Wind Turbine Lightning Current Transfer Unit with Spark Gap

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Solution Overview

Problem

Existing lightning current transfer units in wind turbines face issues with damage from high energy lightning currents and inefficiencies in the slip ring arrangement, and they do not provide adequate electromagnetic compatibility (EMC) with other components.

Innovation Solution

A lightning current transfer unit that incorporates a spark gap between moveable electrical connections to the blade and nacelle, maintaining a constant spark gap distance to ensure reliable lightning current transfer while allowing for movement and reducing the risk of damage from lightning strikes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a slip ring arrangement is used to transfer lightning current from the blade to the nacelle, then electrical connection is maintained, but the arrangement is inefficient and vulnerable to damage from high energy lightning current

Engineering Contradiction:

Improvelightning current transfer reliabilityVSAvoiddamage from lightning current

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful sliding contact interface from the lightning current path by introducing a spark gap. The spark gap isolates the blade and nacelle electrical systems while still allowing lightning current transfer through controlled electrical breakdown, eliminating wear and damage issues associated with continuous sliding contacts.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the electrical parameter state by introducing a controlled air gap that transitions from insulating to conductive during lightning strikes. The spark gap distance is optimized to break down under lightning current conditions while maintaining insulation during normal operation, transforming the connection state dynamically.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a lightning current transfer unit is mounted on the hub and rotates with it, then electrical connection to rotating blades is maintained, but electromagnetic compatibility with other components is not adequate

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidelectromagnetic interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an intermediary spark gap between the rotating blade system and the stationary nacelle. This intermediary allows electrical connection during lightning strikes while blocking continuous electromagnetic interference and radio frequency emissions that would otherwise couple between rotating and stationary components.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If sliding contacts are used to carry current from the shaft to ground, then electrical connection is maintained, but the arrangement is inefficient and prone to damage

Engineering Contradiction:

Improvecurrent transfer capabilityVSAvoidcomponent durability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent removes the vulnerable sliding contact mechanism from the high-current lightning path. Instead, lightning current flows through the spark gap and dedicated down conductors, bypassing the sliding contacts that would otherwise be subjected to high thermal and mechanical stresses.

Inventive Principle:

Principle #2Taking out (Extraction)

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 improved EMC, reduces the risk of damage from lightning strikes, and extends the lifespan of the unit to up to 20 years with easy replaceable components, while being easy to implement on existing wind turbines.

Implementation Method 1

A lightning current transfer portion is provided which comprises a spark gap between an electrical connection to the first portion and an electrical connection to the second portion

Methodology Applied

Scientific EffectSpark gap: Electric Spark

Data Source

PatentEP2859229B1A lightning current transfer unit for a wind turbine

Publication Date: 2019.03.20 VESTAS WIND SYSTEMS AS

Figure 1
Figure 2a~2b
Figure 3a~3b

AI summary

A lightning current transfer unit (100) for a wind turbine, the lightning current transfer unit (100) comprising a first portion (20a) configured to be electrically coupled to an electrically conducting portion of a blade of a wind turbine electrically connected to a down conductor of the blade and a second portion (20b) configured to be electrically coupled to an electrically conducting portion of a nacelle of the wind turbine connected to a down conductor connected to earth. The first portion (20a) and the second portion (20b) are both independently movable to maintain electrical coupling to the electrically conducting portion of the blade and nacelle respectively. A lightning current transfer portion (104) is provided that comprises a spark gap (106) formed between an electrical connection (108) to the first portion (20a) and an electrical connection (110) to the second portion (20b). The electrical connections (108, 110) are moveable with their respective first or second portion (20a, 20b). The spark gap (106) has a spark gap distance (111) and the lightning current transfer portion (104) is configured such that the distance is substantially constant during movement of the first portion (20a), second portion (20b) and electrical connections and such that lightning current is transferred from the first portion (20a) to the second portion (20b).