基于复合暂态能量的多端柔性直流电网自适应差动保护  

Differential Protection for Multi Terminal Flexible DC Power Grid Based on Composite Transient Energy

作　　者：郑涛 陈云飞 马英 李紫肖 Zheng Tao;Chen Yunfei;Ma Ying;Li Zixiao(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Source,North China Electric Power University,Beijing,102206,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京102206

出　　处：《电工技术学报》2025年第5期1440-1454,共15页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金联合基金资助项目(U2166205)。

摘　　要：对于多端柔性直流电网而言,当限流电抗器集中配置在换流站出口时,基于边界元件特性的暂态量保护方案难以适用。针对此问题,该文首先通过分析故障电流行波的传输特性,构造了兼具幅值与方向特征的复合暂态能量;其次,通过定性分析不同位置故障时线路两端故障电流波形特征,明确了区内外故障时线路两端复合暂态能量的差异;在此基础上,为进一步提高区内故障时保护的灵敏性以及区外故障时保护的可靠性,通过构造校正函数自适应调整制动量幅值,提出了一种基于复合暂态能量的多端柔性直流电网自适应差动保护方案;最后,PSCAD/EMTDC仿真结果表明,所提自适应差动保护方案在不同故障条件下均能可靠地识别区内外故障,且其具有较好的耐受过渡电阻以及抗噪声干扰能力。Flexible HVDC transmission systems offer significant advantages in solving the challenges of large-scale renewable energy integration and long-distance power transmission,indicating a major trajectory for the future transformation and growth of power systems.Compared to traditional HVDC systems,flexible HVDC systems are weakly damped,and their fault current rise rate is rapid.If faults are not cleared promptly,converter blockages may occur,demanding higher requirements for quick fault identification.Current engineering practices typically install current-limiting reactors at both ends of flexible HVDC lines.However,with the development of flexible DC grids,a single converter station may have multiple outgoing lines.In such cases,concentrating the current-limiting reactors at the converter station outlet can effectively reduce construction costs and improve economic efficiency.Existing traveling wave protection schemes for multi-terminal flexible HVDC grids typically use the blocking effect of current-limiting reactors on high-frequency components to construct protection criteria.However,when current-limiting reactors are concentrated at the converter station outlet,there are no obvious boundary elements between adjacent lines,significantly reducing the adaptability of traditional protection schemes in boundary-less grid structures.Therefore,new protection schemes that do not rely on boundary elements need to be further investigated.To address these issues,this paper first analyzes the transmission characteristics of fault current traveling waves and constructs a composite transient energy with both amplitude and directional features.To further clarify the variation patterns of the composite transient energy's amplitude and directional characteristics with wave transmission,the paper qualitatively analyzes the waveform characteristics of fault currents at both ends of the line for faults occurring at different locations.For internal faults,the composite transient energy at both ends of the line has the same direct

关 键 词：多端柔性直流电网 电流行波 复合暂态能量 制动量校正函数 自适应差动保护 

分 类 号：TM77[电气工程—电力系统及自动化]