基于电流行波突变特性的多端柔性直流线路纵联保护  

Pilot protection method for multi terminal flexible DC lines based on current traveling wave mutation characteristics

作　　者：郭家浩 樊艳芳[1] 侯俊杰[1] GUO Jiahao;FAN Yanfang;HOU Junjie(School of Electrical Engineering,Xinjiang University,Urumqi 830046,China)

机构地区：[1]新疆大学电气工程学院,新疆乌鲁木齐830046

出　　处：《电力系统保护与控制》2023年第18期31-42,共12页Power System Protection and Control

基　　金：国家重点研发计划项目资助(2021YFB1507000);2022天山英才培养计划项目资助(2022TSYCLJ0019);南方电网科研院科技项目资助(SEPRI-K22B055);新疆维吾尔自治区自然科学基金项目资助(2022D01C365,2022D01C662)。

摘　　要：在柔性直流输电线路中,广泛应用行波保护作为主保护。但行波保护作为单端量保护,耐受过渡电阻能力有限。因此,针对高阻接地故障使得柔性直流输电线路主保护故障识别灵敏度降低问题,提出了一种基于电流行波突变特性的快速纵联保护方法。首先,通过分析线模电流行波在线路上的传播过程,推导出区内外故障时线路两端线模电流行波突变特征。然后,利用最小二乘法对线模电流行波拟合构造保护主判据,并结合启动判据、选极判据构成纵联保护方法。最后,在PSCAD/EMTDC平台搭建四端柔性直流电网模型进行仿真验证。仿真结果表明,所提出的保护方法能快速可靠识别区内外故障,能耐受300Ω过渡电阻和30 dB高斯白噪声,并且对采样频率和通信要求低。Traveling wave protection is widely used as the main protection in flexible DC transmission lines.However,as a single-ended protection,traveling wave protection has limited ability to withstand transition resistance.Therefore,given the problem that there is diminished sensitivity in fault detection for main protection of flexible DC transmission lines caused by high-impedance grounding faults,a fast pilot protection method is proposed based on the abrupt change characteristics of current traveling waves.First,by analyzing the propagation process of the line-mode current traveling wave on the line,the mutation characteristics of the line-mode current traveling wave at both ends of the line during internal and external faults are derived.Second,the least square method is used to fit the line-mode current traveling waves to construct main criterion of protection.The it combines with the starting and pole-selection criteria to form the pilot protection method.Finally,a four-terminal flexible DC power grid model is built on the PSCAD/EMTDC platform for simulation verification.Simulation results show that the proposed protection method can quickly and reliably identify faults both within and outside the zone,and withstand 300©transitional resistance and 30 dB Gaussian white noise.It has low requirement on sampling frequency and communication.

关 键 词：多端柔性直流输电 最小二乘法 高阻接地故障 纵联保护 

分 类 号：TM721.1[电气工程—电力系统及自动化] TM773