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Delegates are invited to meet and discuss with the poster presenters during the poster presentation sessions between 10:30-11:30 and 16:00-17:00 on Thursday, 19 November 2015.

Lead Session Chair:
Stephan Barth, ForWind - Center for Wind Energy Research, Germany
Frank van Egmond MECAL, The Netherlands
Co-authors:
Frank van Egmond (1) F Ferdy Hengeveld (1)
(1) MECAL, Enschede, The Netherlands

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Mr van Egmond is active as a project manager in the wind industry for more than 6 years. His experience covers the design of large offshore wind turbines as well as improvement of existing wind farms, for manufacturers and owners all over the world. Recently, his work focusses more on the topic of life time extension of wind farms


Poster

Poster Download poster (11.18 MB)

Abstract

Challenges and solutions in extending the life time of wind farms

Introduction

More and more on-shore wind plants are reaching their technical end of life. Replacement of old turbines with new, bigger ones (repowering) is difficult because of permitting restrictions in height and size and public acceptance. Therefore there is a desire to keep wind farms in operation for as long as possible after 20 years.

How to decide whether it is suitable/possible to extend the lifetime of your assets? A prescribed approach is not yet captured in norms or standards. However an approach that covers the variety of possible situations is possible, balancing between practical feasibility and limitation of risk. This research discusses the challenges concerning life time extension of wind farms and presents an example of this approach.


Approach

The following influences the decision on life time extension:
• Economics (maintenance, subsidies, revenue, efficiency, etc.)
• Politics (permits, subsidies, environmental aspects, public opinion)
• Technical (health and safety, structure failure)

On technical level, three aspects are important to determine the potential extension of service life:
1. The design of the turbine and wind farm
2. The historical environmental conditions of the wind farm
3. The status of the turbine

Bottom line is: How can the wind farm economically continue to operate without the risk of causing (fatal) injuries caused by structure failure.


Main body of abstract

Turbine design
One should know/analyse the design to begin with. The purpose of this research is to define the baseline potential, to which the actual situation can be hold against.
In the ideal world, the design loads, controller behaviour and design margin in strength is known. In real life (part of) this information is usually missing. Therefore, doing a lifetime extension analyses only based on desk research is usually not sufficient.

Actual situation
The next step is the analyses of the SCADA and maintenance. This gives an insight of the actual situation that was exposed to the turbine (plant). Often maintenance logs and SCADA are not complete or not very comprehensive (especially for the older plants). Making use of information from the same turbines on different plants can be of help.

Status
After the desk research, one should have an idea of the potential margin in lifetime, but also on the risks involved. The input for these inspections are the findings from the desk research. Inspecting a turbine in terms of life time extension focusses on safety and the findings from the desk research are used as guideline.

The outcome and accuracy of a lifetime extension analysis can and will differ per situation. The more data available, the more accurate the analysis. In general it is not uncommon that measures (in terms of maintenance, monitoring etc.) are advised. Whether this measures are worth taking is then again an economical choice.


Conclusion

In order to check the feasibility of wind farm life time extension, all aspects (economics, political and technical) must be accounted for. On technical level a combination of field inspections, desk research and advanced understanding of the technology is required to ensure a safe operation of the wind farm after its design life time.


Learning objectives
• Which aspects influence the feasibility of lifetime extension of a windfarm
• What steps are to be taken in a lifetime extension analysis
• How to deal with incomplete information
• How to combine of desk research and inspections in order to come to the best possible results