基于改进小波阈值去噪和CEEMDAN-HT融合的谐波检测技术

doi:10.16180/j.cnki.issn1007-7820.2023.01.009

摘要/Abstract

摘要：

针对电网环境噪声导致自适应噪声的CEEMDAN谐波检测精度低的问题,文中提出了一种基于改进小波阈值去噪和CEEMDAN-HT融合的谐波检测技术。利用修正因子T_j自适应调整阈值,通过可调参数τ调节阈值函数软、硬特性,并将改进的小波阈值去噪方法应用于谐波信号的预处理。经预处理的信号再进行CEEMDAN分解,可有效抑制模态混叠束缚。运用相关度判据去除虚假分量,并利用Hilbert变换解调包含谐波特征的分量,准确提取其幅频信息。经MATLAB仿真可知,改进小波阈值去噪与CEEMDAN-HT的融合算法可将稳态谐波检测平均误差被控制在1%以下,暂态谐波检测平均误差被控制在2.1%以下,呈现出良好的抗噪性能。

关键词: 改进小波阈值去噪, CEEMDAN, 模态混叠, 修正因子, 虚假分量, 相关度判据, 谐波检测, Hilbert变换

Abstract:

In view of the low accuracy of CEEMDAN harmonic detection of adaptive noise caused by power grid environmental noise, a harmonic detection technology based on improved wavelet threshold denoising and CEEMDAN-HT fusion is proposed in this study. The threshold value is adaptively adjusted by the correction factor T_j, the soft and hard characteristics of the threshold function are adjusted by the adjustable parameter τ, and the improved wavelet threshold denoising method is applied to the preprocessing of harmonic signals. The preprocessed signal is decomposed by CEEMDAN, which can effectively suppress the mode aliasing binding. Relatedness criterion is used to remove false components, and the Hilbert transform is used to demodulate the components containing harmonic characteristics, and the amplitude-frequency information is accurately extracted. MATLAB simulation results show that the fusion algorithm of improved wavelet threshold denoising and CEEMDAN-HT controls the average error of steady-state harmonic detection below 1%, and the average error of transient harmonic detection below 2.1%, showing good anti-noise performance.

Key words: improved wavelet threshold denoising, CEEMDAN, modal aliasing, correction factor, false component, correlation criterion, harmonic detection, Hilbert transform

中图分类号:

TN911

王玉梅,郑义. 基于改进小波阈值去噪和CEEMDAN-HT融合的谐波检测技术[J]. 电子科技, 2023, 36(1): 60-66.

WANG Yumei,ZHENG Yi. Harmonic Detection Technology Based on Improved Wavelet Threshold Denoising and CEEMDAN-HT Fusion[J]. Electronic Science and Technology, 2023, 36(1): 60-66.

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去噪方法	SNR/dB	RMES
软阈值	23.509 6	0.006 7
硬阈值	25.144 4	0.005 9
无修正阈值	26.952 6	0.003 7
改进小波阈值	27.578 6	0.002 8

IMF	相关系数	IMF	相关系数
IMF₁	0.994 0	IMF₅	0.054 2
IMF₂	0.991 3	IMF₆	0.031 8
IMF₃	0.997 8	IMF₇	0.017 4
IMF₄	0.984 6	IMF₈	0.001 6

实际值 /V	EMD+HT		CEEMDAN+HT		本文方法
实际值 /V	检测值 /V	误差 /%	检测值/V	误差 /%	检测值 /V	误差 /%
311.1	286.52	8.59	301.47	3.20	308.62	0.81
31.1	—	—	29.17	6.67	30.89	0.72
24.9	—	—	—	—	24.69	0.81
15.6	—	—	—	—	15.45	0.68

实际值 /V	EMD+HT		CEEMDAN+HT		本文方法
实际值 /V	检测值 /V	误差 /%	检测值/V	误差 /%	检测值 /V	误差 /%
350	—	—	359.69	2.77	351.02	0.29
250	—	—	255.37	2.15	249.14	0.34
150	—	—	146.79	2.14	150.23	0.15
50	47.21	5.58	49.12	1.76	50.07	0.14