Modelling and Experimental Validation of a Pole-To-Ground Protection Device in Low Voltage DC Microgrids

Over the past years, the scientific interest in Low Voltage DC grids as an alternative to traditional LVAC grids has been growing steadily. This is caused by the fact that the amount of renewable energy sources and DC compatible loads in the grid has been increasing significantly. Furthermore, LVDC grids offer a higher efficiency and transmission capacity compared to their AC equivalent. However, the protection of these grids remains a major challenge for their breakthrough. This paper analyses the fault behaviour of an LVDC grid and proposes a prototype for a pole-to-ground protection device. To start with, an overview of the challenges for the protection against the different fault types in a converter-fed LVDC microgrid is presented. Subsequently, a PSCAD model of an LVDC grid for fault studies is discussed and the simulation results are analysed. Then, a test setup is developed to investigate the fault behaviour and the experimental results are presented and compared to the simulations. Finally, a prototype for pole-to-ground fault protection is proposed and its working principle is experimentally verified.