface support. The lifting tool includes at least one lift and at least one lifting cable operably coupled to the lift. The method further includes (ii) coupling at least one lifting cable of the lifting tool to the outer blade section, (iii) disconnecting the outer blade section from the inner blade section such that the inner blade section remains coupled to the rotor hub and the outer blade section is supported by the lifting tool, and (iv) using the lifting tool to lower the outer blade section to a support surface adjacent to the wind turbine.

[0009] In one embodiment, the wind turbine includes a cable system with cable assemblies, wherein one or more of the cable assemblies extend between adjacent blades of a plurality of wind turbine blades, and wherein one or more cable assemblies are attached to the blades at an interface support. In one embodiment, the method further includes adjusting the tension in one or more rotor cables coupled to the blades before disconnecting the outer blade segment from the inner blade segment. For example, adjusting the tension in one or more rotor cables may involve increasing or decreasing the tension, such as releasing the tension in one or more rotor cables. This can be achieved by pitching the blades or by extending or retracting a hydraulic or electric actuator system coupled to at least one of the one or more cables.

[0010] In one embodiment, the wind turbine includes a fairing and an interface bracket. This may be the case, for example, if the wind turbine includes a cable system with cable assemblies, but it may also be in the case of other split-blade designs. The method of this embodiment includes releasing the fairing at the interface bracket from the wind turbine blades before disconnecting the outer blade sections (38a, 38b, 38c) from the inner blade sections (36a, 36b, 36c). This allows for better access to the interface bracket, both regarding the connection of the lifting tool to the interface bracket and regarding the connection of the lifting tool to a mechanism such as bolted connections that secure the outer blade sections to the interface bracket.

[0011] In one embodiment, the lifting tool includes a first mounting bracket and a second mounting bracket. In this method, connecting the lifting tool includes connecting the first mounting bracket to an interface bracket and connecting the second mounting bracket to an outer blade section. The first and / or second mounting brackets may preferably be steel components to be bolted to the interface bracket; lifting holes or eyelets to be bolted to the interface bracket or blade; or lifting sleeves / nets arranged on the outer blade section.

[0012] In one embodiment, connecting at least one lifting cable to the outer blade section includes connecting at least one lifting cable to a second mounting bracket.

[0013] In one embodiment, the at least one lifting cable includes a pair of lifting cables, and connecting the at least one lifting cable to the outer blade section includes connecting each of the pair of lifting cables to the second mounting bracket.

[0014] In one embodiment, the lifting tool further includes a mounting bracket connected to the outer blade section and pivotally connected to the interface bracket, such that the mounting bracket and the interface bracket are rotatable relative to each other about a pivot axis.

[0015] In one embodiment, the method further includes: rotating the blade to a position where the outer blade section is forced toward the interface support by gravity about a pivot axis before disconnecting the outer blade section from the interface support, wherein rotating the blade includes rotating the rotor hub and / or pitching the blade.

[0016] In one embodiment, the method further includes rotating the blades so that the outer blade section is substantially vertical before lowering the outer blade section to the support surface.

[0017] In one embodiment, attaching the lifting tool to the blade includes attaching a crane to an interface bracket. In one embodiment, the method further includes rotating the blade so that it is substantially horizontal before disconnecting the outer blade segment from the inner blade segment.

[0018] In one embodiment, after lowering the outer blade section to the support surface, the method further includes: using a lifting tool to connect at least one lifting cable to another outer blade section; raising the other outer blade section to the inner blade section; and connecting the other outer blade section to the inner blade section.

[0019] In one embodiment, the method further includes the step of detaching the lifting tool from the interface bracket. Optionally, the lifting tool may be moved to another interface bracket on the same wind turbine or an interface bracket on another wind turbine after being detached from the interface bracket.

[0020] An embodiment may include selecting another of a plurality of wind turbine blades and repeating steps i)-iv) for the other blade.

[0021] In one embodiment, selecting leaves includes selecting leaves at a predetermined time based on weather conditions associated with a particular season.

[0022] The embodiment may also include, after selecting each of the blades, after steps i)-iv) for each of the blades, and after the first operation of the modified wind turbine, the method further includes: v) replacing each of the outer blade sections according to steps i)-iv) and operating the wind turbine a second time; and vi) after the second operation; disconnecting the inner blade section from the rotor hub; and connecting another inner blade section to the rotor hub.

[0023] One or more methods of the present invention can allow for low-cost and easily replaceable outer blade sections. Outer blade sections are more susceptible to lightning damage and wear due to leading-edge corrosion. For example, in terms of cost and material consumption, the ability to replace only the outer blade section rather than the entire blade may have greater benefits. Furthermore, the ability to replace only the outer blade section can be optionally combined with wind turbine controller updates, opening up site-specific AEP optimizations. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the general description of the invention given above and the detailed description given below, serve to explain the invention.

[0025] Figure 1 This is a front view of a cable-supported rotor wind turbine with multiple blades, each of which is a separate blade. Figure 2 yes Figure 1 A side view of the wind turbine, not shown for simplicity. Figure 1 The cable system is illustrated, and an embodiment of a lifting tool for modifying a portion of each blade is shown; Figure 3 yes Figure 2 An enlarged view of the lifting tool attached to a blade, as shown; Figure 4A , Figure 4B and Figure 4C yes Figure 2 Side views of wind turbines, illustrating the use of lifting tools for retrofitting a portion of each blade according to one embodiment; Figure 5A , Figure 5B and Figure 5C yes Figure 1 A front view of a wind turbine, not shown for simplicity. Figure 1 The cable system is illustrated, and an embodiment of using lifting tools to modify a portion of each blade is shown; Figure 6A yes Figure 1 A front view of a wind turbine, not shown for simplicity. Figure 1 The cable system is illustrated, and a lifting tool connected to the blade is shown according to one embodiment; Figure 6B It is connected to a blade. Figure 6A A magnified view of the lifting tool shown; and Figure 7A , Figure 7B , Figure 7C and Figure 7D yes Figure 6A The images show front views of wind turbines, illustrating the use of lifting tools to modify a portion of each blade. Detailed Implementation

[0026] Referring generally to the accompanying drawings, embodiments of the invention include a method for retrofitting one or more wind turbine blades on a wind turbine. Embodiments of the invention are advantageous because they economically address blade wear / damage that occurs during wind turbine operation. As an example, the lifting tool can be housed at the wind turbine site and can be installed on the wind turbine at a height where the wind turbine blade or a portion of the blade can be detached from the wind turbine and replaced with a new or refurbished blade portion. A separate ground-supported crane is not required for detaching / lifting each wind turbine blade from / onto the wind turbine. This avoids the cost of a separate mobile crane.

