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Impacts of electric vehicles charging on distribution grid

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Abstract

Large-scale development of plug-in hybrid electric vehicles (PHEVs) will have direct impacts on the distribution grid. PHEV charging impacts on the distribution grid are analyzed through a residential 10 kV feeder in a city from aspects such as impacts on load profile, power loss and voltage quality. Several scenarios of different penetration levels are discussed. The results indicate that under high penetration scenario, uncontrolled charging will pose great pressure on the grid and reasonable PHEV penetration may be helpful to the grid's economic operation. Smart charging method is explored which can optimize the chargeable power in each period according to the short-term load trend, in order to meet the charging requirements, achieve smoother load profile, less power loss and better voltage quality.

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... The increase in number of EVs, while solving some challenges, pose a whole new set of problems especially as it concerns the electric power grid. An increase in EV charging station loads will lead to rise in peak demand, power loss, voltage instability, transformer life reduction and power quality problems (due to harmonics, voltage sag and unbalance) [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. ...
... Shahnia et al. [43] showed that EVs have little impact at the beginning of a low voltage feeder, but have a major impact at the end of the feeder. Li et al. [44] also showed that with more than 50% EV penetration voltage starts to reduce at the end of the feeder. They also suggested a smart charging plan to mitigate the effect of voltage unbalance [44]. ...
... Li et al. [44] also showed that with more than 50% EV penetration voltage starts to reduce at the end of the feeder. They also suggested a smart charging plan to mitigate the effect of voltage unbalance [44]. ...
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Concerns about the need for clean energy and the need to reduce green-house gases have led researchers and engineers to explore adoption of electric vehicle technology. Electric vehicles hold a promising future due to their efficiency, low maintenance cost and zero carbon emission. Unfortunately, due to metric range drawbacks associated with electric vehicles, large scale adoption of electric vehicles still remains relatively low. To solve this issue of range anxiety, optimal placement and sizing methods of electric vehicle infrastructure is essential. This paper presents a review of optimal siting of electric vehicle charging infrastructure. It discusses impacts of electric vehicle charging loads on the distribution network and how large scale electric vehicle penetration would affect the grid. Further, the benefits of electric vehicles on the distribution network as well as the integration of renewable energy resources are presented.
... In terms of the impact on the power grid, research [11] studies the impact of EV from the aspects of load, power grid loss and voltage, indicating that disordered charging will cause serious impact, while intelligent charging is conducive to economic operation. Research [12] proposed a probabilistic charging power model and simulated IEEE-33-node distribution network, indicating that large-scale EV would bring serious challenges to the power grid. In research [13], an EV charging load model was built to study the impact of EV random charging on distribution network, preparing for the study of orderly regulation and management of EV charging. ...
... Â maxðjP A:t À P av:t jÞ; maxðjP B:t À P av:t jÞ; maxðjP C:t À P av:t jÞ (12) where P A.t , P B.t and P C.t are the charging power of phase A, B, and C, respectively, and P av.t is their average value. ...
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The impact of large-scale electric vehicle (EV) charging load on grids has become a hot issue all over the world, which is a strong random process with a variety of factors intertwined, and raises a major problem in research. Therefore, the article presents a decoupling analysis method which studies charging load and normal load independently and then carries out an integrated analysis with the power grid. Firstly, we calculate the average, maximum, minimum, fluctuating power of charging load and their parameters by Monte Carlo method, and get the function laws of vehicle scale and charging power on them. After that, in a scene of large penetration rate, it analyzes the influence of EV on the grid at all levels, and determines the possibility of main problems. By using this method, some conclusions are obtained. The method and the basic laws gained in this paper are universal, and can provide support for the future research of EV’s charging load.
... Furthermore, when the power line loading is low, reasonable access of EV charging load will improve the efficiency and economic operation of the line. But when the penetration rate of EV is high, the additional power demand will result in a heavy burden on transformers and lines, together with the increased power loss, which moves the state of line from the economic operating area to a high-cost operating area [77]. High-penetration of EV in the power grid may also cause serious voltage sag at line terminals, which affects the users' power quality at receiving end. ...
