系统单相接地故障下接地变压器的运行特性分析  

Analysis of the operational characteristics of a grounding transformer when there is a single-phase grounding fault of the system

作　　者：陈蕾 咸日常[1] 郑春旭 高鸿鹏 范慧芳 张冰倩 CHEN Lei;XIAN Richang;ZHENG Chunxu;GAO Hongpeng;FAN Huifang;ZHANG Bingqian(School of Electrical and Electronic Engineering,Shandong University of Technology,Zibo 255000,China;Zibo Power Supply Company,State Grid Shandong Electric Power Company,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]国网山东省电力公司淄博供电公司,山东淄博255000

出　　处：《电力系统保护与控制》2021年第12期56-64,共9页Power System Protection and Control

基　　金：国家“十三五”重点研发计划资助(2016YFB0901303)。

摘　　要：变电站中的接地变压器不仅为中压不接地系统提供中性点,同时兼做站用变为变电站正常运行提供电源保障,确保接地变压器可靠运行对电力系统的安全稳定至关重要。针对变电站配出线路单相接地故障发生频率高、对接地变压器运行状态及其监测影响较大的问题,分析了单相接地故障对接地变压器运行特性的影响因素。结合配电网实际参数在PSCAD软件中建立仿真模型,通过对比单相接地故障时配电网中零序电流的仿真值与电容电流的计算值大小,验证了模型的正确性。在此基础上仿真分析了系统单相接地故障下接地变压器的运行特性。结果表明:系统发生单相接地故障时,接地变压器一次侧电流增大、相位相同,但不会影响其安全稳定运行。在系统单相接地故障燃弧和稳定接地阶段,故障初相角、过渡电阻以及失谐度大小会影响接地变压器一次侧电压、电流幅值。同时,在稳定接地阶段,故障初相角大小会影响其一次侧电压、电流处于稳态的时间。在熄弧阶段时,仅失谐度大小会影响其一次侧电压、电流的振荡恢复过程。The grounding transformer in a substation not only provides a neutral point for the medium-voltage ungrounded system,but also serves as a station for normal operation of the substation.Thus ensuring the reliable operation of the grounding transformer is essential to the safety and stability of the power system.There is a problem of the high frequency of single-phase grounding faults in the distribution lines of substations and the greater impact on the operational status and monitoring of grounding transformers.This paper analyzes the influencing factors of single-phase grounding faults on the operational characteristics of grounding transformers.A simulation model is established in the PSCAD software combined with the actual parameters of the distribution network.The correctness of the model is verified by comparing the simulated value of the zero sequence current with the calculated value of the capacitive current during a single-phase ground fault.The operating characteristics of the grounding transformer under the single-phase grounding fault are simulated and analyzed.The results show that when a single-phase grounding fault occurs,the primary side current of the grounding transformer increases and the phase is the same,but it cannot affect its safe and stable operation.During the arcing and stable grounding stages of a single-phase grounding fault,the initial phase angle of the fault,the transition resistance and the degree of detuning affect the primary voltage and current amplitude of the grounding transformer.In the stable grounding phase,the initial phase angle of the fault affects the time when the primary voltage and current are in a steady state;in the arc extinguishing phase,only the degree of detuning will affect the oscillation recovery process of the primary voltage and current.

关 键 词：接地故障 接地变压器 运行特性 PSCAD 分析 

分 类 号：TM862[电气工程—高电压与绝缘技术] TM41