An analytical method for nodal inertia estimation of power systems

Abstract

The significance of system inertia, especially its non-uniform spatial distribution, is becoming paramount in the current power system scenario. The scope of inertia estimation has traditionally been the estimation of overall or total system inertia. However, as frequency dynamics become increasingly localized with increasing penetration of inverter-based resources (IBRs), the need for higher spatial resolution (geographically localized estimate) and faster temporal resolution (online or continuous estimate) in inertia estimation becomes paramount. This paper proposes an analytical method to estimate the spatial inertia distribution down to the transmission node level, i.e., nodal inertia. Depending on data availability, the proposed method is flexible and can be used in two ways: φ to estimate nodal inertia for any given operating condition (or snapshot), or φ to continuously estimate nodal inertia for both ambient and transient conditions using available local phasor measurement unit (PMU) measurements. The novelty of the proposed method lies in its analytical formulation, which does not require rate of change of frequency (ROCOF) measurements or rate of change of power injections, making it immune to the noise associated with the estimation of these derived quantities. Additionally, the proposed method does not require defining near-zero ROCOF thresholds, which is system-specific and a non-trivial problem. The proposed method is mode-agnostic, which makes it more general than dominant mode-based linearized methods. The applicability of the proposed method is demonstrated through simulation studies performed on the IEEE 39-bus and IEEE 68-bus test systems with varying IBR penetration levels. The robustness of the method is numerically assessed against modeling and measurement uncertainties.

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Identifiers

ORCID for Debargha Brahma: orcid.org/0000-0003-2810-4322

ORCID for Abhinav Kumar Singh: orcid.org/0000-0003-3376-6435

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