... By shifting partial peak load to a low point, 5% to 35% of the extra network investment would be saved. Hence, a smart charging method was proposed in [77] to minimize the sum of total loss and voltage excursion in the multi-period of the power grid. The method includes the constraints of loading rate, load demand and basic power flow equations. ...
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Electric vehicles (EVs) have been rapidly developed during the last few years due to the low-carbon industry and smart grid initiatives. Meanwhile, the impact of large-scale EVs' integration on the reliability and safety of power grids is becoming increasingly prominent. To address and solve these problems, challenges on EV charging control have been presented. Besides, the EV charging load modelling with improved accuracy and rationality is required. To investigate the influencing factors of EV charging load, this survey summarises the existing EV charging load modelling methods. In addition, a new research framework for a scale EV evolution model of charging load is proposed, with an emphasis on reducing the deficiencies of the existing research in dealing with the EV scale development. Moreover, the future research prospect of EV charging load modelling on power system planning, operation, and market design has also been discussed.
... When massive EV charging loads are integrated into grid randomly, uncertain and bidirectional power will inevitably influence the distribution network, resulting in negative impacts on energy loss, characteristic of load profiles and node voltage [8]- [10]. Therefore, it is of great significance to optimize the planning schemes of EV charging facilities. ...
... Operation cost of charging facilities is closely bound up with the charging power of electric vehicles, and has little to do with regions. After calculating the charging power of each candidate site, the overall operation cost is shown in equation (8). ...
... Impacts of EV charging on distribution network load was analyzed in [5], without considering differences of charging power and duration demand of EVs. [6] and [7] presented intelligent charging, however, [6] ignored the owner's response degree to the intelligent charging, and charging power control of each EV in [7] was not easy to achieve. Acceptance ability of EV of IEEE-34 nodes distribution network was analyzed in [8], but it did not consider the TOU power price and smart charging. ...
... Impacts of EV charging on distribution network load was analyzed in [5], without considering differences of charging power and duration demand of EVs. [6] and [7] presented intelligent charging, however, [6] ignored the owner's response degree to the intelligent charging, and charging power control of each EV in [7] was not easy to achieve. Acceptance ability of EV of IEEE-34 nodes distribution network was analyzed in [8], but it did not consider the TOU power price and smart charging. ...
... The planning and construction of charging infrastructure is directly related to the promotion effect and scale of electric vehicles. The charging behavior of electric vehicles has great uncertainty and randomness in time and space [2] . When large-scale electric vehicles are connected to the power grid in disorder, their charging and discharging behavior will affect many aspects of the power grid, such as power system scheduling, distribution network peak and valley difference, power quality, etc. ...
... (4) In order to make the charge peak-to-valley difference as small as possible, the minimum power charging is used at the peak, and the maximum power charging is used in the low valley. Let F1, F2 and F3 respectively be the number of AC level 1, AC level 2 and DC charging devices accessed at peak charging load, and G1, G2 and G3 are the number of AC level 1, AC level 2 and DC charging devices accessed at low charging load, then the peak-valley difference function 2 f can be expressed as follows: ...
... According to the processing results in [31], the return time ( i.e. the initial time when the user accesses the charging station for charging,) satisfies the normal distribution, and its probability density function is (1) ...
... And, the electricity price distribution of each charging period is shown in Table I. The permeability of EV is the ratio of EV charging load to the maximum load of the line [31]. In order to better reflect the degree of user response, this paper uses the permeability setting method for reference and manually sets the responsiveness η to be equal to 0, 30%, 60% and 100% respectively for simulation. ...
... However, as the market penetration increases, uncoordinated charging of EVs will bring a variety of undesirable consequences to the power grid, charging facilities, and end users. For the power grid, such consequences include an "extra peak" of load on the grid, reduced voltage at some nodes in the grid, and increased network loss of the grid [5][6][7]. For charging facilities, such impacts are manifested in the reduced utilization and increased operating costs [8]. ...
