基于故障电压行波传播项指数系数的柔性直流输电线路单端行波保护原理  

Principle of Non-unit Traveling Wave Protection for VSC-HVDC Grids Based on Index of Fault Voltage Traveling Wave Propagation Term

作　　者：张晨浩 宋国兵[1] 李洋 闫吉飞 董新洲[2] ZHANG Chenhao;SONG Guobing;LI Yang;YAN Jifei;DONG Xinzhou(School of Electric Engineering,Xi’an Jiaotong University,Xi’an 710049,Shaanxi Province,China;State Key Lab of Control and Simulation of Power Systems and Generation Equipments(Department of Electrical Engineering,Tsinghua University),Haidian District,Beijing 100084,China)

机构地区：[1]西安交通大学电气工程学院,陕西省西安市710049 [2]电力系统及发电设备控制和仿真国家重点实验室(清华大学电机系),北京市海淀区100084

出　　处：《中国电机工程学报》2021年第24期8424-8436,共13页Proceedings of the CSEE

基　　金：国家重点研发计划项目(2016YFB0900603);国家电网公司科技项目(52094017000W)。

摘　　要：柔性直流电网(voltage source converter-based high voltage DC,VSC-HVDC)对直流线路保护提出了高速动性和高可靠性的要求。首先,推导了柔直电网直流线路发生区内、外故障时线模故障分量电压行波的解析表达式,该解析表达式包含行波传播项和直流线路边界项。理论证明了:线路发生区内故障时,线模故障分量电压行波传播项指数系数大于区外故障时的指数系数,且该指数系数不受过渡电阻影响。之后,引入Levenberg-Marquart(LM)算法提取指数系数构造了高灵敏度、高可靠性的单端快速保护方法及保护方案。最后,仿真验证了推导分析的正确性,验证了提取出的指数系数能有效反映故障位置,且其保护方案能快速可靠地识别不同距离、不同类型的故障,具有较高的耐过渡电阻能力。保护方案无需高采样频率。Voltage source converter-based high voltage DC(VSC-HVDC)grids have raised high-speed operation and high reliability requirements for relay protection.Firstly,the symbolic expressions of the line-mode fault component voltage traveling wave in case of the internal and external faults were derived,which consist of the traveling wave propagation term and the DC line boundary term.It is theoretically demonstrated that(i)the index for the traveling wave propagation term in case of internal faults is greater than that for the external faults,and(ii)the index is independent of fault impedance.Secondly,the Levenberg-Marquardt(LM)algorithm was introduced to extract the index and an index-based non-unit protection method as well as the protection scheme was proposed.The proposed method is theoretically robust and independent of fault impedance and fault type.Finally,in the simulation,the fitting results have indicated that the symbolic expressions are correct and the extracted indices are effective to characterize the location of the faults.Numerous fault cases of different fault distances,fault impedances,and fault types have demonstrated that the proposed protection scheme has high sensitivity,high operation speed,and high reliability.The proposed protection scheme does not require high sampling frequency.

关 键 词：高灵敏度 单端量快速保护 柔性直流电网(VSC-HVDC) Levenberg-Marquardt(LM)算法 行波传播 

分 类 号：TM721.1[电气工程—电力系统及自动化]