Distance Digital Relay Model Developed in Atp “ Foreign Model ” and C + +

This paper presents a new approach in the problem of digital relay development. An interactive model in the simulation program of power system, eg, ATP-EMTP, could properly contribute to the improvement of digital relays. This model is not available and the code for this model has to be created in ATP. There is an internal programming language MODELS in ATP which allows creation of programs themselves but because of its simplicity it is not sufficient for developing sophisticated models as in object oriented programming language. This deficit is compensated for by allowing a suitable interconnection between the ATP computing core and external model developed in another programming language. For this reason, the object oriented programming language C++ was chosen for relay model development. The paper describes the way of linking and compiling of the relay model with ATP. Next, a multifunctional digital relay developed model is introduced with its functional elements, used algorithms and tripping characteristics. Simulation results are presented and correct tripping action is verified at the end.