Assessing the role of hybrid energy storage in generation expansion planning for enhanced frequency stability

As the power grid transforms towards a renewable energy dominant grid, which are associated with frequency stability challenges, it is important to combat these challenges through proper power system planning. This paper therefore investigates the impact of hybrid energy storage (HES) in enhancing the frequency stability of the modern grid. The optimization problem is formulated as a mixed integer quadratic constrained programming model to minimize the system cost, while maximizing system inertia. The proposed model is then implemented on an IEEE 6-bus system, and solved using CPLEX solver in GAMS, with its performance evaluated using two study cases. Case 1 considers only the economic objective (cost), while case 2 considers both the economic objective (cost) and the technical objective (system inertia). The result show that the incorporation of HES in the generation planning model improved the overall system inertia of the system by 11% (from 6.199s in case 1, to 6.901s in case 2), however the total system cost increased by 3% (from 218M$ in case 1 to 2.25M$ in case 2)