Method for upgrading and retrofitting wind turbine

Abstract

In a first aspect of the invention, there is provided a method of upgrading a horizontal axis wind turbine (10) comprising a tower (12), a nacelle (14) rotatably located at a top end of the tower (12), and a rotor (16) having a hub (18) and at least three used blades (20), the invention relates to a method for producing at least three used blades (20) mounted on a hub (18) in a variable pitch manner and extending radially therefrom, the method comprising the steps of: removing the at least three used blades (20) from the hub (18); mounting at least three upgraded retrofit blades (21) on the hub (18), each upgraded retrofit blade (21) extending between a root (22) and an end (24), and each upgraded retrofit blade (21) further comprising a connection point (26) between the root (22) and the end (24); installing a plurality of blade connection members (28), each blade connection member (28) being connected between a corresponding connection point (26) of a pair of upgraded retrofit blades (21); and mounting a tensioning system (32) with the hub (18), the tensioning system (32) configured to adjust a tension force in each blade connection member (28).

Description

Technical Field

[0001] The present invention generally relates to repowering a horizontal axis wind turbine, and more particularly to repowering a horizontal axis wind turbine by replacing a used blade with a repower blade, and a method of operating the repowered wind turbine. Background Art

[0002] Installed and operational wind turbines are typically designed based on design loads, which are determined based on the specific blade type, rotor diameter, and climatic conditions in which the wind turbine is expected to operate. If the rotor diameter can be increased, the wind turbine owner can increase the annual energy production (AEP), thereby increasing annual revenue. In addition, a larger rotor diameter can generate more power at lower wind speeds, which can increase revenue at higher prices per kilowatt-hour (kWh) in certain markets. However, rotor diameter cannot usually be increased, or the increase is very limited, because larger rotors are heavier, resulting in increased loads on bearing components in the hub, nacelle, and / or tower. Summary of the invention

[0003] An object of the present invention is to provide an improved method of upgrading a wind turbine generator.

[0004] Another object of the present invention is to provide an improved method of operating a retrofitted wind turbine.

[0005] According to a first aspect, the present invention provides a method for upgrading a horizontal axis wind turbine, the horizontal axis wind turbine comprising a tower, a nacelle rotatably located at the top end of the tower, and a rotor. The rotor has a hub and at least three used blades, the three used blades being pitchably mounted to the hub and extending radially therefrom. The method comprises the steps of removing the at least three used blades from the hub and mounting at least three upgraded blades on the hub. This typically involves releasing the blades from the hub and remounting the blades on the tower, but in particular for rotors of smaller diameter, such as rotors with a diameter of less than about 100 m, it may be possible to 2022P00050WOCN(JPHEN)

[0006] Lower the rotor to the ground before releasing the blades from the hub and reinstalling them.

[0007] Each upcycled blade extending between a root and an end includes a connection point located between the root and the end. In addition, the method includes: installing a plurality of blade connection members, wherein each blade connection member is connected between corresponding connection points of a pair of upcycled blades; and installing a tensioning system with the hub, wherein the tensioning system is configured to adjust a tensioning force in each blade connection member.

[0008] The connection point and the connection member are arranged so that the blade can pitch in response to changes in the incoming wind. The connection point can be located on the blade surface, inside the blade surface, or on an extension of the blade extending outside the blade surface. The blade connection member can be a single-piece member or an assembly of two or more members, such as two extensions (such as cables) connected to the central frame, optionally together with a tensioning force member connecting the tensioning system to the blade connection member.

[0009] A tensioning system installed with a hub can be, for example, the case where the tensioning system is connected to the hub as a separate system to form an overall retrofit hub (also referred to as hub for short), but the tensioning system can also be at least partially built into a used hub.

[0010] In one example, the used blade is a conventional wind turbine blade of a horizontal axis wind turbine, which is supported only at the blade root during use. In other words, the conventional wind turbine blade is fundamentally different from the upcycled blade used in the present invention, which is supported both via the blade root and via the blade connection member. Conventional wind turbine blades have no connection points, so the connection member described in the present invention cannot be installed between a pair of conventional blades.

