Online optimal transmission line parameter estimation for relaying applications

Yuan Liao, Mladen Kezunovic

Research output: Contribution to journalArticlepeer-review

132 Scopus citations


Transmission line protective relaying algorithms usually require transmission line parameters as inputs and thus accuracy of line parameters plays a pivotal role in ensuring the reliable performance of relaying algorithms. Online estimation of line parameters is highly desirable and various methods have been proposed in the past. These methods perform well when the measurements utilized are accurate; they may yield erroneous results when the measurements contain considerable errors. Based on nonlinear optimal estimation theory, this paper puts forward an optimal estimator for deriving the positive sequence line parameters, capable of detecting and identifying the bad measurement data, minimizing the impacts of the measurement errors and thus significantly improving the estimation accuracy. The solution is based on the distributed parameter line model and thus fully considers the effects of shunt capacitances of the line. Case studies based on simulated data are presented for demonstrating the effectiveness of the new approach.

Original languageEnglish
Pages (from-to)96-102
Number of pages7
JournalIEEE Transactions on Power Delivery
Issue number1
StatePublished - 2009


  • Bad measurement detection and identification
  • Distributed parameter line model
  • Non-linear estimation theory
  • Transmission line parameter estimation

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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