**2. Electric Grid Operation and Control**

Transient stability in large-scale power system is usually demonstrated by time domain simulations over a range of operating conditions and perturbations due to the complexity to dealing with large non-linear models associated to the power systems. Typically, the most demanding scenarios are first analyzed to have the power system with good dynamic performance, and then, similar or better behavior is expected when less demand occurs.

On the other hand, the classical stability analysis based on the power system linearized model has high complexity to attain an accurate linearized model, moreover, new components integration, and the consideration of continuous grid change involves new equilibrium points. These aspects represent another important open research topic.

Thus, we used a complete non-linear representation for transient stability studies in large-scale power system. Besides that, our proposal is proved under three phase faults, which are considered severe disturbances. The solution under these considerations is gotten by numerical methods involving a set of non-linear differential equations modeling all grid components with dynamic behavior.

Some models available in the literature are used to evaluate the proposed strategy. Additionally, the steady state condition and dynamic performance of the power system with excitation is developed in PSS® E. The results gotten are consistent in our simulation platform and the commercial software.
