An Efficient Method for Computing Exact Delay-Margins of Large-Scale Power Systems

Chongtao Li*, Chao Duan, Yulei Cao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


This letter proposes an efficient method for com-puting the delay-margins of large-scale power systems with single constant delay. The method computes the margin by identifying the minimal delay under which some eigenvalues are about to cross the imaginary axis from the left to the right half complex plane. Based on the Rekasius substitution, a new characterization for the crossing points is developed, followed by a method for determining the delay margins. The method only involves eigen-value decomposition on a low-order matrix whose dimension is independent of the system scale. Further leveraging the sparsity of power systems makes it computationally very attractive for practical large-scale system applications.

Original languageEnglish (US)
Article number9144478
Pages (from-to)4924-4927
Number of pages4
JournalIEEE Transactions on Power Systems
Issue number6
StatePublished - Nov 2020


  • Rekasius substitution
  • Time-delay
  • constant delay
  • delay-margin
  • power systems

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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