Electric power-system's global-inertia estimation

This work presents a technique to estimate on-line the global inertia of an electric power system by exploiting the footprint of the principal frequency system dynamics. This method can estimate the inertia provided as a whole by synchronous machines, as well as by converter-interfaced generators controlled to emulate the behavior of the former through virtual inertia. Probing tones are injected by a grid-forming converter-interfaced generator and its virtual rotor speed is used to extrapolate its footprint. As a result, the method requires neither measuring the active power exchange of each synchronous generator nor extrapolating their rotor speeds. Since the proposed technique is entirely data driven, it does not require any model of the power system generators/prime-movers/controllers and of the interconnecting grid. The method is comprehensively tested on a modified version of the IEEE 39-BUS system and a dynamic version of the IEEE 118-BUS system, both containing grid-forming converter-interfaced generators.