高压直流极母线差动保护不平衡电流分析  

Analysis on the Unbalance Current of HVDC Pole Bus Differential Protection

作　　者：田庆 原敏宏 王志平 刘志军 郭凯 胡风 

机构地区：[1]国网运行有限公司晋东南特高压管理处,长治047100 [2]国网运行有限公司宜昌超高压管理处,宜昌443005 [3]国网运行有限公司宜宾特高压管理处,宜宾644000

出　　处：《高电压技术》2009年第4期926-930,共5页High Voltage Engineering

基　　金：国家自然科学基金(50407010);国家电网公司工程技术项目(SGTGY(2007)606)~~

摘　　要：为确保三上工程的顺利投运,以及为后续高压直流输电工程设计提供建议,分析了宜都—华新系统调试期间一次极母线差动保护误动作的情况,提出不平衡电流是本次误动作的主要原因。通过读取故障的原始录波数据,详细分析了这次故障的特征,分析了不平衡电流产生的原因,使这次故障过程得到比较清楚的解释。不同型式的测量设备,或者同型式不同规格的测量设备由于测量范围或暂态特性不同均会形成差动保护的不平衡电流,可能导致保护误动作。同时提出了3种解决方法:增大极母差跳闸的时间定值、计算极母线差流前先低通滤波、选用和线路光学电流互感特性相近的直流滤波器TA,并根据实践探讨各种方法的可行性,提出最终可靠的处理方案。In order to guarantee the trouble-free Operation of the Three Gorges- Shanghai（ abbr. 3GS） HVDC interconnection project and give the advice for the future HVDC projects, we analyzed a fault trip of pole bus differential protection during the system debugging of Yidu-Huaxing 3GS HVDC that connects Central China Power Grid with East China Power Grid. The main reason of this accident is the large unbalance current. The characteristic of unbalance current is studied with the original record data. The behaviors of pole bus differential protection are proposed which can illustrate the fault progress clearly. The large unbalance current comes from the transient characteristic difference or the measurement range difference of measurement equipments, which have not the same structure or dimension. Three corresponding methods are given to prevent this event from happening again： increasing the time threshold of pole bus differential protection; adding the low-pass filter to cutoff the high frequency of differential current; changing the DC filter TA. The reliable scheme is finally adopted according to the feasibility of each method. By means of solving the above mentioned technical problems,the control and protection functions of 3GS HVDC interconnection project is completed, and the accomplishment of the system commissioning test ensures the safe operation of 3GS project.

关 键 词：极母线差动保护 不平衡电流 高压直流 低通滤波 TA特性 线路保护 系统调试 

分 类 号：TM773[电气工程—电力系统及自动化]