光伏电站主变压器比率差动保护对单相接地短路故障的适应性分析  

Adaptability analysis of photovoltaic power station main transformer ratio differential protection to single-phase grounding short circuit fault

作　　者：陈晓龙[1] 朱雨葭 张浩 王聪博 薛志英 CHEN Xiaolong;ZHU Yujia;ZHANG Hao;WANG Congbo;XUE Zhiying(Key Laboratory of Smart Grid of Ministry of Education,Tianjin University,Tianjin 300072,China;China Electric Power Research Institute Co.,Ltd.,Beijing 100192,China)

机构地区：[1]天津大学智能电网教育部重点实验室,天津300072 [2]中国电力科学研究院有限公司,北京100192

出　　处：《电力自动化设备》2023年第10期217-224,共8页Electric Power Automation Equipment

基　　金：国家电网有限公司科技项目(5100⁃202155028A⁃0⁃0⁃00)。

摘　　要：结合逆变器控制策略及我国对光伏并网逆变器低电压穿越的最新要求,分析了光伏电站主变压器发生单相接地短路故障时短路点故障电流的变化规律。在此基础上,计及主变压器绕组接线方式的影响,根据具有比率制动特性的差动保护原理,研究了差动电流与制动电流的变化规律。进一步通过计算差动电流与制动电流之比,分别从过渡电阻大小、光伏电站并网容量等方面定量分析了主变压器比率差动保护在该故障情况下的适应性。理论分析和仿真验证结果均表明,受控制策略的影响,当光伏电站主变压器两侧出口处分别发生单相接地短路故障时,主变压器比率差动保护灵敏度显著降低,并存在拒动风险。Combined with inverter control strategy and the latest requirements of China for low voltage ride through of photovoltaic grid-connected inverters,the variation rule of fault current at short circuit point when the single-phase grounding short circuit fault occurs inside the main transformer is analyzed.On this basis,considering the influence of winding connection mode of the main transformer and principle of ratio differential protection with ratio braking characteristics,the variation rule of differential current and braking current is studied.Further,by calculating the ratio of differential current to braking current,the adaptability of the ratio differential protection in this fault case is quantitatively analyzed from the aspects of transition resistance and grid-connected capacity of photovoltaic power station and so on.The theoretical analysis and simulative verification results show that due to the influence of the control strategy,when the single-phase grounding short circuit fault occurs at both sides of the main transformer,the ratio differential protection sensitivity is significantly reduced,and there is a risk of rejecting tripping.

关 键 词：光伏电站 故障特性分析 低电压穿越 变压器比率差动保护 继电保护 单相接地短路故障 

分 类 号：TM77[电气工程—电力系统及自动化]