一种用于抑制白噪声的分层复阈值算法  

An Algorithm of Complex Multilevel Threshold for Reducing White-noise

作　　者：唐炬[1] 彭莉[1] 谢颜斌[1] 

机构地区：[1]重庆大学高电压与电工理论新技术教育部重点实验室,重庆市沙坪坝区400044

出　　处：《中国电机工程学报》2007年第21期25-30,共6页Proceedings of the CSEE

基　　金：国家自然科学基金项目(50577069)。~~

摘　　要：基于PD信号的复小波变换模极大值随尺度s的增加而增加,而白噪声的复小波变换模极大值随尺度s的增加而减小的特点,创建一种分层复阈值算法。将分层复阈值用于复小波变换对仿真PD信号的去噪,并与全局复阈值算法进行了比较。同时在对仿真PD信号去噪后的波形畸变研究中,为弥补波形相似性参数(NCC)的不足,提出一个新的描述波形相似程度参数——变化趋势参数(VTP),并结合去噪前后的信噪比(SNR)对去噪效果进行综合评价。将分层复阈值技术用于对实验室实测的模拟GIS超高频PD信号的去噪。结果表明,采用分层复阈值技术的复小波变换抑制白噪声的效果更好,在高信噪比(SNR)或噪声抑制比(NRR)的情况下,对信号的畸变也更小。According to the characteristic of modulus maximum of partial discharge（PD） signal and white-noise, an algorithm of complex multilevel threshold is put forward. The de-noising effect of complex multilevel threshold is compared with the effect of complex globe threshold. In order to make up the shortage of NCC, a new parameter--variational trend parameter（VTP） is put forward, which describes the degree of waveforms＇ similarity. The de-noising effect can be synthetically evaluated by VTP, NCC and SNR. Finally, complex multilevel threshold is used to suppress the white-noise in ultrahigh frequency PD signal which is got from stimulant GIS in lab. The findings indicate that this threshold can suppress white-noise effectively with small distortion of PD signal.

关 键 词：局部放电 复小波 变化趋势参数 分层复阈值 白噪干扰 

分 类 号：TM835[电气工程—高电压与绝缘技术]