摘要
我国10 kV中压配电变压器(简称配变)多采用保护接地与低压侧工作接地共地方式,对于配变台区接地故障时对低压系统的转移过电压问题,大多关注工频(稳态)转移过电压而忽略了暂态转移过电压。针对小电流接地方式的中压系统,分析了配变台区接地故障时暂态电流与暂态过电压的计算方法与幅值分布范围,给出了该暂态过电压对低压系统的转移机理。发现中压系统采用小电流接地方式时对低压系统的暂态转移过电压远高于工频转移过电压,可达上千伏;低压系统采用TN接地方式时,低压设备外壳会带有短时过电压,人身触电风险更大。利用MATLAB仿真和现场试验,验证了分析的正确性。
In China 10 kV medium voltage distribution transformers mostly adopt the common grounding mode of protective grounding and low-voltage side working grounding.For the transfer overvoltage of low-voltage system in case of grounding fault in distribution transformer area,they pay more attention to the power frequency(steady-state)transfer overvoltage,but ignore the transient transfer overvoltage.For medium voltage systems with small current grounding mode,the calculation method and amplitude distribution range of transient current and transient overvoltage in case of grounding fault in distribution transformer area are analyzed,and the transfer mechanism of transient overvoltage to low-voltage system is given.It is found that when small current grounding mode is adopted for the medium voltage system,the transient transfer overvoltage to the low voltage system is much higher than the power frequency transfer overvoltage,up to thousands of volts;When TN grounding mode is adopted for the low-voltage system,the shell of low-voltage equipment will have short-time overvoltage,and the risk of personal electric shock is greater.The correctness of the analysis is verified by MATLAB simulation and field test.
作者
林志超
孙荣可
丘桢坤
陈参宁
薛永端
LIN Zhichao;SUN Rongke;QIU Zhenkun;CHEN Canning;XUE Yongduan(Huizhou Power Supply Bureau of Guangdong Power Grid Co.,Ltd.,Huizhou 516001,China;College of New Energy of China University of Petroleum(East China),Qingdao 266580,China)
出处
《供用电》
2022年第6期33-39,共7页
Distribution & Utilization
基金
中国南方电网有限责任公司科技项目(031300KK52180107)。
关键词
配电变压器
台区接地故障
暂态转移过电压
接地方式
低压系统
distribution transformer
grounding fault in station area
transient transfer overvoltage
grounding mode
low voltage system
