Online EV Charge Scheduling Based on Time-of-Use Pricing and Peak Load Minimization: Properties and Efficient Algorithms

Electric vehicles (EVs) endow great potentials for future transportation systems, while efficient charge scheduling strategies are crucial for improving profits and mass adoption of EVs. Two critical and open issues concerning EV charging are how to minimize the total charging cost (Objective 1) and how to minimize the peak load (Objective 2). Although extensive efforts have been made to model EV charging problems, little information is available about model properties and efficient algorithms for dynamic charging problems. This paper aims to fill these gaps. For Objective 1, we demonstrate that the greedy-choice property applies, which means that a globally optimal solution can be achieved by making locally optimal greedy choices, whereas it does not apply to Objective 2. We propose a non-myopic charging strategy accounting for future demands to achieve global optimality for Objective 2. The problem is addressed by a heuristic algorithm combining a multi-commodity network flow model with customized bisection search algorithm in a rolling horizon framework. To expedite the solution efficiency, we derive the upper bound and lower bound in the bisection search based on the relationship between charging volume and parking time. We also explore the impact of demand levels and peak arrival ratios on the system performance. Results show that with prediction, the peak load can converge to a globally optimal solution, and that an optimal look-ahead time exists beyond which any prediction is ineffective. The proposed algorithm outperforms the state-of-the-art algorithms, and is robust to the variations of demand and peak arrival ratios

Towards electric bus system: planning, operating and evaluating

The green transformation of public transportation is an indispensable way to achieve carbon neutrality. Governments and authorities are vigorously implementing electric bus procurement and charging infrastructure deployment programs. At this primary but urgent stage, how to reasonably plan the procurement of electric buses, how to arrange the operation of the heterogeneous fleet, and how to locate and scale the infrastructure are urgent issues to be solved. For a smooth transition to full electrification, this thesis aims to propose systematic guidance for the fleet and charging facilities, to ensure life-cycle efficiency and energy conservation from the planning to the operational phase.One of the most important issues in the operational phase is the charge scheduling for electric buses, a new issue that is not present in the conventional transit system. How to take into account the charging location and time duration in bus scheduling and not cause additional load peaks to the grid is the first issue being addressed. A charging schedule optimization model is constructed for opportunity charging with battery wear and charging costs as optimization objectives. Besides, the uncertainty in energy consumption poses new challenges to daily operations. This thesis further specifies the daily charging schedules with the consideration of energy consumption uncertainty while safeguarding the punctuality of bus services.In the context of e-mobility systems, battery sizing, charging station deployment, and bus scheduling emerge as crucial factors. Traditionally these elements have been approached and organized separately with battery sizing and charging facility deployment termed planning phase problems and bus scheduling belonging to operational phase issues. However, the integrated optimization of the three problems has advantages in terms of life-cycle costs and emissions. Therefore, a consolidated optimization model is proposed to collaboratively optimize the three problems and a life-cycle costs analysis framework is developed to examine the performance of the system from both economic and environmental aspects. To improve the attractiveness and utilization of electric public transportation resources, two new solutions have been proposed in terms of charging strategy (vehicle-to-vehicle charging) and operational efficiency (mixed-flow transport). Vehicle-to-vehicle charging allows energy to be continuously transmitted along the road, reducing reliance on the accessibility and deployment of charging facilities. Mixed flow transport mode balances the directional travel demands and facilities the parcel delivery while ensuring the punctuality and safety of passenger transport

Evaluating Infrastructure Demand and Optimizing Charging Strategies for Battery Electric Bus Fleet - A Pilot Study on Concordia Shuttle Fleet.

The transition from conventional buses to Battery Electric Buses (BEBs) poses significant challenges for transit agencies in terms of feasibility and in identifying potential operational issues. One of the crucial challenges is accurately determining the charging infrastructure demand for effective fleet management of electric buses. Insufficient infrastructure can result in operational problems, increased costs, and dissatisfied passengers. Additionally, high initial and maintenance costs, as well as compatibility issues, further impede infrastructure development. Evaluating infrastructure demand and the performance of different charging strategies in various route and operational conditions is essential in addressing these challenges. This thesis aims to evaluate the charging infrastructure demand and the effect of different charging strategies for a Battery Electric Bus (BEB) fleet using mathematical formulations and simulation modeling, specifically focusing on three scenarios: Depot charging, Depot & Opportunity charging combined, and Opportunity charging. The impact of these scenarios on fleet operations is analyzed using Discrete Event Simulation, with Arena software employed for simulation purposes. Additionally, the thesis evaluates the daily average charging costs, considering appropriate assumptions. The results of the simulations indicate that both the Depot & Opportunity charging combined and Opportunity charging alone scenarios outperform the depot charging strategy in achieving low charging costs. The analysis ascertained that a battery capacity of 300 kWh, coupled with a charging power of 100 kW, suffices to maintain a 100% trip success rate for the Concordia University shuttle fleet under the route conditions considered. However, it is worth noting that the depot charging strategy with overnight charging takes advantage of lower energy costs and grid loads during non-peak hours with proper charging schedules. Overall, the proposed work provides valuable insights for decision-makers and transit agencies looking to deploy electric shuttle bus fleets across different route conditions

