The Limitations of Net Load as Predictor of Power System Inertia

The integration of converter-based generation is displacing traditional energy sources, reducing the rotational inertia within power systems. Inertia has an important role in the stability of power systems; it is important to monitor its behavior. In this context, inertia is usually related to system net load, because the net load level is associated with the number of synchronous units online as a proxy of system inertia. However, when actual data from power systems is considered, the relationship between inertia and net load is not direct, and net load becomes a limited predictor of system inertia.This work explores the limitations of net load as a predictor of system inertia, given its importance for power system stability. In particular, this work considers the influence of data-driven estimation algorithms and unit commitment, in terms of describing the discrepancy between inertia and net load. To conduct this analysis, actual data from the PMU and SCADA systems of the Chilean power systems are considered.