Coordinated Charging of Plug-In Hybrid Electric Vehicles to Minimize Distribution System Losses
TL;DR: From these relationships, three optimal charging algorithms are developed which minimize the impacts of PHEV charging on the connected distribution system and show the additional benefits of reduced computation time and problem convexity when using load factor or load variance as the objective function rather than system losses.
Abstract: As the number of plug-in hybrid vehicles (PHEVs) increases, so might the impacts on the power system performance, such as overloading, reduced efficiency, power quality, and voltage regulation particularly at the distribution level. Coordinated charging of PHEVs is a possible solution to these problems. In this work, the relationship between feeder losses, load factor, and load variance is explored in the context of coordinated PHEV charging. From these relationships, three optimal charging algorithms are developed which minimize the impacts of PHEV charging on the connected distribution system. The application of the algorithms to two test systems verifies these relationships approximately hold independent of system topology. They also show the additional benefits of reduced computation time and problem convexity when using load factor or load variance as the objective function rather than system losses. This is important for real-time dispatching of PHEVs.
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TL;DR: In this paper, the authors survey the literature till 2011 on the enabling technologies for the Smart Grid and explore three major systems, namely the smart infrastructure system, the smart management system, and the smart protection system.
Abstract: The Smart Grid, regarded as the next generation power grid, uses two-way flows of electricity and information to create a widely distributed automated energy delivery network. In this article, we survey the literature till 2011 on the enabling technologies for the Smart Grid. We explore three major systems, namely the smart infrastructure system, the smart management system, and the smart protection system. We also propose possible future directions in each system. colorred{Specifically, for the smart infrastructure system, we explore the smart energy subsystem, the smart information subsystem, and the smart communication subsystem.} For the smart management system, we explore various management objectives, such as improving energy efficiency, profiling demand, maximizing utility, reducing cost, and controlling emission. We also explore various management methods to achieve these objectives. For the smart protection system, we explore various failure protection mechanisms which improve the reliability of the Smart Grid, and explore the security and privacy issues in the Smart Grid.
2,433 citations
01 Jan 2012
TL;DR: This article surveys the literature till 2011 on the enabling technologies for the Smart Grid, and explores three major systems, namely the smart infrastructure system, the smart management system, and the smart protection system.
2,337 citations
Cites background from "Coordinated Charging of Plug-In Hyb..."
...…basic idea of the cloud computing is that the cloud providers, who operate large data centers with massive computation and storage capacities, deliver computing as a service, whereby shared resources, software and information are provided to computers and other devices as a utility over a network....
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TL;DR: In this paper, a decentralized algorithm is proposed to optimally schedule electric vehicle (EV) charging, which exploits the elasticity of electric vehicle loads to fill the valleys in electric load profiles.
Abstract: We propose a decentralized algorithm to optimally schedule electric vehicle (EV) charging. The algorithm exploits the elasticity of electric vehicle loads to fill the valleys in electric load profiles. We first formulate the EV charging scheduling problem as an optimal control problem, whose objective is to impose a generalized notion of valley-filling, and study properties of optimal charging profiles. We then give a decentralized algorithm to iteratively solve the optimal control problem. In each iteration, EVs update their charging profiles according to the control signal broadcast by the utility company, and the utility company alters the control signal to guide their updates. The algorithm converges to optimal charging profiles (that are as “flat” as they can possibly be) irrespective of the specifications (e.g., maximum charging rate and deadline) of EVs, even if EVs do not necessarily update their charging profiles in every iteration, and use potentially outdated control signal when they update. Moreover, the algorithm only requires each EV solving its local problem, hence its implementation requires low computation capability. We also extend the algorithm to track a given load profile and to real-time implementation.
796 citations
TL;DR: In this article, the authors review the current status and implementation impact of V2G/grid-to-vehicle (G2V) technologies on distributed systems, requirements, benefits, challenges, and strategies for VUE interfaces of both individual vehicles and fleets.
