Mapping Grid Inertia: A Deterministic Graph-Theoretic Framework for Coherent Partitioning and RCOI Identification

Abstract: Integrating spectral centrality with an enhanced label propagation technique, a graph-based methodology for regional frequency assessment is presented in this paper. The method identifies two quantities: the system centre of inertia and the coherent electrical communities from which regional centres of inertia are then derived. Generator bus locations and branch admittances are analysed to begin the approach, after which the network is partitioned into clusters that exhibit consistent dynamic behaviour. From these clusters, regional centres of inertia (RCOIs) are identified. Optimisation of the placement of phasor measurement units (PMUs) for monitoring is carried out by the framework. Through validation using the NETS-NYPS benchmark system, appropriate performance is demonstrated by the results. Confirmation of the precision of the identified regional centres of inertia is provided by the RMSE between the analytical COI frequency and the RCOI frequency. Real-time frequency tracking is improved when PMUs are deployed and effective network clustering methods are used, and grid stability is thereby helped to be maintained.