PROTECTION SYSTEM REPRESENTATION IN THE ELECTROMAGNETIC TRANSIENTS PROGRAM

This paper concerns the addition of the few critical elements of a pro tection system to the Electromagnetic Transients Program (EMTP), which is one of the most widely used programs for the simulation of transie nts in power systems. It contains models for almost every major power system component. A protection system consists of instrument transform ers, relays, and circuit breakers. Models for current transformers (CT s) and capacitor voltage transformers (CVTs) are developed, validated, and incorporated in the EPRI/DCG EMTP Version 2.0. The user can defin e the values of the CT and CVT parameters. Total FORTRAN capability ha s been added to the EMTP; new subroutines and an inbuilt structure to allow the linking of user-defined FORTRAN subroutines with the main EM TP are explained. This capability is necessary to simulate computer re lay algorithms. The outputs of the algorithms can be passed to the EMP P, which enables the study of the dynamic interaction between the powe r system and the protection system. The FORTRAN capability can also be used to develop models for relays. Models of specific relays, such as those for line protection (CEY51A and SLY12C) and transformer differe ntial protection (D202 and BDD15B) , are also available. The relay mod els can be used with different settings. These new features in the EMT P together constitute the critical elements of a protection system. Th us, it is now possible to simulate the dynamic interactions between a power system and a protection system.