Transmission lines protection using SIPROTEC numerical relays

Abstract

This paper analyses the fundamental principles of distance protection relays while highlighting the importance of correct relay parameterising through a set of relay tests. Numerical distance relays can have up to 6 distance zones, and nowadays most of them have a quadrilateral (polygonal) characteristic. The specific objective of this study was to apply those principles on a SIPROTEC distance protection 7SA611 relay with the help of Omicron CMC 56 testing device, as well as to describe the testing process. As a part of the testing, DIGSI and Test Universe Software were used. Experimental results confirm the theoretical principles of distance protection and show the advantages of numerical relays. This paper concludes that optimal choice of reach settings and time delays between the zones, as well as zone directions, can significantly impact the selectivity of the protection system, and therefore the scope and time of the outage.