EMTP TACS-FORTRAN interface development for digital controls modeling

A FORTRAN interface to be used with TACS (transient analysis of control systems) in EMTP (electromagnetic transient program) has been developed at Hydro-Quebec to allow the use of FORTRAN language for simulating digital controls for power system components such as static compensators, DC transmission, and relays. The interface has been designed without any time delay between TACS and the FORTRAN subroutines and allows users to benefit from the flexibility of FORTRAN language to ease the task of modeling digital controls. The property of task cyclicity in digital controls can be exploited to reduce the CPU time of each EMTP run. The authors present details of the interface and provide results confirming its advantages for simulation of digital controls within EMTP