A line to ground fault detection technique for ELVDC distribution system in built environment

The rise of DC nanogrids distribution system allows for lower component count, higher overall system efficiency and an ease of integration with renewable energy sources and DC battery storages. In a built environment, the retrofitting to extra-low voltage direct current (ELVDC) for distribution seems promising for residential loads. However, there exists an inherent line to ground fault for line to line voltages higher than that of 60V DC. To prevent the escalation of a line to line fault, it has been proposed to sense and isolate the circuit when a ground to line fault is detected. This paper will present the different fundamental retrofitting sensing designs with the use of different bipolar rail voltages and retrofitted ELVDC distribution systems. Simulations results with the detection circuit are presented in this paper. Fundamental experimental results with intelligent detection circuit are presented to support the sensing and detection technique at extra-low voltage level. This technique uses the built environment equipotential and the isolation between the AC and DC distribution systems. The technique seems favorable to sense and isolate a line to ground fault for an end user ELVDC distribution system.