文档介绍：IIAbstract Besides of power transformer, there is a series of special transformer are demanded by utility applications. Special transformer usually including all kinds of converter transformer; strong current furnace transformer; mining transformer; high-voltage testing transformer; low-capacity single phase to three phase transformer; voltage and current transformer; voltage regulator; electric reactor and variable-frequency transformer bringing into service in recent years. Compared with general power transformer, using Auto-balancing Electronic Power Transformer (A-EPT) to realize phase change is easier, and it also has some other advantages such as the power factor of it’s primary side is adjustable, can ensure the input current has good waveform, maintain the output voltage, and guarantee balance of the primary side when supplying the load with high quality energy. Compared with other frequency conversion scheme, electronic power transformer has its own advantages in frequency division and frequency multiplication. This paper proposed the concept of Special Electronic Power Transformer (SEPT) for the first time. When it was applied in power system, it can help to improve electric power quality and system stability, and it can also realize flexible power transmission and real-time control of power flow in electricity market era, and also it can conform most kinds of distributed generations, all of this are of significance in the construction of work and work. This paper first introduced the fundamental operating principles of the Auto-balancing Electronic Power Transformer and the modulate strategies of Special Electronic Power Transformer. According to the requirement of the modulate strategy, this paper firstly proposed the concept of Park Transformation of multiphase AC system based on the Park Transformation of three phase AC system, and the transformation matrix and its converse matrix of four phase and six phase Park transformation is given here. Thereon,