Agent-Based Multi-Source Wide-Area Current Protection for Systems With Distributed Generators

Abstract

With the introduction of distribution generation, the distribution network changes from radial network into multi-source network, so the traditional inverse-time over-current protection based on radial network is not applicable. The demand for the research of a new type of protection strategy is urgent. This paper introduces the application of intelligent agents to the protection of the distribution system with distributed generators (DGs). The method of fault location is accomplished in two steps. First, find out the node with a T-type branch formed by the DG connection, through comparing amplitude of power frequency variation of each branch to lock the fault branch and to narrow down the fault area between two T-type nodes. So as to find out the specific fault area B, namely the smallest power-cut scope, in the sketchy fault area, amplitude comparison of fault current and PFVC at the line section’s two ends is used to discriminate whether fault occurs in this section. Once this method fails the phase relation between PFVC and load current after the shifted phase would be applied, so that fault area B is located. The scheme of protection is applicable in fault area location for complicated networks with distributed generation and the proposed intelligent multi-agent-based architecture is illustrated.