Ambient PMU Measurements Based Online Regional Inertia Estimation and Monitoring

Accurate inertia estimation is essential to secure and reliable operation of Inverter Based Resource (IBR)-dominated grid. This paper proposes a method to continuously estimate regional inertia using ambient data collected by Phasor Measurement Units (PMUs). This method estimates the regional equivalent rotor speed using frequency measurements and the network admittance matrix based on the frequency divider formula (FDF). This method also estimates the load power response using voltage measurements and estimates the mechanical power using a linear aggregated governor model. The system identification technique is used to depict the relationship between the estimated equivalent rotor speed and the active power imbalance, and then estimated the regional inertia with a sliding data window. The performance of the proposed method has been evaluated using ambient data from the 2000-bus synthetic Texas grid model. The results demonstrate that the mechanical power, load power, and equivalent rotor speed estimation can significantly improve the accuracy.