冲击电压下SF6间隙临界半径现象形成机理  

Mechanism of Critical Radius Phenomena for SF6 Gap Under Impulse Voltages

作　　者：张璐 黄国强 张乔根[2] 张默涵 孙蕾[3] 郭安祥 ZHANG Lu1, HUANG Guoqiang1, ZHANG Qiaogen2, ZHANG Mohanl, SUN LeP, GUO Anxiang1(1. Electric Power Research Institute of State Grid Shaanxi Electric Power Company, Xi＇an 710100, China; 2. State Key Laboratory of Electrical Insulation and Power Equipment, Xi＇an Jiaotong University, Xi＇an 710049, China; 3. Power China Northwest Engineering Corporation Limited, Xi＇an 710065, Chin)

机构地区：[1]国网陕西省电力公司电力科学研究院,西安710100 [2]西安交通大学电力设备电气绝缘国家重点实验室,西安710049 [3]中国电建集团西北勘测设计研究院有限公司,西安710065

出　　处：《高电压技术》2018年第3期796-803,共8页High Voltage Engineering

基　　金：国家自然科学基金(51177132);国家电网公司科技项目(5226SX15001T)~~

摘　　要：为探究冲击电压下SF_6气体放电特性和机理,研制了陡前沿冲击试验装置。固定电极间距,研究了电极曲率半径对SF_6间隙击穿特性的影响。结果表明：冲击电压下,SF_6间隙放电呈现出长空气间隙中所谓的＂临界半径＂效应,即随电极曲率半径减小,间隙50%击穿电压减小,曲率半径小于＂临界半径＂Rcr时,击穿电压基本不变;Rcr不仅随气压减小而增加,也随波头时间减小而增加;气压一定,负极性VFTO和雷电冲击下的临界半径值分别较正极性VFTO和雷电冲击下的大;正、负极性VFTO下临界半径分别较正、负极性雷电冲击下的大;负极性电压下,临界半径在物理上更接近于丝状流注区域,正极性电压下,临界半径更接近于均匀流注区域。＂临界半径＂现象与SF_6气体中流注–先驱–先导放电发展过程相关,因此提出了先导击穿的临界电荷判据来对临界半径现象进行了解释。The steep-fronted impulse voltage test equipment was developed for studying the discharge characteristics and mechanisms of SF_6 gas under impulse voltages. The influences of electrode radius on breakdown characteristics of the distance fixed SF_6 gap were researched. It was found that the discharge behaviors of SF_6 gap presented the so-called critical radius effect occurred in long gap discharge in air. With the decrease of electrode radius, the 50% breakdown voltage of the gap decreased till the critical radius Rcr was reached, and then remained practically constant for further reduction of r. It was found that Rcr increased with the decrease of gas pressure and wave front time. When the pressure was fixed, the critical radius value of negative VFTO or lightning impulse was bigger than that of positive VFTO or lightning impulse, the critical radius value of negative or positive VFTO was bigger than that of negative or positive lightning impulse. For negative voltage, Rcr is physically close to the length of filamentary streamer zone. While for positive voltage, Rcr is close to the length of homogeneous streamer zone. The critical radius phenomenon is related with the streamer-precursor-leader discharge process in SF_6 gas, which is explained by the proposed critical charge criterion of leader breakdown.

关 键 词：气体绝缘开关设备 快速暂态过电压 SF6气体间隙 临界半径 流注 先导 

分 类 号：TM595[电气工程—电器]