Optimal Control of an Inverter-based Virtual Synchronous Generator with Inertial Response

Renewable energy sources are gradually replacing conventional synchronous generators, which are responsible for supplying the power grid inertia damping properties. This paper proposes a nonlinear optimal controller for a renewable energy generation system based on a power electronics inverter, in order to incorporate the system inertia behavior through imitating the rotor inertia of synchronous generators. The main contributions of this paper are: 1) the modeling and synthesis of a nonlinear optimal control scheme for a power inverter such that it dynamically behaves as a conventional synchronous generator, where the active and reactive power are regulated, and provides robustness against utility grid disturbances; 2) the dynamical modeling of the virtual inertia-based inverter generator and its corresponding response to power reference variations and utility grid voltage disturbances. Further, an analysis procedure is presented to compute a predefined value of the inverter inertia constant, proportional to the one that a synchronous generator could provide, but taking into account the rated power of the generator. Simulation results assess the proposed methodology effectiveness