基于等效序阻抗差异特征的低频输电线路差动保护优化方案  

Optimization scheme for differential protection of low frequency transmission line based on equivalent sequence impedance difference characteristics

作　　者：黄涛[1] 文继锋[1] 赵青春[1] 徐晓春[1] 谢华[1] 徐海洋 卜立之 HUANG Tao;WEN Jifeng;ZHAO Qingchun;XU Xiaochun;XIE Hua;XU Haiyang;BU Lizhi(NR Electric Co.,Ltd.,Nanjing 211102,China)

机构地区：[1]南京南瑞继保电气有限公司,江苏南京211102

出　　处：《电力自动化设备》2024年第5期143-150,共8页Electric Power Automation Equipment

基　　金：国家重点研发计划项目(2021YFB2401100)。

摘　　要：低频输电线路故障时,两侧短路电流均由模块化多电平矩阵变换器提供,两侧短路电流相角均受控且幅值相当,导致差动保护灵敏度严重下降。分析了低频输电系统定电压控制侧和功率控制侧的等效正、负序阻抗特征,指出因控制策略不同,系统故障时两侧等效正、负序阻抗特征存在明显差异。分析了低频输电线路区内和区外故障两侧保护装置测量到的等效序阻抗之间的差异性和相似性,基于此特征构建了两侧等效序阻抗差异指标,提出了基于等效序阻抗差异指标的差动保护制动系数优化方法。仿真结果表明,所提方案能够显著提升低频输电线路区内故障时差动保护的动作速度和动作灵敏性。During the fault of low frequency transmission line(LFTL),the short circuit currents on both sides of the line are provided by a modular multilevel matrix converter.The phase angle of the short circuit currents on both sides is controlled and the amplitude is equivalent,resulting in a serious decrease in the sensitivity of differential protection.The characteristics of equivalent positive-and negative-sequence impedances on the voltage control side and power control side of low frequency transmission system are analyzed.It points out that due to different control strategies,there are significant differences in the charac⁃teristics of equivalent positive-and negative-sequence impedances on both sides of the system during faults.Then,the difference and similarity between the equivalent sequence impedances measured by the protection relays on both sides of the LFTL under internal and external faults are analyzed.Based on these features,an indicator for the difference of equivalent sequence impedances on both sides is constructed.A method for optimizing the braking coefficient of differential protection using the indicator is proposed.The simulative results show that the proposed scheme can significantly improve the operation speed and sensitivity of differential protection in case of faults in the LFTL area.

关 键 词：继电保护 差动保护 等效序阻抗 低频输电 受控故障特征 制动系数 控制策略 

分 类 号：TM77[电气工程—电力系统及自动化]