DefinePK

Abstract

Since it is not possible to optimize a standard relaying system to every protection need, Digital Multifunction protection systems are proposed as they have features like cost efficiency, functional flexibility, adaptive relaying and self checking capability. With the advantage of generally available hardware and software, having the speed and capability of digital relays necessary for protection application, it has now become possible for the relay engineers to develop and implement custom protection solutions for those applications where standard packages may not provide the necessary flexibility or performance. A modified Fullcycle Discrete Fourier Transform (FCDFT) Algorithm based digital multifunction relay is proposed which has capability of executing trip command by extracting exact fundamental frequency component, by eliminating harmonics and decaying DC offset component, during faults in power systems. The proposed algorithm was tested for different faults on 220KV, 100km overhead transmission line. Electromagnetic Transient Program (EMTP) and Power System Computer Aided Design (PSCAD) were used to generate waveforms under different fault locations and fault inception angles. The results show that the proposed Digital multi-function relay worked efficiently and reliably.