Interfacing protective relays and relay models to power system modeling software and data files

This paper addresses two important issues: how the relay models and physical relays may be interfaced to the models of power systems capable of simulating fault waveforms and related switching equipment status; how the data files containing recorded waveforms and equipment contacts generated by the actual faults and subsequent fault clearing may be utilized by the relays and relaying systems. The importance of the relay evaluation issue is linked to the capability to test the relays and relaying systems using very accurate representation of a fault event. This capability has not been used at its full extent in the past, yet a variety of options exist that have different performance potentials and implementation constraints. By discussing the options and pointing out the complexity of implementations, this paper sheds some practical light enabling users to better understand the issues involved and consequently make the best choices for their specific needs.