A digital twin model for congestion management and market optimization A case-study of industry park Wetering-Haarrijn and Lage Weide in Utrecht, the Netherlands

Abstract

The electricity grid is increasingly burdened as energy demand rises and various renewable energy generation technologies are integrated. These technologies become more economically profitable, and so are battery energy storage systems (BESS). Renewable energy generation is subjected to tempo-spatial weather conditions and peaks in generation require large grid connections for limited amount of time. This leads to increased grid contract costs for end-users. Besides, the grid becomes satiated with high grid contracts, while the contract size is not often fully utilized. Sizing down grid connection while not controlling energy power flow can lead to congestion, where power flow exceeds nominal capacity. In this research, a case study is conducted on two industrial sites using a digital twin approach and finds the optimal utilization of a BESS in a trade-off between self-consumption, grid fees, battery degradation, and subsidy schemes. While these factors are researched on individual basis, the combination of those is not found in research. Multiple battery control strategies are proposed using case-study data and developed in Python, using Gurobi optimization. Results show degradation is decisive for model behavior, nevertheless, still results in economical attractive solutions. Photovoltaic (PV) generation peaks combined with insufficient BESS capacity raise grid connection, despite raising grid tariff costs. This only applies when there is a large difference in local PV generation and demand and as a result, the system encounters excessive PV generation, which is required to flow through the grid connection. Considering grid fees, self-consumption is deemed not the optimal control strategy, as it pushes the battery to charge and discharge to the grid at non-ideal times and with non-ideal quantity. Subsidies based on grid injection change model behavior and show potential but can only be feasible with sufficient surplus PV generation. This research shows that multiple aspects determine the optimal economic benefits and shows that these aspects are case study specific, and lead in particular to case study specific recommendations. This research also shows that ideal BESS operation is determined by multiple monetary flows as grid fees, subsidy schemes, electricity costs, and that degradation is a decisive factor