| dc.description.abstract | Offshore wind energy has become a major part of the European energy mix, and new and improved technology enables the construction of wind farms with larger installed capacity. One of these large scale projects that has gotten granted consent in the UK is the Dogger Bank Creyke Beck A with an installed capacity of 1.2 GW. From previous work a base case of the collection grid for this project called the Dogger Bank Reference Wind Farm, DRW, has been developed by Kirkeby at SINTEF.
This thesis has evaluated six configurations based on a section of this base case with different design of redundancy to minimize the production losses. The RELRAD methodology, power flow analysis and economic evaluations have been used to determine which is the optimum configuration for the DRW. Factors such as time varying power production, different levels of redundancy, and the costs of power loss in cables has been evaluate to determine their influence on the reliability and economic decision for the collection grid. When analysing the grid designs, only components that changed in number or placement has been evaluated. This included the 66 kV XLPE cables, circuit breakers, and disconnectors.
Two of the configurations, which only offered some redundancy or none at all, was found to have much larger annual outage time than the rest, indicating that these would not be the optimum solution. However, for all configurations the expected interruption costs, cost of power loss, and the cables costs all have had huge contributions to the costs, which made the configurations with long cables much more expensive. The optimum configuration for the Dogger Bank Reference Wind Farm was found to be the multi ring configuration with two times three strings connected to a redundancy cable, and four strings connected to a redundancy cable, offering full redundancy. For all sensitivity analysis performed, the multi ring configuration was still found to be the best solution.
To use this result further, a full reliability analysis of the DRW should be performed to find the actual costs of the DRW. Additionally it would beneficial to dimension the cables for short circuit events to meet the security demands for offshore wind farms. | |
