Wind Turbine Blade Lifting via Nacelle Winch and Tag Lines
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Solution Overview
Problem
Existing systems for raising and lowering wind turbine blades for maintenance are inefficient due to high stress on blades, require smooth terrain, and are limited by wind interference, making them unsuitable for areas with rough terrain or high winds.
Innovation Solution
A system utilizing a winch located in the nacelle with a cable and lifting yoke, combined with tag lines controlled by personnel to stabilize the blade during lifting and lowering, allowing for safe operation in various terrains and wind conditions, using a pick crane and flatbed cradle for horizontal orientation and placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rigid yoke with jaw-like structure is used to grip the blade, then the blade can be raised and lowered, but extreme pressure point stresses are placed on the blade and a smooth flat area is required for crane support
Solution Approach 1:
The patent replaces the rigid yoke with a flexible cable system that wraps around the blade. The cable distributes load across the blade surface rather than concentrating stress at jaw contact points, eliminating the need for smooth flat support areas and protecting the blade from damage.
Solution Approach 2:
The patent introduces a cable as an intermediary between the winch and the blade, replacing the direct rigid mechanical connection of the yoke. This cable intermediary allows for flexible, distributed load application that protects the blade while achieving the same lifting function.
2Ease of operation
If a crane is used to hoist the blade, then the blade can be raised and lowered, but large cranes require smooth flat terrain which is not available in many wind turbine locations
Solution Approach 1:
The patent replaces the complex mechanical system of a large crane with a simpler winch and cable system. The winch can be positioned on the nacelle or ground and uses cable tension to lift the blade, eliminating the need for large crane equipment and smooth flat terrain.
Solution Approach 2:
The patent changes the lifting approach from ground-based crane operation to a system where the winch can be mounted in the nacelle, utilizing the vertical dimension and existing tower structure rather than requiring horizontal ground space and smooth terrain.
3Device complexity
If tag lines are not used during hoisting, then the system is simpler, but the blade may twist or rotate during lifting in windy conditions
Solution Approach 1:
The patent uses tag lines as intermediary control elements that connect the blade to the ground or support structure. These lines act as stabilizing mediators that prevent blade rotation and twisting during lifting without adding complex active control systems.
Solution Approach 2:
The tag lines provide preliminary anti-action against wind-induced blade rotation and twisting before the lifting operation completes. By pre-positioning these constraint lines, the system prevents instability rather than correcting it during the lifting process.
4Device complexity
If the blade is raised without tag lines to prevent twisting, then the system is simpler, but the blade may be blown against the tower in higher winds
Solution Approach 1:
The tag lines serve as intermediary elements that buffer the blade against wind forces. They provide a controlled connection that allows the blade to be stabilized against wind-induced movement without requiring complex active control systems or additional heavy equipment.
Solution Approach 2:
The tag lines provide beforehand cushioning against wind forces by being pre-positioned to constrain the blade. This passive protection system is in place before wind interference occurs, preventing the blade from being blown against the tower without requiring complex real-time control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables safe and efficient lowering and raising of blades up to 1900 kg without causing damage, suitable for all terrains and wind speeds up to 12 m/sec, reducing the need for large cranes and ensuring the blade is not twisted or knocked against the tower.
Implementation Method 1
A cable extends downward from the winch to the blade root where it may be secured to a load cell. The winch raises or lowers the blade by means of a lifting yoke
Implementation Method 2
The use of two cables, one at either side of the blade, provides some protection against the blade's becoming twisted in light winds during hoisting. However, without having taglines to brace the blade against twisting in higher winds
Implementation Method 3
Tag lines between the yoke and the crane are used to turn or otherwise position or manipulate the blade during raising or lowering
Data Source
AI summary
A method of lowering a wind turbine blade after removal from a wind turbine lowers the blade in a vertical position to a point near the ground, and rotates it to a horizontal position for emplacement on a cradle. A winch is situated in the nacelle of the wind turbine. A cable extends downward from the winch to the blade root where it may be secured to a load cell. A tip end shoe is placed around the lower portion of the blade, and includes a crane hook receiving component that is used when the blade orientation is being changed. Tag lines are attached to the root and the tip end shoe, and extend to points on the ground where technicians manipulate them to prevent the blade from being blown into the tower.