特高压混合直流工程快速旁路保护用兆伏级SF_6间隙等离子体喷射触发特性及工程设计  

Triggering Characteristics and Engineering Design of Megavoltage-grade SF6 Gap Plasma Injection for Fast Bypass Protection in Ultra-high Voltage Hybrid DC Projects

作　　者：李晓昂[1] 邵奕凯 李志兵 张然 蒋攀 张乔根[1] LI Xiaoang;SHAO Yikai;LI Zhibing;ZHANG Ran;JIANG Pan;ZHANG Qiaogen(State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University,Xi’an 710049,China;China Electric Power Research Institute,Beijing 100192,China)

机构地区：[1]西安交通大学电工材料电气绝缘全国重点实验室,西安710049 [2]中国电力科学研究院有限公司,北京100192

出　　处：《高电压技术》2024年第6期2614-2622,共9页High Voltage Engineering

基　　金：国家电网公司科技项目(5500-202155107A-0-0-00)。

摘　　要：在江苏白鹤滩±800 kV特高压混合直流工程中,受端交流侧三相接地故障穿越失败时,会在±400 kV柔直母线上产生高幅值过电压,严重威胁柔直阀组安全,而基于等离子体喷射的超快速旁路开关1 ms内将柔直母线快速接地保护柔直阀组是一种全新的解决方案。DC 400 kV触发间隙需满足高耐压(>1.2 MV)、低工作系数(<5%)、短延时(<1 ms)、大通流等严苛要求,而如何实现高气压、长间隙的可靠触发导通,并提出工程化设计方案是关键难题。为此搭建了增强型等离子体喷射触发间隙导通研究平台,重点研究触发电压、气压、间隙长度以及工作系数等关键影响因素对SF_(6)触发间隙导通特性的影响规律。结果表明,提升触发电压可显著提升触发导通概率、降低触发延时,但存在一定的饱和现象;在固定的工作电压下,随气压或间隙长度的增加,工作系数显著减小,导致触发延时骤增且导通概率急剧减小;在相同工作系数下,高气压短间隙的触发导通性能更强。据此提出满足特高压混合直流工程400 kV柔直母线快速接地用DC 400 kV间隙开关,间隙采用复合外套单间隙结构,轮转型触发腔设计实现多次触发。研制了触发间隙试验样机(间隙距离为10 cm、压强为0.5 MPa的SF_(6)),其雷电耐压>1250kV,临界可触发电压<50 kV,导通时延<0.5 ms。该研究结果为特高压混合直流输电系统中柔直阀组快速保护用兆伏级SF_6触发间隙工程应用提供了理论支持和工程初步设计方案。In the Jiangsu Baihetan±800 kV UHV hybrid DC project,when the three-phase ground fault traversal failure on the AC side of the receiving end occurs,a high amplitude overvoltage will be generated on the±400 kV flex bus,which seriously threatens the safety of the flex manifolds,thus the ultra-fast bypass switch based on the plasma injection quickly grounding the flex bus within 1ms to protect the flex manifolds is a brand-new solution.The DC 400 kV trigger gap needs to meet the stringent requirements of high withstand voltage(>1.2 MV),low operating coefficient(<10%),trigger delay(<1 ms),and large through-flow.The key to problems is how to realize the reliable trigger conduction with high air pressure and long gap and to put forward the engineered design scheme.In this paper,a research platform of the trigger gap based on plasma injection was built to research the influence of key factors such as trigger voltage,air pressure,gap length,and operating coefficient on the conduction characteristics of the SF_(6) trigger gap triggered by enhanced plasma jet.The results show that increasing the trigger voltage can significantly improve the conduction probability and reduce the trigger delay,but there is a certain saturation phenomenon.At a fixed operating voltage,with the increase of air pressure or gap length,the working coefficient decreases significantly,resulting in a sudden increase in the trigger delay and dramatic decrease in the conduction probability.At the same working coefficient,the conduction characteristics of the short gap with high air pressure is stronger.Accordingly,it is proposed to meet the extra-high-voltage hybrid DC project 400 kV flexible bus rapid grounding with DC400 kV gap switch,to adopt the gap with a composite jacket single-gap structure,and to adopt a rotating trigger cavity design to achieve multiple triggering.A trigger gap test prototype(gap distance 10 cm,0.5 MPa SF_(6))is designed,of which the lightning withstand voltage is greater than 1250 kV,the critical trigger voltage is lower th

关 键 词：SF_6触发间隙 等离子体喷射 快速旁路开关 触发 工作系数 

分 类 号：TM721.1[电气工程—电力系统及自动化]