Abstract:Dashan 220kV substation is the main power supply station of Dexing Copper Mine, which operation stability is extremely important to the entire open pit mine power supply. In recent years, the main equipment of the substation has been comprehensively transformed. But the related supporting facilities, liaison station and user side equipment backward, and lead to the interference and challenge of various factors on the stability of the whole mine power supply system. For example, the long distance overhead transmission line has a high failure rate, frequent lightning activities frequently test the system’s lightning protection, and some electrical equipment is put into operation automatically without regularity etc. Based on the requirements of safe and stable operation of substation, it is of great significance to analyze and study the stability of power supply system in open pit mine.