采用二次DFT的高精度介损数字测量方法  

High Accuracy Digital Measurement of Dielectric Loss Using Secondary DFT Method

作　　者：严学文[1] 

机构地区：[1]西安邮电学院电子与信息工程系,西安710121

出　　处：《高电压技术》2009年第11期2723-2727,共5页High Voltage Engineering

基　　金：西安邮电学院中青年科研基金(101-0429)~~

摘　　要：为了减小离散傅立叶变换(DFT)算法用于介损测量中出现非同步采样造成的误差,提出了一种改进的算法。在等时间间隔采样的条件下,先使用一次DFT计算出实际的工频周期,修正每个工频周期的实际采样点数,使之满足同步采样条件,再采用二次DFT求出介质损耗角。通过软件仿真,在考虑电网频率波动和谐波含量变化的情况下,模拟采用不同的采样模数转换(A/D)分辩率和采样频率,对该改进算法与传统DFT算法进行分析比较,证明了该改进算法在计算精度、算法稳定性方面大大提高。根据仿真结果,对采用该改进算法的介损测量设备的硬件选型提出了建议,并给出了相应的A/D分辨率、采样频率的建议值。An improved secondary DFT（Discrete Fourier Transform） algorithm under asynchronous sampling was proposed to decrease the error of dielectric loss measurement based on traditional DFT methods. The actual period of the signals sampled by equal time intervals was calculated firstly, then the actual amounts of samples in each period were got to avoid asynchronous sampling, and the dielectric loss angle was got with the secondary DFT algorithm. Considering many disturbance factors such as fluctuation of frequency, harmonic content, different analysis results of these two methods were presented at different A/D（Analog/Digital） resolution and sampling rates. The results of simulation indicate that the dielectric loss angle can be measured more accurately. At the same time, instructive advice about the practical on-site dielectric loss detecting such as hardware selection, A/D resolution, sampiing rate are given.

关 键 词：介质损耗 在线监测 非同步采样 频率修正 离散傅立叶变换 软件仿真 

分 类 号：TM934.32[电气工程—电力电子与电力传动]