Equilibrium analysis of a peer-to-peer energy trading market with shared energy storage in a power transmission grid

With the increasing penetration of renewable energy resources in power systems, energy storage is expected to play a more active role in system regulation. Shared use of energy storage is an emerging business model, and its impact on the power grid needs thorough analysis. This paper proposes a two-layer equilibrium model to study the grid impact of peer-to-peer (P2P) energy trading considering shared energy storage (SES). The upper layer describes the P2P energy transaction among generators and SES units. The generators can freely choose to sell electricity to the SES units or power grid while the SES units can choose to charge or discharge. The physical power transmission grid is considered in the lower layer. It determines the locational marginal price through a real-time optimal power flow model. The locational marginal price in turn affects the decisions of generators and thus the equilibrium of the P2P market in the upper layer. Based on Karush-Kuhn-Tucker (KKT) optimality conditions and the Big-M method, a mixed-integer linear program is developed to compute the equilibrium of the P2P market in the upper layer, and an iteration algorithm is proposed to search the equilibrium point in the transmission grid with the P2P market. Numerical results demonstrate that both generators and SES units can benefit from the P2P energy transaction.