3D Modelling of Heat Dissipation from Offshore High Voltage Cables

Project Rationale:
The transmission of electricity across shelf seas is a major, and increasing, component of the global energy network. The proliferation of offshore windfarms, across the NW European shelf, but with expanding markets in America and South-east Asia, has led to the design and installation of 10’s of thousands of kilometres of within field array cabling and export cabling. In terms of HVDC interconnectors, there are currently 8000 km globally, with typical individual transmission lengths of < 300 km (Ardelean & Minnebo, 2015). The UK is a net importer of electricity at the level of 20.9TWh (5.8% of supply: DBEIS, 2016) and this capacity could potentially triple from the current 4GW capacity by 2025. The power transfer performance of these High Voltage cables is limited by their ability to dissipate heat, which in turn is controlled by the medium in which the cable is buried (Hughes et al., 2015). Therefore an understanding of these thermal dissipation properties plays a primary role in both the rating and the lifetime performance of the cable. The ability to properly understand and potentially control the mode of heat dissipation in space and time could save the renewable energy sector millions of pounds. This project will particularly focus on 3D numerical and physical modelling of the generated heat regime around a cable to enable the accurate interpretation of Distributed Temperature Sensor (DTS) Data that is now commonly recorded from offshore cables. This is critical for the life time management, and in particular fault detection, of cables.

Methodology:
This project will focus on the development of a series of 3D Finite Element models (constructed in COMSOL) and building on the extant models of Hughes et al (2015) and which are available to the student. Emphasis will be placed on a realistic understanding of the physical environment of the seabed (Dix et al., 2017) and how key physical properties (thermal conductivity and permeability) change under both natural marine conditions and during cable installation. The project will also undertake controlled, prototype scale, 3D physical experiments on the thermal environment generated around individual cables in a specifically designed facility at Southampton (building on the original 2D experiments of Emeana et al., 2016). Finally, numerical models will also be calibrated against in situ windfarm DTS data and ground models developed from in situ geophysical and geotechnical data.

Training:
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at Ocean and Earth Science but with strong and close collaboration with the School of Electronics. Specific training will involve both computer modelling and laboratory based work, to include:
(i) COMSOL and MATLAB modelling;
(ii) MATLAB analysis of multi-attribute sensor data;
(iii) Prototype scale three-dimensional physical modelling using existing 3D tank, HV cable and thermal monitoring equipment.
(iv) Ground model construction through the combination of seismic and geotechnical data.
The student will have the opportunity to present their results to academic, government-funded and industrial specialists, and will be thoroughly coached in the skillful delivery of their methods and results to these audiences in both verbal and written form. The student will be rigorously trained in the art of scientific communication in the form of academic papers in international journals, and will have the opportunity to participate in seagoing scientific surveys.