Hybrid-Waveform recognition for magnetizing inrush current

The identification of inrush current has been the focus of relay protection for a long time. In recent years, using waveform symmetry principle to identify inrush current has received more attention. This method identify the waveform of the magnetizing inrush current by comparing current's waveform's shape, size or change rate. However, the traditional waveform recognition method has the defects of long data recognition window, low speed and precision. This paper proposes a new identification method named hybrid waveform recognition and the concept of the standard string wave window to identify magnetizing inrush current. This new method has advantages of high speed, high precision and high reliability.