基于测量波阻抗相位特性的多端混合直流线路保护方案  

A protection scheme of multi-terminal hybrid DC line based on measuring wave impedance phase characteristics

作　　者：戴志辉[1] 邱宏逸 王兴国 郭雅蓉 杨国峰 DAI Zhihui;QIU Hongyi;WANG Xingguo;GUO Yarong;YANG Guofeng(School of Electrical and Electronic Engineering,North China Electric Power University,Baoding 071003,China;China Electric Power Research Institute Co.,Ltd.,Beijing 100192,China;State Grid Xinjiang Electric Power Co.,Ltd.UHV Branch,Urumqi 830002,China)

机构地区：[1]华北电力大学电气与电子工程学院,河北保定071003 [2]中国电力科学研究院有限公司,北京100192 [3]国网新疆电力有限公司超高压分公司,新疆乌鲁木齐830002

出　　处：《电力工程技术》2023年第5期117-127,176,共12页Electric Power Engineering Technology

基　　金：国家自然科学基金资助项目(51877084)。

摘　　要：电网换相换流器和模块化多电平换流器(line commutated converter-modular multi-level converter,LCC-MMC)并联型多端混合直流输电系统结合了基于电网换相换流器型高压直流输电(line commutated converter-high voltage direct current,LCC-HVDC)与基于模块化多电平换流器型高压直流输电(modular multi-level converter-HVDC,MMC-HVDC)的技术优势,但因其不一致的边界特性、特殊的汇流母线结构、不同的换流站控制策略,导致现有的线路保护方案难以直接应用。为此,文中提出一种基于测量波阻抗相位特性的多端混合直流线路保护方案。首先,推导不同故障位置测点处测量波阻抗表达式,发现在高频段内,测点处测量波阻抗相位在区内外故障条件下差异显著,且相位特征与故障距离、类型和过渡电阻等因素无关;接着,利用S变换提取测量波阻抗相位信息,并结合行波高低频能量比判据,实现故障识别;最后,在PSCAD中进行仿真验证。结果表明,所提保护能够区分T区母线与其相邻线路末端故障,在满足快速性的同时具备一定的耐受过渡电阻(500Ω)和抗噪声干扰(20 dB)能力,满足多端混合直流系统线路主保护要求。Line commutated converter-modular multi-level converter(LCC-MMC)parallel multi-terminal hybrid DC transmission system combines the technical advantages of line commutated converter-high voltage direct current(LCC-HVDC)and modular multi-level converter-HVDC(MMC-HVDC).However,due to its inconsistent boundary characteristics,special busbar structures,and different control strategies for converter stations,the existing line protection schemes are difficult to apply directly.Therefore,a protection scheme of multi-terminal hybrid DC line based on measuring wave impedance phase characteristics is proposed.Firstly,the expressions of wave impedance measured at different fault locations are deduced,and it is found that in the high-frequency band,the phase of wave impedance measured at the measurement point is significantly different under the condition of internal and external faults.And the phase characteristics have nothing to do with factors such as fault distance,type and transition resistance.Then,the S-transform is used to extract the impedance phase information of the measured wave,and combined with the high-low frequency energy ratio criterion of the traveling wave to realise the fault identification.Finally,the simulation verification in PSCAD shows that the proposed protection can distinguish the faults of the T-zone bus and the adjacent line end,and has a certain anti-transition resistance(500Ω)and noise immunity(20 dB)while satisfying rapidity.The proposed peotection meets the main protection requirements of the multi-terminal hybrid DC system line.

关 键 词：多端混合直流 波阻抗相位 输电线路故障 S变换 继电保护 T区母线 

分 类 号：TM773[电气工程—电力系统及自动化]