[0027] For this and other purposes, Figure 1 An exemplary wind turbine 10 is shown. The wind turbine 10 includes a tower 12 and an energy generation unit 14 (including a nacelle) disposed at the apex of the tower 12. The tower 12 may be coupled to a base 16 at its lower end. The base 16 may be a relatively large mass embedded in the ground (e.g., concrete, anchor cage, etc.), and the forces on the wind turbine 10 may ultimately be transmitted through this mass. Although not shown, in alternative embodiments, the base 16 may include an offshore platform, etc., used in offshore wind turbine applications. The tower 12 supports the weight of the energy generation unit 14 and is operated to raise the energy generation unit 14 to a height above ground or sea level, at which faster-moving airflows with lower turbulence are typically found.

[0028] In this respect, the energy generation unit 14 converts wind energy into electrical energy. The energy generation unit 14 typically includes a housing or nacelle 20, a rotor 22 having a rotor hub 24 and wind turbine blades 26a, 26b, 26c (e.g., three blades) mounted to and extending radially from the rotor hub 24. The energy generation unit 14 includes a drivetrain with a generator (not shown) for optionally converting mechanical energy into electrical energy via a gear mechanism (not shown). The majority of the drivetrain may be located inside the nacelle 20 of the wind turbine 10. In addition to the generator, the nacelle 20 typically houses a wide variety of components required for converting wind energy into electrical energy, as well as various components required for maintaining, operating, controlling, and optimizing the performance of the wind turbine 10.

[0029] Wind turbine blades 26a, 26b, and 26c are configured to interact with wind. During operation, the wind generates lift and causes rotor 22 to rotate or spin, substantially defining the swept area of ​​wind turbine blades 26a, 26b, and 26c. Energy generation unit 14 generates electricity from the wind passing through the swept area of ​​rotor 22. During their interaction with wind and weather, wind turbine blades 26a, 26b, and 26c are worn. Prolonged exposure to weather during the operation of wind turbine 10 will substantially damage wind turbine blades 26a, 26b, and 26c. After a period of operation, and in order to maintain the operating efficiency of wind turbine 10, worn wind turbine blades 26a, 26b, and 26c, or specific portions of each blade, may be replaced, as described below.

[0030] Continuing with the exemplary embodiment of the wind turbine 10, during operation, the wind turbine blades 26a, 26b, and 26c are supported by a cable system 30, which carries some static and dynamic loads. Essentially, the cable system 30 enables the wind turbine blades 26a, 26b, and 26c to support each other. For example, edge loads and flapping loads are shared among the wind turbine blades 26a, 26b, and 26c via the cable system 30.

[0031] exist Figure 1In this example, the cable system 30 includes three cable assemblies 32a, 32b, and 32c for each wind turbine blade 26a, 26b, and 26c (one cable assembly 32a, 32b, and 32c for each wind turbine blade 26a, 26b, and 26c). Each cable assembly 32a, 32b, and 32c is connected to the rotor 22 at three locations: one at the rotor hub 24, and one at a corresponding interface bracket 34a, 34b, and 34c at each of two adjacent wind turbine blades 26a, 26b, and 26c. That is, each cable assembly 32a, 32b, and 32c is connected to adjacent wind turbine blades 26a, 26b, and 26c and between adjacent wind turbine blades 26a, 26b, and 26c, as well as connected to the rotor hub 24. As shown in the figure, this forms a Y-shaped cable structure between adjacent wind turbine blades 26a, 26b, 26c and rotor hub 24.

[0032] Although not shown, the tension in cable system 30 can be adjusted via a hydraulic or electrical actuator system contained in rotor hub 24. For example, one or more of cable assemblies 32a, 32b, 32c can be operatively coupled to a hydraulic cylinder (not shown) extending from rotor hub 24. Movement of the hydraulic cylinder increases or decreases the tension in one or more of cable assemblies 32a, 32b, and / or 32c. The tension in each of assemblies 32a, 32b, 32c can be adjusted by operation of a tensioning system as described in one or both of PCT applications PCT / DK2021 / 050374 and PCT / DK2022 / 050051. Adjustment of the tension in cable assemblies 32a, 32b, and / or 32c can be performed before modifying any one or each of the outer blade sections 38a, 38b, 38c. As another example, releasing the tension in one or more cable assemblies 32a, 32b, 32c can be achieved by pitching one or more blades of blades 26a, 26b, 26c about their longitudinal axis. In the case of modification of the outer blade sections, cable assemblies 32a, 32b, and / or 32c can be released from the blades, as this allows for better access to the interface support. However, it has been found advantageous that cable assemblies 32a, 32b, 32c remain connected to the interface support during modification of the outer blade sections 38a, 38b, 38c, while adjusting the tension in the cable assemblies 32a, 32b, 32c to enable them to carry at least a portion of the load of the lifting tools (42, 62, 72) during modification of the outer blade sections 38a, 38b, 38c. In this way, cable assemblies 32a, 32b and / or 32c are advantageous to the method of the present invention, which is particularly advantageous for wind turbines having cable systems having cable assemblies 32a, 32b, 32c extending between adjacent blades 26a, 26b, 26c of a plurality of wind turbine blades 26a, 26b, 26c, and one or more of the cable assemblies 32a, 32b, 32c being attached to the blades 26a, 26b, 26c at interface supports 34a, 34b, 34c.

