基于改进的Cohen类时频分布的间谐波检测  

Detection Method of Interharmonics Based on Improved Cohen Time-frequency Distribution

作　　者：刘开培[1] 马秉伟[1] 周莉[1] 王波[2] 郑卫东[2] 史洪彬[2] 

机构地区：[1]武汉大学电气工程学院,武汉430072 [2]南阳供电公司,南阳473000

出　　处：《高电压技术》2008年第9期1949-1953,共5页High Voltage Engineering

基　　金：国家自然科学基金(50677048)~~

摘　　要：由于Cohen类时频分布在检测间谐波时,存在众多交叉项,会导致虚假频率的产生,为在实际应用中抑制交叉项,可通过求解电力系统谐波与间谐波的模糊函数,得到其特点即交叉项基本上都是处在平行于τ轴的位置,自项基本都分布在τ轴上。据此,提出通过改造核函数来滤除τ轴以外的信息,从而达到抑制交叉项的思路以及在模糊域提出对锥形分布的核函数的改进(包括提出了一个基于新的核函数的分布)。仿真实验表明,这两种方法均具有较强的抑制交叉项的能力,在提高时频分辨率的同时,也减少了计算量。A lot of cross components which could result in appearance of false frequencies, when the Cohen time-frequency distributions were applied on interharmonics dection, so it is difficult to suppress cross terms. Based on the analysis of ambiguity function of harmonics and interharmonics in power system, it is found that the cross terms paralleled with r axes while self terms are in τ axes. Accordingly, the method is put forward to suppress cross terms through improving the kernel function to get rid of the information out of τ axes. In time-lag domain, the kernel function of cone-shaped distribution（CSD） is improved, and a distribution based on a new kernel function is put forward further. Simulation show that the two methods have powerful ability of cross term suppression and can increase the time-frequency resolved capability, at the same time reduce the computational complexity.

关 键 词：Cohen类时频分布 检测 间谐波 交叉项 模糊函数 核函数 锥形分布 

分 类 号：TM935[电气工程—电力电子与电力传动]