Introdução de frota 100% elétrica de autocarros no transporte público: um passo para a mobilidade sustentável

O setor da mobilidade é essencial para o normal funcionamento da sociedade, tendo-se assistido com o passar dos anos a uma evolução em tecnologias utilizadas, oferta de serviços e veículos usados. Apesar disso, este setor é responsável por quase 25% das emissões de gases com efeito estuda na Europa, sendo uma das principais causas de poluição atmosférica nas grandes cidades, contribuindo para um estilo de vida menos saudável e, consequentemente, para o aumento dos níveis de doenças associadas. A introdução da e-mobilidade e veículos elétricos no transporte público urbano pode ser considerado um fator chave para uma futura mobilidade sustentável, contribuindo para a redução da poluição do ar e das emissões de gases de efeito estufa, para além de assegurar as necessidades da população. Neste contexto, este projeto para além de esclarecer o funcionamento de veículos elétricos e os comparar com veículos tradicionais movidos por combustão interna, em aspetos como funcionamento de baterias, estratégias de carregamento, demonstrar possíveis impactos da adoção desta nova opção, e dar a conhecer diferentes abordagens relativas à implementação deste tipo de veículos, procura igualmente demonstrar quais os possíveis custos que este novo panorama traz. É efetuada a medição e a comparação de custos relativos à nova frota, manutenção e operação, incluindo custos relacionados com possíveis novos serviços de viatura e tripulantes. Inclusive, é medido e comparado o impacto ambiental de uma frota 100% elétrica, através da estimação dos níveis de emissões de CO2. Para a realização do estudo é usado o exemplo da STCP, empresa de transporte público que atua na Área Metropolitana do Porto, onde, após parametrização de dados referentes aos veículos elétricos, incluindo limitações como a autonomia, é feita a simulação do planeamento operacional utilizando o software desenvolvido e mantido pela OPT, GIST.The mobility sector is essential for the normal functioning of society, and over the years, there has been an evolution in technologies used, services offered, and vehicles used. Despite this, this sector is responsible for almost 25% of greenhouse gas emissions in Europe. It is one of the leading causes of air pollution in large cities, contributing to a less healthy lifestyle and associated diseases. The introduction of e-mobility and electric vehicles in urban public transport can be considered a key factor for future sustainable mobility, contributing to the reduction of air pollution and greenhouse gas emissions and ensuring the needs of the population. In this context, this project, besides clarifying the reader about the operation of electric vehicles and comparing them with traditional vehicles powered by internal combustion, in aspects such as battery operation and charging strategies, demonstrate possible impacts of the adoption of this new option, and make known different approaches regarding the implementation of this type of vehicles, tries to show what are the possible costs that this new scenario brings. Costs related to the new fleet, maintenance and operation costs are measured and compared, including expenses related to potential new vehicle and crew services. The environmental impact of a 100% electric fleet is also measured and reached through the estimation of CO2 emission levels. To carry out the study, the example of STCP is used, a public transport company operating in Porto Metropolitan Area, where, after parameterization of data relating to electric vehicles, including limitations such as autonomy, the simulation of operational planning is made using the software developed and maintained by OPT, GIST.Mestrado em Engenharia e Gestão Industria

Practice and Innovations in Sustainable Transport

The book continues with an experimental analysis conducted to obtain accurate and complete information about electric vehicles in different traffic situations and road conditions. For the experimental analysis in this study, three different electric vehicles from the Edinburgh College leasing program were equipped and tracked to obtain over 50 GPS and energy consumption data for short distance journeys in the Edinburgh area and long-range tests between Edinburgh and Bristol. In the following section, an adaptive and robust square root cubature Kalman filter based on variational Bayesian approximation and Huber’s M-estimation is proposed to accurately estimate state of charge (SOC), which is vital for safe operation and efficient management of lithium-ion batteries. A coupled-inductor DC-DC converter with a high voltage gain is proposed in the following section to match the voltage of a fuel cell stack to a DC link bus. Finally, the book presents a review of the different approaches that have been proposed by various authors to mitigate the impact of electric buses and electric taxis on the future smart grid