An Electric Power System (EPS) is a function of multivariable order in which the dynamic response is influenced by a wide range of devices with different characteristics and response times. Stability is a condition of balance between opposite active forces in the system. Depending on the network topology, operating conditions and the shape and magnitude of the disturbances, these opposing forces may experience the sustained imbalance that leads to various forms of instability. Currently, the EPS is changing its behavior from slow to fast dynamics due to the insertion of renewable energy sources and HVDC systems with power electronic converters. Additionally, the stability of the EPS can be assessed through offline simulation and mainly by reducing the detail of the elements to improve simulation times. However, these simplifications are no longer valid with the emergence of power converters in electrical systems. Indeed, phasor-type simulations are not capable of capturing fast dynamics, therefore they must be migrated to EMT-type simulations. For this reason, the simulation technique called Co- simulation that addresses this problem seeks to improve simulation times without losing the precision of the system state variables. This thesis presents different types of Co-simulation in the current EPS from coupling programs of different natures to models in different time scales. This work has also developed the different types of simulations and how they interact in the Co-simulation environment. On the other hand, the entire VSC structure has been developed which is a key element that has changed the behavior of the system dynamics. Finally, with all of the above, a way to represent the Co-simulation in EPS has been implemented. In this model, it has been concluded that fast dynamics in the EPS such as short circuits, Co- simulation provides better simulation times rather than EMT simulation but with errors. On the other hand, slow events such as changes in demand/generation continue to be valid phasor simulations since they are less demanding in simulation time and maintain the precision of the EMT model