Adjustable Lifting Frame for Wind Turbine Blade Mounting
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Solution Overview
Problem
The existing methods for mounting wind turbine rotor blades to a hub on a nacelle face challenges such as limited ground space, the need for large cranes, and difficulties in rotating large rotor assemblies, especially in seabased environments and gearless direct drive wind turbines, where rotating the rotor hub is complex.
Innovation Solution
The method involves mounting rotor blades to a rotor hub already on the nacelle, keeping the hub in a fixed position and tilting each blade by approximately ±60° for individual mounting, with the third blade mounted horizontally, and using a lifting frame with adjustable tilt wires and a pitch wire to adapt angles without rotating the hub or changing the pitch of the mounting sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rotor blades are mounted to a hub on the ground and then lifted as one piece, then the mounting process is simpler, but the area needed for mounting and the size of crane required increase significantly
Solution Approach 1:
The rotor assembly is segmented into separate components: the hub is mounted to the nacelle first, and then each blade is lifted and mounted individually to the hub. This segmentation eliminates the need for large ground area and small crane, as each blade can be handled separately by smaller lifting equipment.
2Ease of operation
If the assembled rotor is lifted to the nacelle in one piece, then mounting is straightforward, but the rotor must be turned by 90° in mid air which is difficult for large rotors
Solution Approach 1:
Instead of lifting the complete rotor assembly and rotating it in mid-air, the approach is inverted: the hub is first mounted to the nacelle in its final position, and then the blades are individually lifted and attached. This eliminates the complex mid-air rotation operation entirely.
3Area of stationary object
If rotor blades are mounted individually to a hub on the nacelle, then ground space and crane size are reduced, but the hub must be rotated to different positions for each blade which is complex for gearless direct drive wind turbines
Solution Approach 1:
The lifting frame is designed with dynamic, adjustable components including telescopic struts and adjustable tilt wires that can change length and angle. This allows the lifting frame to adapt to different blade positions and orientations without requiring rotation of the hub, making the process suitable for gearless direct drive wind turbines where hub rotation is complex.
4Device complexity
If lifting frames with fixed geometry are used, then the structure is simpler, but they cannot adapt to different blade orientations and require hub rotation
Solution Approach 1:
The lifting frame incorporates dynamic elements including telescopic struts that can extend and retract, and tilt wires with adjustable lengths. These dynamic components enable the lifting frame to adapt to different blade orientations and mounting positions without requiring hub rotation, resolving the contradiction between structural simplicity and adaptability.
Data Source
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AI summary
A method of mounting wind turbine rotor blades (21) to a rotor hub (35) with blade mounting sections (37) while the rotor hub (35) is already mounted to a nacelle located at the top of a wind turbine tower (39) is provided. In this method the rotor hub (35) is kept in a same fixed rotational position for all rotor blades (21) and the rotor blades (21) are tilted by individual tilt angles for mounting them to the mounting sections (37) of the rotor hub (35). In addition, a lifting frame for lifting a wind turbine rotor blade (21) to a rotor hub (35) is provided which allows for performing the method.