Geometric Methods for Assessing the Value and Demands of Energy Storage in Power System Operation

ABSTRACT Driven by the desire of a low‐carbon society, the penetration level of renewable generation in the power grid of China will still grow fast in the near future. As the synchronised generators whose output is controllable are gradually replaced by volatile energy resources, energy storage is expected to play a vital role in regulation services and flexibility provision. Because the capital cost of energy storage is still relatively high, it is important to assess the value or demand of energy storage before making an investment decision. This paper presents two representative mathematical tools to achieve this target in a geometric fashion. The first one is the multi‐parametric programming method. It depicts the reduced cost by deploying energy storage through post‐optimal value function, which is easy to visualise or can be embedded in high‐level optimisation problems such as storage sizing. The second one is a polyhedral projection method. It represents all feasible power‐energy capacity pairs of a storage unit to achieve a certain target. The above methods remove the need of repeatedly solving a large number of problems with varying capacity parameters. Simple examples are given for illustration, and the presented methods can also directly handle problems with complex models and constraints.