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Conference programme 

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Poster session

Lead Session Chair:
Stephan Barth, Managing Director, ForWind - Center for Wind Energy Research, Germany
Christina Angeloudi DONG Energy Wind Power, Denmark
Christina Angeloudi (2) F P Igor Kozine (1) Iván Arana (2) Nicolaos Cutululis (1)
(1) DTU, Copenhagen, Denmark (2) DONG Energy A/S, Gentofte, Denmark

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Presenter's biography

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

Christina Angeloudi was born in 1988 and she is currently working as Project Planner for Offshore Wind Farms at DONG Energy. She received her MSc degree in Wind Energy from the Technical University of Denmark (DTU) in 2014 and her Dipl. Eng. degree from the Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, in 2012. Her main technical interest is planning and development of wind farms.


Availability Aspects in Large Offshore Wind Farms


There is currently a strong focus in the industry and academia to reduce the cost of energy from wind and make the technology competitive to conventional technologies. Improving the availability of wind farms, optimizing the operation and maintenance concepts, reducing the foundation and cable installation costs are some of the elements the market leaders in offshore wind energy and collaborators constantly seek to improve to reach this aim.


Despite the advantages offshore wind offers, there are challenges that need to be overcome. Installation of offshore wind farms is more difficult than onshore and expensive and, additionally, accessibility for maintenance is often limited depending on the weather conditions, availability of maintenance equipment and crew, and distance from the shore. Even when the external conditions permit maintenance, the cost is still higher than the equivalent onshore. As a result, improvement of the availability of offshore wind farms (OWFs) is a very important factor, which can confront the limited accessibility for maintenance by reducing the OWF component failures.

Main body of abstract

The paper presents a methodology to assess the electrical infrastructure of a large OWF, in terms of availability. With this methodology, the large OWF structure can be assessed to improve the availability of the system. To achieve this, the critical components of the OWF are identified, whose failures lead to high production losses, and their effects are minimized by using dependability analysis methods and proposing new solutions. Moreover, the availability analysis is extended by identifying failures of the OWF that would lead to non-compliance with Grid Codes, as one of the types of failures causing loss of availability.

The methodology is based on the bottom-up dependability methods Event Tree Analysis (ETA) and Failure Modes and Effects Analysis (FMEA). These methods prove to complement each other, providing a comprehensive approach to the dependability analysis of large OWFs. FMEA provides a good summary of how single component failures affect the system availability, while ETA supplements FMEA by investigating the effects of multiple component failures along with the application of external conditions.


The methodology for assessing the OWF electrical infrastructure to achieve increased system availability is presented and it can be used for the development of future OWFs to achieve higher availability or even for improving the electrical infrastructure of existing ones. The methodology provides flexibility regarding the complexity of the OWF design and the desired degree of detail of the analysis.

Learning objectives
Starting from a reference OWF structure, the paper presents the detailed steps of the proposed methodology, together with an example of how to assess the impact of modifications of OWF electrical infrastructure on the overall availability.