Method for assembling blades and counterweights

Abstract

The present invention relates to a method for assembling blades and counterweights on a direct drive wind turbine, characterised in that both the blades (3) and the counterweights, either passive (4) or active (5), are vertically lifted and lowered from the ground to the bushing (2) by means of cables (5) that are controlled by a lifting and lowering mechanism provided inside the bushing (2). The invention is also characterised in that the assembly method is combined with a wind turbine self-hoisting system. Firstly, prior to hoisting the assembly, a tower segment (1), a nacelle, a rotor (2) and the counterweights (4,9) are mounted and then new tower segments are introduced through the bottom portion, to finish mounting the blades (3) in three consecutive steps.

Description

[0001] METHOD OF ASSEMBLING BLADES AND COUNTERWEIGHTS

[0002] DESCRIPTION OF THE INVENTION

[0003] The present invention describes a method of assembling wind turbine blades without the use of cranes and counterweights used to keep the rotor balanced during assembly.

[0004] Background

[0005] The assembly of a wind turbine begins with the tower, followed by the addition of the nacelle and hub, and finally the blades. As the blades are assembled one by one, an imbalance is created in the rotor assembly consisting of the hub and blades. Counterweights are used to counteract this imbalance, and the hub is rotated to position successive blades with the help of an auxiliary crane.

[0006] The known state of the art protects various solutions for the use of counterweights. Patent W003012291A1 mounts three counterweights on the hub, locking one of the counterweights in a lateral position. The counterweight is removed, and the first blade is installed. The hub is rotated until another counterweight is in a lateral position, and it is again replaced with a blade. The assembly is completed with the same procedure. The counterweight is made up of different masses that can be added or removed so that the combined torque acting on the rotor is always zero.

[0007] Patent WO2014076825A1 first assembles a counterweight and a blade. The counterweight is articulated, and by moving its mass and rotating the rotor, the CG of the counterweight is adjusted in the circumferential direction of the rotor. The second blade is then coupled. The counterweight has a mass inside that can be moved, and it also has a hydraulic system for articulation.

[0008] Counterweights continue to evolve over time. In US2016090962A1, the counterweight has a double joint and hinge elements capable of being locked in any position. Furthermore, the beam supporting the counterweight is extendable. In US2019085818A1, the counterweight is filled with a fluid or solid mass using a pumping system. The beam supporting the counterweight is telescopic. In CN114321276A, the counterweight is a cylinder with a liquid storage tank adjustable by a sliding trapdoor.

[0009] 1

[0010] REPLACEMENT SHEET (RULE 26) counterweight pivots through an axis that connects the hub with the adjustable tank.

[0011] What is common to blade assembly with counterweights is that the blades are mounted horizontally using an auxiliary crane. This is the case in patent US2020072187A1, where the active counterweight is articulated with a pivoting mechanism connected to the hub's drive and braking mechanisms, allowing the three blades to be mounted horizontally. This is also the case in patent EP3805553A1, where the counterweight is an articulated joint that, with the help of an auxiliary crane, moves the rotor to the position that allows a blade to be attached horizontally.

[0012] The use of counterweights for blade assembly is limited to lifting methods that use an auxiliary crane to lift the blade horizontally and assemble it onto the hub.

[0013] The lifting of blades on wind turbines that cannot rotate their rotors during blade assembly (all direct-drive wind turbines) and where large cranes cannot or are not desired to be used for blade assembly is an unsolved problem.

[0014] Description

[0015] The object of the invention is the development of a method that allows the installation of the blades of a "direct drive" wind turbine using counterweights and also using a blade raising and lowering system located inside the hub.

[0016] To do this, both the counterweights and the blades are placed on the ground next to the wind turbine tower. Using the lifting system inside the hub and cables passing through the hole where the blade root is anchored, the counterweights and blades are hoisted. Each time an element is hoisted, the hub is rotated so that a new blade hole is correctly oriented in the lower horizontal position for the next hoist.