[0033] If the entire blade is modified, the tension in cable assemblies 32a, 32b and / or 32c can be released before modifying any individual blade or each blade in blades 26a, 26b, 26c.

[0034] In an exemplary embodiment, each of the plurality of wind turbine blades 26a, 26b, 26c is a modular blade. A modular blade may have two or more blade segments assembled end-to-end in the longitudinal direction. The length of each blade segment is less than the total length of the assembled blade. The blade segments may be manufactured and transported separately to the site of the wind turbine 10. When assembled end-to-end, these segments form the wind turbine blades 26a, 26b, 26c. As an example, and referring to… Figure 1 Each blade 26a, 26b, 26c may include an inner blade segment and an outer blade segment joined together at interface supports 34a, 34b, 34c. Referring to blade 26a, for example, the inner blade segment 36a is coupled to the rotor hub 24 at one end. The inner blade segment 36a defines the root end of blade 26a. The interface support 34a is coupled to the end of the inner blade segment 36a opposite to the rotor hub 24 at a first split position 28a. The outer blade segment 38a is coupled to the interface support 34a at a second split position 40a. The outer blade segment 38a defines the end of blade 26a.

[0035] Similarly, referring to blade 26b, the inner blade section 36b is connected to the rotor hub 24 at one end. The inner blade section 36b defines the root end of blade 26b. The interface bracket 34b is connected to the end of the inner blade section 36b opposite to the rotor hub 24 at the first split position 28b. The outer blade section 38b is connected to the interface bracket 34b at the second split position 40b. The outer blade section 38b defines the end of blade 26b. And, referring to blade 26c, the inner blade section 36c is connected to the rotor hub 24 at one end. The inner blade section 36c defines the root end of blade 26b. The interface bracket 34c is connected to the end of the inner blade section 36c opposite to the rotor hub 24 at the first split position 28c. The outer blade section 38c is connected to the interface bracket 34c at the second split position 40c. In other words, the inner blade section 36c is connected to the outer blade section 38c via the interface bracket 34c. The outer blade section 38c defines the tip of the blade 26c.

[0036] As shown in the figure, interface brackets 34a, 34b, and 34c separate the inner blade sections 36a, 36b, and 36c from the outer blade sections 38a, 38b, and 38c. Each of the blade sections 36a-36c and 38a-38c is connected to the corresponding interface bracket 34a, 34b, and 34c by a stud (not shown). Thus, at the first and second separation positions 28a-c and 40a-c, a joint is formed between the interface brackets 34a, 34b, and 34c and each of the blade sections 36a-36c and 38a-38c. The interface brackets 34a, 34b, and 34c provide lengthwise separation between the inner blade sections 36a, 36b, and 36c and the outer blade sections 38a, 38b, and 38c, even though the blade sections 36a-36c and 38a-38c are many times longer than the interface brackets 34a, 34b, and 34c. Split blades are described in detail in one or both of the jointly owned PCT applications PCT / DK2021 / 050374 and PCT / DK2022 / 050051, the entire contents of which are incorporated herein by reference. The connection point between the cable system 30 and each blade can be located outside the wind turbine blade, although at the interface supports 34a, 34b, and 34c. For example, cable connections can extend outward from the interface supports 34a, 34b, and 34c and can be used to connect to the cable system 30.

[0037] In view of the above, in the exemplary embodiment, each blade 26a, 26b, 26c is an assembly of three parts. For example, (i) wind turbine blade 26a is an assembly of inner blade section 36a, interface bracket 34a, and outer blade section 38a; (ii) wind turbine blade 26b is an assembly of inner blade section 36b, interface bracket 34b, and outer blade section 38b; and (iii) wind turbine blade 26c is an assembly of inner blade section 36c, interface bracket 34c, and outer blade section 38c. As shown, cable system 30 is connected to each of the interface brackets 34a, 34b, 34c. Although Figure 1 The illustration shows a split blade integrated with the cable system 30, but embodiments of the invention are not limited to this. Figure 1 The cable-stayed wind turbine is shown. For example, the method disclosed herein is applicable to split blades without a cable system.

[0038] Regarding blade wear due to weather exposure during operation, most damage to wind turbine blades occurs in the outer third of the blade length. Based on this and referring to... Figure 1In the wind turbine 10, most of the damage to each of the blades 26a, 26b, and 26c occurs in the outer blade sections 38a, 38b, and 38c. Therefore, according to an embodiment of the invention, by replacing the outer blade sections 38a, 38b, and 38c, most of the blade damage caused by the operation of the wind turbine 10 can be resolved. Advantageously, only the sections of the wind turbine blades 26a, 26b, and 26c that are causing most of the damage are replaced.

[0039] In one exemplary embodiment, a method of retrofitting a wind turbine blade typically includes attaching a lifting tool to an interface bracket 34a, 34b, 34c of a selected one of wind turbine blades 26a, 26b, 26c. It has been found particularly advantageous to use interface brackets 34a, 34b, 34c for temporary positioning of the lifting tool because the interface brackets are robust elements placed between the inner blade sections 36a, 36b, 36c and the outer blade sections 38a, 38b, 38c and adapted to transfer structural loads between the blade sections. In particular, it has been found that interface brackets 34a, 34b, 34c are more suitable than the general surface of the blades for providing a robust and well-defined connection point. After attaching the lifting tool to the selected blade 26a, 26b, 26c, the outer blade sections 38a, 38b, 38c are disconnected from their respective interface brackets 34a, 34b, 34c. As an example, technicians can detach the outer blade sections 38a, 38b, 38c from the interface supports 34a, 34b, 34c via access from a human basket or using a robot. With the lifting tool in place, the detached outer blade sections 38a, 38b, 38c are lowered toward the ground using the lifting tool. New outer blade sections are then lifted and connected to the corresponding interface supports 34a, 34b, 34c via the reverse process. This may include attaching the lifting tool to the new outer blade section, raising the new outer blade section with the lifting tool, and connecting the new outer blade section to the corresponding interface supports 34a, 34b, 34c. Preferably, the attachment, disconnection, lowering, and raising are repeated for each wind turbine blade 26a, 26b, 26c. However, it should be observed that the method of the present invention can be used for only one wind turbine blade, i.e., for example, in cases where it is unlikely that the outer blade section has been damaged by, for example, lightning strikes or bird strikes, only one end needs to be replaced. A mobile ground-supported crane is not required. Furthermore, embodiments of the lifting tool may only require 20% of the mass of a single blade 26a, 26b, or 26c.

