Transient harmonics can be analyzed by short time Fourier Transform (STFT) and wavelet transform respectively. However, there are disadvantages in both of them. The former cannot have favorable result except for having a suitable window, and the latter cannot acquire single harmonic frequency and its amplitude. After comparing the advantages and disadvantages of STFT and wavelet transform which are used to analyze signal of transient harmonic in power system, combining their merits, a novel STFT based on the special frequency band is proposed in this paper. Multiresolution analysis is used to detect the fault time and determine the main frequency range of transient signal. Then the central point and proper width of window of STFT can be obtained. Consequently the accuracy and efficiency of STFT can be improved greatly, frequency components and its amplitudes of transient signal can be obtained accurately and quickly by this method. An on-line system to inspect and analyze transient waveform is designed based on LabVIEW, through which the feasibility and the accurateness of this method have been verified.
[1]
Kit Po Wong,et al.
Wavelet-transform-based algorithm for harmonic analysis of power system waveforms
,
1999
.
[2]
F. Brouaye,et al.
Fourier transform, wavelets, Prony analysis: tools for harmonics and quality of power
,
1998,
8th International Conference on Harmonics and Quality of Power. Proceedings (Cat. No.98EX227).
[3]
C. Parameswariah,et al.
Frequency Characteristics of Wavelets
,
2002,
IEEE Power Engineering Review.
[4]
Eugene Wong.
Frequency-Domain Analysis
,
1983
.
[5]
Michel Meunier,et al.
New signal processing tools applied to power quality analysis
,
1999
.