小电阻接地系统单相接地故障特征分析  

Transient Characteristic Analysis of Single-phase Ground Fault in Low Resistance Grounding System

作　　者：李华 朱一民 陈琳 马海军 丁继波 张文海[2] LI Hua;ZHU Yimin;CHEN Lin;MA Haijun;DING Jibo;ZHANG Wenhai(Ningxia Coal Industry Co.,Ltd.,CHN Energy Group,Yinchuan,Ningxia 750004,China;College of Electrical Engineering,Sichuan University,Chengdu,Sichuan 610065,China)

机构地区：[1]国家能源集团宁夏煤业有限责任公司,宁夏银川750004 [2]四川大学电气工程学院,四川成都610065

出　　处：《广东电力》2022年第12期56-65,共10页Guangdong Electric Power

摘　　要：小电阻接地系统中实际存在大量瞬时性、高阻性的单相接地故障,进行故障暂稳态特征分析有助于该类故障的准确检测识别。为此考虑到过渡电阻为固定电阻或是非线性电弧电阻的情况,建立小电阻接地系统单相接地故障的暂态等值电路,并且定量给出故障状态为欠阻尼和过阻尼时的过渡电阻范围;然后,求解得到欠阻尼和过阻尼2种状态下故障电流的解析表达式,对比不同阻尼状态下故障电流的组成成分;分析故障电流幅值以及暂态分量的衰减因子、主谐振频率随过渡电阻、故障初相角等参量的变化规律并给出其分布范围;最后,通过电缆电弧故障试验平台记录的试验数据以及PSCAD/EMTDC中的仿真数据,分析不同过渡电阻和故障初相角对故障电流工频和暂态幅值的影响。分析结果表明:根据过渡电阻的大小,欠阻尼和过阻尼状态下的故障电流分别由工频分量、暂态高频/直流分量以及纯直流分量组成;故障初相角越接近电压峰值则暂态分量的幅值越大;随着过渡电阻的增加,故障电流幅值减小,欠阻尼状态下的衰减因子增加,过阻尼状态下的衰减因子减小,主谐振频率则呈现先增后减的趋势。For the single-phase ground fault in the low resistance grounding system, there are plenty of transient and high-impedance single-phase ground faults in the real power system. It is useful for accurate detection and identification of these faults by analyzing the fault transient and steady characteristics. Considering that the fault resistance is the fixed or nonlinear arc resistance, the transient equivalent circuit of single-phase ground fault in the low resistance grounding system was established, and fault resistance range was given quantitatively as the fault state was under damping or over damping. Then, the analytical expressions of fault current under under damping and over damping were obtained, and the fault current components under different damping states were analyzed and compared. The changing laws of fault current amplitude, attenuation factor and main resonance frequency of transient components with parameters such as fault resistance and fault initial phase angle(FIPA) were analyzed and their distribution ranges were given. Through experimental data recorded in the cable arc fault laboratory and simulated data in PSCAD/EMTDC, the amplitude of fundamental frequency and transient components of fault current with different fault resistances and FIPAs were analyzed. The analysis results show that the fault currents with state of under/over damping consist of a power frequency, transient high frequency/DC and pure DC components according to the fault resistance. The closer FIPA is to the voltage peak, the greater the transient fault component amplitude is. With the increase of fault resistance, the fault current decreases, the attenuation factor increases under the state of under damping while the, while the attenuation factor decreases under the state of over damping. Meanwhile, the main resonance frequency increases first and then decreases with the increase of fault resistance.

关 键 词：小电阻接地系统 单相接地故障 过渡电阻 等值电路 暂态分析 

分 类 号：TM711.2[电气工程—电力系统及自动化]