摘要
单位长度的电缆线路与架空线路相比,电感较小但耦合电容要大许多倍。缆-线混合的配电线路,较短架空线路发生单相高阻接地时,可能会出现健全线路零序电流波形的相似性变差,故障线路与某些健全线路的零序电流波形较为相似的情况,将导致基于相关分析进行故障选线的方法失效。在分析缆-线混合线路各馈线零序电流故障特征频率可能不一致的基础上,为避开TA饱和引起的间断角,选取故障后1/4周期各馈线零序电流的短窗数据,利用S变换确定配网故障零序电流的主导特征频率,并比较此主导特征频率上各馈线零序电流的S变换能量来实现故障选线。理论分析和仿真验证表明,该方法选线准确、可靠。
As known, earth inductance per unit length of overhead-cable mixed lines is smaller than that of overhead line, while earth capacitance per unit length of overhead-cable mixed lines is larger than that of overhead line. When single-phase-to-ground fault occur to the short overhead line in the distribution network of overhead line and underground cable mixed lines, the comparability of zero sequence current of the lines in good condition is weakened. In contrast, the zero sequence current of the lines in good condition and fault lines is similar. For this reason, the correlation analysis method seems to failure in the fault line detection. An approach to the solution of this problem is presented under the analyzing the variance of fault characteristic frequency of zero sequence current in each feeder line in the distribution network of overhead line and underground cable mixed lines. In order to avoid the effect of TA＇s disconnection angle, the short window data of first 1/4 cycle are selected. The S-transform is carried out to determine the main characteristic frequency of fault zero sequence current. Then, the fault line is detected by S-transform energy at main characteristic frequency of zero sequence current in each feeder line. The theoretic analysis and simulations demonstrate the feasibility and validity of this approach.
出处
《电工技术学报》
EI
CSCD
北大核心
2009年第10期152-159,共8页
Transactions of China Electrotechnical Society
基金
国家自然科学基金(50977039
90610024
50467002
50347026)
云南省自然科学基金(2005F0005Z
2004E0020M)重点资助项目
关键词
缆-线混合线路
单相接地故障
S变换能量
主导特征频率
Overhead line and underground cable, single-phase-to-ground fault, S-transform energy, main characteristic frequency
