Wind Turbine Lightning Current Transfer Unit with Segmented Contacts
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Solution Overview
Problem
Existing lightning current transfer units for wind turbines face issues with contacts bouncing off their surfaces due to imperfections, leading to sparks and electromagnetic interference, and suffer from high wear and inefficient discharge of lightning and static charges.
Innovation Solution
A lightning current transfer unit with a primary and secondary contact system, where the secondary contact moves relative to the primary contact and is biased by a secondary spring, ensuring continuous electrical connection and reducing wear, and a discharge cable with a high cross-sectional area to handle lightning currents efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single contact system is used, then the device complexity is reduced, but the reliability of electrical connection deteriorates due to contacts bouncing off imperfect surfaces
Solution Approach 1:
The contact system is divided into a primary contact and a secondary contact, each serving distinct functions. The primary contact handles high-current lightning discharge while the secondary contact ensures continuous electrical connection by compensating for surface imperfections and bounce, thereby resolving the contradiction between simplicity and reliability.
Solution Approach 2:
The secondary contact is designed to move relative to the primary contact and is biased by a secondary spring to maintain constant pressure against the contact surface. This excessive action of continuous pressure compensation ensures reliable connection even when the primary contact bounces, resolving the reliability issue without significantly increasing overall system complexity.
2Reliability
If the primary contact is biased strongly towards the slideway, then the electrical connection reliability is improved, but the wear of the contact increases
Solution Approach 1:
The contact system is segmented into primary and secondary contacts with different functions. The primary contact uses a main spring biased towards the slideway to ensure reliable electrical connection during normal operation, while the secondary contact with a secondary spring compensates for bounce and surface imperfections, distributing the wear and extending service life.
Solution Approach 2:
The secondary contact is designed to move relative to the primary contact and is biased by a secondary spring to maintain constant pressure against the contact surface. This partial action of the secondary contact compensating for bounce reduces the wear on the primary contact while maintaining reliable electrical connection.
3Reliability
If the secondary contact is made to move relative to the primary contact, then the reliability of electrical connection is improved by compensating for bounce, but the device complexity increases
Solution Approach 1:
The contact mechanism is segmented into a primary contact assembly and a secondary contact assembly, each with its own spring biasing system. This segmentation allows the secondary contact to independently move and compensate for bounce while maintaining a relatively simple overall structure that can be manufactured and maintained with standard engineering practices.
4Productivity
If a discharge cable with high cross-sectional area is used, then the efficiency of lightning current discharge is improved, but the weight of the cable increases
Solution Approach 1:
The discharge cable is designed with a high cross-sectional area to handle the high current density of lightning strikes efficiently. This parameter change in cable geometry optimizes the electrical performance for lightning protection while the weight increase is accepted as a necessary trade-off for safety and reliability in this critical application.
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
The solution provides a reliable and efficient discharge of lightning and static charges, reducing the likelihood of sparks and electromagnetic interference while extending the service life of the contacts by maintaining a continuous electrical connection and limiting high current through the secondary contacts.
Implementation Method 1
a first main spring biasing the first slider towards the first slideway
Implementation Method 2
a secondary spring arranged between the first main spring and the secondary contact such that the secondary spring biases the primary contact away from the first slideway and biases the secondary contact towards the first slideway
Implementation Method 3
the lightning current is transferred to the main shaft 10 of the wind turbine through a pitch bearing 13 or any other mechanism between the blade and the shaft
Data Source
AI summary
A lightning current transfer unit for a wind turbine, the wind turbine comprising a first part and a second part being rotatable relative to each other, wherein the lightning current transfer unit is arranged to provide electrical contact between the first and second parts, the lightning current transfer unit comprising: a first current transfer portion comprising a first slider and configured to be electrically coupled to a first electrically conducting slideway of the first part of the wind turbine, the first slider being rotatable relative to the first slideway; a second current transfer portion configured to be electrically coupled to an electrically conducting portion of the second part of the wind turbine; a first main spring biasing the first slider towards the first slideway; wherein the first slider comprises: a primary contact biased towards the first slideway by the first main spring; a secondary contact arranged to move relative to the primary contact; and a secondary spring arranged between the first main spring and the secondary contact such that the secondary spring biases the primary contact away from the first slideway and biases the secondary contact towards the first slideway.