A Security-constrained Unit Commitment-based Optimal Battery Usage Pattern Model

Abstract

This paper discusses multiple strategies of security-constrained unit commitment (SCUC)-based optimal battery usage pattern models to drive the charging and discharging of different batteries and help the operation cycles satisfy their preferences according to battery characteristics. Previous studies mainly focus on either battery storage integration as a controllable resource into the grid with high penetration of renewable energy, or battery degradation costs as additional terms in the objective function of SCUC. In comparison, this paper first considers whether battery operation cycles satisfy their preferences according to specific battery characteristics. It discusses a full charging/discharging strategy for Ni-Cd batteries, which have a memory effect and prefer deep cycles. Then, the paper explores a shallow cycle strategy for Lithium-ion, lead acid, and Ni-H batteries, which have no memory effect and prefer shallow cycles for long service life. Subsequently, it is extended to a hybrid strategy when batteries with/without memory effects are at the same node. The proposed model minimizes the total operation cost of SCUC while including the penalties for battery usage strategies. The original problem is a mixed integer non-linear programming (MINLP) one, and then it can be mathematically converted into a mixed integer linear programming (MILP) one. Consequently, the models with multiple strategies are tested through IEEE 6-node power system. Computational results show that, compared to the base case without any strategy, the proposed optimal battery usage pattern approaches have an advantage in driving Ni-Cd batteries toward deep cycles, guiding Lithium-ion batteries towards shallow cycles, and improving the flexibility of performance with hybrid applications.