基于谐波闭锁涌流的样本电流分析

Analysis of Sample Current Based on Harmonic Restraint Inrush Current

分析了二次谐波励磁涌流制动使用的2种差电流:Y,d转换差电流ia-ib和D,y转换差电流ia-i0。分析表明,2种方法识别涌流效果相当,存在转换过程中造成二次谐波减小情况,空投时容易出现误动情况,不宜采用分相闭锁。在基于更真实反映励磁电流的基础上,提出了采用样本电流ia+xi0判断励磁涌流的方法。理论证明该方法能够有效判断励磁涌流,实现单相制动,提高了变压器差动保护励磁涌流闭锁的可靠性和空投故障灵敏性。同时,通过10 000多组的批量实验仿真数据和现场空投实例,验证了新方法较其他差电流具有更高的可靠性和灵敏性。

By analyzing two-kind differential current（DC） such as： DC with delta-star and with star-delta connection used for second harmonic magnetic inrush current restrained,it shows that the former has no advantage over the later on identifying the inrush,and the decreasing situation of second harmonic is existing in transformation process.In addition,because wrong act may occur when transformer energized,split-phase blocking should not be adopted.A new sample current method for effectively judging the magnetic inrush currents is proposed,it can realize single-phase braking,improve reliability of inrush current blocking and no-load fault sensitivity of magnetic inrush current restraint for transformer differential protection.The new method shows higher sensitivity and reliability than that of other differential current,which is proved by more than 10 000 groups of batch experimental simulation data and field no-load energized examples.