基于小波模极大值理论的励磁涌流新判据研究

针对励磁涌流引起变压器纵联差动保护误动的问题,提出了一种基于小波变换和模极大值理论来辨别励磁涌流与故障电流的新依据。该方法根据励磁涌流含有大量非周期分量和波形间断角,而故障电流保持基频正弦波的特点。首先利用小波分解原始信号,再利用模极大值理论选取模极大值点,通过模极大值点之间的数值关系可以鉴别不同电流信号。经过Matlab/Simulink仿真分析,表明该方法能够准确可靠地区分励磁涌流和故障电流。

Research of inrush current identification based on wavelet and modulus maximum

Aiming at the problem that inrush current can lead to the mal-operation in differential transformer protec-tion, and this paper came up with a new method to identify inrush current and fault current based on wavelet transform and modulus maximum .Because the inrush current contains a large component of non-periodic components and dead angle, while fault current always keeps its fundamental frequency , the new method is just based on these characteris-tics.Firstly, it uses wavelet to decompose original signals , and then, select maximal points based on the theory of modulus maximum , by using the numerical relations between maximal points can distinguish different current signals . By adopting Matlab/Simulink , the simulation results show that this method can distinguish inrush current and fault current reliably .