Test System Of Auto-balancing Electronic Power Transformer

Auto-balanceing Electronic Power Transformer (A-EPT) is a type of Electronic Power Transformer (EPT) with the ability of Auto-balancing, which aims at the voltage regulation and power transmission of power net. Compared with the traditiational transformer, one of its significant advantage is that the current of the primary side, the voltage of the second side and the power factor can be flexibly controlled, and with the normal Electronic Power Transformer, it has the ability of keeping system auto-balancing: whatever the primary side or the second side is not balance, it can keep another side balance. EPT can not only promote the power quality, immprove the system stability, but also conform a variety of distributed power resources, achieving flexible power transmission. So, the researches on EPT (A-EPT) are significant for the Green & Ditial Grid construction.In this paper, the main point is the research on A-EPT experimental system. First, the paper summarys the development and current state and some representative structure of EPT, then presents the basic theory and topology of A-EPT, and also the control strategy of the experimental system in this paper. Basing on the former contents, the hardware of system is proposed in detail, including the main circuit and the control circuit topology, the parmater of component elements is caculated in theory either. Then the software running in DSP2812 is shown in program flow. The experimental results show that, the A-EPT tester system not only has the ability of EPT, but also the ability of auto-balancing.Based on the theory of cells cascaded multilevel converter, the structure of a three phase line voltage cascaded multilevel converter and its control strategy are proposed in the end of this paper. Simulation results show that such topological structure can increase the output voltage class and decrease the THD. Such cascaded structure can be used as either dc-to-ac converter or ac-to-dc inverter directly in three-phase system without transformers. Experimental results of dc-ac of 3-module demonstrate the feasibility of the proposed converter topology.