Storage Right-Based Hybrid Discrete-Time and Continuous-Time Flexibility Trading Between Energy Storage Station and Renewable Power Plants

Renewables, widely regarded as the predominant energy in the future, have primary responsibility for future power supply adequacy and thus are becoming the main flexibility demander considering their self-induced uncertainties. This paper proposes a novel storage right-based hybrid discrete-time and continuous-time (HT) flexibility trading between energy storage station (ESS) and renewable power plants (RPP), where ESS sells flexibility for profits and RPPs buy flexibility to hedge power supply shortage risks. The flexibility package (FP), composed of energy/power/ramping capacity rights and stored energy sell/recycle, is proposed as the trading product to reach a higher profit for ESS and to provide a more customized selection for RPPs. The HT bilevel optimization is proposed for flexibility trading, where the upper-level discrete-time (DT) optimization decides the arbitrage schedule and FP price of ESS and the lower-level continuous-time (CT) optimization decides the bidding strategy and FP order of each RPP. The enhanced solution space transformation and the KKT condition method are utilized to reduce the HT bilevel optimization into common DT optimization which is then linearized into mixed-integer linear programming for tractable calculation. Case studies validate the higher profits of ESS and the lower power supply shortage risks of RPPs under the proposed method.