摘要
提出了应用正弦函数的特征和模糊贴近度原理相结合的方法来识别变压器的故障电流和励磁涌流。变压器正常运行、内部短路、外部短路时波形具有正弦波形特征,而励磁涌流波形因包含非周期分量、间断角不具有正弦波形的特征。假设所研究波形均为正弦波形,通过直接寻找可以得到峰值的实际值,通过理论计算可以得到峰值的理论值,然后求实际值和理论值比值的绝对值。利用绝对值的大小区分故障电流和励磁涌流。理论分析和动模实验结果表明:本方法原理简单,易于实现,可以准确识别故障电流和励磁涌流,即使在空载合闸于内部短路故障时保护也能迅速可靠动作,并具有抗CT饱和的能力。
This paper proposes a new method of using the sine principle combined with the fuzzy degree of nearness to identify the short circuit current and inrush current of transformers. Under transformer internal and external faults, the three- phase current is mainly sinusoidal. However, the inrush current is featured by no periodic and dead angle, so it is not sinusoidal. This paper assumes that all the waveforms researched are sine waveforms. The actual value of the hump can be found directly. And the theoretical value can be got by calculating. Through the dimension of the absolute value the short circuit current and the inrush current can be distinguished. The results of theoretical analysis and dynamic simulation show that the method mentioned here can identify the short circuit current and the inrush current precisely , and make it rapid and reliable for the protective relay to trip even if switching on under no- load conditions with an internal fault occurring. It also can resist CT saturation.
出处
《华北电力大学学报（自然科学版）》
CAS
北大核心
2007年第6期23-27,共5页
Journal of North China Electric Power University：Natural Science Edition
关键词
正弦函数特征
峰值
模糊贴近度
变压器
故障电流
励磁涌流
sine principle
hump
fuzzy degree of nearness
transformer
short circuit current
inrush current
