Likströmsnät i byggnader: En undersökning av ett potentiellt energi- och resurseffektivare elsystem
The internal distribution grid in buildings is, just like the rest om the grid, based on alternating current technology. Though today most of the electricity consumers in a building use direct current in their final stage. Also the use of photovoltaics, battery systems and electric vehicles are increasing and they also use direct current. Direct current grids in buildings is an idea to minimize the amount of conversions between AC and DC within the building, instead the idea is to centralize the rectification and thereby lower the conversion losses. The purpose of this thesis is to investigate the phenomenon DC-grids and the Swedish market for it. This is done to find out the feasibility and possibilities of a DC-grid in an office building today. Through a market investigation the solutions and knowledge of this day has been summarized, they are then used to find a recommendation for what parts in an office building that can be supplied with direct current form a DC-grid. According to the investigation there are solutions at the Swedish market for building an internal DC-grid at 350VDC or +/-380VDC (760VDC) depending on what is the priority in the project in question. Since not all electricity consumers can use DC a hybrid between AC and DC is most relevant today. Electrical units that can use direct current today are lighting, ventilation, laptops, mobile phones, tablets, servers and smaller office appliances and telephony. Possibly heat pumps and other pumps might also be able to be supplied by direct current. The electrical units that still need to be supplied by AC are the copier rooms, the elevators, the kitchen areas and the garage with the EV chargers.