University of Twente Student Theses


Optimization of offshore wind farm power cable routing : development of a tool that optimizes the power cable route design for offshore wind farms

Roetert, Thomas Jonathan (2014) Optimization of offshore wind farm power cable routing : development of a tool that optimizes the power cable route design for offshore wind farms.

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Abstract:Up to now methods to optimize cable route layout are only based on a flat seabed and do not take the seabed dynamics into account (Jenkins et al., 2013; Morelissen et al., 2003). The result of this approach is that power cable coverage is not guaranteed over the wind farm design lifetime. The cable optimization is mainly executed based on shortest routes instead of cost reduction over the entire design lifespan. Therefore the aim of this research is: “The development of a Matlab based tool to optimize the power cable route design based on expected morphological behaviour in the design lifetime of an offshore wind farm” To find the optimized cable layout a tool is developed including the optimization under a flat, static and dynamic seabed. These three steps help to identify the impact of bedforms on cable positions. First, the cable layout is determined based on a flat and static seabed. Found layouts show large similarities with the original layout in terms of total length. Thereby, the original layout is used during the optimization under a dynamic seabed. All connections in the original layout are optimized in vertical and horizontal direction. The aim for this step is to minimize weights of all connections. Cable weights are determined based on the cost function incorporating risk of failure and costs of failure, cables and monitoring. Combining all optimized connections shows that all vertical optimizations lead to a decrease in costs. Results of the horizontal optimization depend on the fixed burial depth and bed level change. Combined with an option to include case-specific information, it can be assumed that the tool is general applicable. Parameters used in the vertical and horizontal optimization were all fixed. To show the influence of the different parameters a rough sensitivity analysis is executed. A parameter from all four cost function parts, risks, power loss, costs of repair and initial cable costs, is analysed. Main conclusions are that the magnitude of the parameter, amount of turbines affected and the dynamics of the crossed area form the greatest influence on total costs. Since the tool is designed to find the optimized cable layout over the wind farm design lifetime, also parameter sensitivity after survey prediction is analysed. Results show that survey prediction only has influence on parameter sensitivity during the horizontal optimization. In addition, only connections interfering with sand waves were affected. The results of this research make a contribution towards renewable energy targets. With the aid of this tool, cable coverage can be guaranteed, reliability increases and project costs and risk of cable failure decreases.
Item Type:Essay (Master)
Deltares, the Netherlands
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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