Proposal of a novel control method of Li-ion battery system for regenerative energy utilization in traction power supply system

To make use of residual regenerative energy in d.c. traction power supply system, some energy storage systems have already installed in Japan. We, East Japan Railway Company, also installed two Lithium ion battery systems at Haijima Substation in 2013 and at Okegawa Substation in 2014, respectively. They contributed to reduce traction power supply from substation about 5-8% annually. Because the load of railway operation is heavy during the rush hour time in the morning and in the evening and light during the daytime, it is difficult to set appropriate control parameters for charging and discharging the battery system to be effective both during the rush hour and during the daytime. To solve this problem, the control parameters are changed depending on the time in our second installation of energy storage system at Okegawa. In this method, however, the parameter change is scheduled in advance and the system is able to accept the change of the receiving voltage influence by the grid condition. To make the system more effective, a novel control method to change parameters depending on the load condition moment by moment. By introducing this method, it is possible to change the control parameters flexibly even when the receiving voltage from the gird is changed. The effectiveness of the proposed method is shown, in this paper, based on the measured data at Okegawa Substation.