大型变压器局部放电多目标定位实验
罗目成1，李卫国2，文习山3
(1．长沙理工大学电气与信息工程学院，长沙410076；
2．华北电力大学电气与电子工程学院，北京102206；
3．武汉大学电气工程学院，武汉430072)
Experimental Study on Partial Discharges Localization
Within Large Transformer
LUO Ri-cheng1，LI Wei—guo2，WEN Xi—shan3
(1．School of Electrical and Information Engineering，Changsha University of Science and Technology，
Changsha 410076．China；
2．School of Electrical＆Electronic Engineering，North China Electric Power University，Beijing 102206，China；
3．School of Electrical Engineering，Wuhan University，Wuhan 430072，China)
Abstract：In order to research and realize partial discharge(PD)sources localization within power transformer and to improve the accuracy of localization．a new method is presented in this paper．which is based on spatial spectrum estimation．Two ultrasonic sensor arrays are located on the inner walI of the transformer tank to detect the ultrasonic signal emitted by the partial discharge sources．Spatial spectrum estimation technique and information theoretic criteria are used in analyzing the signal feature information(Direction-of-Arrival(DOA)．number of signal etc，and the number of partial discharge signal estimation and direction-of-arrival estimation were accomplished．A uniform linear array(ULA)consisting of 4 isotropic acoustic sensors was developed．a suit of experiment system for partial discharge sources localization testing system was established，and a series of experiments on multiple PD sources localization for single partial discharge source and two partial discharge sources were performed，The results of localization show that：the method can effectively estimate the location parameter of multiple partial discharge sources in a high estimated accuracyand Set up solid theoretical and experimental foundation for multiple partial discharge sources localization in large power transformer．
Key words：power transformer；partial discharges：acoustic emission；ultrasonic inspection；spatial spectrum estimarion；array signal processing；fault localization
0 引 言
大型电力变压器内部局部放电源的准确定位，一直是高电压设备绝缘检测领域的难题，长期以来得不到很好的解决[1-4]，在过去的几十年中，出现了多种定位方法，但总体效果并不十分理想[5-7]。主要是变压器内部绝缘结构复杂、电磁环境十分恶劣，严重制约了对放电信号的有效提取；同时放电脉冲信号为时变量，其幅度、相位和频率是起伏的，单次或有限次测量无法完整反映放电信号的真实特性，故根据局部放电脉冲传播特性原理建立的各种电气定位方法难以给出放电源的几何位置[8-10]；此外，超声波定位方法在定位算法上是基于变压器内的单点放电，但实际上，变压器内部往往存在多点同时放电的情形，故基于声发射传播特性的超声波定位法难以有效分辨出各个放电信号的时延[11-13]。为研究解决电力变压器内部局部放电源的定位
问题．提高放电源的定位准确度，本文借助局部放电时产生的超声波信号，提出了一种基于阵列信号处理技术的局部放电多目标定位新方法[14-16]。方法通过在变压器油箱内壁安装一个超声波传感器阵列，利用其接收放电源辐射的超声波信号，应用信息论准则和空间谱估计理论，分析阵列传感器所接收信号的特征信息(信号源数、波达方向)，完成放电源数和放电源方位的估计。本文实验研究了上述方法，整个实验系统是在介质为空气的情况下完成，阵列采用四阵元均匀线阵，为了获得信号的方位角和俯仰角，实验对同一放电源的空间位置进行2次测量，分别估计出信号的方位角和俯仰角。
