背靠背直流输电故障闭锁后过电压分析和优化  

Analysis and optimization of overvoltage after fault blocking in back-to-back DC transmission

作　　者：刘乔 王俊生[1] LIU Qiao;WANG Junsheng(NR Electric Co.,Ltd,Nanjing 211102)

机构地区：[1]南京南瑞继保电气有限公司,南京211102

出　　处：《电气技术》2024年第3期79-84,共6页Electrical Engineering

摘　　要：背靠背直流输电系统某些靠近接地点端发生直流母线接地故障时,系统闭锁后会出现过电压现象。本文分析其原因为故障点与接地点形成短路回路,引起阀短路保护先于极区接地保护动作。此类故障情况下,阀短路保护动作后执行立刻闭锁,在闭锁过程中造成直流系统过电压;而单独的直流母线接地故障执行正常闭锁,或者单独的阀短路故障执行立刻闭锁,均不会出现闭锁后的过电压现象。本文引入接地点电流作为辅助判据,提出两种优化方法。当发生相同的靠近接地点端直流母线接地故障时,控制系统有选择性地执行不同闭锁方式,可有效避免闭锁后出现直流系统过电压,有利于电力系统故障的可靠隔离,降低系统一次设备运行风险。When a DC bus ground fault occurs near the grounding point in a back-to-back DC transmission system,overvoltage may occur after the system is blocked.This paper analyzes the short-circuit circuit formed between the fault point and the grounding point,which causes the valve short-circuit protection to act before the pole grounding protection.In such a fault situation,the valve short-circuit protection action X block,causing overvoltage in the DC system during the blocking process.But the DC bus ground fault to act Y block,or the valve short-circuit fault to act X block,does not appear the overvoltage phenomenon after blocking.In this paper,the ground current is introduced as an auxiliary criterion,and two optimization methods are proposed.When the same DC bus ground fault occurs near the grounding side,the control system selectively performs different blocking mode.It can effectively avoid the DC system overvoltage after blocking,and is beneficial to the reliable isolation of power system faults and reduce the risk of the system’s primary equipment operation.

关 键 词：背靠背 直流输电 接地故障 过电压 闭锁 

分 类 号：TM721.1[电气工程—电力系统及自动化]