Economic Potential of Battery Storage in Grid Expansion Planning for Renewables Integration

Conference slides from the 15th Trans-Atlantic Conference, Novembre 2023 Abstract : The growing penetration of renewables challenges sub-transmission grid expansion planning as the available grid connection capacity is progressively saturated. In this paper, we developed a model to study the interplay of battery storage and grid investments under a strong penetration of renewable energy on sub-transmission. We model a co-optimisation of grid investments, storage investments, and dispatch for a simplified power system. We also develop an iterative optimisation approach to represent the grid line capacities as discrete variables. Line capacities resulting from a first optimisation are rounded up or down to the nearest multiple of their nominal value. A second optimisation is used to re-evaluate storage capacities with the two discretised networks. These are only second-best solutions, which do not necessarily encompass the initial mixed-inter linear problem's solution. Under favourable conditions, we observe line investments partially replaced by large storage capacities. Without one of these conditions, storage is no longer a good complement to the grid but remains a good potential complement to PV power. Rounding down the grid capacities releases more space for storage but at a higher system cost. Rounding upward can reduce storage investments. Sensitivity analyses are run on multiple parameters (solar power, storage and line cost, marginal cost) to study the dynamics of investments. This co-optimisation highlights the complementarity of storage and grid investments with high PV generation. Representing discrete line capacity most likely reduces storage investments.