Study on the Optimal Operation of ESS Considering Urban Railway Load Characteristic

Abstract

-This paper proposes the optimal operation of ESS (Energy Storage System) in the substation of urban railway in an economical point of view. Since the load patterns of urban railway have different characteristics with the general power demand pattern, the characteristics motivate us to develop the optimal operation algorithm for ESS under Korean electricity billing system. We also introduce two different ESS operation strategies for peak load shaving and electricity consumption charge minimization respectively, and formulate each scheme. Historical data from Namgwangju substation are used for economical comparison of the strategies. The results show that the proposed algorithm is the most cost-effective ESS operation scheme among the strategies and reduces around 5 percent of electric charges compared to the charge without ESS operation.

Cooperative Operation Schedules of Energy Storage System and Demand Response Resources Considering Urban Railway Load Characteristic under a Time-of-Use Tariff

“…The TOU pricing is a rate plan that the unit price of electricity is divided into two or three sectors depending on power consumption by season or the time of day [9]. This plan consists of capacity charges and energy charges [9], and is designed to recover those charges in the power supply [14]. The TOU pricing belongs to a typical price-based DR program, balancing electricity usage by shifting demand from the peak time to off-peak times.…”

“…The TOU pricing belongs to a typical price-based DR program, balancing electricity usage by shifting demand from the peak time to off-peak times. Also, this pricing plan provides an incentive for consumers who reduce their power consumption [9]. In other words, this pricing plan allows power suppliers to compensate for the cost of generating energy and to induce to load patterns as the supplier intended.…”

“…In South Korea, industrial electricity tariff induces DR to consumers with the TOU rate plan (see Table 1 as an example) [9]. The capacity charge is set to the highest amount of power demand during the previous 12 months when the peak load occurred [9,22]. The capacity charge can be reduced when the peak load decreases.…”

“…ESS can support or replace power consumption of a railway station so that the air-conditioning and ventilation facilities in a station can be in operation as it was, while the power consumption pattern of the railway station can be managed according to electricity bills. Therefore, the Operation of ESS, can maximize saving electricity costs without degrading customer satisfaction [9][10][11][12].…”

“…Alternatively, we can estimate the DR capacity by modeling the correlation between power consumption and user utility. This method can adjust the DR capacity to provide the desired utility level of a railway station [9,18,20]. However, it is difficult to estimate the DR capacity, compared to the pre-calculation method.…”