Location analysis of electric vehicle charging stations for maximum capacity and coverage

Electric vehicle charging facility location is a critical component of long-term strategic planning. Integration of electric vehicles into mainstream adoption has unique characteristics as it requires a careful investigation of both electric and transportation networks. In this paper, we provide an overview of recent approaches in location analyses of electric vehicle charging infrastructures. We review approaches from classical operations research for fast and slow charging stations. Sample formulations along with case studies are presented to provide insights. We discuss that classical methods are appropriate to address the coverage of charging networks which is defined as average time or distance to reach a charging station when needed. On the other hand, calculating required capacity, defined as the individual charging resources at each node, is still an open research topic. In the final part, we present stochastic facility location theory that uses queuing and other probabilistic approaches

Sliding Mode Control Strategy for Three-Phase Three-Level T-Type Shunt Active Power Filters

In this paper, a sliding mode control (SMC) strategy is proposed for three-phase three-level T-type shunt active power filters (SAPF). The proposed control strategy has the ability to balance the capacitor voltages with respect to the neutral-point. The proposed SMC strategy is formulated in the natural frame which eliminates abc/dq transformation and two PI controllers compared to the design in the dq frame. In natural frame, only one PI controller is needed to generate the amplitude of grid current reference. The output of the PI controller is multiplied by the unity sinusoidal waveforms, obtained from the grid voltages, so as to obtain the grid current references. The filter current references are obtained by subtracting the measured load currents from grid current references. The performance of the proposed control method is investigated by simulation study during steady-state and transients caused by load change. It is shown that the grid currents are almost sinusoidal with small THD, grid currents and dc-link voltage track their references and capacitor voltages are balanced with respect to the neutral-point

An online model for scheduling electric vehicle charging at park-and-ride facilities for flattening solar duck curves

Electrical power systems with high solar generation experience a phenomena called "duck curve" which require conventional power generators to quickly ramp-up their output, thus resulting in financial losses. In this paper, we propose an online model (OLM) for scheduling the charging of electric vehicles (EV) located at park-and-ride facilities for flattening solar "duck curves". This model provides a significant improvement to existing ones for similar systems in the sense that the availability of information is related to the time period for which the optimization is done. In addition, a procedure for finding the schedules for EV charging that significantly decreases the ramping requirements is introduced. Proposed procedure includes a combination of a heuristic function and a neural network (NN) to make a decision on which EVs will be charged at each time period. The training of the NN is done based on optimal solutions for problem instances corresponding to the full information model (FIM). The computational experiments have been performed for instances reflecting different levels of solar generation and EV adoptions and prove highly promising. They show that the OLM manages to find schedules of similar quality as the FIM, while having some more desirable properties

An Effective Model Predictive Control Method With Self-Balanced Capacitor Voltages for Single-Phase Three-Level Shunt Active Filters

This paper presents an effective model predictive control (MPC) method for single-phase three-level T-type inverter-based shunt active power filters (SAPFs). The SAPF using T-type inverter topology has not been reported in the literature yet. Contrary to most of the existing MPC methods, the proposed MPC method eliminates the need for using weighting factor and additional constraints required for balancing dc capacitor voltages in the cost function. The design of cost function is based on the energy function. Since the factor used in the formulation of the energy function does not have any adverse influence on the performance of the system, the cost function becomes weighting factor free. The weighting factor free based MPC brings simplicity in the practical implementation. The effectiveness of the proposed MPC method has been investigated in steady-state as well as dynamic transients caused by load changes. The theoretical considerations are verified through experimental studies performed on a 3 kVA system

Förhandlingar om kulturföremål. Parters intressen och argument i processer om återförande av kulturföremål

Disputes over demands for a return of cultural objects, in many cases museum objects, are well known. But such conflicts can also be seen as negotiations, which can be analyzed as well. This thesis adds a negotiation perspective and by a close scrutiny points out certain factors and arguments which can facilitate a process, cause a blocking, or rescind a blocking. By referring to such a process as a form of negotiation, this might bring about possibilities for the parties involved, which they otherwise would not been considering. It may occur that behind a party's arguments some interests could have been hidden consciously, or been surpassed by something else, which can cause a blocking. The aim of this thesis is to highlight the actors' different perspectives in negotiations concerning return of cultural objects, how they argue in a negotiation position and how the process can affect the management of cultural objects. The negotiation perspective can generate knowledge for increased understanding of motives behind the parties' positions. The specific traits of negotiation processes and what arguments and interests that may be important during the passage of events are examined in two case studies. One case is about the process of the return of medieval ecclesiastical objects from a museum context to two rural churches on Gotland, Sweden. The other study examines the process of negotiating the return of a totem pole from the Museum of Ethnography in Stockholm to the people of Haisla First Nation, Canada. The material that has been analyzed in this thesis shows in which phase in the process and why the parties changed their opinion, thus making a constructive solution possible. The thesis identifies aspects that the parties considered important in the negotiation process, and the outcome indicates how essential factors are valued in cases where the return of cultural objects are negotiated. Values and arguments, present in the case studies, are identified and categorized, which then are compiled into tables in order to make them comparable. These tables show in what period turning points took place in the process, and which aspects made parties change their respective standpoint, as the situation shifted from disagreement to consensus. For instance, groups of arguments that associates to the categories are: place, cultural identity, conservation and economy, are strong indicators of what some people find important. This thesis shows why and how the parties were convinced of the benefits of a solution grounded in consensus. By using a negotiation perspective the analysis identifies incentives that created a progressive process. The findings are useful for better understanding of future processes of returning cultural objects and benefit the development of the management of cultural heritage

