ADJUSTMENT OF THE CHARGE–DISCHARGE PARAMETERS OF A STATIONARY ENERGY STORAGE SYSTEM FOR DC ELECTRIC RAILWAYS USING PI CONTROL

Recent years have seen the introduction of stationary energy storage systems (SESSs) to mitigate the following problems commonly observed in DC traction power supply networks, namely: (1) the occasional loss of line receptivity for the regenerative trains when there is not enough load within the power supply network; and (2) the drop of line voltage when the traction load is too high. Commonly the charge and discharge current of an SESS is controlled using I-V characteristic controller, which determines the current depending on the terminal voltage of the SESS. However, it is known that it is a very difficult task to adjust threshold voltages such as charge start voltage. Thus, the authors propose a new approach to the determination of the voltage parameters using the PI controllers. In this research, we propose a method to adjust voltage thresholds using PI control and control method of SOE (State of Energy) to arbitrary value. Then, we propose two methods for controlling RMS current at the same time as the SOE, and we present the results of the simulation-based analyses of the proposed approach.