Dealing with front-end white noise on differentiated measurements such as  frequency and ROCOF in power systems

Andrew J. Roscoe; Steven M. Blair; William Dickerson; Gert Rietveld

doi:10.1109/TIM.2018.2822438

Dealing with front-end white noise on differentiated measurements such as frequency and ROCOF in power systems

Andrew J. Roscoe, Steven M. Blair, William Dickerson, Gert Rietveld

Electronic And Electrical Engineering

Research output: Contribution to journal › Article

1 Citation (Scopus)

Abstract

This paper describes the way that white noise (including quantised input section sampling) imparts errors onto frequency and rate-of-change-of-frequency (ROCOF) measurements. The main paper focus concerns the use of filtered heterodyned (i.e. Fourier) analyses for single-phase and 3-phase systems, and the filtered Clarke transform for 3-phase systems. The rules and equations governing the effect of white noise on frequency and ROCOF are formulated for these techniques, explaining the subtle effects of aliasing, splitting signals and noise into their positive and negative frequency components, and the correlation or de-correlation of noise. It is shown that - as expected - for 3-phase AC measurements, averaging 3 single-phase Fourier measurements produces the same performance against noise as using a method based on Clarke’s transform, if identical filtering is used. Furthermore, by understanding the theory behind the frequency and ROCOF measurement processes, it is shown that to achieve the lowest RMS errors, in the presence of front-end white noise (alone, ignoring other dynamic signal and power quality aspects), a filter which provides ~40 dB/decade attenuation (i.e. a 2-boxcar cascade) is recommended for a frequency measurement, but a filter which rolls off at ~60 dB/decade (i.e. a 3-boxcar cascade) is recommended for a ROCOF measurement.

Language	English
Number of pages	14
Journal	IEEE Transactions on Instrumentation and Measurement
Early online date	25 Apr 2018
DOIs	10.1109/TIM.2018.2822438
Publication status	E-pub ahead of print - 25 Apr 2018

Fingerprint

frequency measurement

White noise

white noise

cascades

filters

Power quality

alternating current

attenuation

sampling

Sampling

Keywords

frequency measurement
frequency estimation
white noise
Gaussian noise
colored noise
signal to noise ratio
power system measurements
finite impulse response filters
Fourier transforms
phasor measurement units

Cite this

Roscoe, A. J., Blair, S. M., Dickerson, W., & Rietveld, G. (2018). Dealing with front-end white noise on differentiated measurements such as frequency and ROCOF in power systems. IEEE Transactions on Instrumentation and Measurement . https://doi.org/10.1109/TIM.2018.2822438

Roscoe, Andrew J. ; Blair, Steven M. ; Dickerson, William ; Rietveld, Gert. / Dealing with front-end white noise on differentiated measurements such as frequency and ROCOF in power systems. In: IEEE Transactions on Instrumentation and Measurement . 2018.

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abstract = "This paper describes the way that white noise (including quantised input section sampling) imparts errors onto frequency and rate-of-change-of-frequency (ROCOF) measurements. The main paper focus concerns the use of filtered heterodyned (i.e. Fourier) analyses for single-phase and 3-phase systems, and the filtered Clarke transform for 3-phase systems. The rules and equations governing the effect of white noise on frequency and ROCOF are formulated for these techniques, explaining the subtle effects of aliasing, splitting signals and noise into their positive and negative frequency components, and the correlation or de-correlation of noise. It is shown that - as expected - for 3-phase AC measurements, averaging 3 single-phase Fourier measurements produces the same performance against noise as using a method based on Clarke’s transform, if identical filtering is used. Furthermore, by understanding the theory behind the frequency and ROCOF measurement processes, it is shown that to achieve the lowest RMS errors, in the presence of front-end white noise (alone, ignoring other dynamic signal and power quality aspects), a filter which provides ~40 dB/decade attenuation (i.e. a 2-boxcar cascade) is recommended for a frequency measurement, but a filter which rolls off at ~60 dB/decade (i.e. a 3-boxcar cascade) is recommended for a ROCOF measurement.",

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note = "(c) 2018 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.",

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Roscoe, AJ, Blair, SM, Dickerson, W & Rietveld, G 2018, 'Dealing with front-end white noise on differentiated measurements such as frequency and ROCOF in power systems' IEEE Transactions on Instrumentation and Measurement . https://doi.org/10.1109/TIM.2018.2822438

Dealing with front-end white noise on differentiated measurements such as frequency and ROCOF in power systems. / Roscoe, Andrew J.; Blair, Steven M.; Dickerson, William; Rietveld, Gert.

In: IEEE Transactions on Instrumentation and Measurement , 25.04.2018.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Dealing with front-end white noise on differentiated measurements such as frequency and ROCOF in power systems

AU - Roscoe, Andrew J.

AU - Blair, Steven M.

AU - Dickerson, William

AU - Rietveld, Gert

N1 - (c) 2018 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.

PY - 2018/4/25

Y1 - 2018/4/25

N2 - This paper describes the way that white noise (including quantised input section sampling) imparts errors onto frequency and rate-of-change-of-frequency (ROCOF) measurements. The main paper focus concerns the use of filtered heterodyned (i.e. Fourier) analyses for single-phase and 3-phase systems, and the filtered Clarke transform for 3-phase systems. The rules and equations governing the effect of white noise on frequency and ROCOF are formulated for these techniques, explaining the subtle effects of aliasing, splitting signals and noise into their positive and negative frequency components, and the correlation or de-correlation of noise. It is shown that - as expected - for 3-phase AC measurements, averaging 3 single-phase Fourier measurements produces the same performance against noise as using a method based on Clarke’s transform, if identical filtering is used. Furthermore, by understanding the theory behind the frequency and ROCOF measurement processes, it is shown that to achieve the lowest RMS errors, in the presence of front-end white noise (alone, ignoring other dynamic signal and power quality aspects), a filter which provides ~40 dB/decade attenuation (i.e. a 2-boxcar cascade) is recommended for a frequency measurement, but a filter which rolls off at ~60 dB/decade (i.e. a 3-boxcar cascade) is recommended for a ROCOF measurement.

AB - This paper describes the way that white noise (including quantised input section sampling) imparts errors onto frequency and rate-of-change-of-frequency (ROCOF) measurements. The main paper focus concerns the use of filtered heterodyned (i.e. Fourier) analyses for single-phase and 3-phase systems, and the filtered Clarke transform for 3-phase systems. The rules and equations governing the effect of white noise on frequency and ROCOF are formulated for these techniques, explaining the subtle effects of aliasing, splitting signals and noise into their positive and negative frequency components, and the correlation or de-correlation of noise. It is shown that - as expected - for 3-phase AC measurements, averaging 3 single-phase Fourier measurements produces the same performance against noise as using a method based on Clarke’s transform, if identical filtering is used. Furthermore, by understanding the theory behind the frequency and ROCOF measurement processes, it is shown that to achieve the lowest RMS errors, in the presence of front-end white noise (alone, ignoring other dynamic signal and power quality aspects), a filter which provides ~40 dB/decade attenuation (i.e. a 2-boxcar cascade) is recommended for a frequency measurement, but a filter which rolls off at ~60 dB/decade (i.e. a 3-boxcar cascade) is recommended for a ROCOF measurement.

KW - frequency measurement

KW - frequency estimation

KW - white noise

KW - Gaussian noise

KW - colored noise

KW - signal to noise ratio

KW - power system measurements

KW - finite impulse response filters

KW - Fourier transforms

KW - phasor measurement units

UR - http://dx.doi.org/10.21227/H20926

UR - http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=19