Virtual Battery Model for EV Parking Lots Enhances Profitability and Reduces Charging Costs

Researchers from the University of Vaasa propose an efficient virtual battery model for EV parking lots, enabling charger-sharing to handle uncertainties and significantly increase profitability by hosting more vehicles with fewer chargers. This model outperforms traditional methods in computational efficiency and scalability, offering a practical solution for future EV infrastructure planning.

A study conducted by Mahoor Ebrahimi, Miadreza Shafie-khah, and Hannu Laaksonen from the School of Technology and Innovations at the University of Vaasa in Finland addresses the growing need for efficient charging solutions in electric vehicle parking lots (EVPLs) as the penetration of electric vehicles (EVs) increases. The substantial investment costs associated with installing numerous charging stations pose significant financial challenges. To mitigate these costs, the paper proposes a charger-sharing model that allows multiple EVs to be charged by a single charger rather than each EV having its own dedicated charger. This innovative approach aims to optimize the use of available chargers, thereby increasing the number of EVs that can be hosted and charged within an EVPL.

Innovative Virtual Battery Model to Handle Uncertainties

The proposed solution revolves around a virtual battery model that can handle the uncertainties associated with EV arrivals and departures. This model views the EVPL as a time-variant battery, with parameters that change based on the patterns of EV arrival and departure. The virtual battery model simplifies the energy management process by using the cumulative distribution function (CDF) of a truncated normal distribution to estimate the number of EVs arriving and departing each hour. By comparing this model with a scenario-based method in day-ahead (DA) and real-time (RT) power market participation, the researchers demonstrate that the virtual battery model performs comparably well but with a significantly lower computational burden around 2.24% of the scenario-based method.

Economic Benefits of Charger-Sharing

Key findings from the study indicate that employing charger-sharing can dramatically increase the profitability of EVPLs. For instance, with 200 EV chargers, an EVPL can host approximately 3200 EVs, while the exclusive charger approach can only accommodate 200 EVs. This substantial difference underscores the efficiency and economic benefits of the charger-sharing model. The motivation behind the study stems from the need to optimize the operation and planning of EV charging infrastructure. Most existing models either ignore uncertainties or are too complex and computationally demanding to be practical for large-scale applications. The virtual battery model offers a straightforward, low-computation solution for aggregated EV charging, considering the uncertainties of EV arrivals and departures without imposing significant computational demands.

Efficient Energy Management without Computational Burden

The proposed virtual battery model provides a practical approach to managing the energy requirements of EVPLs. By treating the EVPL as a virtual battery with time-variant parameters, the model can efficiently estimate the number of arriving and departing EVs and optimize the charging and discharging processes accordingly. This approach enables efficient energy management without imposing significant computational demands. The model's validation framework compares its performance with the scenario-based method, proving its effectiveness and computational efficiency. The results show that the virtual battery model's performance in uncertainty modelling is similar to that of the scenario-based approach, but with a much lower computational burden. This low computational burden is particularly important for large-scale problems, where numerous uncertainties from various sources, such as renewable energy generation, must be considered.

Validation and Profitability Analysis

The research also highlights the profitability of the charger-sharing approach. By employing this method, EVPLs can significantly enhance their profits by hosting more EVs and optimizing the use of charging infrastructure. The study presents several scenarios with different charging tariffs, demonstrating that a higher tariff motivates EVPL owners to accommodate more EVs. When the charging tariff is sufficiently high, the EVPL can host around 3200 EVs with just 200 EV chargers, considering the characteristics of EVs and EV chargers explained in the case study section. In contrast, the exclusive charger approach allows only 200 EVs to enter the parking facility and undergo charging. This substantial increase in the number of hosted EVs underscores the efficiency and economic benefits of the charger-sharing model.

Implications for Future Planning and Decision-Making

The paper emphasizes the practical implications of these findings for planning and operational decision-making in EV charging infrastructure. The proposed model's low computational burden makes it suitable for large-scale studies, where multiple uncertainties from various sources, such as renewable energy generation, must be considered. The virtual battery model offers a viable solution for the efficient and cost-effective operation of EVPLs, addressing a critical need in the evolving landscape of electric vehicle infrastructure. Overall, the study presents a practical and innovative approach to managing EV charging in parking lots, highlighting the substantial economic and operational benefits of the charger-sharing model. This research contributes significantly to the ongoing efforts to optimize EV charging infrastructure and enhance the sustainability and efficiency of electric vehicle operations.