The influence of electric vehicle charging strategies on the sizing of electrical energy storage systems in charging hub microgrids. (1st September 2020)

• Record Type: Journal Article
• Authors: Haupt, Leon; Schöpf, Michael; Wederhake, Lars; Weibelzahl, Martin
• Is Part Of: Applied energy. Volume 273(2020)
• Publication Date: 2020-09-01
• Subjects: Commercial microgrid -- Charging hub -- Charging strategies -- Vehicle-to-grid -- Stationary electrical energy storage -- Battery sizing; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2020.115231
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: Charging hub microgrids increasingly gain importance in electric mobility. Stationary electrical energy storage is a key component in charging hub microgrids. Sizing storage is practically relevant and non-trivial. The optimal size is sensitive to the mix of electric vehicles' charging strategies. The results of our case study indicate bidirectional charging may not pay off. Abstract: Economic, ecologic, and social benefits support the rapid diffusion of grid-connected microgrids (MG). Economic feasibility still stands out as the primary goal of commercial MGs. A stationary electrical energy storage system (ESS) is often a central component of MGs, facilitating islanding and cost-effective management of main grid use. Therefore, previous research has focused on the sizing of stationary ESS. The advent of large-scale electric vehicle (EV) charging hub MGs (CHMGs) such as the one along the freeway A8 near Augsburg, Germany, profoundly changes the economically optimal capacity of stationary ESS. While it is well conceived that EVs can be aggregated and then compensated for stationary ESS, research still lacks quantifiable evidence and methodological guidance on how the charging strategy (immediate, controlled, bidirectional) influences the economically optimal capacity of the stationary ESS. To address this gap, this paper proposes a method that includes a mixed-integer linear programming model for scheduling decisions under various conceivable ESS capacities and provides scenario analyses on the EV charging strategies as well as on ESS cost. Thereby, the method thus identifies the economically optimal capacity of the ESS. The results show that in the considered CHMG near Augsburg, the stationary ESS sizing decision is relevant in all but extreme scenarios. In particular, the economically optimal stationary ESS capacity soars if more than 65% of the EVs begin to charge immediately and the storage costs falls below 150 EUR/kWh. In contrast, smaller portions of controlled charging EVs can already drastically reduce stationary ESS. Remarkably, this paper also gives quantitative evidence that investments in bidirectional charging do not to pay off in the CHMG near Augsburg.