Equivalent Circuit Of Electronic Power Transformer And Its Application

With the development of the applications of high power electronic technology to power systems, a novel transformer-electronic power transformer has been studied for many years. Compared with traditional transformer, EPT has a lot of advantages. A significant advantage is that the voltage of the primary side, the current of the second side and the power of both sides can be flexibly controlled. With EPT applied to power system, firstly the power quality and the power system stability can be improved. Then, the flexible transmission mode and the power flows control in real-time are possible. Furthermore, a variety of distributed power resources can expect to be conformed. Thus, the researches on EPT are significant for the Green & Digital Grid construction.The basic theory and the present state of EPT are introduced in this paper. Each module of the EPT that based on AC/DC/AC converter is analyzed in detail, and it's calculation model is simplified for the sake of electrical calculation and simulation. The validity of the simplification of the isolation module is proved. From the analysis of every module, the equivalent circuit of EPT is obtained and the third-order mathematical model of EPT is proposed. A new optimal coordinated control strategy for generator-EPT unit is designed by using mathematical model of EPT and third-order mathematical model of generator. Simulation results show that high power factor and good output voltage is obtained by control of EPT and the excitation generator. Two disturbances are set in the simulation, the results show the system has damping characteristic in disturbances. Compared with the same instance when using traditional power transformer, the advantage of EPT is proved.