Novel Multiple Power Conversion System for The Voltage Source Power Converter using Phase-Shifting Transformer

This paper proposes a novel multiple power conversion system using voltage source power converters and phase shifting transformer suited for application to power systems. Conventionally, for harmonic elimination, serial composition method of out-put voltages of power converter units using serially connected windings of transformers has been applied. But, the conventional method has imbalance problems of transformer voltages and of voltages of DC-link connected in series. This proposed converter has a transformer with primary windings connected in parallel or with common primary winding. By this method, the imbalance problems can be remarkably solved, and harmonic elimination can be provided. On the other hand, harmonic currents flow between the power converter units. For solving this problem, coupling reactors or leakage transformers are used to suppress harmonic cross currents. And these suppression methods are analyzed in detail. In conclusions, we can see following advantages. (1) Voltage imbalance problems can be remarkably solved. (2) Harmonic problems can be remarkably solved. (3) More high voltage can be realized.