[0040] exist Figure 1In an exemplary embodiment of the wind turbine 10, the steps of connecting, disconnecting, lowering, and raising are performed three times, once for each of the three blades. After replacing each of the outer blade sections 38a, 38b, and 38c, the wind turbine 10 returns to operation. Retrofitting according to embodiments of the invention can be performed according to a standard maintenance schedule. Utilizing the availability and cost-efficiency of embodiments of the methods disclosed herein, blade sections, such as outer blade sections 38a, 38b, and 38c, can be replaced according to a schedule independent of the specific damage suffered by any of the blades 26a, 26b, and 26c. In other words, outer blade sections 38a, 38b, and 38c can be replaced according to a predetermined maintenance schedule to maintain the wind turbine 10 at peak operating efficiency. However, embodiments of the invention can be used for emergency replacement of one or more of the outer blade sections 38a, 38b, and 38c in the event of unplanned blade damage, such as due to bird strikes, lightning strikes, or leading-edge erosion. As another example, the outer blade sections 38a, 38b, and 38c can be replaced according to seasonal weather variations at the location of the wind turbine 10. For example, the outer blade sections 38a, 38b, and 38c can be replaced with outer blade sections 38a, 38b, and 38c of different designs. If a low-wind season or a season with higher temperatures leading to lower air density (e.g., summer in Northern Europe) is expected, the differently designed sections can be longer. Similarly, if a high-precipitation season and / or a cold season is expected, or if the wind turbine 10 operates in a typhoon-affected area, the differently designed sections can be shorter.

[0041] In an exemplary embodiment, the outer blade sections 38a, 38b, and 38c may be designed to have a different and shorter design life than the inner blade sections 36a, 36b, and 36c. In this way, the outer blade sections can be considered wear parts with a shorter lifespan than the inner blade sections. When designed for a shorter lifespan, the mass of the outer blade sections can be reduced, resulting in a lower load on the load-bearing structure and thus lower costs. For example, the outer blade sections may be designed to have half, one-third, or a smaller portion of the design life of the inner blade sections 36a, 36b, and 36c. In this way, after replacing the outer blade sections 38a, 38b, and 38c, the modified wind turbine can operate, for example, two, three, or more times. The inner blade sections 36a, 36b, and 36c can also be considered wear parts, wherein the design life of the inner blade sections 36a, 36b, and 36c is shorter than the design life of the wind turbine. Similarly, if the inner blade sections 36a, 36b, and 36c are not worn, the outer blade sections 38a, 38b, and 38c can be replaced without replacing them. Then, if the wind turbine is not worn when the inner blade sections 36a, 36b, and 36c need replacement, then those sections can be replaced. Preferably, the replacement of the inner blade sections 36a, 36b, and 36c is combined with the replacement of the outer blade sections 38a, 38b, and 38c, so that the entire blade is replaced when the inner blade sections 36a, 36b, and 36c are replaced. Since replacing the entire blade requires a full-size crane, the ability to selectively replace the outer blade sections or both inner and outer sections allows for improved predictive maintenance, where the replacement of the outer blade can be performed as a relatively simple operation requiring only, for example, attaching lifting tools to the interface bracket via a climber or drone. In many cases, this allows for the postponement of entire blade repairs or replacements until a more suitable time, such as when a crane is available for another operation nearby or when the probability of a favorable weather window is high. The ability to replace only outer blade sections using lifting equipment without a full-size crane also allows for the replacement of another blade section throughout the year. For example, shorter outer blade sections and / or sections with higher corrosion resistance can be utilized during seasons with expected strong winds, while longer outer blade sections and / or sections with more affordable leading-edge protection can be utilized during seasons with expected milder winds. This seasonal switching of outer blade sections also allows for the scheduled maintenance of unused outer blade sections and thus prevents or reduces the likelihood of unplanned maintenance of the wind turbine.

[0042] In one embodiment, and referring to Figure 2 , Figure 3 , Figure 4A , Figure 4B and Figure 4CThe lifting tool 42 is used to modify one or more of blades 26a, 26b, and 26c. Before or after attaching the lifting tool 42 to blade 26a, the rotor 22 can be... Figure 1 Rotate to the position shown Figure 2 The position shown. For example, rotor 22 can rotate counterclockwise (as indicated). Figure 1 (As shown by arrow 44) to position blade 26a at the 6 o'clock position, for example, as Figure 2 As shown. Blade 26a in Figure 2-4B The image shows it as pointing straight down or parallel to tower 12.

[0043] refer to Figure 2 and Figure 3 Once the selected blade 26a is oriented at the 6 o'clock position, the lifting tool 42 is attached to the blade 26a. An exemplary lifting tool 42 is shown having an upper mounting bracket 46a attached to the interface bracket 34a and a lower mounting bracket 46b attached to the outer blade section 38a. As an example, the upper mounting bracket 46a can be bolted to the interface bracket 34a, but other forms of attachment may include, for example, a steel component to be bolted to the interface bracket, or lifting holes or eyelets to be bolted to the interface bracket or the blade. Although not shown, the upper mounting bracket 46a can be attached to the inner blade section 36a or a combination of the interface bracket 34a and the inner blade section 36a.

