Discussion about neutral grounding mode of Active Distribution Network

The selection of neutral grounding mode is a basic problem closely related to the safety and stability of distribution network. Technical characteristics of every kind of grounding mode are very clear for conventional distribution network, and both effective and non-effective grounding modes have been widely used around the world. Different from conventional distribution network, the neutral grounding mode of Active Distribution Network (ADN) which contains a large amount of DGs, is decided by the grounding modes of main network and DG. So neutral grounding mode selection of ADN is more complex and needs to be re-examined. Possible grounding mode combinations of main network and DG are proposed, and grounding mode transformation in different operating states of DG (including grid-connecting state and off-grid state) and in single-phase earth fault handling process, is analyzed in ADN. Grounding mode selection of DG in both existing distribution network and brand new distribution networks are discussed. A preliminary study on neutral grounding mode of AND, is made in this paper.