Synchronization in a power balance system with inertia and nonlinear derivatives

We consider synchronization of the all-to-all power grid model with inertia and nonlinear terms of the first- and second-order derivatives. This model was derived from the energy conservation law in [G. Filatrella, A. H. Nielsen, and N. F. Pedersen, Eur. Phys. J. B, 61 (2008), pp. 485-491]. Since the model contains a nonlinear differential operator, we cannot use a Lyapunov functional and an a priori estimate method directly. In this paper, we provide a new framework to obtain complete phase and frequency synchronization of the power grid model. We assume that the coupling strength and the moment of inertia are positive and the initial data are near the synchronization state. After applying an appropriate transform, we derive a system of differential equations whose coefficient matrix is negative definite. The initial data assumption and the negative definite coefficient matrix lead to the global existence and synchronization of the power grid model with a nonlinear differential operator. For both identical and nonidentical cases, the exponential decay for the frequency difference is determined and the square of frequencies converges to the average of the normalized energy feeding rates.