Optimized Control Strategy Of Stationary Ultracapacitor Energy Storage System Based On Dynamic Threshold

ABSTRACT:Ultracapacitor energy storage system applied in metro power supply system can achieve regenerative braking energy recovery. The traditional control strategy usually focus on the self-control of energy storage system. Based on the traditional control strategy,this article study the optimization control strategy from the perspective of the whole system.To begin with,the article analyze the traction/braking characteristic and voltage limiting of regenerative braking of the metro train,then discuss the influence of DC voltage to the regenerative braking power. Next, the model of24pulse rectifier of the metro power supply system is established, then the idea no-load DC voltage and realistic no-load DC voltage of power supply system is obtained. On the basic, the novel metro power supply system with Ultracapacitor energy storage system is established which can be the analytical model of control strategy.The article study the control method of bi-directional DC/DC converter, deduce the unified small signal model of bi-direcitonal DC/DC converter,then propose the unified current controller and verified the validity though the simulation.Based on the control object of optimal energy saving and analysis of the influence of charging and discharging voltage threshold, the article propose the control strategy based on the dynamic discharge voltage threshold and verified the validity though the simulation.In the end, the article design and develop the200kW stationary ultracapacitor energy storage system, and test it in the rolling stock depot of Beijing Subway line10. In the test period, the control strategy based on the dynamic voltage threshold and the function of energy saving is verified.