A METHOD OF REPOWERING A WIND TURBINE

Abstract

In a first aspect of the present invention there is provided a method of repowering a horizontal-axis wind turbine comprising a tower, a nacelle located rotatably at the apex of the tower, and a rotor having a hub and at least three used blades mounted pitchably to the hub and extending radially therefrom, the method comprising the steps of uninstall the at least three used blades from the hub, install at least three repower blades to the hub, each repower blade extending between a root and a tip, and each repower blade further comprising a connection point located between the root and the tip, install a plurality of blade connecting members, each blade connecting member being connected between corresponding connection points of a pair of repower blades; and install a tensioning system with the hub, the tensioning system being configured to adjust a tension in each blade connecting member.

Claims

1. A method of repowering a horizontal-axis wind turbine comprising a tower, a nacelle located rotatably at the apex of the tower, and a rotor having a hub and at least three used blades mounted pitchably to the hub and extending radially therefrom, the method comprising: uninstall the at least three used blades from the hub, install at least three repower blades to the hub, each repower blade extending between a root and a tip, and each repower blade further comprising a connection point located between the root and the tip, install a plurality of blade connecting members, each blade connecting member being connected between corresponding connection points of a pair of repower blades; and install a tensioning system with the hub, the tensioning system being configured to adjust a tension in each blade connecting member.

2. The method according to claim 1, wherein the used blades are conventional wind turbine blades supported only at the blade root during operation of the wind turbine.

3. The method according to claim 1, wherein the tensioning system comprising a plurality of linear actuators, each linear actuator being coupled between the hub and a blade connecting member, optionally via a tension member.

4. The method according to claim 1, wherein the repower blade is installed to hub via a coning adjustment member arranged between the blade root and the hub.

5. The method according to claim 1, wherein the tensioning system is an independent unit attached near the front of the hub, the tensioning system comprising a separate system for powering the linear actuators.

6. The method according to claim to 4, wherein the tensioning system comprises a system for powering the linear actuators which is integrated with a blade pitch system of the hub by a shared system for powering the linear actuators.

7. The method according to claim 1 further comprising: deinstall the hub from nacelle, install the tensioning system with the hub away from the nacelle, and install the hub with tensioning system to the nacelle.

8. The method according to claim 1 further comprising replacing a component of the wind turbine selected from a group of main bearing, a gearbox, a generator, a blade bearing, a pitch system component, a yaw system component, a main shaft, and a base frame.

9. The method according to claim 1 wherein the repower blades are at least 15% longer than the used blades, preferably the repower blades are at least 20% longer than the used blade.

10. The method of operating a wind turbine repowered according to claim 1, wherein the maximum tip speed during operation of the wind turbine generator with used blades is the same as the maximum tip speed during operation of the wind turbine generator with the repower blades.

11. The method of operating a wind turbine repowered according to claim 1, wherein the maximum hub angular rotation speed during operation of the wind turbine generator with used blades is the same as the maximum hub angular rotation speed during operation of the wind turbine generator with the repower blades.

12. The method according to claim 1 further comprising installing an updated control software adapted to control the linear actuators.

13. The method according to claim 12 wherein the updated control software is further adapted to implement the method.

14. (canceled) Please add the following new claims:

15. A horizontal-axis wind turbine, comprising: a tower; a nacelle disposed rotatably at the apex of the tower; and a rotor having a central hub adapted for receiving at least three used blades mounted pitchably to the hub; and a repower blade configured for repowering the wind turbine, the repower blade extending between a root and a tip, and comprising a connection point located between the root and the tip.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Examples of the present invention will now be described by way of non-limiting example only, with reference to the accompanying figures, in which:

[0023] FIG. 1 is a schematic perspective view of a horizontal axis wind turbine comprising used blades;

[0024] FIG. 2 is a schematic perspective view of a horizontal axis wind turbine comprising repower blades, blade connecting members and tensioning system; and

[0025] FIG. 3 schematically shows a used blade and a repower blade.

DETAILED DESCRIPTION

[0026] FIG. 1 shows a horizontal-axis wind turbine 10 comprising a tower 12 and a nacelle 14 mounted rotatably on the tower 12. A rotor 16 with a hub 18 and used blades 20 connected pitchable to the hub 18. Each blade has a root 22 connected to the hub 18 and a tip 24 extending away from the hub 18.

[0027] FIG. 2 shows a horizontal-axis wind turbine 10 after replacement of the used blades 20 (see FIG. 1) with repower blades 21 and adding the further required components. Particularly, the wind turbine 10 of FIG. 2 comprises a tower 12 and a nacelle 14 mounted rotatably on the tower 12. A rotor 16 with a hub 18 and repower blades 21 connected pitchable to the hub 18. Each blade has a root 22 connected to the hub 18 and a tip 24 extending away from the hub 18. Furthermore, each blade 21 has a connection point 26 for receiving a blade connecting member 28. Preferably (as shown), the connecting point 26 may receive two blade connecting members 28one for each neighbouring blade 21, but in some cases (not shown) the blade 21 comprises two connecting points 26 arranged with same or similar distance from the blade root 22 and each the connecting point may receive one blade connecting member 28 from one of the neighbouring blades 21.

[0028] The wind turbine also comprises a tensioning system 32 arrange with the hub 18, e.g. integrated with the hub 18 or arranged as an extension to the hub 18. The tensioning system 32 is adapted to adjust the tension in the blade connecting members 28 for example by pulling a part of the connection member toward the hub by linear actuators 34 optionally via a tension member 36.

[0029] In FIG. 3, a comparison between the used blade 20 and the repower blade 21 is shown. The main differences being the length, where the length of the repower blade R.sub.repower is much longer that the length of the used blade R.sub.used. Furthermore, the repower blade 21 comprises a connecting point 26 for receiving a blade connecting member 28.

[0030] Due to the advantages of the reinforcement of the repower blade 21 by the blade connecting members 28 during use both with respect to flapwise loads and edgewise loads the repower blade 21 has reduced strength requirement and hence may be more slim, more light weight and/or have a better aerodynamic profile particularly for section of the blade between the blade root and the connection point 26.

[0031] The repower blade 21 may be a split blade. Particularly, the repower blade may comprise a root part and a tip part connected with a blade connection element, which preferably comprises the connection point.