The rise of Renewable Energy Sources (RES) connected to the distribution sys- tem, either alongside or replacing traditional turbine-generator power plants, is leading to Low-Inertia Power Systems. These systems require the development of innovative solutions to effectively manage frequency stability. The Real Time Simulation (RTS ) is a fundamental tool for testing and enhancing strategies and hardware solutions before their implementation on the field. This work examines the various aspects of implementing a RTS for a distribution electrical grid, covering from the theoretical foundations of simulations to the prac- tical application of a model using an OPAL-RT simulator. Modeling a distribution power network poses unique challenges compared to the more commonly simulated transmission grids.