Harmonic Analysis Based on an Enhanced Cosine-Window Interpolation FFT Algorithm

doi:10.11985/2016.04.003

Abstract

Abstract:

There are difficulties in performing integral cycle truncation and synchronized sampling for fast Fourier algorithm in power harmonic analysis, thus result in frequency leakage, and the exact harmonic parameters can not be detected. The sampling signal is truncated by using cosine-window, then double-spectrum-line interpolation algorithm is used to correct the result, and compensate the spectral leakage caused by non-synchronized sampling to obtain high measurement accuracy. An enhanced cosine-window is proposed and its spectral characteristics are analyzed. The applicable correction formulas are obtained by fitting of polynomials and calculating burden is decreased. The simulation results show that the enhanced cosine-window interpolation FFT algorithm can control the spectral leakage efficiently and increase detection accuracy.

Key words: Fast Fourier transform, harmonic analysis, synchronized sampling, spectral leakage, cosine-window, polynomial fit

CLC Number:

TM714.01

Li Zhigang,Wang Tao,He Yigang,He Wei,Su Yuanyuan. Harmonic Analysis Based on an Enhanced Cosine-Window Interpolation FFT Algorithm[J]. Journal of Electrical Engineering, 2016, 11(4): 15-21.

Figures/Tables 11

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References 10

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	Hanning 窗	Hamming 窗	Blackman 窗	改进余弦窗
旁瓣电平峰值/dB	-31	-42	-58	-62
旁瓣衰减速率/(dB/oct)	18	6	18	18

	基波	3次谐波	5次谐波	7次谐波	9次谐波	5.5次谐波	6.5次谐波
理论值	220	12	7	3.2	1.8	0.5	0.2
Hanning窗	220.009 8	12.022 8	7.004 1	3.200 7	1.799 9	0.499 2	0.198 2
Blackman窗	220.004 0	12.009 5	7.002 5	3.199 8	1.800 0	0.500 0	0.199 4
改进余弦窗	220.003 5	12.007 8	7.002 1	3.199 9	1.800 0	0.500 0	0.200 0

	基波	3次谐波	5次谐波	7次谐波	9次谐波	5.5次谐波	6.5次谐波
理论值	50	150	250	350	450	275	325
Hanning窗	49.998 6	149.960 2	249.992 2	350.007 8	449.996 9	274.998 6	325.006 3
Blackman窗	49.999 0	149.978 9	249.993 0	350.007 0	449.998 4	274.999 2	325.003 1
改进余弦窗	49.999 2	149.982 2	249.993 7	350.006 6	449.998 6	274.999 6	325.002 3

	基波	3次谐波	5次谐波	7次谐波	9次谐波	5.5次谐波	6.5次谐波
理论值	20	58	102	82	36	15	46
Hanning窗	20.035 3	58.910 1	102.008 6	82.045 2	36.043 3	15.008 9	45.950 0
Blackman窗	20.017 8	58.432 7	101.996 4	81.967 2	36.033 2	15.006 2	45.962 4
改进余弦窗	20.017 7	58.411 2	101.998 0	81.992 5	36.032 6	15.004 3	45.973 8

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