[0011] In one example, the tensioning system may include a plurality of linear actuators, such as one linear actuator per blade, each linear actuator coupled between the hub and the blade connection member. The coupling between the hub and the blade connection member is typically via the tensioning system, and may also be via a tensioning force member.

[0012] In one example, the upgraded blade is mounted to the hub via a tapered adjustment member arranged between the blade root and the hub. The tapered adjustment member typically has two circular connections, connected to the pitch bolt connection circle and the blade root, respectively. The two circular connections are arranged at a slight angle, such as an angle between 0.5 and 6°, to allow the taper angle and / or sweep angle of the hub to blade connection to be changed. A wind turbine having a variable pitch blade connection member supporting the blade supports reduced flapping loads, and the load reduction can increase as the taper angle of the blade increases. In addition, increasing the taper can reduce the risk of tower strikes. Unfortunately, it was found that increasing the taper angle also increases the pitch loads during pitch change, so if the tapered adjustment member is arranged between the blade root and the hub as part of the upgrade method2022P00050WOCN(JPHEN)

[0013] If the blades are mounted between the hubs, it is preferred to reinforce or replace the pitch system, such as the pitch actuators and / or blade bearings, during the upgrade method.

[0014] In one example, the tensioning system is a separate unit attached near the front of the (used) hub. The tensioning system comprises a separate system for powering the linear actuator, such as a separate hydraulic system or a separate electrical system. In this way, no rearrangement or reconnection in the hub is required and the downtime of the wind turbine for the upgrade can be reduced. However, some parts of the hub may need to be reinforced in order to attach the separate tensioning unit to the hub, but such reinforcement can usually be done without destroying and reconnecting the electrical and / or hydraulic connections in the (used) hub.

[0015] In another example, the tensioning system includes a system for powering a linear actuator that is integrated with the blade pitch system of the hub via a shared system for powering the linear actuator. Such integration can be achieved, for example, by sharing (a portion of) a hydraulic system or (a portion of) an electrical system for pitch.

[0016] In one example, the method may include removing the hub from the nacelle, installing the tensioning system with the hub remote from the nacelle, and installing the hub with the tensioning system to the nacelle. This may be a preferred method if the tensioning system is integrated into the hub to some extent, for example, by installing a hydraulic reservoir in the hub, or using a common electrical system or hydraulic pump for the pitch system and the tensioning system.

[0017] In one example, during a wind turbine upgrade, other components of a used wind turbine are repaired or replaced. For example, the replaced wind turbine components may be selected from the group consisting of a main bearing, a gearbox, a generator, a blade bearing, a pitch system component, a yaw system component, a main shaft, and a base frame. In some cases, replacing or strengthening components may increase the output or power rating of the wind turbine. For example, the main bearing may need to be strengthened, the gearbox may need to be adjusted for a different rotational speed or torque, and the generator may be upgraded to increase power generation.

[0018] The upcycled blade may be at least 15% longer than the used blade, preferably the upcycled blade may be at least 20% longer than the used blade. In some cases, particularly when one or more other components of the wind turbine (such as the pitch system) are reinforced, the upcycled blade may be at least 25% longer than the used blade, preferably the upcycled blade may be at least 30% longer than the used blade. Preferably, the upcycled blade is at most 35% longer than the used blade, preferably the upcycled blade is at most 25% longer than the used blade.

[0019] Another aspect of the invention relates to a method of operating a wind turbine upgraded according to another aspect of the invention. In one example, the maximum tip speed of the wind turbine generator during operation with the used blades is the same as the maximum tip speed of the wind turbine generator during operation with the upgraded blades. The maximum rotational speed may be adjusted as follows:

[0020]

[0021] where ω Max Repowered is the maximum rotational speed and Rotor diameter is the rotor diameter, i.e. (2xR + hub diameter). This allows the same generator and (optional) gearbox to be reused, where a longer blade length allows the maximum power to be reached earlier. This is particularly important when the used wind turbine is an intermediate or advanced wind turbine located at a low wind site or a medium wind site. Reaching the maximum power earlier can here allow more energy to be generated, especially at low wind speeds where the energy value may be higher.

