Optimal control strategy of onboard supercapacitor storage system for light railway vehicles

The paper deals with the use of onboard supercapacitors for Light Rail Vehicles. The practical utilization of supercapacitors requires suitable control strategy of bidirectional dc/dc power converters for the regulation of power flows between the contact line and the electrical drives of the power-train. The control strategy is based on the simplified mathematical model of both the electrical drive and the electrical railway network. A one-side dc supplied streetcar contact line has been considered. The target of the control is to minimize the mean square voltage deviation at the vehicle pantograph and the power losses along the line. This allows to limit the peak currents of the contact line and to recover partially the kinetic energy of the vehicle during the braking periods. Optimization theory has been used for the determination and implementation of the real time control strategy. Experimental tests made on a laboratory scale prototype have proved that the suggested control strategy is very effective and applicable to a real streetcar.