Ocean grid research (SP5) is Ocean Grid’s Collaborative and Knowledge-building Project. As such, its research is open and results will be published. It will foster open research and innovation aiming at advancing the state of the art in four critical thematic areas. The involvement of industry stakeholders will ensure that research is aligned with industry needs and that the activities will strengthen the innovation capabilities of all partners.
The subproject is led by SINTEF, who will conduct research in all work packages. NTNU will contribute in all work packages and supervise four Ph.D/Postdoc candidates. The time horizon for this subproject is beyond 2030 for which hydrogen is expected to be significant as a large-scale energy carrier together with an offshore electric grid.
Subproject five is Ocean Grid's Collaborative and Knowledge-building Project, which is divided into four parts:
- Grid expansion optimisation (led by SINTEF): Develop optimisation models and tools to help identify optimal step-by-step offshore energy infrastructure buildout while considering uncertainties.
- Energy market design (led by SINTEF): Understand impact of market design with regards to offshore wind energy taking into account European demand and flexibility needs. Quantifying effects on expected price variations and wind farm profitability.
- System interoperability (led by NTNU): Identify technical approaches to assess and ensure interoperability in a converter dominated offshore power system.
- Wet design cables (led by SINTEF): Develop reliable and long-life subsea power cable designs by assessing the effect of water migration into new and improved insulation systems. Improve processes for material and cable manufacturing to increase the cleanliness of the insulation system.
Expected results
- Models and decision support tools for optimal investments in offshore energy infrastructure including both electrical and hydrogen transmission
- Modelling framework for market design for operation of an offshore grid in Norway
- Theoretical and numerical tools for reducing interoperability risks and for improving the effectiveness of interoperability assessments in converter-dominated offshore systems
- Higher reliability of inter-array cables also for higher system voltage levels (>66 kV AC)
- New tests to elucidate the effect of salt water on long-term service performance which can be reliably included in future cable standards and recommendations
- Educate four PhDs/postdocs in critical topics for the development of offshore grids (SP5.1-SP5.4)
Meet our PhD candidates
Sofie Brandtzæg Hårberg
Affiliation: NTNU
Nationality: Norwegian
Supervisor: Prof. Mari-Ann Einarsrud (NTNU)
Period: 2022-2025
Thesis: Materials for wet-design high voltage subsea power cables
Background
I am 23 years old from Steinkjer, and I have been living in Trondheim for the past five years. I completed my master’s degree from the Chemical Engineering and Biotechnology study program at NTNU in June 2022. My specialization was materials science and energy technology, which provided me with knowledge and experience on a broad variety of methods for materials characterization. I wrote my thesis as part of the functional materials and materials chemistry (FACET) group at NTNU, which I will continue to stay a part of as a PhD candidate.
About my thesis
Among the most essential components of the offshore power grids are the subsea power cables. Increasing their reliability and durability is therefore an important part of realigning the Norwegian offshore industry from oil and gas towards renewable wind energy. To contribute to this, my PhD project will investigate the cause and mechanism of water treeing in the insulation system of wet-design HVAC subsea power cables. The water trees are complex networks of microvoids and channels filled with water, and they are currently the major degradation mechanism of the wet-design HVAC cables.
The cleanliness of the insulation system will be assessed using a variety of characterization techniques to locate contaminations in new and aged cable cores. This includes sample preparation by cryo-microtomy, investigating the morphology by electron microscopy and chemical analyses by energy dispersive X-ray spectroscopy and secondary ion mass spectroscopy, amongst others. Finally, new and improved materials for the insulation system will be developed based on the findings of these analyses.
Trond Markus Tutturen
Affiliation: NTNU
Nationality: Norwegian
Supervisor: Dr. Jon Are Suul (NTNU/SINTEF)
Period: 2022-2025
Thesis: Control design for ensuring interoperability of power electronic converters
Background
I am a PhD candidate at the institute of engineering cybernetics, with background from electric power engineering. I come from a small place in the southeast of Norway with the name Eidsberg. My favourite hobbies are playing beach volleyball, playing guitar and mountain hiking.
About my thesis
My contribution to the Ocean Grid research project is through WP3.2 Converter design for interoperability. The aim is to investigate if interoperability in a power electronics dominated ac-grid can be ensured through control design of the converters. The starting point is to use the principles of robust control and passivity-based control strategies to offer robustness against change of parameters of the operating condition of the power system. The motivation for this thesis is to ensure that converters can safely be connected to a power electronics dominated power systems, which allows for scalability of offshore wind parks.