[0044] In the illustrated embodiment, and referring to Figure 3The lifting tool 42 includes a lift 50 and a lifting cable 52. The lifting cable 52 is operatively connected to the lift 50 and the lower support 46b. The lift 50 is fixed to the upper support 46a, for example, by a cable 54, and is thus suspended from the upper support 46a under gravity. The lifting cable 52 operatively extends from the lift 50 to the lower support 46b. As shown, a second lift 50 can be fixed to the upper support 46a on the side opposite to the first lift 50. Therefore, the second lift 50 can be suspended from the upper support 46a by the second cable 54 due to gravity. The second lifting cable 52 operatively extends from the lift 50 to the lower support 46b. The pair of lifts 50 can be operated simultaneously to maintain an equal load on each lift during the lowering and raising of the outer blade section 38a. Embodiments of the invention are not limited to the lifting tool 42 having an upper support 46a and a lower support 46b. For example, the lifting tool 42 may include a single support, such as support 46a, secured to the inner blade section 36a and / or interface bracket 34a, from which one or more lifts 50 and cables 52 extend to the outer blade section 38a. Instead of a single support, the lifting tool 42 may include one or more eye bolts (not shown) secured to the interface bracket 34a. Furthermore, in addition to or as an alternative to the lower support 46b, a net or rope net (not shown) may be used to surround or enclose the outer blade section 38a to secure it during retrofitting. In other words, embodiments of the invention are not limited to the upper support 46a and lower support 46b shown. Although not shown, the lifting tool 42 and / or lifts 50 and cables 52 may be stored in the nacelle 20 and lowered from the nacelle 20 via an internal crane to engage with the blade 26a.

[0045] In one embodiment (not shown), the lifting tool's elevator is arranged away from the interface support, for example, on the ground, in the nacelle, on the nacelle, in the hub, or in the inner section of the blade, and the lifting tool includes pulleys arranged at the interface support for transferring lifting cables from the elevator to the outer blade section.

[0046] Reference Figure 4A and Figure 4B Once the lifting tool 42 is operably connected to the blade 26a, as Figure 4AAs shown, a technician disconnects the outer blade section 38a from the inner blade section 36a. For example, the technician can disconnect the outer blade section 38a at its connection with the interface bracket 34a (i.e., at the outermost split position 40a). In this case, the inner blade section 36a remains connected to the rotor hub 24, and the interface bracket 34a remains connected to the inner blade section 36a. After the outer blade section 38a is disconnected, its weight is supported by the lifting tool 42. That is, the entire outer blade section 38a is suspended from the inner blade section 36a at the interface bracket 34a under the influence of gravity. The lifting tool 42 transfers the weight load to the rotor 22. In the exemplary embodiment shown, the outer blade section 38a is held suspended with its end pointing downwards or towards the ground.

[0047] like Figure 4B and Figure 4C As indicated by arrow 56, technicians operate the lift 50 to lower the outer blade section 38a to a position adjacent to the base 16 of the wind turbine 10, such as lowering it to... Figure 4C On the transport vehicle shown. In an exemplary embodiment, a guide cable 60 is secured to the end of the outer blade section 38a, allowing technicians to control the position of the end of the section as the operation of the elevator 50 further lowers the outer blade section 38a toward the ground.

[0048] Although not shown, once the outer blade section 38a is fully lowered, and therefore there is no tension in the cable 52, the lower support 46b is removed from the outer blade section 38a. The lower support 46b can then be attached to a new or refurbished outer blade section (not shown), and the cable 52 is attached to the lower support 46b. A technician can then operate the lift 50 to raise the new or refurbished outer blade section to the interface support 34a. Once in the adjacent position, the new or refurbished outer blade section is attached to the interface support 34a. The modification can continue by rotating the next blade 26b or 26c to the 6 o'clock position. The technician can then replace the outer blade sections 38b and 38c in a similar manner using the lifting tool 42.

[0049] In one embodiment, and now refer to Figure 5A , Figure 5B and Figure 5C The lifting tool 62 is used to modify one or more of blades 26a, 26b, and 26c. The lifting tool 62 differs from... Figure 2-4CThe lifting tool 62 is shown in the figure. As illustrated, the lifting tool 62 is an auxiliary crane or similar device including a lift and a cable operably connected to the lift. The lifting tool 62 can be housed in the nacelle 20 during operation of the wind turbine 10. When blades 26a, 26b, and 26c are scheduled for retrofitting, the lifting tool 62 is lowered from the nacelle 20 or otherwise approached to one of the interface supports 34a, 34b, and 34c. Technicians then attach the lifting tool 62 to the interface supports 34a, 34b, and 34c. Before or after attaching the lifting tool 62 to blade 26a, the rotor 22 can be rotated to… Figure 5A The position shown is for attaching the lifting tool 62 to the interface bracket 34a. Although not shown, the rotor 22 can be rotated to position the blade 26a at the 6 o'clock position before attaching the lifting tool 62.

[0050] Once the lifting tool 62 is attached to the blade 26a and referenced Figure 5B Rotor 22 rotates according to arrow 64, positioning blade 26a at the 3 o'clock position. As shown, blade 26a is horizontal (i.e., parallel to the ground), and lifting tool 62 is oriented in the operating position to support the weight of outer blade section 38a. Cable 66 is lowered from the auxiliary crane and secured to outer blade section 38a. Attachment of cable 66 to outer blade section 38a can be achieved via a belt or webbing (not shown) that wraps around outer blade section 38a and is designed to retain the weight of outer blade section 38a once it is disconnected from interface bracket 34a.

