*Sean Keller urges wind plant operators to have a comprehensive strategy in place to deal with parts failure.*

Like any piece of electro-mechanical equipment, wind turbines will fail at some point. It's not a question of if but when. When parts fail after warranty periods are up, operators face a number of hard decisions. Should they replace the failed part or repair it? Has the part been discontinued or is it difficult to source? Does technical documentation still exist for the part? Why did the part fail? This may require detailed investigation and analysis by experienced engineers and technicians to establish the root cause. Are there performance issues with a particular part?

Operators need to adopt an holistic engineering solution to report failure symptom trends, epidemic failures, third party module issues, and evidence of design quality and reliability issues.

*Parts storage*

Several factors come into play when designing such a solution with the aim of ensuring repairs are carried out swiftly and efficiently. The location, storage and transportation of spare parts is crucial. In many cases, spares are kept close to the windfarm site in temporary buildings, which do not offer the optimal environmental conditions for electro-mechanical parts. As a result, parts can become unusable or need to be repaired or refurbished before they can be installed.

This problem can be avoided if parts are stored centrally under strictly controlled environmental conditions. Sensitive electronics are particularly vulnerable to changes in temperature, humidity, static charges and so forth, so must be stored properly.

*Tracking*

Being able to track spare parts is equally important. An efficient asset management system should be able to provide 24/7 visibility of where a particular part is located, its age and condition. This can not only save valuable time in finding a part but can also highlight any deficiencies in stock, which can then be rectified.

Wind turbine parts generally have a high unit cost, therefore the cost of a replacement part can be as much as three times the cost of repairing an existing part. The cost of ownership can be significantly reduced by careful management of existing parts. If there are performance or reliability issues, detailed testing and analysis of the equipment in a simulated factory test environment can be employed to determine the root cause.

If parts are unavailable, discontinued or difficult to source, it can prove to be a major headache for operators. One operator experienced five months downtime (at an estimated loss of €250,000) due to long lead times on rotor current controller parts.

*Audit trail*

At every stage in the repair or refurbishment process it is crucial that the highest quality assurance standards are adhered to and that a full audit trail can be produced showing the progress of the repair and certifying that the relevant quality standards have been complied with. Wherever possible, once a part becomes defective it should be immediately swapped out for a fully functional part and the defective part repaired so that a stock of good parts is always available. Parts pooling schemes between operators can also help ensure that contingency stocks are kept high.

In this difficult economic climate, wind turbine operators need to exploit all possible opportunities for cutting costs and maximising profits. Having a comprehensive strategy in place to manage parts repair, refurbishment and logistics can make a major contribution to achieving these goals.

Sean Keller is business unit director of DEX Renewables, a renewable energy engineering specialist.