长电缆对合空载变压器过电压的影响研究  

Study on Influence of Long Cable on Overvoltage of No-load Transformer

作　　者：汪恒 杨军景 李翔宇 王群锋 魏震 WANG Heng;YANG Jun-jing;LI Xiang-yu;WANG Qun-feng;WEI Zhen(DC Center of State Grid Henan Eiectric Power Company,Zhengzhou 450000,China)

机构地区：[1]国网河南省电力公司直流中心,河南郑州450000

出　　处：《变压器》2023年第4期43-48,共6页Transformer

摘　　要：为了研究发电厂并网过程中合闸过电压的发展规律及影响因素,首先研究了空载变压器合闸过程中产生过电压的机理,根据主升压变压器的实际测试数据计算其非线性工作区,然后基于电磁暂态分析程序(ElctroMagnsients Transients Program,简称EMTP),在500kV发电厂等效简化模型的基础上,对空载变压器合闸产生的过电压暂态特性进行了仿真。最后,以升压变压器高压侧XLPE电缆长度为变量,研究了XLPE电缆对空载变压器合闸产生的过电压的影响,并提出了抑制过电压的措施。结果表明,在电厂并网过程中,空载变压器会产生明显的过电压。在合闸角下,最大合闸过电压可达857.07kV,是额定电压的2倍,合闸过电压持续时间约为80μs。输电电缆长度变化可能引起谐振现象,此时对合闸过电压存在明显影响,同时也对合闸涌流有明显影响,利用串联合闸电阻或电抗器可以很好的抑制过电压。ln order to study the development law and influencing factors of switching on overvoltage in the process of power plant grid connection,the mechanism of overvolt-age generated in the process of closing no-load transformer is studied firstly,and its nonlinear working area is calculated based on the actual test data of main step-up transformer,and then based on Elctro-Magnsients Transients Program(EMTP).Based on the equivalent simplified modeling of a 5ookV power plant,the transient characteristics of overvoltage generated by switching on no-load transformer are simulated.Finally,taking the length of XLPE cable on the high-voltage side of step-up transformer as variable,the influence of XLPE cable on the overvoltage generated by closing no-load transformer is studied,and suggestions for suppression are put forward.The results show that during the grid connection of the power plant,the no-load transformer will produce a significant overvoltage.At the closing angle,the maximum closing overvoltage can reach 857.07kV,which is twice the rated voltage,and the closing overvoltage dura-tion is about 8Ous.The change in the length of the transmission cable may cause reso-nance phenomena,at this time there is a significant impact on the closing overvoltage,but also has a significant impact on the closing inrush current,the use of series joint thyristor or reactor can be a good suppression of overvoltage.

关 键 词：倒送电 XLPE电缆 合空变 过电压 

分 类 号：TM406[电气工程—电器]