Reliability Assessment under High Penetration of EVs Including V2G Strategy (original) (raw)
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International Journal of Electrical Power & Energy Systems, 2020
Fast-growing electric vehicles load can impose various reliability concerns and peak demand increase in electric power systems, particularly distribution networks. From a power system point of view, electric vehicles can be considered as random moving loads. A new probabilistic approach is, therefore, proposed in this paper to evaluate the impact of electric vehicles on the reliability performance of power distribution systems. A two-layer stochastic electric vehicle charging demand estimation model is proposed. The model comprises of a traffic layer representing the spatial-temporal distributions of electric vehicles and an electrical network layer describing the electric vehicles charging demand. A Dynamic Hidden Markov Model is used to capture the electric vehicle movements in the traffic layer. Electric vehicle travel patterns and charging demand are simulated using a sequential Monte Carlo simulation approach considering the vehicle distance traveled, the type of charging location and the driver class. The proposed approach and the models are used to perform reliability studies on an example test system, and a series of analysis results are presented.
Frontiers in Energy Research, 2022
The use of large-scale electric vehicles (EVs), along with technological advances in battery energy storage systems (BESS), offers numerous technical and economic benefits to the smart distribution system. Parking lots not only provide EV owners with the opportunity to charge their BESS but also contribute power to the grid via vehicle-to-grid (V2G) technology, which significantly improves the reliability of distribution systems. In addition, parking lots equipped with V2G capability can participate in the electricity market as a producer. In this study, the reliability of a smart radial distribution system in the presence of EVs is investigated. It should always be borne in mind that parking lots can improve system reliability if the charging and discharging strategies are optimally and correctly scheduled. On the contrary, the parking lot participates in sending power to the grid in a situation where the profit is appropriate. Accordingly, in this study, first, five optimal strategies for scheduling the process of EV charging and discharging in a parking lot equipped with V2G capability are proposed to maximize parking profits. The proposed strategies include constraints on the amount of power exchange between the parking lot and the distribution system and the random and stochastic nature of quantities, such as when EVs enter and exit the parking lot and their BESS charge amounts when entering the parking lot. The results demonstrate that using the proposed optimal charging and discharging strategies scheduling increases the parking profit by 31% and also improves the reliability of the understudy distribution system by 9%.
Stochastic Analyses of Electric Vehicle Charging Impacts on Distribution Network
IEEE Transactions on Power Systems, 2014
A stochastic modeling and simulation technique for analyzing impacts of electric vehicles charging demands on distribution network is proposed in this paper. Different from the previous deterministic approaches, the feeder daily load models, electric vehicle start charging time, and battery state of charge used in the impact study are derived from actual measurements and survey data. Distribution operation security risk information, such as over-current and under-voltage, is obtained from three-phase distribution load flow studies that use stochastic parameters drawn from Roulette wheel selection. Voltage and congestion impact indicators are defined and a comparison of the deterministic and stochastic analytical approaches in providing information required in distribution network reinforcement planning is presented. Numerical results illustrate the capability of the proposed stochastic models in reflecting system losses and security impacts due to electric vehicle integrations. The effectiveness of a controlled charging algorithm aimed at relieving the system operation problem is also presented.
Energy Conversion and Management, 2015
The unmanaged charging of plug-in-hybrid-electric vehicles (PHEVs) may adversely affect electric grid reliability because a large amount of additional electrical energy is required to charge the PHEVs. In this paper, a comprehensive method to evaluate the system reliability concerning the stochastic modeling of PHEVs, renewable resources, availability of devices, etc. is proposed. In addition, a novel risk management method in order to reduce the negative PHEVs effects is introduced. This method, which consists of managed charging and vehicle-to-grid (V2G) scenarios, can be practically implemented in smart grids because the bidirectional-power-conversion technologies and two-way of both the power and data are applicable. The introduced method was applied to a real 20 kV network of the Hormozgan Regional Electric Company (HREC) of Iran which is considered as a pilot system for upgrading to smart distribution grid. The results showed that the smart grid's adequacy was jeopardized by using the PHEVs without any managed charging schedule. The sensitivity analyses results illustrated that by using the risk management scenarios, not only did the PHEVs not compromise the system reliability, but also in the V2G scenario acted as storage systems and improved the well-being criteria and adequacy indices. The comparison between the results based on the proposed method and the other conventional approaches in addition to study of various parameters uncertainty emphasized the advantages of the proposed method.
