Dynamic power cable installation for floating windturbines

Abstract

Offshore wind energy is often considered the Formula One of renewable energies. It is a proven technology that provides millions of people with clean and affordable power. However, the available locations for bottom-fixed turbines are being depleted quickly, while the potential of wind energy in deeper waters is immense. Installing power cables for these large floating electricity generators is more complex than for fixed wind turbines. In November 2025, DEME will install the first dynamic cable for an offshore floating wind farm. During the preparation phase, DEME encountered several challenges related to the attachment of ancillaries and low operability. This thesis focuses on the limitations associated with dynamic cable installation.

This research is structured into three main phases. The first phase consists of an extensive literature study conducted to gain insight into the equipment required for the installation process and the ancillaries that must be attached to the cable to keep it properly in place. The second phase involves developing a new vessel layout to enhance the workability of this installation setup. Once a new configuration is established, the third phase consists of building a model of the setup using the time-domain software OrcaFlex. This model was then used to simulate various environmental scenarios, and the results were analysed to compare different methods based on operability.

Key findings from the literature study highlight the complexities of the cable installation process. These complexities include operational weather windows, onboard logistics, ancillary handling, installation speed, and the limitations of the cable, ancillaries, and equipment. One of the main considerations is the importance of risk-mitigating measures to ensure the safe deployment of the cable and its ancillaries.

Multiple concepts were explored and developed with the goal of improving onboard processes and the overall operability of the system. A multi-criteria analysis resulted in the selection of a stinger frame as an alternative to the current cable installation setup.

Cable modelling was performed to obtain the required insights into cable behaviour. The output from the model identifies the limiting factors during installation, such as curvature, sidewall pressure, and cable tension. The simulations include scenarios with various combinations of environmental conditions, such as wave height, wave direction, and wave period.

The simulations showed that a rigid stinger does not improve operability. Due to increased motions at the stinger tip, tensions rise, which further limits operations. However, the risk of minimum bend radius (MBR) breach for the buoyancy modules (BMUs) in the splash zone was reduced significantly by decreasing the time they spend in high-risk positions. Sidewall pressure (SWP) did not prove to be a critical parameter. These findings suggest that a more advanced stinger design could help increase operability.

This thesis provides valuable insights and recommendations for future research, supporting the offshore wind industry’s transition towards floating solutions to access deeper waters with higher energy yields. This development will further strengthen the global supply of sustainable renewable energy.