The Research on Characteristics of Electronic Power Transformer for Distribution System

The 3-phase and 4-wire distribution electronic power transformer (D-EPT) is composed of the input three phase PWM rectifier, medium frequency transformer and output single phase inverters. In this paper, the operation principle of D-EPT is analyzed and its control scheme is designed. For the PWM rectifier, an outer loop control of the dc voltage and an inner loop control of ac current are adopted. Then, a dual-loop control is implemented for the output inverters based on the RMS value and instantaneous value of output voltage respectively. The simulation results show that D-EPT has good steady-state and dynamic load characteristics under the proposed control scheme.