Work

A unified framework for co-optimization of PFR and FFR reserves using linearized tri-criteria frequency constraints

Year: 2025

Type: article

Abstract: The increasing penetration of inverter-based resources reduces system inertia and heightens concerns about frequency stability. This paper proposes a systematic methodology for jointly optimizing primary frequency response (PFR) and fast frequency response (FFR) reserves so that three critical stability metrics—rate of change of frequency (RoCoF), frequency nadir, and quasi-steady-state (QSS) frequency—are simultaneously satisfied within linear constraints. Based on a simplified system frequency response (SSFR) model, dynamic simulations are used to derive multi-criteria PFR-FFR equivalency ratios and establish corresponding linear reserve requirement constraints that add no integer variables to existing optimization models. In tariff-based ancillary service markets like Korea’s, the methodology identifies optimal reserve combinations using the derived multi-criteria equivalency ratios and tariff levels. In security-constrained economic dispatch (SCED)-based co-optimization, integrating these linear reserve constraints ensures all stability thresholds are met across various inertia levels, outperforming the current approach adopted by ERCOT. The framework therefore offers a practical, market-ready tool for optimizing frequency reserves procurement in low-inertia power systems.

Source: International Journal of Electrical Power & Energy Systems

DOI: 10.1016/j.ijepes.2025.111392

Authors: Jongin Kim, Jae Woong Shim, Hunyoung Shin

Institutions: Hongik University, Sangmyung University

Language: English

Topic: Frequency Control in Power Systems

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Affordable and clean energy, Industry, innovation and infrastructure

Open Access status: gold

Estimated APC paid: $3,920