电能质量信号去噪中小波选取特点的研究  

Research on the characteristics of wavelet selection in power quality signal de-noising

作　　者：龚静 Gong Jing(School of Electrical and Information Engineering,Beijing University of Civil Engineering and Architecture,Beijing 100044,China)

机构地区：[1]北京建筑大学电气与信息工程学院,北京100044

出　　处：《电测与仪表》2022年第5期129-135,共7页Electrical Measurement & Instrumentation

基　　金：国家公派留学基金资助项目(201809960015);北京建筑大学市属高校基本科研业务费专项资金(X20075)。

摘　　要：有效滤除电能质量信号中的噪声是电能质量检测的重要前提,然而小波特性却对去噪效果有着很大的影响。针对此问题,文中给出了一种可调阈值函数,通过对可调参数的控制,可以使得该阈值函数在软硬阈值函数之间变动,兼具两者的优点。在深入研究小波的正交性、支撑长度、正则性、消失矩阶数、对称性等特性的基础上,提出为达到最好的去噪效果小波选取应满足的五个特点。采用db 5、haar、bior 2.2、rbio 3.1四种小波对电压暂降、暂升、中断、振荡、谐波扰动信号进行四尺度分解,计算噪声标准差的基础上进一步引入算子修正阈值,利用提出的新阈值函数对小波细节系数进行去噪处理,分析小波逆变换重构信号的细节,并计算出去噪后的信噪比和均方误差,实验结果表明在不同噪声强度干扰下,db 5小波都具有最佳的去噪效果,这证明了所提出的电能质量信号去噪中小波选取应该遵循的五个特点的正确性和可靠性。Effective de-noising in power quality signal is an important prerequisite for power quality detection;however,the wavelet features have a great impact on the de-noising effect.Aiming at this problem,an adjustable threshold function is firstly proposed.By controlling the adjustable parameters,the proposed threshold function can be changed between hard and soft threshold functions.On the basis of deeply studying the wavelet features,such as orthogonality,support length,regularity,order of vanishing moment,symmetry,etc.,in order to achieve the best de-noising effect,five features of wavelet selection that should be satisfied are proposed in this paper.db 5,haar,bior 2.2 and rbio 3.1 are used to decompose voltage sag,swell,interruption,oscillation and harmonics signals into four scales.On the basis of calculating the standard deviation of noise,the operator is introduced to modify the threshold,and the new threshold function is used to de-noise the wavelet detail coefficients.After de-noising,the details of the reconstructed signal are analyzed,and the SNR and MSE are calculated.The experimental results show that db 5 wavelet has the best de-noising effect under different noise intensity,which proves the correctness and reliability of the five wavelet characteristics in power quality signal de-noising proposed in this paper.

关 键 词：小波特性 电能质量 去噪 消失矩 阈值 

分 类 号：TM93[电气工程—电力电子与电力传动]