[0051] Then, the technician can disconnect the outer blade section 38a from the interface bracket 34a. The weight of the outer blade section 38a is then supported by the lifting tool 62 attached to the interface bracket 34a. (See reference...) Figure 5C After detaching from the interface bracket 34a, the outer blade section 38a is suspended from the cable 66. A technician operates the lifting tool 62 to extend the cable 66. This lowers the outer blade section 38a toward the ground or supporting surface. The lowering of the outer blade section 38a is typically indicated by arrow 70. As shown, in an exemplary embodiment, the outer blade section 38a maintains its longitudinal axis in a horizontal orientation, i.e., parallel to the ground. This is consistent with… Figure 4B The downward-facing orientation shown contrasts with the longitudinal axis of the outer blade section 38a being perpendicular to the ground. Although not shown, the cable 66 disconnects from the outer blade section 38a once it is fully lowered to the point where there is no tension in the cable 66. The lifting tool 62 can be connected to a new or refurbished outer blade section (not shown) via the cable 66. A technician can then operate the lift of the lifting tool 62 to raise the new or refurbished outer blade section to the interface bracket 34a.

[0052] Once in the adjacent position, the new or refurbished outer blade section is connected to the interface support 34a. This can be achieved by rotating the blade 26a to... Figure 5A The modification continues at the indicated position, where the lifting tool 62 can be removed from the interface bracket 34a. Once removed, the next blade 26b or 26c rotates to... Figure 5A As shown in the diagram, at this location, the lifting tool 62 can be attached to the blade 26b or 26c at the corresponding interface bracket 34b, 34c. Then, as described above... Figure 5B and Figure 5C The modification will proceed as described. Then, the technicians can replace the outer blade sections 38b and 38c in a similar manner using lifting tool 62.

[0053] In one embodiment, and now refer to Figure 6A and Figure 6B The lifting tool 72 is used to modify one or more of blades 26a, 26b, and 26c. For example, the lifting tool 72 differs from... Figure 2 and Figure 5A The lifting tools 42 and 62 are shown. (As shown) Figure 6B As shown, the lifting tool 72 includes a mounting bracket 74 that connects the outer blade segment 38a to the interface bracket 34a at a pivot axis 76. Thus, the lifting tool 72 is connected to the interface bracket 34a on one side and is pivotable about the axis 76 on that side. The lifting tool 72 operates as a hinge about the pivot axis 76. The pivot axis 76 is spaced apart from the longitudinal axis of the blade 26a. The lifting tool 72 is also connected to the outer blade segment 38a. The mounting bracket 74 may have a dog-legged configuration. As shown, a short leg portion 80 of the mounting bracket 74 is used to connect to the interface bracket 34a and form the pivot axis 76. A longer leg portion 82 extends from the short leg portion 80 at an obtuse angle and secures the outer blade segment 38a adjacent to the interface bracket 34a. Thus, the mounting bracket 74 spans the outermost split position 40a. For example, the longer leg portion 82 may at least partially surround the outer blade segment 38a.

[0054] Before connecting the lifting tool 72 to the blade 26a, the rotor 22 can rotate to Figure 6AThe position shown (e.g., where blade 26a is at the 6 o'clock position) facilitates the attachment of lifting tool 72 to interface bracket 34a. Similar to the other lifting tools 42 and 62, lifting tool 72 can be housed in nacelle 20 during operation of wind turbine 10. When blades 26a, 26b, and 26c are scheduled for replacement, lifting tool 72 is lowered from nacelle 20 or otherwise approached to one of interface brackets 34a, 34b, and 34c. Technicians then attach lifting tool 72 to interface brackets 34a, 34b, and 34c at pivot shaft 76. For example, pivot shaft 76 may be formed on interface bracket 34a as… Figure 1 The cable system 30 shown is at a cable connection point. Therefore, the cable system 30 can be disconnected from this location before the lifting tool 72 is connected to the interface bracket 34a.

[0055] In another embodiment, the mounting bracket 74 may be permanently disposed on the outer blade section, preferably hinged to the interface bracket at the pivot shaft 76, thereby facilitating the connection of the lifting tool to the interface bracket.

[0056] The connection at pivot 76 can be permanent, so disconnecting the outer blade section 38a requires releasing the outer blade section 38a from the mounting bracket 74. However, it is preferred that the connection at pivot 76 is temporary, so disconnecting the outer blade section 38a requires releasing the outer blade section 38a from the mounting bracket at the pivot. In one embodiment, the release of the outer blade section 38a from the mounting bracket can be achieved by removing a component forming the pivot (such as a bolt or cylindrical member). In another embodiment, at least one of the mounting bracket 74 and the interface bracket 34a has a hook-shaped connector to the pivot, which allows the interface bracket 34a to be released from the mounting bracket 74 at the pivot by opening the hook-shaped connector.

[0057] refer to Figure 7A After the lifting tool 72 is attached to the interface bracket 34a and the outer blade section 38a, the rotor 22 rotates away from the 6 o'clock position in the direction indicated by arrow 84. This rotation brings the blade 26a to a position where the outer blade section 38a at the outermost split position 40a is pushed towards the interface bracket 34a by gravity around the pivot shaft 76. In this position of the rotor 22, the outer blade section 38a can be supported by the pivot shaft and held towards the interface bracket 34a at the outermost split position 40a by gravity. Therefore, the multiple studs securing the outer blade section 38a to the interface bracket 34a can be safely removed by a technician. Once disconnected from the interface bracket 34a, the outer blade section 38a is held in place and connected to the interface bracket 34a at the pivot shaft 76 by the lifting tool 72.

[0058] Reference Figure 7A and Figure 7B Rotor 22 rotates counterclockwise in the direction of arrow 86. At a certain position on rotor 22, gravity pulls the outer blade section 38a away from the interface support 34a by causing it to rotate about pivot axis 76. The weight of the outer blade section 38a is borne at pivot axis 76. Therefore, the outer blade section 38a may tend to remain in a position with its tip pointing downwards, where the longitudinal axis of the outer blade section 38a is approximately perpendicular to the ground.

[0059] refer to Figure 7B and Figure 7C Rotor 22 rotates further counterclockwise according to arrow 86. With further rotation, the inner blade section 36a is brought to the 3 o'clock position. This is in Figure 7C As shown in the diagram. When rotor 22 rotates to... Figure 7C During the position shown, the outer blade segment 38a further rotates clockwise (opposite to the rotation of rotor 22) about the pivot axis 76. This local rotation about the pivot axis 76 is caused by... Figure 7B Arrow 92 is shown in the image.

