Inertia Estimation of the 60 Hz Japanese Power System From Synchrophasor Measurements

This paper proposes a new approach to estimate the inertia of the 60 Hz Japanese power system from the background signals of phasor measurement units. Regarding the constraint boundaries, the entire system is divided into two control areas, which can be represented by an equivalent two-generator model based on small-signal stability analysis. The ambient inertia of each area, including both generation and demand sides can be estimated by measuring the corresponding phase difference and interchange power with respect to the extracted proportions of the frequency response, inter-area oscillation, and synchronizing power. Then, the sum of the estimated inertia for each area gives the total inertia of the entire 60 Hz system. The method was validated on the benchmark model of the Japan transmission network, and its sensitivity is evaluated by conducting various system operations on generator control effects. The efficiency and robustness were verified through real measurements under diverse system conditions. The results confirm that the developed approach can accurately estimate the system inertia during normal operation, enabling nearly continuous inertia tracking trajectory.