Online Estimation of POI-Level Aggregated Inertia Considering Frequency Spatial Correlation

Online estimation of power system inertia provides the essential basis for frequency stability analysis and control. This paper proposes an approach to estimate the aggregated inertia at the point of interconnection (POI), which can be further used to calculate the power system total inertia and to monitor the inertia spatial distribution. Based on the spatial correlation of the power system frequency, the general correlation between the rotor speed and network bus frequency is derived. Furthermore, the phasor measurement unit placement principle for inertia estimation is given, and the impacts of redundant and lacking frequency measurement are analyzed. The proposed method is designed for the field implementation scenario, where ambient measurement data are used and the requirement for mechanical power measurement is relaxed. Simulation results carried out on the modified IEEE 39-bus System show that the proposed approach can accurately estimate POI-level inertia under different conditions, including poor data quality, lacking POI frequency, parameter and topology error, and renewable power generation penetration.