Better underwater power
For four years, senior scientist Bjørn Gustavsen and his colleagues at SINTEF Energy Research have worked on the development of simulation tools for underwater power. The results will soon be implemented in the oil and gas sector.
This is just like the fjord crossing debate for the Hardanger Fjord. It is more expensive and technically more complicated to use underwater electricity cables than the overhead grid. Another matter is that simulating the behaviour of the system before laying cables on the seabed and turning the power on, will reduce the risk of unforeseen problems. Otherwise, anything that does not function will quickly become very expensive.
Typical applications of the simulation tool are the pumps and compressors installed on the seabed that provide power to oil and gas installations.
- Therefore our goal has been to simulate the electrical behaviour of the system in detail from A to Z, says Gustavsen.
Oil companies and the suppliers
This is a Knowledge-building Project with User Involvement (KMB) where the Research Council of Norway has funded about 40 per cent. The rest has come from a consortium of Norwegian and international companies.
Three KMBs have been run in parallel: One has focused on power electronics, the second in materials and the third on power systems which has engaged Gustavsen and his group. This project has encompassed the entire underwater power system. This means that the project group has developed and improved models for the specific components and has analysed the typical power systems in different operational situations. They have worked with the modelling of cables, transformers, converters and motors. One of the researchers is a post-doc from Italy who has also been engaged in the modelling activities.
- We had some surprises, and have learned a lot. The know-how gained has been passed on to our project partners in reports and software, and will be useful in future analyses of underwater power systems.
- Using the analytic tool we can now analyse a variety of phenomena that can cause problems with the operation of subsea power systems. Examples of this are mechanical vibrations in generators caused by the lack of symmetry in the cable construction and interference by converters. We are also in a position to make more accurate calculations of the phenomena associated with the connection of long cables where the complex interactions between the cable and transformer are included. The level of detail in the modelling must be adapted to the phenomena investigated. However, we can take into account both frequency dependence and non-linearities, adds Gustavsen.
New project underway
- The project has given us the opportunity to excel in some areas, and in turn has meant that we have received funding for a new knowledge-building project this year with support from the Research Council and a number of industrial partners and system operators. We are pleased that NTNU is once again involved through a doctoral study and we will have a post-doc at the Delft University of Technology, Netherlands.
Just as the new know-how will be used in planned projects, the present project builds on previously acquired knowledge, adds Bjørn Gustavsen.
Laboratory measurements of cable for model verification.