Overcurrent relay based integrated protection scheme for distribution systems

This paper reports on the development of integrated protection for power system. The background of the development is firstly introduced, in which a centralized protection system (or relay) provides the protection of multiple power plant or a substation. A novel integrated protection scheme for distribution system is described. The scheme is based on overcurrent protection technique, in which specially designed protection relays are installed at each substation of a network. In the proposed scheme, one integrated relay is responsible for the protection of every line sections connected to the substation busbar. The conventional directional overcurrent and new adaptive accelerated protection algorithms are implemented into the relay with multiple overcurrent settings to cover all the protected line sections. The paper includes studies of a typical multi section distribution network to demonstrate the principle of the scheme. Studies show that the new scheme not only offer the new protection features for individual power line, but also provide the characteristics of integrated protection.