68 research outputs found
Benders-and-Price approach for electric vehicle charging station location problem under probabilistic travel range
No full textThe impacts of transmission topology control on the European electricity network
No full textThe EU is targeting a 20% share of energy from renewable resources by 2020 and this increase is in turn expected to lead to operational challenges that will require various congestion management actions by system operators. In this paper, we deal with topology control of the transmission network as a congestion management resource and evaluate the impacts of topology control on the European electricity network. To do this, we co-optimize unit commitment and transmission switching over 24 hours and we use a decomposition scheme to tackle the resulting large-scale problem. Our analysis is conducted on different scenarios of load and renewable power generation. We find that topology control results in significant cost savings within Europe which tend to be inversely related to net load. The robustness of our results is supported by an extensive sensitivity analysis
Congestion management through topological corrections: A case study of Central Western Europe
No full textThe integration of an increasing amount of renewable generation within Europe is posing operational challenges that require various balancing actions. System operators therefore need to rely increasingly on the active control of the transmission network. Transmission topology control is a fast and economical option to add flexibility to the transmission system. We model the current methodology for controlling congestion in the Central Western European (CWE) market and quantify the benefits of topology control. We also compare the results with a nodal pricing model. Our computational results suggest that topology control can significantly reduce congestion management costs under the current market coupling regime whereas the benefits of topology control are limited under nodal pricing. Topology control emerges as an attractive and implementable means of managing congestion as it provides a significant percentage of the cost savings that would be achieved by overhauling the existing European market design and shifting to a nodal pricing regim
Optimizing the Operation of Animal Shelters to Minimize Unnecessary Euthanasia: A Case Study in the Seoul Capital Area
No full textTo build a sustainable social system in the future, the promotion of animal welfare, as well as human welfare, is essential. In this study, we address the issues related to animal euthanasia that are commonly encountered in animal shelters. Many animals entering an animal shelter are euthanized in shelters due to the lack of physical facilities, and new strategies are needed to reduce such euthanasia. For this purpose, we show that it is possible to reduce euthanasia numbers by utilizing the space resources of the animal shelters efficiently and by sharing these space resources appropriately among shelters. To achieve this, we propose mathematical optimization models that determine operational schedules of given shelters with the objective of minimizing euthanasia rates. To demonstrate the superiority of our approaches, we conducted a case study at the animal shelters in the Seoul capital area. Through the case study, we show that operating schedules obtained from our model can reduce euthanasia significantly, 30% on average, due to the efficient utilization of facility space in the shelters. We demonstrate that our approaches can have a high impact on improving animal welfare in shelters if they are properly combined with strategies encouraging adoptions
Optimal Scheduling for Electric Vehicle Charging under Variable Maximum Charging Power
No full textThe large-scale integration of electric vehicles (EVs) into power systems is expected to lead to challenges in the operation of the charging infrastructure. In this paper, we deal with the problem of an aggregator coordinating charging schedules of EVs with the objective of minimizing the total charging cost. In particular, unlike most previous studies, which assumed constant maximum charging power, we assume that the maximum charging power can vary according to the current state of charge (SOC). Under this assumption, we propose two charging schemes, namely non-preemptive and preemptive charging. The difference between these two is whether interruptions during the charging process are allowed or not. We formulate the EV charging-scheduling problem for each scheme and propose a formulation that can prevent frequent interruptions. Our numerical simulations compare different charging schemes and demonstrate that preemptive charging with limited interruptions is an attractive alternative in terms of both cost and practicality. We also show that the proposed formulations can be applied in practice to solve large-scale charging-scheduling problems
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