Abstract: Plug-in vehicles can behave either as loads or as a distributed energy and power resource in a concept known as vehicle-to-grid (V2G) connection. This paper reviews the current status and implementation impact of V2G/grid-to-vehicle (G2V) technologies on distributed systems, requirements, benefits, challenges, and strategies for V2G interfaces of both individual vehicles and fleets. The V2G concept can improve the performance of the electricity grid in areas such as efficiency, stability, and reliability. A V2G-capable vehicle offers reactive power support, active power regulation, tracking of variable renewable energy sources, load balancing, and current harmonic filtering. These technologies can enable ancillary services, such as voltage and frequency control and spinning reserve. Costs of V2G include battery degradation, the need for intensive communication between the vehicles and the grid, effects on grid distribution equipment, infrastructure changes, and social, political, cultural, and technical obstacles. Although V2G operation can reduce the lifetime of vehicle batteries, it is projected to become economical for vehicle owners and grid operators. Components and unidirectional/bidirectional power flow technologies of V2G systems, individual and aggregated structures, and charging/recharging frequency and strategies (uncoordinated/coordinated smart) are addressed. Three elements are required for successful V2G operation: power connection to the grid, control and communication between vehicles and the grid operator, and on-board/off-board intelligent metering. Success of the V2G concept depends on standardization of requirements and infrastructure decisions, battery technology, and efficient and smart scheduling of limited fast-charge infrastructure. A charging/discharging infrastructure must be deployed. Economic benefits of V2G technologies depend on vehicle aggregation and charging/recharging frequency and strategies. The benefits will receive increased attention from grid operators and vehicle owners in the future.
788 citations
TL;DR: This paper presents a future perspective of industrial information technologies to accelerate the market introduction and penetration of advanced electric drive vehicles and provides a comprehensive survey of the EVs in the field of industrial informatics systems.
Abstract: Economics and environmental incentives, as well as advances in technology, are reshaping the traditional view of industrial systems. The anticipation of a large penetration of plug-in hybrid electric vehicles (PHEVs) and plug-in electric vehicles (PEVs) into the market brings up many technical problems that are highly related to industrial information technologies within the next ten years. There is a need for an in-depth understanding of the electrification of transportation in the industrial environment. It is important to consolidate the practical and the conceptual knowledge of industrial informatics in order to support the emerging electric vehicle (EV) technologies. This paper presents a comprehensive overview of the electrification of transportation in an industrial environment. In addition, it provides a comprehensive survey of the EVs in the field of industrial informatics systems, namely: 1) charging infrastructure and PHEV/PEV batteries; 2) intelligent energy management; 3) vehicle-to-grid; and 4) communication requirements. Moreover, this paper presents a future perspective of industrial information technologies to accelerate the market introduction and penetration of advanced electric drive vehicles.
720 citations
Cites background from "Coordinated Charging of Plug-In Hyb..."
...The PHEV-10 power capacity target is 830 W/kg and the PHEV-40 power target is 380 W/kg....
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References
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TL;DR: In this article, the authors proposed a coordinated charging strategy to minimize the power losses and to maximize the main grid load factor of the plug-in hybrid electric vehicles (PHEVs).
Abstract: Alternative vehicles, such as plug-in hybrid electric vehicles, are becoming more popular The batteries of these plug-in hybrid electric vehicles are to be charged at home from a standard outlet or on a corporate car park These extra electrical loads have an impact on the distribution grid which is analyzed in terms of power losses and voltage deviations Without coordination of the charging, the vehicles are charged instantaneously when they are plugged in or after a fixed start delay This uncoordinated power consumption on a local scale can lead to grid problems Therefore, coordinated charging is proposed to minimize the power losses and to maximize the main grid load factor The optimal charging profile of the plug-in hybrid electric vehicles is computed by minimizing the power losses As the exact forecasting of household loads is not possible, stochastic programming is introduced Two main techniques are analyzed: quadratic and dynamic programming
2,601 citations
"Coordinated Charging of Plug-In Hyb..." refers background or methods in this paper
...2090913 largely mitigated by coordinated charging [1], [4], [5]....
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...Minimizing Losses Formulation The loss minimization as given in [5] is...
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...[1], [5] which is sufficient for the average daily driving distance of 33 miles (53 km) established by EPRI [1]....
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...RELATIONSHIP BETWEEN LOSSES, LOAD FACTOR, AND LOAD VARIANCE It has been shown that minimizing distribution system losses with the addition of PHEVs also minimizes the voltage impacts of their integration [4], [5]....
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...In previous studies, coordinated charging has been performed using sequential quadratic optimization [4], [5], [11], dynamic programming [12], and heuristic methods [1], [13]....
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TL;DR: In this article, the impact of different levels of plug-in electric vehicle penetration on distribution network investment and incremental energy losses is evaluated based on the use of a large-scale distribution planning model which is used to analyze two real distribution areas.