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... Compared to conventional cars, electric vehicles have incomparable advantages in promoting energy conservation and emission reduction, reducing operating costs and generalizing new energy utilization [1]. With EV abundantly available, it will have influence on the security and stability of power gird, and also bring hardship to the repair and maintenance of EV chargers [2][3][4]. Monitoring and evaluating the operating state of EV chargers timely and accurately, can help deal with the fault and optimize the maintenance strategy of EV chargers. ...
... It would not need to transform 10 kV distribution grids under the AC slow charging mode for vast majority of communities and commercial office buildings, only if EVs are accounting for over 20% of total automobiles. Moreover, a larger number of EVs, a higher charging rate and more random charging behaviors will intensify the reform of the distribution grids under the DC fast charging mode [64]. ...
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... Electric vehicles (EVs) can help to reduce carbon emission, however, it will also cause serious effects on power quality, reliability and node voltages [1][2][3][4][5][6]. Transfer capacities of distribution networks can be increased, as well as reliability and integrated capacities of distributed generations (DGs), because EVs can be used not only as loads, but also as distributed stored energy [7]. ...
... The EV penetration rate is the ratio of the EV charging load to the maximum load. Under different penetration rates, the influence of random charging of EVs on the distribution network is studied in [23]. In order to have a better reflection of the users' response, we made reference to the penetration rate-setting method and carried out simulations with the responsiveness η being 0, 30%, 60% and 100%, respectively. ...
... As a prominent representative of renewable energy development, electric vehicles have replaced traditional fuel vehicles and became an important trend leading the development of the automotive industry. In the future, the mass access of electric vehicles will have a great impact on the stable operation of the power system [1][2][3][4][5], there are mainly voltage, grid loss and harmonic research at the level of system distribution network at present. Wang Hui uses Monte Carlo algorithm to simulate the charging and discharging power curve of electric vehicles by analyzing the influence of load, voltage and network loss in the system according to different electric vehicle penetration rates [6]. ...
... Several charging strategies have been proposed to reduce the impacts of PHEV charging load on power system networks. In [14], [16], [20] smart charging based on minimization power losses is discussed. This technique is focused to reduce power loss in the network. ...
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... In the discorded charging cases, it will enlarge the load difference between peak and valley, which will need extra power to meet charging load requirements [18][19]. Secondly, terrible charging load may increase the voltage deviation [20][21][22][23] to cause the asymmetry of three-phrase voltage [24,25] and incremental losses of distribution network [26,27]. Thus, economic loss could be made. ...
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As the electric vehicle(EV)charging is playing an important role in distribution network, it has attracted more and more attention. In order to clarify the relationship between the operation mode of EVs, peak charging load and peak power load of grid, this paper defines two key parameters: coincidence factor and mutual coincidence factor. The variation tendencies of these two parameters under different EVs scale and charging rate are also analyzed. Based on the characteristics of EV charging load and the power load of distribution network in residential area, an evaluation method for distribution network supportability is proposed. Finally effectiveness of the evaluation method are verified by distribution network in residential area. The results show that by choosing the capacity of transformer properly, the ability of the distribution network for the integration of EV can be greatly improved.
Conference Paper
With large integration of plug-in hybrid electric vehicle (PHEV) and distributed generation (DG), a good regulation ability of the power grid is required for PHEVs random charging and DG's intermittency. Considering safe and economic operation of the power grid and charging cost of PHEV owners, vehicle-to-grid (V2G) is a multi-objective and multi-constrained optimization problem by nature. A multi-objective optimization coordination model is proposed for PHEV and DG integration. Objectives of this model are maximum synthetic load ratio, minimum node voltage deviation and power loss ratio, lowest V2G service cost of the grid and charging cost of PHEV owners. By dynamic regulating PHEV charging and discharging power, power fluctuation between load and DG can be matched well and the impact of DG intermittency on the power grid will be de creased. A real 10kV feeder is simulated.
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