[0060] Once the inner blade section 36a is at the 3 o'clock position ( Figure 7C The outer blade section 38a can be positioned at or near the 6 o'clock position. In other words, the outer blade section 38a is oriented approximately vertically, with the blade tips pointing towards the ground. For example, the longitudinal axis of the outer blade section 38a can be oriented perpendicular to the ground and the inner blade section 36a, and can be approximately parallel to the tower 12.

[0061] refer to Figure 7D In one embodiment, with the inner blade section 36a in the 3 o'clock position, cable 88 is attached to the outer blade section 38a. For example, cable 88 may be attached to the end opposite to the end of the outer blade section 38a. The attachment of cable 88 to the outer blade section 38a may be made by a tape or webbing (not shown) that surrounds the outer blade section 38a and is designed to retain the weight of the outer blade section 38a once it is disconnected from the interface bracket 34a. Cable 88 may be operatively attached to a lift (not shown) that is attached to the interface bracket 34a or to the inner blade 36a. A technician can then disconnect the outer blade section 38a from the interface bracket 34a. The weight of the outer blade section 38a is then borne by cable 88 attached to the interface bracket 34a.

[0062] To lower the outer blade section 38a, a technician operates a lifting tool 72 to extend cable 88. This lowers the outer blade section 38a from the interface bracket 34a toward the ground or supporting surface, as indicated by arrow 90. In the exemplary embodiment shown, the mounting bracket 74 remains attached to the interface bracket 34a during the lowering of the outer blade section 38a. In an alternative embodiment, the mounting bracket 74 is preferably disengaged from the interface bracket 34a at the pivot 76 and remains attached to the outer blade section 38a during lowering.

[0063] In another embodiment, cable 88 is connected to outer blade section 38a before inner blade section 36a reaches the 3 o'clock position. For example, cable 88 may be connected before rotor 22 rotates counterclockwise, and cable 88 may carry a portion of the load that would otherwise be carried by pivot shaft 76.

[0064] Although not shown, once the outer blade section 38a is fully lowered to the point where there is no tension in the cable 88, the cable 88 disconnects from the outer blade section 38a. The lifting tool 72 can be connected to a new or refurbished outer blade section (not shown) via the cable 88. A technician can operate the lifting tool 72's hoist to raise the new or refurbished outer blade section to the interface bracket 34a. Once in the abutment position with the interface bracket 34a, the new or refurbished outer blade section is connected to the mounting bracket 74 of the lifting tool 72. With the new or refurbished outer blade section connected to the interface bracket 34a only at the pivot 76, the rotor 22 rotates clockwise. This rotation causes the new or refurbished outer blade section to rotate counterclockwise about the pivot 76 of the lifting tool 72. The new or refurbished outer blade section rotates toward the abutment position with the interface bracket 34a.

[0065] Once rotor 22 is in Figure 7A At the location shown, the new or refurbished outer blade section is adjacent to the interface bracket 34a. At this location, a technician uses multiple studs to secure the new or refurbished outer blade section to the interface bracket 34a. Once the blade 26a is reassembled, the lifting tool 72 is removed from the blade 26a.

[0066] Once the lifting tool 72 is removed and if another outer blade section 38b or 38c needs to be replaced, the next blade 26b or 26c rotates to... Figure 6A As shown in the diagram, at this location, the lifting tool 72 can be attached to blade 26b or 26c. Then, as described above... Figures 7A-7D The modification will proceed as described. Then, the technicians can replace the outer blade sections 38b and 38c in a similar manner using lifting tool 72.

[0067] According to any embodiment of the invention, during the operational life of the wind turbine 10, and possibly after multiple outer blade sections have been replaced, the inner blade sections 36a, 36b, and 36c may be replaced due to cumulative damage on them. Therefore, although the outer blade sections 38a, 38b, and 38c suffer damage at a higher rate than the inner blade sections 36a, 36b, and 36c, the inner blade sections 36a, 36b, and 36c will eventually be replaced as well. In this regard, the entire blades 26a, 26b, and 26c can be replaced. This achieves the replacement of both the inner and outer blade sections, as well as the interface brackets (34a, 34b, and 34c). This can also be part of an upgrade or retrofit of the wind turbine, where the rotor and optional other major components are replaced to provide an upgraded configuration for the wind turbine. For example, the replacement of the inner blade sections 36a, 36b, and 36c can be carried out using a crane, where the entire blade is removed and replaced. Without being bound by any plan, for every three replacements of the outer blade sections 38a, 38b, and 38c, the inner blade sections 36a, 36b, and 36c can be replaced once. For example, the outer blade sections 38a, 38b, and 38c can be replaced twice using lifting tools 42, 62, and 72, and then each of the blades 26a, 26b, and 26c is replaced entirely.

[0068] The embodiments of the present invention take a single-rotor HAWT as an example, but it is similarly useful for multi-rotor HAWTs. In multi-rotor HAWTs, the method can be used to retrofit wind turbine blades using the same steps and sequence as described above, thereby achieving the same advantages.

[0069] While the invention has been described through various preferred embodiments, and while these embodiments have been described in some detail, the applicant does not intend to limit the scope of the appended claims or restrict them in any way to such details. Other advantages and modifications will be apparent to those skilled in the art. Therefore, various features of the invention can be used alone or in any combination, depending on the user's needs and preferences.

