Multi-Timescale Optimal Scheduling of a Renewable Power to Ammonia System with a Variable Medium-Term Horizon

Renewable Power to Ammonia (RePtA) systems provide an important pathway for the accommodation of renewable energy and promoting the low-carbon transition of the conventional ammonia industry. With the increasing penetration of renewable energy in power systems, output fluctuations and forecast errors are posing growing challenges for RePtA system operations, making multi-timescale optimal scheduling increasingly important. This study proposes a multi-timescale optimal scheduling model for a RePtA system with a variable medium-term horizon. First, a key component model is established to characterize the system’s operations under a dynamic time interval regulation strategy. Then, stage-wise scheduling models are developed, where the medium-term stage adaptively generates a variable horizon based on the long-term scheduling results to better match renewable output variations. Finally, a multi-timescale coordinated operation strategy is proposed to ensure effective coordination among scheduling decisions across different timescales. Through a case study, it is demonstrated that the proposed method improves the total system profit by 5.12% and reduces the purchasing cost of electricity by 76.85% when compared with conventional scheduling strategies.