Hossein Emami - Production Technology Research Institute(PTRI) of Iranian Academi Center for Education,Culture and Research(ACECR) of Khuzestan

Distributed generation (DG), similar to other generators require electrical protection against system short-circuit and unusual conditions. Adding DG to the electric power distribution systems, can reduce the reliability, protection, system stability and power quality to consumers. The challenges associated with DG, protecttion against the unscheduled islanding, is an important issue. It is essential that the islands are immediately detected and the DG is disconnected from the distribution network or taking it under control. According to distribution utility Standards, the island must be detected in less than 2 seconds. In this paper a new method for detecting active synchronous type generator island DG, based on negative sequence impedance measurement is introduced. A negative sequence impedance islanding detection (NSIID) method is an improvement in the impedance measurement techniques for the detection of an island due to the negligible non detection zone and specifically large threshold window. Finally The algorithm for implementing this network protecting approach will be presented. In this paper, simulations have been done in Digsilent and results have been analyzed.

fault Negative Sequence Impedance, Distributed Generation (DG), islanding detection, intentional-islanding, Active method, short-circuit