Power Margin Ratio -- A Large-Signal System Strength Metric for Inverter-Based Resources-Dominated Power Systems

Fuente: arXiv
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Autores principales: Qiu, Zitian, Gu, Yunjie
Formato: Preprint
Publicado: 2026
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author Qiu, Zitian
Gu, Yunjie
author_facet Qiu, Zitian
Gu, Yunjie
contents As the growing penetration of inverter-based resources (IBRs) in modern power systems, the system strength is decreasing. Due to the inherent difference in short-circuit capacity contributions of synchronous generators and inverters, the short-circuit ratio is not a one-size-fit-all metric to assess the system strength. Following the distinct dynamic behavior of the IBR in small- and large-signal disturbance, the system strength is separated accordingly. To address the large-signal system strength assessment, a control type-dependent metric, Power Margin Ratio (PMR), is proposed in this paper. PMR is defined as the ratio between the maximum power that can be injected to the system without causing any instability and the nominal power of the IBR. It can be obtained via power flow calculation with a modified algorithm. The theoretical foundation of PMR is established from the viewpoint of dynamical systems. PMR is identical to SCR for the single-plant-infinite-bus system, while presents advancement for multi-infeed power systems. Comprehensive case studies and discussions have validated that PMR reveals the large-signal system strength from a static perspective.
format Preprint
id arxiv_https___arxiv_org_abs_2602_11429
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Power Margin Ratio -- A Large-Signal System Strength Metric for Inverter-Based Resources-Dominated Power Systems
Qiu, Zitian
Gu, Yunjie
Systems and Control
As the growing penetration of inverter-based resources (IBRs) in modern power systems, the system strength is decreasing. Due to the inherent difference in short-circuit capacity contributions of synchronous generators and inverters, the short-circuit ratio is not a one-size-fit-all metric to assess the system strength. Following the distinct dynamic behavior of the IBR in small- and large-signal disturbance, the system strength is separated accordingly. To address the large-signal system strength assessment, a control type-dependent metric, Power Margin Ratio (PMR), is proposed in this paper. PMR is defined as the ratio between the maximum power that can be injected to the system without causing any instability and the nominal power of the IBR. It can be obtained via power flow calculation with a modified algorithm. The theoretical foundation of PMR is established from the viewpoint of dynamical systems. PMR is identical to SCR for the single-plant-infinite-bus system, while presents advancement for multi-infeed power systems. Comprehensive case studies and discussions have validated that PMR reveals the large-signal system strength from a static perspective.
title Power Margin Ratio -- A Large-Signal System Strength Metric for Inverter-Based Resources-Dominated Power Systems
topic Systems and Control
url https://arxiv.org/abs/2602.11429