Direct-Drive Wind Turbine Lightning Layout to Cut SPD Requirements
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Solution Overview
Problem
Direct drive wind turbines face high requirements for surge protection devices (SPDs) due to the classification of lightning protection zones, leading to increased costs.
Innovation Solution
The lightning protection arrangement includes protection conductors mounted on external surfaces of the electrical generator and hub, reclassifying certain zones as 'zone 2' according to the IEC 61400-24 standard, thereby eliminating the need for additional SPDs at transitions between zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protection conductors are mounted inside the hollow fixed shaft and annular space, then the lightning protection zones are classified as zone 1 requiring SPDs, but this increases the requirements and costs for surge protection devices
Solution Approach 1:
The protection conductor is moved from an internal position (inside the hollow fixed shaft and annular space) to an external position (mounted on the external surface of the rotor house). This spatial repositioning changes the classification of the internal zones from zone 1 to zone 2, thereby reducing SPD requirements while maintaining protection effectiveness.
2Device complexity
If protection conductors are mounted on external surfaces of the electrical generator and hub, then the zones can be classified as zone 2 eliminating SPD requirements, but this requires modification of the external structure
Solution Approach 1:
The external surface of the rotor house is utilized as a mounting surface for the protection conductor, serving both as a structural component and as a platform for lightning protection. This multi-functional use of the external surface avoids additional structural modifications while achieving the desired zone classification.
3Reliability
If multiple protection conductors are installed to cover all zones, then comprehensive lightning protection is achieved, but this increases the quantity of conductors and installation complexity
Solution Approach 1:
The protection conductor is extracted from the internal configuration (where multiple conductors would be needed to cover different zones) and repositioned to an external location on the rotor house. This single external conductor is sufficient to achieve zone 2 classification for both the hollow fixed shaft and annular space, reducing the total quantity of conductors required.
Data Source
AI summary
Provided is a direct drive wind turbine that includes: a hub, at least one blade fixed to the hub, a nacelle on which the hub is rotatably mounted for rotating about a rotational axis, the nacelle including an electrical generator connected to the hub in order to receive rotational energy from the hub, a tower on which the nacelle is mounted, and a lightning protection arrangement including a plurality of protection conductors extending between the at least one blade and the tower, the plurality of protection conductors including at least a first protection conductor mounted on an external surface of the electrical generator.