PROTECTION SYSTEM REPRESENTATION IN THE ELECTROMAGNETIC TRANSIENTS PROGRAM

This paper concerns the addition of the few critical elements of a protection system to the Electromagnetic Transients Program (EMTP), which is one of the most widely used programs for the simulation of transients in power systems. It contains models for almost every major power system component. A protection system consists of instrument transformers, relays, and circuit breakers. Models for current transformers (CTs) and capacitor voltage transformers (CVTs) are developed, validated, and incorporated in the EPRI/DCG EMTP Version 2.0. The user can define the values of the CT and CVT parameters. Total FORTRAN capability has been added to the EMTP; new subroutines and an inbuilt structure to allow the linking of user-defined FORTRAN subroutines with the main EMTP are explained. This capability is necessary to simulate computer relay algorithms. The outputs of the algorithms can be passed to the EMPP, which enables the study of the dynamic interaction between the power 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 differential protection (D202 and BDD15B) , are also available. The relay models can be used with different settings. These new features in the EMTP together constitute the critical elements of a protection system. Thus, it is now possible to simulate the dynamic interactions between a power system and a protection system.