Optimal scheduling of Flexible Ramping Capacity in short-term electricity markets

Variable and uncertain conditions associated with increasing renewables introduce prominent challenges in the optimal power system operation and necessitate the reinforcement of flexible capability potential provided by the system resources. To address these challenges, some U.S. ISOs have incorporated specific “flexible ramp products” in their short-term scheduling processes. This paper proposes an enhanced modeling approach to underpin flexibility in European Central Dispatch systems. The model employs a “multi-timing” day-ahead scheduling method, which allows for the optimal procurement of such ramp products on an intra-hourly (“real-time”) basis, when concurrently optimizing energy and reserves over hourly time intervals. Additionally, a probabilistic method for the quantification of the flexibility requirements is proposed, to align the real-time system ramping needs with the intra-hourly optimization intervals. The model is evaluated using the Greek power system for three market configurations. Results demonstrate enhanced flexibility features in terms of market efficiency and system reliability.