20kV配电网电压互感器一次侧电流的仿真与分析  

Simulation and Analysis of Primary Side Current of PT in 20 kV Distribution Network

作　　者：陈锐 曾杰 郑雅玲 刘尧 刘超 陈燕萍[2] 韩永霞[2] CHEN Rui;ZENG Jie;ZHENG Yaling;LlU Yao;LlU Chao;CHEN Yanping;HAN Yongxia(China Southern Power Grid Technology Co.,Ltd.,Guangzhou,Guangdong 510080,China;School of Electric Power Engineering,South China University of Technology,Guangzhou,Guangdong 510640,China;Zhuhai Power Supply Bureau of Guangdong Power Grid Co.,Ltd.,Zhuhai,Guangdong 519000,China)

机构地区：[1]南方电网电力科技股份有限公司,广东广州510080 [2]华南理工大学电力学院,广东广州510640 [3]广东电网有限责任公司珠海供电局,广东珠海519000

出　　处：《广东电力》2022年第2期54-65,共12页Guangdong Electric Power

基　　金：国家自然科学基金项目(51807068)。

摘　　要：横琴新区20kV配电网近年发生多次电压互感器(potential transformer,PT)高压熔丝异常熔断事故,亟需开展事故原因分析及防护措施研究。通过对横琴新区20kV配电网PT熔丝熔断故障情况的统计分析及PT过电流产生机理分析,指出永久性单相接地故障是PT一次侧熔丝熔断的主要原因。因此,基于PSCAD/EMTDC建立了典型接线20kV配电网单相接地故障的电磁暂态仿真分析模型,仿真分析永久性单相接地故障下PT一次侧电流的影响因素及抑制措施。理论及仿真结果均表明,PT一次侧过电流由带存储电荷的电缆线路对地电容与PT形成的低频非线性振荡引起,是导致PT熔丝熔断的主要原因;PT一次侧电流的主要影响因素包括断路器动作时间、故障点接地电阻、中性点接地电阻、PT接线方式、PT励磁特性等。最后提出通过控制被切除故障电缆的长度、提高PT的励磁特性曲线拐点、降低中性点接地电阻、采用合适的PT接线形式等降低PT一次侧电流的防护措施,避免其熔丝熔断事故频发。The 20 kV distribution network in Hengin new area has experienced many abnormal fusing accidents of high-voltage fuses of the potential transformer(PT)in recent years,which cries out for cause analysis of the accident and research on protective measures.Based on the statistics and mechanism analysis of fusing faults of PT in 20 kV distribution network in Hengqin new area and the analysis of the overcurrent generation mechanism of the PT,this paper proposes that the permanent single-phase ground fault is the main reason for PT fuse fusing.It establishes an electromagnetic transient simulation model of the single-phase grounding fault of typical 20 kV distribution network based on PSCAD/EMTDC to study the influencing factors on the primary side current of PT under permanent single-phase grounding faults and corresponding suppression measures.Theoretical and simulation results both show that the overcurrent on the primary side of PT is caused by the low-frequency nonlinear oscillation formed by the ground capacitance of the cable lines with storage charge and the PT,which is the main reason for PT fuse blown.The main influencing factors of the primary side current include circuit breaker operating time,fault point grounding resistance,neutral grounding resistance,PT wiring mode,PT excitation characteristics,and so on.Thus,the paper proposes protective measures such as controlling the length of the faulty cable to be removed,increasing the inflection point of the excitation characteristic curve of PT,reducing the neutral ground resistance and adopting a suitable PT wiring mode to reduce the primary side current,so as to avoid frequent occurrence of PT fuse fusing accidents.

关 键 词：20kV 配电网 单相接地故障 电压互感器 低频非线性振荡 熔丝熔断 故障仿真 

分 类 号：TM74[电气工程—电力系统及自动化]