[0017] First, the counterweights, consisting of a steel support and a concrete block, are raised. Then the blades are raised, and as the second and third blades are raised, their corresponding counterweights are lowered.

[0018] Active counterweights can also be used, which change the rotor's CG thanks to their articulated structure. Counterweights whose mass is formed by a reservoir that can be filled with liquid can also be used to vary the rotor's balance. The use of these active counterweights can reduce the number of counterweights and the number of steps required for blade assembly.

[0019] All lifts are performed vertically and without the use of large external cranes.

[0020] This method has the following advantages:

[0021] 2

[0022] REPLACEMENT SHEET (RULE 26) - Assembly with wind speeds of up to 15 m / s, compared to the limitations of 7-9 m / s for the assembly of complete rotors in this type of “direct drive” wind turbines.

[0023] - Reduction of costs in cranes and auxiliary elements.

[0024] Brief description of the drawings

[0025] A very brief description follows of a series of drawings intended to assist in a better understanding of the invention and which are expressly related to an embodiment of said invention, presented as a non-limiting example. Figure 1 shows the assembly steps using two passive counterweights.

[0026] Figure 2 shows a schematic of a passive counterweight.

[0027] Figure 3 shows the assembly stages using a single active counterweight.

[0028] Figure 4 shows a practical implementation with passive counterweights mounted on the ground before authorizing the wind turbine.

[0029] Figure 5 shows another practical implementation with an active counterweight mounted on the ground before authorizing the wind turbine.

[0030] Detailed description

[0031] As shown in Figure 1, the wind turbine consists of a tower (1), a nacelle and a hub (2) where the assembly must be completed by adding the blades (3). The blades (3) are mounted one by one and due to their weight, an imbalance is created in the hub (2) when the rotor rotates. To counteract this imbalance, counterweights (4) are used during assembly and, in turn, the hub (2) is rotated to place the successive blades (3). All the elements mentioned are located on the ground, close to the tower (1).

[0032] The steps followed during the assembly method are as follows:

[0033] - A blade raising / lowering system with hoists and cables is installed inside the hub (2).

[0034] - The raising / lowering system inside the hub raises the first counterweight (4) which is fixed in the hub (2) in a position of 180 e .

[0035] - The hub (2) is turned using the wind turbine generator or special tools installed on the wind turbine shaft for this purpose, until the counterweight (4) is positioned at 300 e and is fixed through the rotor locking system that all wind turbines have.

[0036] - With the lifting system, the second counterweight is raised, leaving it fixed in a position of 180 e and the hub (2) is turned another 120 e leaving the hub gap

[0037] 3

[0038] REPLACEMENT SHEET (RULE 26) (2) in the lower horizontal position.

[0039] - The ascent / descent system has cables (5) that are anchored to the root of the blade and raise it vertically.

[0040] - Once the first blade (3) is fixed, the hub is turned 120 eand the first counterweight (4) is lowered using the ascent / descent system, leaving the hub cavity where said counterweight (4) was fixed in the lower horizontal position. The second blade (3) is raised and fixed to the rotor.

[0041] - The process of rotating the hub, lowering the counterweight, and raising the third blade is repeated, thus completing the blade assembly method in three consecutive steps.

[0042] Figure 2 shows a design of the counterweight (4) formed by a metal support (6) that has two ends: one of the ends with anchoring means (7) to be fixed to the hub and the opposite end with a mass (8), preferably concrete, in the form of a block.

[0043] As shown in Figure 3, there is another practical embodiment in which the two passive counterweights (4) are replaced by a single active counterweight (9). This counterweight consists of a metal mechanism (6) with a joint (10) and an active element that allows this joint to move during assembly to balance the rotor's center of gravity. The process used with this counterweight is as follows:

[0044] - The lifting system inside the hub raises the first active counterweight (9) which is fixed in the hub (2) in a position of 180 e .

[0045] - The counterweight (9) is moved by means of its joint (10) and the hub (2) is turned using the wind turbine generator or special tools installed on the wind turbine shaft for this purpose, until the counterweight (9) is positioned at 300 e and is fixed through the rotor locking system that all wind turbines have.