Capacity optimization of EV charging networks : a greedy algorithmic approach

In the recent years, there has been a steady increase in the use of electrical vehicles (EV). Their further adoption is becoming more dependent on the quality of service provided by the charging infrastructure. In this paper, the focus is on optimizing the charging infrastructure from the point of minimizing the service drop modelled using the standard M/M/c/c loss queue. To be exact, a mathematical model is proposed for the problem of optimizing capacities at individual stations in an EV charging network. The novelty is in considering the relation of capacity of a charging station to its arrival rate. Due to the non-linearity of the problem, a greedy algorithm combined with a local search is developed for finding near optimal configurations of the system. The new model is evaluated using real-world data for population density and existing charging infrastructure for metropolitan areas. The conducted computational experiments, show that charging networks optimized using the proposed model, significantly better reflect the state-on-the-ground than standardly used models, while maintaining a low service drop rate

A multiobjective analysis of the potential of scheduling electrical vehicle charging for flattening the duck curve

In this paper, we investigate the demand-flexibility of large-collections of electric vehicles (EVs) by scheduling their demand to flatten the electricity duck curve that emerge as a result of growing solar power production. The scheduling problem is investigated in a bi-objective setting and an additional objective function related to the amount of charge provided to EVs is also analyzed. The first objective is the minimization of the ramp-up requirements of the system. The second objective reflects the quality of service and the potential level of charging station's profit margins. An important characteristics of the proposed model is the effect of total charging capacity on the two objective functions. The analysis is carried out based on a quadratic programming model which is used to calculate the Pareto Front of the two objective functions. This is done through a case study based on real-world data for EV driver behavior, solar generation, and energy consumption. The computational experiments show that there is a high level of competition between these two objectives. Moreover, the effect of different maximal charging capacities on these objectives is observed

Finite control set model predictive control for grid-tied quasi-Z-source based multilevel inverter

In this paper, a finite control set Model Predictive Control (MPC) for grid-tie quasi-Z-Source (qZS) based multilevel inverter is proposed. The proposed Power Conditioning System (PCS) consists of a single-phase 2-cell Cascaded H-Bridge (CHB) inverter where each module is fed by a qZS network. The aim of the proposed control technique is to achieve grid-tie current injection, low Total Harmonic Distortion (THD) current, unity power factor, while balancing DC-link voltage for all qZS-CHB inverter modules. The feasibility of this strategy is validated by simulation using Matlab/Simulink environment

Probabilistic assessment of community-scale vehicle electrification using GPS-based vehicle mobility data : a case study in Qatar

To avoid the operational consequence of thermal rating exceedance and the financial consequence of excessive reinforcement, the impact of domestic charging of electric vehicles (EVs) on power distribution networks must be accurately assessed prior to accepting vehicle electrification at the community-scale. Although driven by routine, charging behaviour patterns are also influenced by geography, meteorological conditions and season, hence will have a localised element to them that could reduce the diversity of charging load profiles. To model this uncertainty, this paper develops a probabilistic methodology to quantify EV home charging demands based on vehicle mobility data and underlying trip characteristics. Models articulate the departure time distribution using a mixture of von Mises distributions, and incorporate non-negative conditional distributions of trip durations, distances and parking durations, which in turn generalise localised charging behaviours. The resulting load profiles are used to drive a community electric network model based on a distribution feeder in Qatar, a country with high per km energy consumption, to quantify impact scenarios of high temperature and driving habit in terms of voltage and thermal stability. Results indicate that overnight domestic charging is sufficient to support daily trips and local networks are capable of hosting high EV penetration despite peaks

Real-Time Selective Harmonic Mitigation Technique for Power Converters Based on the Exchange Market Algorithm

Hand-in-hand with the smart-grid paradigm development, power converters used in high-power applications are facing important challenges related to efficiency and power quality. To overcome these issues, the pre-programmed Pulse-Width Modulation (PWM) methods have been extensively applied to reduce the harmonic distortion with very low power switching losses for high-power converters. Among the pre-programmed PWM techniques, Selective Harmonic Elimination (SHE) has been the prevailing solution, but recently, Selective Harmonic Mitigation (SHM) stands as a superior alternative to provide further control of the harmonic spectrum with similar losses. However, the large computational burden required by the SHM method to find a solution confines it as an off-line application, where the switching set valid solutions are pre-computed and stored in a memory. In this paper, for the first time, a real-time implementation of SHM using an off-the-shelf mid-range microcontroller is presented and tested. The Exchange Market Algorithm (EMA), initially focused on optimizing financial transactions, is considered and executed to achieve the SHM targets. The performance of the EMA-based SHM is presented showing experimental results considering a reduced number of switching angles applied to a specific three-level converter, but the method can be extrapolated to any other three-level converter topology.Ministerio de Ciencia e Innovación de España TEC2016-78430-RJunta de Andalucía P18-RT-1340Fondo Nacional de Investigación de Qatar NPRP 9-310-2-13