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

Roscoe, Andrew J. and Dyśko, Adam and Marshall, Ben and Lee, Martin and Kirkham, Harold and Rietveld, Gert (2017) The case for redefinition of frequency and ROCOF to account for AC power system phase steps. In: 2017 IEEE International Workshop on Applied Measurements for Power Systems, 2017-09-20 - 2017-09-22. (https://doi.org/10.1109/AMPS.2017.8078330)

[thumbnail of Roscoe-etal-AMPS-2017-redefinition-of-frequency-and-ROCOF-to-account-for-AC-power-system-phase-steps]
Preview
 Text. Filename: Roscoe_etal_AMPS_2017_redefinition_of_frequency_and_ROCOF_to_account_for_AC_power_system_phase_steps.pdf
Accepted Author Manuscript
Download (921kB)| Preview

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.

ORCID iDs

Roscoe, Andrew J. ORCID logoORCID: https://orcid.org/0000-0003-1108-4265, Dyśko, Adam ORCID logoORCID: https://orcid.org/0000-0002-3658-7566, Marshall, Ben, Lee, Martin, Kirkham, Harold and Rietveld, Gert;
  • Item type:Conference or Workshop Item(Paper)
    ID code:61522
    Dates:
    Date
    Event
    20 September 2017
    Published
    8 August 2017
    Accepted
    Notes:(c) 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.
    Subjects:Technology > Electrical engineering. Electronics Nuclear engineering
    Department:Faculty of Engineering > Electronic and Electrical Engineering
    Depositing user: Pure Administrator
    Date deposited:08 Aug 2017 15:25
    Last modified:13 Nov 2024 01:35
    URI:https://strathprints.strath.ac.uk/id/eprint/61522
CORE (COnnecting REpositories)