Comparison of internal grid topologies of offshore wind farms regarding reliability and economic performance metrics analysis

Abstract

Despite higher winds, the investment and operation and maintenance costs of offshore wind farms are still high as compared to onshore solutions. This highlights the importance of an increased reliability, because the occurrence of a failure can result in long downtimes due to inaccessibility of the site during harsh weather conditions. This study performs a reliability analysis of the internal grid of an offshore wind farm, comparing different topologies and their economic outcome. The research addresses both a redundancy between each pair of two strings (classical redundancy design) and a redundancy between already redundantly paired sets of strings (newly proposed redundancy design). The results show that the use of a redundancy scheme leads to a positive Net Present Value (NPV) and an interesting Internal Rate of Return (IRR), which can be an appealing investment. Moreover, it is more profitable to simply rate the cables to support normal operation conditions at rated power rather than increasing the cable ratings to support all failure scenarios. Overall, the topology that shows the best economic results combined with a good reliability is the topology with cable ratings based on regular conditions with a redundancy in the middle of the string between each pair of two strings.