An Algorithmic Approach for Identifying Critical Distance Relays for Transient Stability Studies

Ramin Vakili, Mojdeh Khorsand, Vijay Vittal, Bill Robertson, Philip Augustin

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


After major disturbances, power system behavior is governed by the dynamic characteristics of its assets and protection schemes. Therefore, modeling protection devices is essential for performing accurate stability studies. Modeling all the protection devices in a bulk power system is an intractable task due to the limitations of current stability software, and the difficulty in updating the setting data for thousands of protection devices. One of the critical protection schemes that is not adequately modeled in stability studies is distance relaying. Therefore, this paper proposes an iterative algorithm that uses two methods to identify the critical distance relays to be modeled in stability studies: (i) apparent impedance monitoring, and (ii) the minimum voltage evaluation (MVE). The algorithm is implemented in Python 3.6 and uses the GE positive sequence load flow analysis (PSLF) software for performing stability studies. The performance of the algorithm is evaluated on the Western Electricity Coordinating Council (WECC) system data representing the 2018 summer-peak load. The results of the case studies representing various types of contingencies show that to have an accurate assessment of system behavior, modeling the critical distance relays identified by the algorithm suffices, and there is no need for modeling all the distance relays.

Original languageEnglish (US)
Article number9373951
Pages (from-to)107-117
Number of pages11
JournalIEEE Open Access Journal of Power and Energy
StatePublished - 2021


  • Distance relays
  • identifying critical protective relays
  • minimum voltage evaluation
  • power system protection
  • power system stability
  • relay misoperation
  • transient stability study

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


Dive into the research topics of 'An Algorithmic Approach for Identifying Critical Distance Relays for Transient Stability Studies'. Together they form a unique fingerprint.

Cite this