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Frequency estimation by demodulation of two complex signals

Akke, Magnus LU (1997) IEEE Summer Meeting In IEEE Transactions on Power Delivery 12(1). p.157-163
Abstract
This paper presents a method for frequency estimation in a power system by demodulation of two complex signals. In power system analysis, the αβ-transform is used to convert three phase quantities to a complex quantity where the real part is the in-phase component and the imaginary part is the quadrature component. This complex signal is demodulated with a known complex phasor rotating in opposite direction to the input. The advantage of this method is that the demodulation does not introduce a double frequency component. For signals with high signal to noise ratio, the filtering demand for the double frequency component can often limit the speed of the frequency estimator. Hence, the method can improve fast frequency estimation of signals... (More)
This paper presents a method for frequency estimation in a power system by demodulation of two complex signals. In power system analysis, the αβ-transform is used to convert three phase quantities to a complex quantity where the real part is the in-phase component and the imaginary part is the quadrature component. This complex signal is demodulated with a known complex phasor rotating in opposite direction to the input. The advantage of this method is that the demodulation does not introduce a double frequency component. For signals with high signal to noise ratio, the filtering demand for the double frequency component can often limit the speed of the frequency estimator. Hence, the method can improve fast frequency estimation of signals with good noise properties. The method loses its benefits for noisy signals, where the filter design is governed by the demand to filter harmonics and white noise. The method has been previously published, but not explored to its potential. The paper presents four examples to illustrate the strengths and weaknesses of the method. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
demodulation filtering theory frequency estimation parameter estimation power systems signal processing
in
IEEE Transactions on Power Delivery
volume
12
issue
1
pages
157 - 163
publisher
IEEE--Institute of Electrical and Electronics Engineers Inc.
conference name
IEEE Summer Meeting
external identifiers
  • scopus:0030779305
ISSN
1937-4208
DOI
10.1109/61.568235
language
English
LU publication?
yes
id
80c46c6c-970a-4bb0-8edf-56fa7396cce0 (old id 4589044)
date added to LUP
2014-08-25 11:44:59
date last changed
2017-07-23 03:56:40
@article{80c46c6c-970a-4bb0-8edf-56fa7396cce0,
  abstract     = {This paper presents a method for frequency estimation in a power system by demodulation of two complex signals. In power system analysis, the αβ-transform is used to convert three phase quantities to a complex quantity where the real part is the in-phase component and the imaginary part is the quadrature component. This complex signal is demodulated with a known complex phasor rotating in opposite direction to the input. The advantage of this method is that the demodulation does not introduce a double frequency component. For signals with high signal to noise ratio, the filtering demand for the double frequency component can often limit the speed of the frequency estimator. Hence, the method can improve fast frequency estimation of signals with good noise properties. The method loses its benefits for noisy signals, where the filter design is governed by the demand to filter harmonics and white noise. The method has been previously published, but not explored to its potential. The paper presents four examples to illustrate the strengths and weaknesses of the method.},
  author       = {Akke, Magnus},
  issn         = {1937-4208},
  keyword      = {demodulation filtering theory frequency estimation parameter estimation power systems signal processing},
  language     = {eng},
  number       = {1},
  pages        = {157--163},
  publisher    = {IEEE--Institute of Electrical and Electronics Engineers Inc.},
  series       = {IEEE Transactions on Power Delivery},
  title        = {Frequency estimation by demodulation of two complex signals},
  url          = {http://dx.doi.org/10.1109/61.568235},
  volume       = {12},
  year         = {1997},
}