Charge storage is an important research topic in smart grid and distributed generation system, pumped storage as one of the most popular large-scale charge storage methods has attracted increasing attention. However, the motor generator of the pumped charge station has high input voltage and heavy load, so in order to get grid connected safely, being soft started by a high voltage converter is necessary. In the view of the existing high voltage high power converters, only the voltage source inverter Multi-stage Series-connection high voltage frequency converters are suitable for this application, and this paper gives analysis of such converters. Based on Carrier Wave Phase-Shifted modulation, this paper proposes a multi-stage Series-connection high voltage frequency converter with balanced output power of the step-down transformer’s secondary windings, in which a winding burdens three symmetry three-phase to single-phase MC outputs, and the same phase outputs of the MC are cascaded at the secondary side of the transformers, letting out one phase of high-voltage AC output. The circuit is consisted of a step-down industry frequency transformer at the network side, three-phase to single-phase MC arrays, a step-up high frequency transformer at the load side and filter components. The simulation result based on MATLAB/SIMULINK shows that the proposed multi-stage Series-connection high voltage frequency converter is feasible and low-cost.
Non-conventional Cascade Multilevel Inverter with Lower Number of Switches by Using Multilevel PWM
