Dynamic performance for discharging process of pumped thermal electricity storage with reversible Brayton cycle

Pumped thermal electricity storage (PTES) is suitable for large-scale energy storage applications because of its low cost and no geographical constraints. In this study, the performance of PTES system for adjusting the net power output of the heat engine cycle to meet the load demand variation, is investigated. Based on the off-design condition models of turbomachinery and heat exchangers, the heat engine cycle dynamic model of a 5 MW PTES system is established. The disturbance simulation of the user-side load is carried out, and the dynamic response results are obtained. The inventory control strategy of working fluid is proposed to control the net power output to follow the variations of the load demand. The traditional PI controller is used in the two control processes of 50% ramp-down in load demand and a typical day load demand in Zhangbei District of north China. The results indicate that the net power output of the heat engine cycle can follow the variation of load demand in time. With the inventory control strategy, the heat engine cycle mode of PTES system can adjust the net power output to meet changes in load demand.