摘要
直流系统中因电缆接头松脱、接触不良、导线绝缘破裂等原因引起的直流故障电弧,不易熄灭且难以检测,产生的高温容易引发火灾。该文搭建了一套直流电弧模拟实验平台,研究电源电压、电流和电极间距对电弧特性的影响,证明了电弧电流和电极间距是影响电弧特性的主要因素,而电源电压值决定能否产生稳定的电弧。同时,分别建立了电弧的等效电阻、电压和功率与电流、电极间距之间的数值拟合模型,通过该模型获得的电弧R-I、V-I、P-I 特性以及预测模型,与青海光伏实验基地的实验数据基本吻合。同时,基于平衡态等离子体理论和Chapman-Enskog方法,获得不同电弧介质(纯空气和含铜蒸气)下的电导率-温度曲线,并利用COMSOL 对不同间距下的电弧电阻进行仿真分析,含铜蒸气条件下的仿真结果与实测数据基本一致。以上研究结果为进一步研究小电流直流故障电弧的通用特性提供了理论基础。
DC arc is generated by failure connection, poor contacts and insulation failure of cables, it is difficult to extinguish and to be detected, and the extreme high temperature roused by arc may cause fire. It is of great significance to study DC arc characteristics. In this paper, a DC arc fault test platform was set up. The influence of voltage, current of DC power supply and electrode distance on arc characteristics is studied from abundant experiment data. It is proved that current and gap distance were the main factors affecting arc characteristics, and the DC voltage may guarantee whether arc is generated and maintained or not. Meanwhile, numerical fitting arc models as arc resistance R versus I (current) and L (electrode distance) and also V=f(I, L), P=g(I, L) are established respectively. The R-I, V-I and P-I characteristics curves are almost consistent with the discrete experimental data. Finally, based on the equilibrium plasma theory and Chapman-Enskog method,σ(conductivity)-T(temperature) curves are obtained for different arc dielectric medium such as pure air and air with different percentage of copper vapor. Then software COMSOL is used to simulate and analyze the arc resistance under different electrode spacing. The simulation results with copper vapor are almost consistent with the measured data. The results of this paper provide a theoretical basis for further study on the general characteristics of DC arc fault.
作者
熊兰
曾泽宇
杨军
钟昱铭
郭珂
Xiong Lan;Zeng Zeyu;Yang Jun;Zhong Yuming;Guo Ke(State Key Laboratory of Power Transmission Equipment & System Security and New TechnologyChongqing University ,Chongqing ,400044 ,China;State Grid Electric Power Research Institute of Qinghai Power Supply Branch ,Xining ,810000 ,China)
出处
《电工技术学报》
EI
CSCD
北大核心
2019年第13期2820-2829,共10页
Transactions of China Electrotechnical Society
基金
国家自然科学基金项目(51477021)
国网青海省电力公司科技项目(SGQHDKYODWJS1700060)资助
关键词
直流电弧
电弧电阻
电极间距
铜蒸气
电弧特性
数学模型
DC arc
arc resistance
electrode distance
copper vapor
arc characteristics
mathematical model
