Dc Leakage Current in Isolated Grid-Connected dc Nanogrid - Origins and Elimination Methods

The LVdc system is a relatively new trend in the distribution sector, which seems to grow widely in the near future due to its promising advantages. In this context, LVdc protection and grounding are challenging issues. Although the galvanically isolated connection mode of dc nanogrid to the ac grid has high reliability, the leakage current can still be injected into the ac grid through the interwinding capacitors and the insulation resistance between the primary and secondary windings of the transformer. The way of grounding the dc nanogrid can also be a determining factor in the leakage current and its dc components. This study deals with the leakage current in the galvanically isolated dc nanogrid. Then, it examines the dc leakage current and its relationship with the dc nanogrid grounding and finally provides solutions to remove the dc components in the leakage current.