基于动态电阻串联的高阻接地故障精确建模  

Accurate Modeling of High Impedance Fault Based on Dynamic Impedance Series Connection

作　　者：钟逸涵 邓丰[1] 史鸿飞 徐帆 李鑫瑜 Zhong Yihan;Deng Feng;Shi Hongfei;Xu Fan;Li Xinyu(School of Electrical&Information Engineering,Changsha University of Science and Technology Changsha 410114 China;State Grid Xiangtan Power Supply Company,Xiangtan 411100 China)

机构地区：[1]长沙理工大学电气与信息工程学院,长沙410114 [2]国网湖南省电力有限公司湘潭供电公司,湘潭411100

出　　处：《电工技术学报》2024年第7期2046-2059,共14页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金(52077008);湖南省自然科学基金杰出青年项目(2022JJ10048);湖南省湖湘青年科技创新人才项目(2021RC3097)资助。

摘　　要：现有各类高阻接地故障模型缺乏对故障发展全过程的物理解释,难以准确模拟故障的非线性特征。该文根据现场录波数据,深入研究高阻接地故障的物理过程,归纳可知故障电流波形的非线性畸变来源于两个方面:空气间隙击穿引起的非线性与接地介质本身的非线性。据此提出高阻接地故障的故障电阻由电弧电阻和接地电阻串联组成,进而建立基于动态电阻串联的高阻接地故障新模型。首先,利用汤逊原理分析空气介质击穿过程中动态电弧的产生,建立了故障点指数电弧模型;然后,研究故障电流在土壤中的流散过程,结合土壤电阻率变化规律,求解接地电阻随故障电流变化的表达式,建立接地电阻模型;最后,在PSCAD中将二者串联,搭建高阻接地故障新模型,结合现场故障数据并与其他模型对比,验证了该文所提模型能更准确地表征不同接地介质下高阻接地故障的非线性特征,为后续研究高阻接地故障辨识提供更精确的数据支撑。High impedance fault(HIF)may occur in distribution lines owning to harsh weather condition,which is difficult to be detected due to its over thousands of ohms impedance,posing a huge hazard to human and electric equipment.Therefore,the safety risks and the lack of actual HIF data make it essential to require an accurate HIF model.However,only based on heat balance or dielectric breakdown theories,existing HIF models fail to capture nonlinear characteristics due to the insufficient physical interpretation of HIF.Thus,considering the entire fault physical process,a HIF model based on dynamic impedance in series is proposed.By comparing it with other models,the simulation results verify that the proposed model characterizes HIF nonlinear characteristics under various grounding media with higher accuracy.The HIF experiments under laterite soil had been carried out in the 1:1 real distribution network testing field.Based on the recorded waveforms,the HIF physical processes are analyzed,specifically including the arc ignition and extinction characteristics and the current dispersion in soil.The findings suggest that the nonlinearity of grounding medium and air breakdown process are the primary contributors to the nonlinear distortion of fault current waveforms.Correspondingly,it can be revealed that the HIF fault impedance is composed of arc impedance and ground impedance in series.On this basis,a new HIF model based on dynamic impedance in series is proposed.Firstly,the Thompson Theory is utilized to describe the arc ignition and extinction characteristics in air breakdown process,based on which the dynamic exponential arc impedance model can be established.Secondly,with the analysis of the fault current dispersion process,the variation curve of soil resistivity with electric field intensity is obtained,then the grounding impedance can be calculated to establish the grounding impedance model.Though the analysis of grounding impedance only takes laterite soil as an example,it is worth noting that this is just an approa

关 键 词：配电网 高阻接地故障 电弧电阻 接地电阻 非线性特征 

分 类 号：TM77[电气工程—电力系统及自动化]