基于故障相电压与零序电流相位比较的中性点不接地系统高阻接地故障保护方法  

Protection method for high-impedance grounding fault in neutral isolated system based on comparative phase analysis of fault phase voltage and zero-sequence current

作　　者：王鹏玮 徐丙垠[1,2] 王超 陈恒 WANG Pengwei;XU Bingyin;WANG Chao;CHEN Heng(School of Electrical and Electronic Engineering,Shandong University of Technology,Zibo 255000,China;Shandong Kehui Electric Power Automation Co.,Ltd.,Zibo 255000,China)

机构地区：[1]山东理工大学电气与电子工程学院,山东淄博255000 [2]山东科汇电力自动化股份有限公司,山东淄博255000

出　　处：《电力自动化设备》2024年第10期148-156,共9页Electric Power Automation Equipment

基　　金：国家电网有限公司总部科技项目(5500⁃202221138A⁃1⁃1⁃ZN)。

摘　　要：为降低电力线路故障引发森林火灾的风险,中压配电网接地保护须可靠检测过渡电阻为12kΩ的接地故障。穿越林区的10 kV中压配电系统主要采用中性点不接地方式,现有保护方法依赖零序电压检测故障方向,耐过渡电阻能力不超过6 kΩ,无法满足防治森林火灾的要求。为此,提出了一种基于相电压与零序电流相位比较的中性点不接地系统高阻接地故障保护方法,作为高阻接地故障的后备保护。通过中性点不接地系统高阻接地故障等值电路分析,发现在现有保护的动作死区内,故障相电压与故障线路零序电流近似同相,与健全线路零序电流近似反相的规律,使用故障相电压作为极化量,构造了通过故障相电压与零序电流的相位关系来判断故障方向的高阻接地故障保护方法。相较于现有保护方法,所提方法的耐过渡电阻能力从6 kΩ提升至12 kΩ。所提方法能可靠检测导线触树故障,将保护能力边界提升至防范森林火灾的安全范围内。数字仿真与现场人工试验均验证了所提方法的有效性。To mitigate the risk of forest fire caused by power line fault,the grounding fault protection of medium voltage distribution network must reliably detect grounding fault with transition resistances up to 12 kΩ.The 10 kV medium voltage distribution system traversing forested area predominantly employ neu⁃tral isolated mode.The existing protection methods rely on zero-sequence voltage to detect the fault direc⁃tion,with a transient resistance capacity not exceeding 6 kΩ,which is inadequate for forest fire prevention.Accordingly,a protection method for high-impedance grounding fault in neutral isolated system based on comparative phase analysis of fault phase voltage and zero-sequence current is proposed as backup protec⁃tion for high-impedance grounding fault.Analysis of the equivalent circuit for high-impedance grounding fault in neutral isolated system reveals that within the dead zone of existing protections,the fault phase voltage is approximately in-phase with the zero-sequence current of fault line and approximately anti-phase with the zero-sequence current of healthy line.Using the fault phase voltage as a polarizing quantity,a pro⁃tection method is devised to determine the fault direction based on the phase relationship between the fault phase voltage and zero-sequence current.Compared to the existing methods,the transient resistance ca⁃pability of the proposed method is enhanced from 6 kΩto 12 kΩ.The proposed method can reliably de⁃tect tree contact single-phase-to-ground fault,and advance the protection capability to within the safety mar⁃gin for forest fire prevention.The effectiveness of the proposed method is validated through digital simula⁃tion and field manual test.

关 键 词：中压配电网 高阻接地故障 接地故障保护 森林火灾防治 导线触树故障 

分 类 号：TM77[电气工程—电力系统及自动化]