Agent-based protection scheme for distribution networks with distributed generators

This paper describes a novel protection scheme for a distribution network with distributed generators. The network is divided into several segments to facilitate fault isolation. Relay agents protecting the system are installed at points of interconnection between different network segments. These relay agents communicate with the neighboring agents through an asynchronous communication network. A wavelet transform coefficients based technique is proposed to identify the direction of a fault with respect to a node in the network by measuring the transient currents in the branches connected to the node. Relay agents, which use this technique to determine the fault directions with respect to their locations, then collaboratively determine the faulted zone. Simulation studies using PSCAD/EMTDC reveals that this scheme is capable of identifying and locating faults with very high accuracy even for high impedence faults