Impedance-Based Online Estimation of Nodal Inertia and Primary Frequency Regulation Capability

Wuqi Zhang, Yunfeng Wen, C. Y. Chung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

10 Citations (Scopus)


Accurate estimation of inertia and primary frequency regulation (PFR) capability is important to ensure frequency stability in low-inertia power systems. This paper investigates how the inertia and PFR capability of a power source node can be evaluated using a non-invasive online estimation method from the impedance perspective. Based on small perturbation injection, a novel approximate relationship between the impedance and corresponding frequency response transfer function (FR(s)) is deduced. The features of the FR(s)'s magnitude response curve, i.e., resonance frequency and DC gain, are then used to develop an overall implementation framework for nodal inertia and PFR capability estimation in real time. This method provides new insights with respect to obtain the synchronous and non-synchronous converter interfaced generator's inertia constant and PFR capability for grid operators via impedance calculation and measurements. Case studies on a modified 9-bus system and NETS-NYPS 68-bus system demonstrate the effectiveness of the proposed impedance-based estimation approach.

Original languageEnglish
Article number9807390
Pages (from-to)2748-2760
Number of pages13
JournalIEEE Transactions on Power Systems
Issue number3
Publication statusPublished - 1 May 2023


  • Inertia estimation
  • low-inertia power systems
  • primary frequency regulation capability
  • renewable energy sources

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


Dive into the research topics of 'Impedance-Based Online Estimation of Nodal Inertia and Primary Frequency Regulation Capability'. Together they form a unique fingerprint.

Cite this