摘要
多端柔性直流电网(multi-terminal flexible direct current,MTDC)复杂的故障暂态特性对直流线路保护的动作性能要求更高。该文基于MTDC电网故障暂态分析模型,通过推导区内、区外故障时测量阻抗的频域特征,揭示不同故障位置测量阻抗的差异。然后引入最小二乘法(leastsquare method,LSM),将线路两侧多频段的测量阻抗实际计算值与理论值拟合,利用两端拟合曲线的斜率构造高可靠性的直流线路纵联保护方案,并提出线路正负极低频功率比进行故障选极。仿真结果验证了理论分析的正确性,表明该方法能够灵敏、可靠、快速地识别区内外不同类型的故障,抗过渡电阻能力强,受噪声影响小,对系统参数变化具有较强的适应性。
The complicated fault transient characteristics of the multi-terminal flexible direct current(MTDC) grid require higher performance for the DC line protection.Based on a model for fault transient analysis of the MTDC grid,the frequency domain expressions of the measured impedance are derived in case of the internal or the external faults,and the difference of the measured impedance under different fault positions is revealed.Furthermore,the least square method(LSM) is introduced to fit the actual calculated value of the measured impedance of the multiple frequency bands at the both sides of the DC line with the theoretical value.Then,a highly reliable DC line pilot protection scheme is constructed by using the slope of the fitting curve with the both ends.Finally,the ratio of low-frequency power component of the bipolar lines is used to select the faulted pole.The simulation results verifies the correctness of the theoretical analysis and demonstrates that the proposed protection scheme has high sensitivity,reliability and operation speed to distinguish the internal and external faults.Meanwhile,the protection scheme has strong fault transition resistances and anti-noise abilities and applies to the circumstances when the system parameters vary.
作者
杨冬锋
王鹤
刘晓军
张国华
刘闯
YANG Dongfeng;WANG He;LIU Xiaojun;ZHANG Guohua;LIU Chuang(Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology(Northeast Electric Power University),Ministry of Education,Jilin 132012,Jilin Province,China;DC Technical Center of State Grid Corporation of China,Xicheng District,Beijing 100052,China)
出处
《电网技术》
EI
CSCD
北大核心
2022年第12期4699-4709,共11页
Power System Technology
基金
国家自然科学基金项目(51877035)。
关键词
多端柔性直流电网
测量阻抗
最小二乘法
纵联保护
故障识别
multi-terminal DC grid
measured impedance
least square method
pilot protection
fault identification