[0046] - With the ascent system the first blade (3) is raised, the hub (2) is turned 120 e and the second blade is raised (3).

[0047] - The active counterweight (9) returns to its original, completely straight position. The hub is turned 120°. e and the counterweight (9) is lowered, raising the last blade (3).

[0048] In another embodiment, the mass (8) of the counterweights (4,9) is formed by a refillable tank with the introduction of fluid or with the addition of portions of solid mass, ensuring the variation of the balancing of the rotor as desired.

[0049] Figures 4 and 5 show an assembly process where a system of

[0050] 4

[0051] REPLACEMENT SHEET (RULE 26) authorized to raise the first tower section (1), the nacelle and the hub (2) and gradually introduce new tower sections from below until the final tower is completed. As shown in Figure 4, the two passive counterweights (4) are mounted with a small auxiliary crane at the same time as the first tower section (1), the nacelle and the hub (2). These counterweights (4) do not interfere with the auto-hoisting system that borders the initial assembly and the assembly thus formed is raised and new tower sections (1) are introduced from below.

[0052] As shown in Figure 5, the active counterweight (9) is mounted and rotated at the same time as the first tower section (1), the nacelle and the hub (2). Said counterweight (9) does not interfere with the auto-lifting system and the assembly thus formed is raised and new tower sections (1) are introduced from below.

[0053] Once the assembly of the wind turbine has been completed, the blades (3) are lifted as explained in figures 1 and 3.

[0054] REPLACEMENT SHEET (RULE 26)

Claims

CLAIMS 1 - Method of assembling blades and counterweights in the hub (2) of a wind turbine that is supported on a tower (1) or a first section of tower (1), which mounts inside an ascent / descent system, with rotation means and with a rotor locking system, characterized in that: - Before starting the installation of the blades (3), at least one counterweight (4,9) is installed, which allows the rotor to be balanced during the following assembly phases, - the blades (3) are installed from the ground and vertically with the cables (5) of the ascent system passing through the gaps in the blade root, completing the assembly in three consecutive steps, - each time a blade (3) is installed, the bushing (2) is turned 120 e using the wind turbine generator or special equipment installed on the wind turbine shaft, and is secured by the rotor locking system, - when the counterweight (4.9) is positioned at 180 e , it is lowered in a vertical position with the cables (5) of the descent system before raising the new blade (3) with the same system in ascent mode. 2- Method of assembling blades and counterweights according to the first claim, characterized in that the counterweights (4) used are two: the first one is installed, the hub (2) is turned 120 e and the second one is installed, the bushing is turned again 120 e and it starts with the blades (3), both counterweights are formed by a metal support (6) that has two ends: one with anchoring means (7) to be fixed to the hub (2) and the opposite end with a mass (8) in the form of a block. 3- Method of assembling blades and counterweights according to the first claim, characterized in that the counterweight (9) used is one, and is formed by a metallic mechanism (6) with an articulation (10) and an active element that allows this articulation to be moved during assembly to balance the center of gravity of the rotor, and that has two ends: one with anchoring means (7) to be fixed to the hub (2) and the opposite end with a mass (8) in the form of a block, once the counterweight (9) is assembled it is articulated and rotated 120 e to begin assembling the blades (3). 6 REPLACEMENT SHEET (RULE 26) 4- Method of assembling blades and counterweights according to the previous claims, where the mass (8) is formed by a tank that can be filled with liquid to vary the balancing of the rotor. 5- Method of assembling blades and counterweights according to any of the previous claims, characterized in that the mentioned counterweights are mounted with an auxiliary crane during the assembly of the first tower section (1), the nacelle and the hub (2), in the following stage an auto-lifting system is added around it that does not interfere with said counterweights (4,9) and the assembly is hoisted and new tower sections are introduced from the bottom, finally the hub (2) is rotated and the blades (3) are added in three consecutive steps. REPLACEMENT SHEET (RULE 26)

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