Probabilistic Frequency Hazard Analysis: Adapting the Seismic Hazard Framework to Power System Frequency Exceedance Risk

Abstract

The declining synchronous inertia in power systems undergoing the energy transition increases the sensitivity of system frequency to generation and interconnector disturbances, making accurate frequency risk quantification increasingly important. Existing methods for frequency risk assessment, while valuable, lack formal uncertainty quantification, continuous hazard curves, and source-level disaggregation. This paper introduces Probabilistic Frequency Hazard Analysis (PFHA), a framework that adapts the mathematical architecture of Probabilistic Seismic Hazard Analysis (PSHA), the standard methodology in earthquake engineering, to power system frequency exceedance risk. The PFHA hazard integral computes annual exceedance rates by integrating over all combinations of loss sources, disturbance sizes, and system operating states through a frequency response prediction equation with calibrated aleatory variability. The framework is implemented with a 51-source catalogue constructed from operational data, empirical loss distributions from settlement-period generation records, Bayesian occurrence rate estimation, a dual analytical and physics-based frequency response prediction architecture, and a 324-path logic tree for epistemic uncertainty quantification. Application to the Great Britain power system using four years of operational data demonstrates agreement with the independently developed Frequency Risk and Control Report to within a factor of 1.5 at 49.2 Hz, while also quantifying the risk reduction from Dynamic Containment and Low-Frequency Demand Disconnection controls. To the author's knowledge, this is the first published explicit PSHA-style hazard-integral formulation for bulk power-system frequency exceedance risk.