The case for redefinition of frequency and ROCOF to account for AC power system phase steps

Andrew J. Roscoe, Adam Dyśko, Ben Marshall, Martin Lee, Harold Kirkham, Gert Rietveld

Research output: Contribution to conferencePaper

24 Citations (Scopus)
119 Downloads (Pure)

Abstract

All conventional techniques for measuring frequency result in large deviations to the perceived or calculated frequency when the AC waveform undergoes a phase step. The deviation magnitude and duration are dependent on the phase step magnitude, and the applied windowing/filtering. Such phase steps do occur in the power system, and the erroneous frequency calculation can result in inappropriate reactions by some rapidly-responding control and protection systems. If the frequency measurand is further differentiated to ROCOF (Rate of Change of Frequency), the excursion magnitudes can become far larger than any normally expected values of ROCOF. This paper discusses the meaning of the terms frequency and ROCOF, and presents a modified concept of frequency and ROCOF. This is done by allowing rapid phase steps to be disaggregated from frequency in the AC waveform model equation. This allows new measurands “underlying frequency”, and “underlying ROCOF” to be defined, as a pair of linked parameters, independent from a separate dynamic phase parameter. These new measurands have the potential to offer much more useful and stable information to be sent to fast-acting control and protection systems, than the existing measurands of AC frequency and ROCOF, particularly during fault events and large switching or disconnection events.
Original languageEnglish
Number of pages6
DOIs
Publication statusPublished - 20 Sep 2017
Event2017 IEEE International Workshop on Applied Measurements for Power Systems - Liverpool, United Kingdom
Duration: 20 Sep 201722 Sep 2017
http://2017.amps.ieee-ims.org/

Conference

Conference2017 IEEE International Workshop on Applied Measurements for Power Systems
Abbreviated titleAMPS
CountryUnited Kingdom
CityLiverpool
Period20/09/1722/09/17
Internet address

Keywords

  • frequency estimation
  • power system control
  • power system faults
  • power system protection
  • reliability
  • rate of change of frequency

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  • Projects

    Research Output

    • 24 Citations
    • 1 Paper

    Smart grid measurement uncertainty: definitional and influence quantity considerations

    Dickerson, W., Goldstein, A., Kirkham, H., Martin, K., Roscoe, A., de Vries, R. & Wright, P., 5 Mar 2018, (Accepted/In press). 5 p.

    Research output: Contribution to conferencePaper

    Open Access
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  • Cite this

    Roscoe, A. J., Dyśko, A., Marshall, B., Lee, M., Kirkham, H., & Rietveld, G. (2017). The case for redefinition of frequency and ROCOF to account for AC power system phase steps. Paper presented at 2017 IEEE International Workshop on Applied Measurements for Power Systems, Liverpool, United Kingdom. https://doi.org/10.1109/AMPS.2017.8078330