摘要
提出了一种双端量直流线路保护算法,以保证直流配电系统安全可靠运行。通过分析直流双极短路故障差动电流频段分布,发现线路分布电容电流与故障电流的能量频段存在明显差异,利用区内故障时差动电流的能量主要分布在低频段,而区外故障时差流能量主要分布在高频段的特点,提出了基于能量分布的差动保护原理,给出了具体的动作判据与保护流程,分析了各种因素对保护的影响。仿真结果验证了所提保护算法的可行性,保护具有天然的选择性,可耐受较高过渡电阻、噪声(20d B)以及一定的同步误差(40?s),保护出口时间在3ms以内。本原理将分布电容的影响变为保护的制动量,因此区外故障时分布电容电流不会造成保护误动。
A main line protection is proposed to guarantee reliable operation of VSC-DC distribution systems. Characteristics of differential current frequency bands are presented. For an internal pole-pole fault, the energy of differential current is mainly distributed in low frequency band. In contrast, for an external pole-pole fault, the energy of differential current is mainly distributed in high frequency band. Then, a differential protection based on energy distribution is proposed. Protection operation criteria and logic are presented. Various factors influencing merit of the protection are analyzed. Simulations verify feasibility of the proposed protection scheme. The protection has absolute selectivity and can withstand 10？ fault resistance, 20 d B white noise and 40μs synchronization error. The protection operates in less than 3ms, not affected by distributed line capacitance.
出处
《电网技术》
EI
CSCD
北大核心
2017年第9期3058-3065,共8页
Power System Technology
基金
国家重点研发计划基金资助项目(2016YFB0900503)
中央高校基本科研业务费基金项目(2016ZZD01)
国网公司科技项目("柔性变电站成套设计技术研究及设备研制研究项目")(SGRI-DL-71-15-011)~~
关键词
差动保护
频段
直流配电系统
电压源换流器
故障分析
小波变换
differential protection
frequency band
DC distribution system
VSC
fault analysis
wavelet transform
