Protection relay software models in interaction with power system simulators

Modelling and simulation software developed for analysing protective relaying applications and relay design concepts in power distribution is described in the paper. The intention was to develop an open system that is easy to use and allows simple future expansions. Easy to use presumes that the software should be suitable for teaching purposes. This is achieved by introducing new libraries of signal sources and relay elements developed in the MATLAB/SIMULINK environment. Combined with the SIMULINK/SimPowerSystems, the mentioned libraries enable a variety of studies aimed at better understanding protective relay design approaches and procedures and related applications in power system.