2014
Authors
Iria, JP; Soares, FJ; Franchin, IG; Silva, N;
Publication
2014 IEEE INTERNATIONAL ELECTRIC VEHICLE CONFERENCE (IEVC)
Abstract
This paper describes a novel Electric Vehicle (EV) charging management system which was designed to control the EV load considering simultaneously the EV owners requirements and the electrical network technical limitations. The system was developed to be integrated with existing commercial equipment for smart grids, such as distribution transformer controllers, SCADA systems and Electrical Vehicles Charging Stations. The performance of the smart charging system was evaluated using a typical Portuguese low voltage network as test case, where several EV were assumed to exist. The results obtained prove the effectiveness of the system, as it allowed charging all the EV according to their owners' preferences without increasing the network peak load or creating voltages or overload problems.
2014
Authors
Heleno, M; Sumaili, J; Meirinhos, J; da Rosa, MA;
Publication
INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS
Abstract
Many applications of Fuzzy Power Flow have been proposed not only for operational purposes considering uncertainties, but also for planning exercises with high level of intermittent sources, interconnection presence and, more recently, electric vehicles load. However, their use in real systems is not usual, mainly where the uncertainty level can be significant. This is due to the low accuracy of the results related to the classical methods, and the computational burden needed to achieve a high level of accuracy in the symmetric approaches. This paper aims to present a linearization of the Symmetric Fuzzy Power Flow in order to reduce the computational effort and make it possible for it to achieve high levels of accuracy when applied to real systems. With the purposes of demonstrating the applicability of the proposed approach, several IEEE test systems and a planning configuration of the Portuguese Transmission System will be studied.
2014
Authors
Marques, V; Bento, N; Costa, PM;
Publication
ENERGY
Abstract
The concept of SG (Smart Grids) encompasses a set of technologies that raise the intelligence of the electrical networks, such as smart meters or instruments of communication, sensing and auto-correction of networks. Nevertheless, the cost is still an important obstacle for the transformation of the current electricity system into a smarter one. Regulation can have an important role in setting up a favorable framework that fosters investments. However, the novelty with SG is the disembodied character of the technology, which may change the incentives of the regulated network companies to invest, affecting the effectiveness of the regulatory instruments ("cost plus" or "price cap"). This paper demonstrates that the solution to this "Smart" paradox requires strong incentive regulation mechanisms able to stimulate the adoption of SG technologies. Moreover, the regulation should not jeopardize conventional investments that are unable to be substituted by SG. Thus, a combination of performance regulation and efficiency obligations may be necessary.
2014
Authors
Lopes, A; Araujo, RE;
Publication
2014 IEEE INTERNATIONAL ELECTRIC VEHICLE CONFERENCE (IEVC)
Abstract
This paper proposes a fault tolerant control (FTC) scheme based on sliding mode control for multi-motor electric vehicles. A design method of a sliding mode tracking controller with control allocation is developed based on the information provide by fault detection and identification (FDI) mechanism. The vehicles states yaw rate and longitudinal velocity are simultaneously controlled to track their references. A particular attention is given to study the effect of non-perfect fault estimation. The control allocation explore the over actuated system in order to redistribute the control effort when a fault occurs. Simulations in various driving scenarios with different faults are carried out with a high-fidelity, CarSim, full-vehicle model. Simulation results show the effectiveness of the proposed FTC approach.
2014
Authors
Varajao, D; Miranda, LM; Araujo, RE;
Publication
2014 16TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'14-ECCE EUROPE)
Abstract
Energy storage in low voltage grid is receiving increased attention due to renewables integration and consumption growth, challenges faced nowadays by grid operators. In this work, a study of main implementation issues for community energy storage (CES) is presented along with a comparison between possible solutions for the bidirectional isolated power conversion system (PCS) to interface a battery pack with the electric power grid. The aim of this research is to increase the power density of the power converter and keeping simultaneously the same reliability of traditional solutions. These goals are pursued to be achieved through the reduction of the conversion stages and utilization of new optimization methodologies to reduce the volume of the passive components. The proposed topology for the PCS is based on a matrix converter (MC) that performs a direct AC to AC conversion between the grid and a high-frequency transformer (HFT). With this solution it is possible to eliminate the traditional DC-link capacitor and obtain a single-stage power conversion with bidirectional power flow capability. This proposed solution is evaluated and compared with a conventional two-stage topology through extensive simulation. Two prototypes systems were designed for a 10kW PCS to connect the three-phase 230/400Vrms, 50Hz mains to a battery pack with voltage range of 320V to 490V. Simulation results are presented to assess the power quality provided by the front-end and the battery side converters, as well as performance evaluation and efficiency analysis.
2014
Authors
Pinto, C; Barreras, JV; de Castro, R; Schaltz, E; Andreasen, SJ; Araujo, RE;
Publication
2014 IEEE VEHICLE POWER AND PROPULSION CONFERENCE (VPPC)
Abstract
This paper presents a comparative study of the influence of different aggregated electrical circuit battery models in the sizing process of a hybrid energy storage system (ESS), composed by Li-ion batteries and supercapacitors (SCs). The aim is to find the number of cells required to propel a certain vehicle over a predefined driving cycle. During this process, three battery models will be considered. The first consists in a linear static zeroeth order battery model over a restricted operating window. The second is a non-linear static model, while the third takes into account first-order dynamics of the battery. Simulation results demonstrate that the adoption of a more accurate battery model in the sizing of hybrid ESSs prevents over-sizing, leading to a reduction in the number of cells of up to 29%, and a cost decrease of up to 10%.
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.