Claims

1. A method for retrofitting a wind turbine (10), said wind turbine (10) having a plurality of wind turbine blades (26a, 26b, 26c) connected to a rotor hub (24), wherein, Each of the plurality of wind turbine blades (26a, 26b, 26c) is a split blade, the split blade defining an inner blade section (36a, 36b, 36c) connected to the rotor hub (24) and an outer blade section (38a, 38b, 38c) connected to the inner blade section (36a, 36b, 36c) at an interface bracket (34a, 34b, 34c), the method comprising: Select blades (26a, 26b, 26c) from the plurality of wind turbine blades (26a, 26b, 26c); and For the blades (26a, 26b, 26c), the method further includes: (i) Connecting lifting tools (42, 62, 72) to the interface brackets (34a, 34b, 34c), the lifting tools (42, 62, 72) including at least one lift (50) and at least one lifting cable (52, 66, 88) operably connected to the at least one lift (50). (ii) Connecting at least one lifting cable (52, 66, 88) of the lifting tool (42, 62, 72) to the outer blade section (38a, 38b, 38c). iii) Disconnecting the outer blade sections (38a, 38b, 38c) from the inner blade sections (36a, 36b, 36c) while keeping the inner blade sections (36a, 36b, 36c) connected to the rotor hub (24), and supporting the outer blade sections (38a, 38b, 38c) by the lifting tools (42, 62, 72); and iv) Using the lifting tools (42, 62, 72), the outer blade sections (38a, 38b, 38c) are lowered to the support surface adjacent to the wind turbine (10).

2. The method according to claim 1, wherein, The wind turbine (10) includes a cable system (30) having cable assemblies (32a, 32b, 32c), wherein one or more of the cable assemblies (32a, 32b, 32c) extend between adjacent blades (26a, 26b, 26c) of the plurality of wind turbine blades (26a, 26b, 26c), and wherein the one or more cable assemblies (32a, 32b, 32c) are attached to the blades (26a, 26b, 26c) at the interface brackets (34a, 34b, 34c).

3. The method according to claim 2, wherein, Before disconnecting the outer blade sections (38a, 38b, 38c) from the inner blade sections (36a, 36b, 36c), the method further includes: releasing the fairing at the interface bracket (34a, 34b, 34c) of the wind turbine blades (26a, 26b, 26c).

4. The method according to claim 2 or 3, wherein, Before disconnecting the outer blade sections (38a, 38b, 38c) from the inner blade sections (36a, 36b, 36c), the method further includes adjusting the tension in one or more of the cable assemblies (32a, 32b, 32c) connected to the blades.

5. The method according to any one of the preceding claims, wherein, The lifting tool (42) includes a first mounting bracket (46a) and a second mounting bracket (46b), and wherein connecting the lifting tool (42) includes connecting the first mounting bracket (46a) to the interface bracket (34a, 34b, 34c) and connecting the second mounting bracket (46b) to the outer blade section (38a, 38b, 38c).

6. The method according to claim 5, wherein, Connecting the at least one lifting cable (52) to the outer blade section (38a, 38b, 38c) includes connecting the at least one lifting cable (52) to the second mounting bracket (46b).

7. The method according to claim 5 or 6, wherein, The at least one lifting cable (52) includes a pair of lifting cables (52), and wherein connecting the at least one lifting cable (52) to the outer blade section (38a, 38b, 38c) includes connecting each of the pair of lifting cables (52) to the second mounting bracket (46b).

8. The method according to any one of claims 1-4, wherein, The lifting tool (72) also includes a mounting bracket (74) connected to the outer blade sections (38a, 38b, 38c) and pivotally connected to the interface brackets (34a, 34b, 34c), such that the mounting bracket (74) and the interface brackets (34a, 34b, 34c) can rotate relative to each other about a pivot axis (76).

9. The method according to claim 8, further comprising: Before disconnecting the outer blade sections (38a, 38b, 38c) from the interface brackets (34a, 34b, 34c), the blades (26a, 26b, 26c) are rotated to a position where the outer blade sections (38a, 38b, 38c) are forced toward the interface brackets (34a, 34b, 34c) by gravity around the pivot axis 76, wherein rotating the blades (26a, 26b, 26c) includes rotating the rotor hub (24) and / or pitching the blades (26a, 26b, 26c).

10. The method according to claim 8 or 9, wherein, Before lowering the outer blade sections (38a, 38b, 38c) to the support surface, the method further includes rotating the blades (26a, 26b, 26c) so that the outer blade sections (38a, 38b, 38c) are substantially vertical.

11. The method according to any one of claims 1-4, wherein, Connecting the lifting tool (62) to the blades (26a, 26b, 26c) includes connecting the crane to the interface bracket (34a, 34b, 34c).

12. The method according to claim 11, wherein, Before disconnecting the outer blade segments (38a, 38b, 38c) from the inner blade segments (36a, 36b, 36c), the method further includes rotating the blades (26a, 26b, 26c) such that the blades (26a, 26b, 26c) are substantially horizontal.

13. The method according to any one of the preceding claims, wherein, After lowering the outer blade sections (38a, 38b, 38c) to the support surface, the method further includes: Connect the at least one lifting cable (52, 66, 88) to another outer blade section (38a, 38b, 38c). Using the lifting tools (42, 62, 72), the other outer blade section is raised to the inner blade section (36a, 36b, 36c); and Connect the other outer blade section to the inner blade section (36a, 36b, 36c).

14. The method according to any one of the preceding claims further comprises: Select another blade from the plurality of wind turbine blades (26a, 26b, 26c); as well as Repeat steps i)-iv) for the other blade (26a, 26b, 26c).

15. The method according to any one of the preceding claims, wherein, The selection of the leaves (26a, 26b, 26c) includes the selection of the leaves (26a, 26b, 26c) periodically throughout the year based on seasonal weather.

16. The method according to any one of claims 1-14, wherein, After selecting each of the blades (26a, 26b, 26c), after steps i)-iv) for each of the blades (26a, 26b, 26c), and after the first operation of the modified wind turbine (10), the method further includes: v) Replace each of the outer blade sections (38a, 38b, 38c) on each of the blades (26a, 26b, 26c) according to steps i)-iv), and operate the modified wind turbine a second time; and vi) After the second time, the inner blade sections (36a, 36b, 36c) are disconnected from the rotor hub (24); and another inner blade section (36a, 36b, 36c) is connected to the rotor hub (24).

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