Abstract:With the rapid development of renewable energy and the increasing demand for flexibility in power system, a flexible ramping service transaction mechanism and a coordinated optimization strategy for day-ahead dispatching of distribution network are designed considering the characteristics of energy storage system. Firstly, the supply and demand balance mechanism of flexible ramping demand is analyzed, and then a bidding strategy for energy storage to provide flexible ramping services is established based on the state of charge of energy storage system. Secondly, after establishing a model for flexible ramping service transactions, an optimal dispatching strategy for distribution network considering flexible ramping transaction plans is established. And then, in order to ensure the coordinated optimization results of the transaction plan and the dispatch plan, the analysis target cascading is used to decouple and solve the model. Finally,the effectiveness of the proposed strategy and model is verified by IEEE 33-node system.