The silvery building on the Aalborg East campus is specially built to accommodate the new MV lab (medium voltage laboratory), which can be used, for example, to test power electronics for future, large offshore wind turbines under safe conditions.
- For several years, we have experienced growing interest in designing and testing power electronic converters at higher than normal voltage because it offers lower power loss and less weight in larger wind turbines. In the past, we have tried to conduct tests in the protected areas of other labs, but these have never functioned optimally, says Claus Leth Bak, Professor, Department of Energy Technology.
In conjunction with subcontractors, he has therefore been responsible for the technical design of a brand new lab. Inside the building there is a fully protected, explosion-proof, 60-square-meter test room with high ceilings and a special water-based cooling system. The researchers can control and follow the tests from a separate control room where, in addition to a lot of measuring equipment, there are also a security locking system and automatic safety ground. In general, "safety" is a consistent theme throughout the specifications. But if you want to test whether the security works, you need to do something dangerous.
- If we have a poorly designed device for testing in the laboratory, and it explodes in the air, we need to be sure that it is done in such a way that we can just let out the smoke, sweep the floor and make a new design, says Claus Leth Bak.
Fire truck showed up
The first nerve-racking moment in the new laboratory came when the 20 kV from the distribution network had to be connected to the lab. It went as scheduled and triggered only a pleasant loud hum from the large custom-built transformer. The next more serious test was designed to go wrong. The researchers made a short circuit where they connected the two electrical phases directly to each other with a two-meter long wire. Then they pressed the button immediately after one of the technicians from the power supplier had set his mobile phone to film the outcome in slow motion.
- It triggered a loud bang that could be heard in several offices around the Department of Energy Technology. Shortly thereafter the fire department came with sirens, but fortunately, it was just that the test room's fire sensors were too sensitive for the purpose. Except for this everything went as it should. The video of the explosion shows glowing copper shooting around the room, which highlights the need for a secure test facility for this type of testing, says Claus Leth Bak.
The medium voltage laboratory (MV lab) is a 20 kV grid, three-phase power laboratory. The facilities include two test fields where 20, 10, 6 or 3 kV and 2 MVA can be used, and two test fields where 0.69 or 0.4 kV and 800 kVA can be used. In addition, there are a 300 kW water-based cooling capacity, a fully protected and explosion-proof test room with a floor area of 60 square meters and a 6-meter high ceiling and a separate control room.
HEF NET (now Eniig) has been responsible for the electrical design and construction according to AAU's specifications, while ABB Energy has supplied two custom-designed MV converters to the lab. Both companies and their people get plenty of praise from the energy researchers for the support, helpfulness and resourcefulness.
MV lab is part of a general expansion and renovation of the laboratories at the Department of Energy Technology at Aalborg University, which now has at its disposal some of the scientific world's most advanced and modern facilities in energy. The department has more than tripled in size over the last five years, and an important element is its collaboration with industry. One of the aims of the new lab facilities is to increase collaboration further – also with small and medium-sized enterprises in the energy sector.
Claus Leth Bak, Professor, Department of Energy Technology, AAU, Tel.: +45 9940 9240; Mobile: +45 3031 0944.
John K. Pedersen, Head of the Department of Energy Technology, Tel.: +45 2129 3464.
Carsten Nielsen, Science Journalist, Aalborg University, Mobile: +45 2340 6554.