摘要
为提高我国220kV及以上变压器保护正确动作率,提出了一种基于模糊贴近度原理的识别变压器励磁涌流的新方法。该方法通过比较归一化后前后半周期波形的贴近程度来区分励磁涌流和故障电流:励磁涌流的波形畸变严重,在波形上以间断角和波形不对称的形式出现,因此归一化后前后半波贴近程度低,接近于0;而内部故障电流波形含有较少的2次谐波和高次谐波分量,在波形上以对称的形式出现,前后半波贴近程度高,接近于1。同时,应用模糊数学工具将该原理的3种类型相结合以使其优势互补。理论分析和动模实验结果表明:该方法原理简单、易于实现,可准确识别故障电流和励磁涌流,即使空载合闸于内部短路故障时保护也能迅速可靠动作。
A novel algorithm based on the principle of fuzzy degree of nearness to distinguish magnetizing inrush current is proposed. This method separates magnetizing inrush current and short circuit current by means of comparing the degree of nearness between the pre-half and the post-half cycle. As the waveform of inrush current is distorted wave, the degree of nearness between its pre-half and the post-half cycle is low, which approaches 0. And three types of the algorithm with fuzzy theory are combined to make their dominances complementary each other. 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 protective relay trip rapid and reliable even if switching on under no-load conditions with a internal fault.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2008年第1期154-157,共4页
High Voltage Engineering
基金
高等学校博士学科点专项科研基金(20060079009)~~
关键词
变压器
纵联差动保护
模糊理论
模糊贴近度
励磁涌流
短路电流
transformer
longitudinal differential protection
fuzzy theory
fuzzy degree of nearness
inrush current
short circuit current
