NEW ISLANDING DETECTION TECHNIQUE IN PRESENCE OF DISTRIBUTED GENERATION

Abstract

This thesis presents five passive local islanding detection methods for a distributed generation (DG) system connected to a utility grid. Various non-islanding events along with islanding conditions at different values of active and reactive power mis-matches have been simulated using PSCAD/EMTDC software package. The simulation results indicate that the proposed schemes are capable to detect islanding condition rapidly even with zero active and reactive power mis-matches. Further, they eliminates non detection zone (NDZ) completely, works perfectly for multiple DG systems and avoids nuisance tripping during various non-islanding events. Moreover, performance of the proposed schemes remains immune to change in capacity of DG, location of DG and length of distribution line. Comparative evaluation of the proposed schemes with the existing schemes clearly indicates the superiority of the proposed schemes. The proposed schemes can detect islanding situation within a cycle, which is less than 150 ms required in a re-closer.