To follow the trend of world energy revolution and the revolution of things, ubiquitous power of things, integrated energy system concept was first proposed, the ubiquitous power of Internet of things is the key energy construction. In this new age, the traditional form with a positive net change significantly, many conventional AC distribution network equipment, large line losses, low reliability, flexibility DC distribution network (referred to as the "DC distribution") because of line loss small, high-efficiency power supply, there is no phase imbalance and other issues favored by many researchers. This article reviews the common failure modes and protection configuration, fault protection principle electric characteristic and DC distribution network, relay protection technology trends. At the same time the development of direct distribution network relay technology are summarized and pointed out that the next step possible directions.