Planning Scheme Design for Multi-time Scale Energy Storage at the City Level

With the increasing expansion of renewables, energy storage plays a more significant role in balancing the contradiction between energy supply and demand over both short and long time scales. However, the current energy storage planning scheme ignores the coordination of different energy storage over different time scales in the planning. This paper forces the unified energy storage planning scheme considering a multi-time scale at the city level. The battery energy storage, pumped hydro storage and hydrogen energy storage are considered to meet the power balance on the daily scale, monthly scale and annual scale. To minimize the total cost of energy storage, the capacity and outputs of energy storage are determined. With unified storage models, mixed-integer programming is applied to integrate the multiple time scale storage operation in the planning. The proposed planning scheme considers the trade-off between the flexibility and the cost of different types of energy storage. The results show that pumped hydro storage can undertake a large amount of power contradiction. The battery energy storage and the hydrogen energy storage meet the short-term and long-term energy imbalance respectively.