Measurement and modeling of voltage and frequency dependences of low-voltage loads

The loads, which are connected to the electrical networks today, have a different composition and, to a large extent, substantially other technical behavior than several years ago. Energy-saving lamps, LEDs, electrical loads with switched-mode power supplies and many other power electronic based devices replaced older technologies. Thereby the voltage and frequency dependence of the whole load composition has changed in an unknown degree and direction. In this paper, measurements are presented which are used to evaluate the load behavior in low-voltage networks (LVN). Voltage and frequency changes have been applied to the LVN using an emergency generator. The measured active and reactive power reactions have been used to estimate accurate load models and appropriate parameters. A novel reactive power load model is proposed to deal with the challenge of compensation effects and small absolute values.