Design Optimisation of Power Cable Configurations for Floating Offshore Wind Turbines

• Main Author: Schnepf, Anja
• Format: Dissertation
• Language: English
• Subjects: floating offshore wind turbines; flytende vindturbiner; offshore teknologi; vindturbiner

The present work investigates the design of dynamic inter-array power cable configurations for floating offshore wind turbines (FOWTs). It builds upon traditional design processes by integrating optimisation methods. Extensive reviews are provided on the current state of power cable configuration design, drawing parallels with umbilical and riser configurations in the oil and gas industry. Various power cable configurations are analysed under different environmental conditions. This research examines a newly proposed concept, the suspended power cable configuration. Environmental conditions strongly influence the feasibility of the configuration, with viable configurations identified for various locations. Different cable types show varied responses to the currents and motions induced by FOWTs. Among the investigated suspended configurations, those featuring multiple subsea buoys along their length are the most feasible. These configurations provide adequate buoyancy to maintain the power cable at midwater while having a reduced drag area, thus limiting cable excursions. An overview is provided on the objectives, variables, and constraints affecting the design of power cable configurations. Constraints are especially important to consider in every design because each location has unique conditions that must be carefully taken into account. Environmental loads represent the primary constraint for all power cable configurations, with currents and marine growth being the most significant factors. Typically, insufficient data are available to design power cable configurations with minimal risk of failure. Various constraints, including response constraints such as maximum allowable cable tensions and bending, as well as lifecycle constraints spanning installation, operation, maintenance, and decommissioning, must also be considered. This work proposes the integration of optimisation procedures into the design methodology. Specifically, the integration of the algorithms Sequential Least Squares Programming (SLSQP) and Efficient Global Optimization (EGO) into the design procedure is presented. Their application demonstrates significant improvements in cable configuration design.