摘要
目前微机母线保护最常用的方法是电流瞬时值差动保护。这种方法受电流互感器 (TA)饱和的影响而容易误动作。一种解决的方法是当 TA饱和时闭锁母差保护。但该方法当故障由区外转为区内时保护会拒动。文中利用小波变换能检测信号奇异性的原理 ,提出了一种实时检测 TA饱和区和线形区的一种新方法。在故障开始后对 TA二次电流实时进行多尺度小波变换 ,由于 TA二次电流波形在故障发生时刻、进入饱和时刻和出饱和时刻都有奇异性 ,分别对应小波模极大值 ,因此可根据小波模极大值的不同特征判断对应时刻的是进饱和点还是出饱和点 ,从而实现 TA饱和区闭锁、线形区开放的母差保护。
The bus differential protection based on instantaneous values of currents is the most useful scheme nowadays. But it is easy to be influenced by current transformer saturation and to make mal-operations. One of solutions is to block the relay when current transformer is saturating. But this method can make the relay refuse to trip when a fault transfers to inside the protected zone from outside. In this paper, a new method is proposed to detect and distinguish current transformer saturation and linear sections, and the wavelet transform theory is used to detect the singular points of signals. Because the current waveforms got from current transformer have singularity at the points of fault occurrence, the start of saturation and the end of saturation, we can distinguish these points according to their characters on-line. Thus, to open or block it in current transformer linear or saturation sections, the bus differential protection can be realized.
出处
《电力系统自动化》
EI
CSCD
北大核心
2001年第10期27-30,共4页
Automation of Electric Power Systems
关键词
电流互感器
饱和
小波变换
母线保护
微机保护
电力系统
Busbars
Electric fault currents
Electric instrument transformers
Wavelet transforms
