News from Department of Energy Technology

New PhD project to study the impact of underground cables on the Danish electrical transmission grid

In the wake of the recent heated discussion about grid expansions in Western and Southern Jutland, a new PhD project will investigate one of the impacts on a power system using underground cables instead of overhead lines. In time, this may lead to a larger percentage of the transmission grid being underground, which is a pronounced wish from the general public.

Photo used with permission from © Energinet

With undergrounding cables it is very difficult to ensure power quality, and at the same time, it is very costly to establish underground cables compared to overhead lines. Investigating methods to increase the usage of underground cables is an important contribution to the development of green energy.

Increased number of electricity lines

As Denmark is transitioning to renewable energy, one aspect is that wind turbines and solar panels have to be placed where there is wind and room for solar power plants, which will often be in coastal and rural areas, with some distance to the major cities. As a result, electricity lines must be established across the countryside, often to the regret of local residents. The research of this PhD project can contribute to solutions to these societal challenges.

Technical challenges

This PhD project will address some of the technical challenges found on the West Coast expansion and elsewhere, with the purpose of developing methods for analysis of harmonic propagation and amplification in meshed transmission systems; in other words: to find a method to estimate the harmonic levels with high accuracy and then to design solutions that can deal with the technical challenges. Currently, Energinet estimates that only 15% of the transmission grid for the West Coast link can be underground – simply because of the challenges with harmonics. Similar limitations might be found when expanding the grid in other locations. (Energinet is an independent public enterprise owned by the Danish Ministry of Climate, Energy and Utilities. Energinet owns, operates and develops the transmission systems for electricity and natural gas in Denmark.)

Photos used with permission from © Energinet

Collaboration between Energinet and Department of Energy Technology

The PhD project is financed entirely by Energinet, and it is a continuation of a previous project between Energinet and the Department of Energy Technology: DANPAC (DANish Power system with AC Cables), which ran from 2008 to 2015 and focused also on underground cables.

The new PhD student is Bjarne Søndergaard Bukh, who comes from a position as Senior Analyst at Energinet. Bjarne is well known at the Department of Energy Technology as he received his Masters’ Degree from the Department in 2007.

Contact information

Professor Claus Leth Bak
Direct phone: +45 9940 9281

Associate Professor Filipe Faria da Silva
Direct phone: +45 9940 9280

Industrial PhD Fellow Bjarne Søndergaard Bukh
Direct phone: +45 9940 8835

More information

Research programme: Modern Power Transmission Systems
PhD project description: Methods for Harmonic Analysis in Meshed transmission Systems