Abstract: Plug-in electric vehicles (PEVs) present environmental and energy security advantages versus conventional gasoline vehicles. In the near future, the number of plug-in electric vehicles will likely grow significantly in the world. Despite the aforementioned advantages, the connection of PEV to the power grid poses a series of new challenges for electric utilities. This paper proposes a comprehensive approach for evaluating the impact of different levels of PEV penetration on distribution network investment and incremental energy losses. The proposed approach is based on the use of a large-scale distribution planning model which is used to analyze two real distribution areas. Obtained results show that depending on the charging strategies, investment costs can increase up to 15% of total actual distribution network investment costs, and energy losses can increase up to 40% in off-peak hours for a scenario with 60% of total vehicles being PEV.
1,113 citations
TL;DR: This work proposes an aggregator that makes efficient use of the distributed power of electric vehicles to produce the desired grid-scale power and applies the dynamic programming algorithm to compute the optimal charging control for each vehicle.
Abstract: For vehicle-to-grid (V2G) frequency regulation services, we propose an aggregator that makes efficient use of the distributed power of electric vehicles to produce the desired grid-scale power. The cost arising from the battery charging and the revenue obtained by providing the regulation are investigated and represented mathematically. Some design considerations of the aggregator are also discussed together with practical constraints such as the energy restriction of the batteries. The cost function with constraints enables us to construct an optimization problem. Based on the developed optimization problem, we apply the dynamic programming algorithm to compute the optimal charging control for each vehicle. Finally, simulations are provided to illustrate the optimality of the proposed charging control strategy with variations of parameters.
1,045 citations
"Coordinated Charging of Plug-In Hyb..." refers background or methods in this paper
...The second is that these objectives can be easily integrated as loss constraints in other PHEV charging objective functions such as those in [12], [13] which minimize system operating costs to, or maximize profits to, an aggregator....
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...Such optimizations may focus on charging cost minimization or some vehicle-to-grid profit maximizations [12], [13]....
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...In previous studies, coordinated charging has been performed using sequential quadratic optimization [4], [5], [11], dynamic programming [12], and heuristic methods [1], [13]....
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TL;DR: The smart grid model offers the best potential for maximum utilization of RESs to reduce cost and emission from the electricity industry.
Abstract: The electricity and transportation industries are the main sources of greenhouse gas emissions on Earth. Renewable energy, mainly wind and solar, can reduce emission from the electricity industry (mainly from power plants). Likewise, next-generation plug-in vehicles, which include plug-in hybrid electric vehicles (EVs) and EVs with vehicle-to-grid capability, referred to as “gridable vehicles” (GVs) by the authors, can reduce emission from the transportation industry. GVs can be used as loads, energy sources (small portable power plants), and energy storages in a smart grid integrated with renewable energy sources (RESs). Smart grid operation to reduce both cost and emission simultaneously is a very complex task considering smart charging and discharging of GVs in a distributed energy source and load environment. If a large number of GVs is connected to the electric grid randomly, peak load will be very high. The use of traditional thermal power plants will be economically and environmentally expensive to support the electrified transportation. The intelligent scheduling and control of GVs as loads and/or sources have great potential for evolving a sustainable integrated electricity and transportation infrastructure. Cost and emission reductions in a smart grid by maximum utilization of GVs and RESs are presented in this paper. Possible models for GV applications, including the smart grid model, are given, and results are presented. The smart grid model offers the best potential for maximum utilization of RESs to reduce cost and emission from the electricity industry.
762 citations
"Coordinated Charging of Plug-In Hyb..." refers background or methods in this paper
...The second is that these objectives can be easily integrated as loss constraints in other PHEV charging objective functions such as those in [12], [13] which minimize system operating costs to, or maximize profits to, an aggregator....
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...Such optimizations may focus on charging cost minimization or some vehicle-to-grid profit maximizations [12], [13]....
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...In previous studies, coordinated charging has been performed using sequential quadratic optimization [4], [5], [11], dynamic programming [12], and heuristic methods [1], [13]....
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TL;DR: In this article, the authors predict that the introduction of PHEVs could impact demand peaks, reduce reserve margins, and increase prices, and the type of power generation used to recharge the PHEV and associated emissions will depend upon the region and the timing of the recharge.
599 citations
"Coordinated Charging of Plug-In Hyb..." refers background in this paper
...It has been shown, however, that serious problems can arise under uncoordinated opportunistic charging scenarios [2]....
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