新能源经柔直送出场景下功角变化导致比相式距离保护不正确动作机制分析  

Analysis of the Incorrect Operation Mechanism of the Phase Comparison Distance Protection Caused by the Change of Power Angle in the Scenario of MMC-HVDC Connected Renewable Power System

作　　者：周泽昕 于溯 李勇[2] 王兴国 柳焕章[2] ZHOU Zexin;YU Su;LI Yong;WANG Xingguo;LIU Huanzhang(China Electric Power Research Institute,Haidian District,Beijing 100192,China;Central China Power Grid Co.,Ltd.,Wuhan 430077,Hubei Province,China)

机构地区：[1]中国电力科学研究院有限公司,北京市海淀区100192 [2]华中电网有限公司,湖北省武汉市430077

出　　处：《中国电机工程学报》2023年第5期1730-1738,共9页Proceedings of the CSEE

基　　金：国家自然科学基金联合基金项目(U2166205)。

摘　　要：新能源电源经柔性直流输电线路接入交流系统已经成为电力系统中的典型场景。以基于模块化多电平换流器的柔性直流(modular multilevel converter-high voltage direct current,MMC-HVDC)受端交流线路配置的正序电压为极化电压的比相式距离保护为研究对象,结合受端换流器的控制策略,分析了新能源经柔性高压直送出系统中柔直受端交流线路发生短路故障场景下该保护的适应性:在发生相间金属性短路故障情况下,距离保护存在区内短路拒动以及反向区外短路误动的风险。为探究保护不正确动作机制,首先在电压平面上分析了参量变化对距离保护动作行为的影响,揭示了距离保护内在的系统功角与短路容量约束,推导了距离保护正确动作的功角边界。通过将柔直侧系统进行合理等值,受端交流线路发生相间金属性短路故障后,受端换流器控制策略使得系统等值功角增大,距离保护特性位于动作边界,存在拒动/误动风险。利用RTDS建立了风电经柔直送出系统的仿真模型,分析了受端交流线路故障后系统的等值功角特征,验证了距离保护的不正确动作特性。It has become a typical scenario in the power system that the renewable energy power is connected to the AC system through the flexible DC transmission line.Taking the positive sequence voltage-polarized phase-comparison distance protection of the AC line connected to the receiving end of the modular multilevel converter-high voltage direct current(MMC-HVDC)as the object,while considering the control strategy of the MMC-HVDC,this paper analyzes the performance of the distance protection when the short-circuit fault occurs on the AC system.The distance protection may refuse to operate when the internal fault occurs and mis-operate when the external fault occurs.In order to explore the mechanism of the incorrect operation,the influence of parameter changes for operation of distance protection is analyzed on the voltage plane,the inherent constraints of power angle and short-circuit capacity for distance protection are revealed,and the power angle boundary for correct operation of distance protection is deduced.By equating the MMC-HVDC system reasonably,the control strategies of the inverter increase the equivalent power angle of the system when the internal short-circuit fault occurs on the AC line.The performance of distance protection is on the boundary,which means there is a risk of non-operation/mis-operation.A typical scenario simulation model of a new power system is established by RTDS,the equivalent power angle characteristics of the system for the AC line fault are analyzed,and the incorrect operation of distance protection is verified.The fault of the AC line at the receiving end are analyzed,and the incorrect operation characteristics of the distance protection are verified.

关 键 词：柔性直流输电 比相式距离保护 不正确动作 电压平面 系统功角 

分 类 号：TM77[电气工程—电力系统及自动化]