Metoder för kartläggning och analys av nätförluster i lågspänningsnät

Sammanfattning: An important process for grid companies in order to reduce power losses in electricity distribution grids is to figure out where and how they appear. This report describes the factors that cause power losses in low voltage distribution grids and methods for how they could be measured and analyzed. Measurement data for consumed and injected energy were collected for twelve low voltage distribution grids owned by Gävle Energi AB in order to analyze the size of the power losses and how the measurement uncertainty affects the collected data. Then models of three of the grids were created in MATLAB in order to analyze the data and the power losses were calculated to be compared to the collected data. Curve fitting were also used as a method in order to analyze the power losses from collected data. The results show that the losses in the studied grids are low. The measurement uncertainty is also low when losses are studied for long time periods, but high when losses are studied for short periods such as single hours. The calculated power losses from the MATLAB calculations seem to be lower than the measured power losses, which could indicate that a more complex model is needed for these kinds of studies. With a good interaction between the grid information system and the system that is storing measurement data it should be possible for grid companies to chart their power losses and with an accurate model of the grids the power losses can be calculated theoretically which should make it possible to analyze the causes of power losses in low voltage distribution grids.