Research On Power Regulation System And Control Method Based On Cascade Converter

In recent years, with increasing injection power from the wind farms to the grid, the stability and reliability of the Power system is experienced rigorous ordeal. So there is an urgent need for active and reactive power regulation system to solve the power quality issues. In conventional systems, H-bridge cascade converter is applied to high voltage, large capacity power regulation system due to the advantages such as its simple structure, modularity, high efficiency and redundant control.This paper describes an active and reactive power regulation system based on a cascade converter. The active and reactive power control which is indispensable for the system's proper operation is concentrated in this paper. Furthermore, the balance of three-phase DC link voltage is very important for the reliable operation of H-bridge cascade power regulation system. A novel strategy to balance the DC link voltage for the star-connected cascade power regulation system is proposed in this paper. The strategy is designed based on the negative-sequence voltage injection and is compared with the conventional zero-sequence voltage injection based strategy. The simulation results verify the theoretical analysis and the effectiveness of the proposed strategy.The experimental platform of the cascade power regulation system which the cascade number N=1 is established. The experiment results demonstrate that the proposed system and the reactive power control strategy are correct and feasible. It is also established a foundation for the subsequent experiment platform.As a result of the output power of the wind farm can be regulated by the cascade power regulation system, so it has important value and significance for improving the stability of the power system and increasing the wind power to the grid.