[0022] In another example, the maximum hub angular rotational speed of the wind turbine generator during operation with the used blades is the same as the maximum hub angular rotational speed of the wind turbine generator during operation with the upgraded blades. This situation typically requires replacing / upgrading the generator (and optional gearbox) because a higher maximum power is reached. Typically, higher tip speeds will result in increased noise levels and may result in higher blade wear. However, more energy can be generated. In order to ensure that the wear of the components of the upgraded wind turbine is limited to an acceptable level, it is preferred that one or more components of the drive train are replaced during the upgrade using this option. Typically, the drive train components replaced are one or more of the gears, generators and / or converters.

[0023] In one example, the upgrading method comprises the step of installing updated control software adapted to control the linear actuator and thereby the tension in the blade connection member. The adjustment of the tension may be substantially static, e.g. infrequently over a longer period of operation, even only once, or it may be frequent, or even dynamic, where it is adjusted during each revolution or at least several times per operating hour.

[0024] Another aspect of the present invention relates to the use of an upgraded blade for upgrading a horizontal axis wind turbine, the horizontal axis wind turbine comprising a tower, a nacelle rotatably located at a top end of the tower, and a rotor having a central hub, the central hub being adapted to receive at least three used blades mounted to the hub in a variable pitch manner. The upgraded blade extends between a root and an end, and comprises a connection point, wherein the connection point is located between the root and the end. The connection point is used to connect a blade connection member to the blade. In some examples, the connection point is preferably 2022P00050WOCN(JPHEN)

[0025] The connection point may be located between 25% and 60% of the total blade length from the blade root. In a preferred example, the connection point may be located between 40% and 50% of the total blade length from the blade root. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Examples of the present invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0027] Figure 1 is a schematic perspective view of a horizontal axis wind turbine including used blades;

[0028] Figure 2 is a schematic perspective view of a horizontal axis wind turbine including upgraded blades, blade connection members and a tensioning system; and

[0029] Figure 3 Used blades and upcycled blades are schematically shown. DETAILED DESCRIPTION

[0030] Figure 1 A horizontal axis wind turbine 10 is shown, which includes a tower 12 and a nacelle 14 rotatably mounted on the tower 12. A rotor 16 has a hub 18 and used blades 20 that are pitchably connected to the hub 18. Each blade has a root 22 connected to the hub 18 and an end 24 that extends away from the hub 18.

[0031] Figure 2 The used blade 20 (see Figure 1 ) is replaced with an upgraded blade 21 and a horizontal axis wind turbine 10 after further required components are added. Specifically, Figure 2 The wind turbine 10 in the embodiment includes a tower 12 and a nacelle 14 rotatably mounted on the tower 12. The rotor 16 has a hub 18 and upgraded blades 21 connected to the hub 18 in a pitchable manner. Each blade has a root 22 connected to the hub 18 and an end 24 extending away from the hub 18. In addition, each blade 21 has a connection point 26 for receiving a blade connection member 28. Preferably (as shown), the connection point 26 can receive two blade connection members 28 - one for each adjacent blade 21, but in some cases (not shown), the blade 21 includes two connection points 26, which are arranged at the same or similar distance from the blade root 22, and each connection point can receive one blade connection member 28 from one of the adjacent blades 21.

[0032] The wind turbine further comprises a tensioning system 32 arranged with the hub 18, e.g. integrated with the hub 18 or arranged as an extension of the hub 18. The tensioning system 32 is adapted to adjust the tension in the blade connection member 28, e.g. by pulling a portion of the connection member towards the hub via a linear actuator 34, optionally via a tensioning force member 36.

[0033] exist Figure 3 In FIG. 2 , a comparison between a used blade 20 and an upgraded blade 21 is shown. Main 2022P00050WOCN (JPHEN)

[0034] The difference lies in the length, where the length of the upgraded blade is R repower Than the length of the used blade R used Furthermore, the upcycled blade 21 comprises a connection point 26 for receiving a blade connection member 28 .

[0035] Due to the advantages of the reinforcement of the upgraded blade 21 by the blade connection member 28 in terms of flapping loads and edgewise loads during use, the strength requirements of the upgraded blade 21 are reduced, so the upgraded blade 21 can be thinner, lighter and / or have a better aerodynamic profile, especially for the section of the blade located between the blade root and the connection point 26.

