Grounding architectures for enabling ground fault ride-through capability in DC microgrids

Distributed generation in the power grid will result in considerable efficiency improvement and increase in reliability and stability of the grid. And DC microgrids have clear benefits such as higher reliability, higher efficiency, better compatibility with DC loads, expandability and etc., over their AC equivalent systems. Although DC microgrids have clear advantages over the AC microgrids, but there is not sufficient information available on their grounding. Realizing the grounding of DC systems would accelerate employing of these systems in the power grid. Grounding is a complex topic involving many design considerations and trade-offs and it is needed to ensure the safety of personnel and equipment as well as detection of ground fault in the system. Grounding of DC power system should be designed to 1) minimize the leakage current during normal operation, 2) maximize the safety of personnel and equipment under fault conditions. This work examines the different grounding methods and system architectures and discusses the design trade-offs in terms of safety, reliability, detection, mitigation, noise, and cost. We examine impedance grounding, isolation, and bi-polar architectures and discuss their benefits with respect to these criteria.