A new method to identify inrush current by composite calculation

This paper reviews the characteristics of inrush current and analyses its causes. The development of digital substation and the concept of integrated protection are also outlined. The paper studies different models to simulate several kinds of inrush and internal short-circuit fault. Through these models, the new composite algorithm is analysed in order to verify the reliability and sensitivity of the new method. By comparing the action situation of traditional inrush restrain principle and the new composite method, the new method owns better identification reliability.