  The increasing integration of power electronic devices is driving the
development of more advanced tools and methods for the modeling, analysis, and
control of modern power systems to cope with the different time-scale
oscillations. In this paper, we propose a general methodology based on the
singular perturbation theory to reduce the order of systems modeled by ordinary
differential equations and the computational burden in their simulation. In
particular, we apply the proposed methodology to a simplified power system
scenario comprised of three inverters in parallel---controlled as
synchronverters---connected to an ideal grid. We demonstrate by time-domain
simulations that the reduced and decoupled system obtained with the proposed
approach accurately represents the dynamics of the original system because it
preserves the non-linear dynamics. This shows the efficiency of our technique
even for transient perturbations and has relevant applications including the
simplification of the Lyapunov stability assessment or the design of non-linear
controllers for large-scale power systems.