Modeling of Uncertainties in Electric Vehicle Charging and Its Impact on the Electric Grid
2015
Electric Vehicles represent an important and futuristic alternative to conventional vehicles. However, the effect of charging electric vehicles on electric grids must be taken into account to prevent accidental overloading of the distribution grid due to simultaneous charging/discharging of electric vehicles. As electric vehicles gain more popularity with consumers, power companies and utilities must be prepared for the added load. To assist in this preparation, power companies will need accurate load forecasting algorithms. This paper presents the development of an algorithm that forecasts the load for Battery Electric Vehicles, or BEVs at 15 minute intervals for any day between January 1, 2011 and December 31, 2023. The forecast algorithm uses the projected BEV growth rate, the population of the parking lot or garage of inquiry, and a probability distribution which relates the state of charge (SOC) of the vehicle’s battery to the percent of EV owners that require such charging dai...
C I Stochastic Analysis of the Impact of Electric Vehicles on Distribution Networks
Advances in the development of electric vehicles, along with policy incentives, will see a wider uptake of this technology in the transport sector in future years. However, large penetrations of EVs could lead to adverse effects on power system networks, especially at the residential distribution network level. These effects could include excessive voltage drop and thermal loading of network components. A stochastic method is developed to take account of the uncertainties associated with EV charging and the technique is implemented on a residential test network using power system simulation software. The results show how voltage levels, component loading network losses are impacted from EV charging, taking into account the probabilistic behaviour of the EV owners.
Engineering Science and Technology, an International Journal, 2018
The use of Plug-in electric vehicles (PEV) are increasing in recent years because of its environmental friendly nature over the conventional vehicles. In the upcoming years, the use of PEVs will increase significantly. The connection of PEVs to the distribution system will lead to the new challenges. This paper evaluates the impact of PEV connection on system reliability. Studies are carried out for different PEV penetration levels to analyze the impact. Some PEVs are operated in vehicle to grid (V2G) mode to support the system peak loads. Distributed generation (DG) units are integrated with charging stations to reduce the PEVs charging impact on the system. In the present study, charging stations are integrated with solar PV units which magnifies the intention of PEV usage. Along with the system reliability evaluation, Expected Energy Not Charged (EENC) is proposed to measure the reliability of the PEVs in the system. The combined effects of PEV charging and DGs are also studied. The impact assessment is done for two practical systems.
IEEE Access, 2021
Unanticipated faults can hinder the operation of the utility grid, consumers, and businesses. This study aims to ensure the continued power supply to the consumers during outages and peak hours from the stored energy in the batteries of electric vehicles (EVs). Considering the bi-directional charging feature, the energy capacity model of the EV-batteries in a centralized parking lot (PL) and distributed EVs is developed. Various factors that affect the energy capacity of EVs are considered and modeled. The optimal location of PL and charging/discharging time and rate are found for reliability improvement, losses reduction, and voltage regulation of the distribution system. The problem is formulated as a mixed-integer multi-objective optimization problem. The first objective function is formulated to maximize the energy output from the EVs-batteries during blackouts or to minimize the energy not supplied (ENS) to the consumers, whereas the second objective function minimizes the losses of the distribution system. Moreover, an IEEE 37 Node-Test Feeder and seven test cases are considered for this study. Simulation results show that PL of EVs could be employed as a power source during the islanded and grid-connected mode for improvement of reliability in the power systems. INDEX TERMS Distribution system reliability, electric vehicle (EV), energy not supplied (ENS), parking lot (PL), smart charging, vehicle-to-home (V2H), vehicle-to-grid (V2G). power engineering from Sungkyunkwan University, South Korea. He is currently working as an
Stochastic analysis of the impact of plug-in hybrid electric vehicles on the distribution grid
IET Conference Publications, 2009
Alternative vehicles, such as plug-in hybrid electric vehicles (PHEVs), become more popular. The batteries of these PHEVs are designed to be charged at home, from a standard outlet in the garage, or on a corporate car park. These extra electrical loads have an impact on the distribution grid. The uncoordinated power consumption on a local scale can lead to grid problems. Therefore coordinated charging is proposed. The exact forecasting of household loads is not possible, so stochastic programming is introduced. The stochastic approach represents an error in the forecasting of the daily load profiles. Two main program techniques are analyzed: quadratic and dynamic programming. The coordination of the PHEVs reduces the power losses and improves the power quality. The estimation of the costs of grid reinforcement must be compared with the cost of the implementation of a smart metering system for the coordination of the charging.
Energy Reports, 2021
Advances in wireless power transfer technology provide the possibility to construct electrified roads and charge electric vehicles driving on the road. Dynamic charging mode enables the contactless interaction of electric vehicles with the power grid and has a promising prospect, but it may also bring about potential challenges to the power grid such as reliability deterioration. Electric buses serve as the forerunner to use this new charging mode due to their fixed driving patterns. Thus, it is needed to investigate its potential impact on power distribution system reliability. In this paper, first, the electric bus dynamic charging model is constructed, and then the impacts of this model on power distribution system reliability are studied. Simulation results indicate that compared with the non-dynamic charging mode, the electric bus dynamic charging mode does not cause additional deterioration to the reliability performance and has a slightly better effect.