Understanding Impacts of Frequency Calculations on Underfrequency Load Shedding

Research output: Contribution to conferencePaperpeer-review


Power system fundamental frequency-dependent protection decisions and control decisions are increasingly common in the distribution system space. Understanding the algorithms used in frequency measurements is critical to understanding the decisions made by the many intelligent electronic devices in the power system. These decisions are critically important for reliability analysis for interconnected power systems as they bear directly on resource planning to mitigate under-frequency conditions that would result in under-frequency load shedding (UFLS). This work aims to improve the understanding of frequency measurement algorithms, evaluate the intelligent electronic devices that use frequency measurements for decision making, and understand the algorithms' direct impact on frequency related decision making. First, this work presents background information on the use of frequency measurements in protection logic, specifically UFLS. Second, the paper presents a relay hardware evaluation test bed used to detect and protect systems from under-frequency events. Finally, the paper presents the dynamic events used to evaluate commercially available, off-the-shelf relay equipment and the results from the relay evaluation.

Original languageAmerican English
Number of pages5
StatePublished - 2023
Event2023 IEEE Rural Electric Power Conference, REPC 2023 - Cleveland, United States
Duration: 25 Apr 202327 Apr 2023


Conference2023 IEEE Rural Electric Power Conference, REPC 2023
Country/TerritoryUnited States

Bibliographical note

Publisher Copyright:
© 2023 IEEE.

NREL Publication Number

  • NREL/CP-5D00-85523


  • COMTRADE playback
  • controller evaluation
  • frequency measurement
  • phase-locked loop
  • relay evaluation
  • under-frequency load shedding


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