Reliable Rate-of-Change-of-Frequency Measurements: Use Cases and Test Conditions

Gert Rietveld,Andrew J. Roscoe,Paul S. Wright

doi:10.1109/tim.2020.2986069

Gert Rietveld, Andrew J. Roscoe + Show 1 more

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https://doi.org/10.1109/tim.2020.2986069

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Abstract

Based on user expectations and requirements, this article discusses three use cases (UCs) for measurements of power system frequency and rate-of-change-of-frequency (ROCOF) measurements, specifying accuracy and latency requirement for each UC. Furthermore, a set of realistic test conditions are proposed, extending those of the present IEC/IEEE 60255-118-1 standard, to ensure ROCOF measuring instruments are adequately tested on their suitability for reliable ROCOF measurements in power systems. Target worst case ROCOF errors (RFEs) are given for each test waveform and UC. Several published ROCOF algorithms are tested using the proposed test conditions. A selection of the test results is reported and compared against the target RFEs. The results show that the defined tests are indeed helpful in evaluating the ROCOF algorithms, and furthermore that the algorithms can be designed to meet all the requirements on RFEs for the tests proposed in this article.

Highlights

P OWER system frequency and rate-of-change-offrequency (ROCOF) are important metrics in the context of increasing levels of distributed generation; they are used as inputs to control systems for protection, power balance management, and provision of system inertia of electricity grids [1]–[4].As with any measurand, a user would ideally wish for noise- and error-free data which are available with minimum delay
We extend this work with the presentation of a full set of phasor measurement units (PMUs) test signals, extending those of the present IEC/IEEE 60255-118-1 standard, including an evaluation of the accuracies achieved by three different synchrophasor algorithms under these conditions for three different use-case (UC) scenarios
4) Discussion: The test results are a useful comparison of three different algorithms and their implementations for the THE MINIMUM AND MAXIMUM ROCOF RECORDED VALUES, RESPECTIVELY

Summary

Introduction

P OWER system frequency and rate-of-change-offrequency (ROCOF) are important metrics in the context of increasing levels of distributed generation; they are used as inputs to control systems for protection, power balance management, and provision of system inertia of electricity grids [1]–[4]. A user would ideally wish for noise- and error-free data which are available with minimum delay (or latency). The measurement of frequency and ROCOF is sensitive to power system disturbances and noise. Since they are the first and second derivatives of the measured phase, any noise in the Manuscript received December 2, 2019; revised February 6, 2020; accepted March 9, 2020. Date of publication April 6, 2020; date of current version August 11, 2020. The Associate Editor coordinating the review process was Ferdinanda Ponci. (Corresponding author: Gert Rietveld.)

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