[0036] The upcycled blade 21 may be a split blade. In particular, the upcycled blade may comprise an end component and a root component connected by a blade connection, the blade connection preferably comprising a connection point.

Claims

1. A method for upgrading a horizontal axis wind turbine (10), the horizontal axis wind turbine comprising a tower (12), a nacelle (14) rotatably located at a top end of the tower (12), and a rotor (16), the rotor (16) having a hub (18) and at least three used blades (20), the at least three used blades (20) being variably mounted to the hub (18) and extending radially therefrom, the method comprising the following steps: - removing the at least three used blades (20) from the hub (18), - installing at least three upgraded blades (21) on the hub (18), Each upcycled blade (21) extends between a root portion (22) and an end portion (24), and each upcycled blade (21) further comprises a connection point (26) located between the root portion (22) and the end portion (24), - installing a plurality of blade connection members (28), each blade connection member (28) being connected between corresponding connection points (26) of a pair of upgraded blades (21); as well as - Mounting a tensioning system (32) with the hub (18), the tensioning system (32) being configured to adjust the tension in each blade connection member (28).

2. The method according to claim 1, wherein: The used blade (20) is a conventional wind turbine blade which is supported only at the blade root (22) during operation of the wind turbine (10).

3. The method according to claim 1 or 2, wherein: The tensioning system (32) includes a plurality of linear actuators (34), each linear actuator (34) being coupled between the hub (18) and a blade connection member (28), optionally via a tensioning force member (36).

4. A method according to any one of the preceding claims, wherein: The upgraded blade (21) is mounted on the hub (18) via a conical adjustment member arranged between the blade root (22) and the hub (18).

5. A method according to any one of the preceding claims, wherein: The tensioning system (32) 2022P00050WOCN (JPHEN) Being a separate unit attached near the front of the wheel hub, the tensioning system (32) includes a separate system for powering the linear actuator (34).

6. The method according to any one of claims 1 to 4, wherein: The tensioning system (32) includes a system for powering the linear actuator (34) that is integrated with the blade pitch system of the hub (18) via a shared system for powering the linear actuator (34).

7. The method according to any one of the preceding claims, further comprising the steps of: - removing the hub (18) from the nacelle (14); - installing the tensioning system (32) with the hub (18) remote from the nacelle (14); as well as - Mounting the hub (18) with the tensioning system (32) on the nacelle (14).

8. The method according to any of the preceding claims, further comprising the step of replacing a component of the wind turbine selected from the group consisting of a main bearing, a gearbox, a generator, a blade bearing, a pitch system component, a yaw system component, a main shaft and a bed frame.

9. A method according to any one of the preceding claims, wherein: The upcycled blade (21) is at least 15% longer than the used blade (20), preferably, the upcycled blade (21) is at least 20% longer than the used blade (20).

10. A method of operating a wind turbine (11) upgraded according to any one of claims 1 to 9, wherein: The maximum tip speed of the wind turbine generator (10) during operation with the used blades (20) is the same as the maximum tip speed of the wind turbine generator (11) during operation with the upgraded blades (21).

11. A method of operating a wind turbine (11) upgraded according to any one of claims 1 to 9, wherein: The maximum hub angle rotation speed of the wind turbine generator (10) with the used blades (20) during operation is 2022P00050WOCN (JPHEN) and the maximum hub angle rotation speed of the wind turbine generator (11) with the upgraded blades (21) during operation is the same.

12. The method according to any one of claims 1 to 9, further comprising the step of installing updated control software suitable for controlling the linear actuator (34).

13. The method according to claim 12, wherein: The updated control software is further adapted to implement the method of claim 10 or claim 11 .

14. Use of an upcycling blade (21) for upcycling a horizontal axis wind turbine (10), the upcycling blade (21) extending between a root (22) and an end (24) and comprising a connection point (26) located between the root (22) and the end (24), the horizontal axis wind turbine (10) comprising a tower (12), a nacelle (14) rotatably located at the top end of the tower (12) and a rotor (16) having a central hub (18), the central hub (18) being adapted to receive at least three used blades (2) mounted variably to the hub (18).

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