• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1276-1282
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• 2013

This paper proposes a stochastic modeling of plug-in electric vehicles (PEVs) distribution in power systems, and analyzes the corresponding clustering characteristic. It is essential for power utilities to estimate the PEV charging demand as the penetration level of PEV is expected to increase rapidly in the near future. Although the distribution of PEVs in power systems is the primary factor for estimating the PEV charging demand, the data currently available are statistics related to fuel-driven vehicles and to existing electric demands in power systems. In this paper, we calculate the number of households using electricity at individual ending buses of a power system based on the electric demands. Then, we estimate the number of PEVs per household using the probability density function of PEVs derived from the given statistics about fuel-driven vehicles. Finally, we present the clustering characteristic of the PEV distribution via case studies employing the test systems.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.632-639
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• 2018

최근 플러그인 전기자동차에 대한 적극적인 보급 정책이 추진되고 있으나 플러그인 전기자동차는 전력계통에 직접 연계되어 충전수요를 공급받기 때문에 충전수요의 집중도에 따라서는 전력계통의 설비확충이 요구될 수도 있다. 반면 전력계통의 설비확충은 많은 시간과 투자가 소요되어 현실적으로 제한될 수밖에 없기 때문에 기존의 전력망을 효율적으로 이용하여 플러그인 전기자동차의 충전수요를 안정적으로 공급하는 것은 플러그인 전기자동차의 보급 확대에도 중요한 요소라고 할 수 있다. 따라서 본 논문에서는 주어진 전력계통에서 선로조류와 모선전압과 같은 제약조건을 만족하면서 플러그인 전기자동차의 충전수요를 공급하기 위한 충전계획 수립방안을 제안한다. 이를 위해 자동차의 주행 패턴과 충전 요금제를 기준으로 플러그인 전기자동차 충전수요의 요구량과 충전 시작시간을 전기자동차별로 모델링 한 후 이를 전력계통 모델에 연계하여 조류계산을 계산하여 전력계통의 운전 상태를 모의하였다. 또한 선로의 전력조류와 모선의 전압에 대한 제약 조건의 만족 여부를 확인하며 제약조건에 위반이 발생하는 경우 이를 완화하기 위해 제약조건에 직접 관련된 플러그인 전기자동차의 충전수요를 조정하여 계통제약의 만족여부를 재확인하는 과정을 반복함으로써 주어진 전력계통의 제약조건을 만족할 수 있는 플러그인 전기자동차의 충전계획을 수립하였다.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.820-828
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• 2016

The sizable electrical load of plug-in electric vehicles may cause a severe low-voltage problem in a distribution network. The voltage drop in a distribution network can be mitigated by limiting the power consumption of a charging station. Then, the charging station operator needs a method for appropriately distributing the restricted power to all plug-in electric vehicles. The existing approaches have practical limitation in terms of the availability of future information and the execution time. Therefore, this study suggests a heuristic method based on priority indexes for fairly distributing the constrained power to all plug-in electric vehicles. In the proposed method, PEVs are ranked using the priority index, which is determined in real time, such that a near-optimal solution can be obtained within a short computation time. Simulations demonstrate that the proposed method is effective in implementation, although its performance is slightly worse than that of the optimal case.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.859-864
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• 2015

This paper analyzes the impact of Plug-in Electric vehicles(PEVs) on power demand and voltage change when PEVs are connected to the domestic distribution system. Specifically, it assesses PEVs charging load by charging method in accordance with PEVs penetration scenarios, its percentage of total load, and voltage range under load conditions. Concretely, we develop EMTDC modelling to perform a voltage distribution analysis when the PEVs charging system by their charging scenario was connected to the distribution system under the load condition. Furthermore we present evaluation algorithm to determine whether it is possible to adjust it such that it is in the allowed range by applying ULTC when the voltage change rate by PEVs charging scenario exceed its allowed range. Also, detailed analysis of the impact of PEVs on power distribution system was carried out by calculating existing electric power load and additional PEVs charge load by each scenario on new-town in Korea to estimate total load increases, and also by interpreting the subsequent voltage range for system circuits and demonstrating conditions for countermeasures. It was concluded that total loads including PEVs charging load on new-town distribution system in Korea by PEVs penetration scenario increase significantly, and the voltage range when considering ULTC, is allowable in terms of voltage tolerance range up to a PEVs penetration of 20% by scenario. Finally, we propose the charging capacity of PEVs that can delay the reinforcement of power distribution system while satisfying the permitted voltage change rate conditions when PEVs charging load is connected to the power distribution system by their charging penetration scenario.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.742-751
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• 2018

Electric vehicles (EV) are emerging as the future transportation vehicle reflecting their potential safe environmental advantages. Vehicle to Grid (V2G) system describes the hybrid system in which the EV can communicate with the utility grid and the energy flows with insignificant effect between the utility grid and the EV. The paper presents an optimal power control and energy management strategy for Plug-In Electric Vehicle (PEV) charging stations using Wind-PV-FC-Battery renewable energy sources. The energy management optimization is structured and solved using Multi-Objective Particle Swarm Optimization (MOPSO) to determine and distribute at each time step the charging power among all accessible vehicles. The Model-Based Predictive (MPC) control strategy is used to plan PEV charging energy to increase the utilization of the wind, the FC and solar energy, decrease power taken from the power grid, and fulfil the charging power requirement of all vehicles. Desired features for EV battery chargers such as the near unity power factor with negligible harmonics for the ac source, well-regulated charging current for the battery, maximum output power, high efficiency, and high reliability are fully confirmed by the proposed solution.