1,721,711 research outputs found
The great season of railway electronic drives
No full textThe article provides an overview of the steps taken by electronic drives for railway vehicles, from the first steps of the '70s to the gradual diffusion up to the total affirmation of today, highlighting the confrontation of very different technological solutions, in fierce competition between them. Alternatives not only referring to the choice of power circuits (voltage-source or currentsource inverters, single-stage or two-stage converters, two-level or three-level), but also the type of electric traction motors (synchronous or induction, single or double star), the cooling systems of power converters (oil, natural or deionised water). The evolution of power electronic components (thyristors, GTO, IGBT) and that of the components and the electronic control circuits for the converters (from the wired logic to the microprocessors) had great influence. The conclusions show the differences between the situation at the time and the current phase of technology
Application of multiterminal HVDC interconnections in European transmission grid
No full textThis study focuses on one of the main concepts regarding strategies to be adopted to reach the European policy targets, regarding Green House Gas emissions (GHG). The subsidization of renewable energy sources showed its limits, due to the fact that such power plants can create several problems to the power grids they are connected to, and for this reason the implementation of new or more advanced grid configurations may be a more effective approach to enable the diffusion of further renewable energy sources across the EU. One of the more interesting concepts regarding grid configurations, which allow the integration of renewable energy sources, is the increase of transmission capacity across countries, by means of multiterminal High Voltage Direct Current (HVDC) grids, together with a fully integrated European electricity market. This study will focus on the drivers behind the adoption of such a strategy and the challenges that will need to be faced
Knowledge Extraction From PV Power Generation With Deep Learning Autoencoder and Clustering-Based Algorithms
Full text linkThe unpredictable nature of photovoltaic solar power generation, caused by changing weather conditions, creates challenges for grid operators as they work to balance supply and demand. As solar power continues to become a larger part of the energy mix, managing this intermittency will be increasingly important. This paper focuses on identifying daily photovoltaic power production patterns to gain new knowledge of the generation patterns throughout the year based on unsupervised learning algorithms. The proposed data-driven model aims to extract typical daily photovoltaic power generation patterns by transforming the high dimensional temporal features of the daily PV power output into a lower latent feature space, which is learned by a deep learning autoencoder. Subsequently, the Partitioning Around Medoids (PAM) clustering algorithm is employed to identify the six distinct dominant patterns. Finally, a new algorithm is proposed to reconstruct these patterns in their original subspace. The proposed model is applied to two distinct datasets for further analysis. The results indicate that four out of the identified patterns in both datasets exhibit high correlation (over 95%) and temporal trends. These patterns correspond to distinct weather conditions, such as entirely sunny, mostly sunny, cloudy, and negligible power generation days, which were observed approximately 61% of the analyzed period. These typical patterns can be expected to be observed in other locations as well. Identified PV power generation patterns can improve forecasting models, optimize energy management systems, and aid in implementing energy storage or demand response programs and scheduling efficiently
Reversible Traction Substations in DC Railway Systems: A Comparative Study of Approaches
No full textIn line with the overall goals of EU climate commitment and railway operators, reducing CO2 emission and eco-friendly transport systems together with increased energy efficiency have received more attention during the last years. In this context, a significant contribution of studies is dedicated to the capabilities and potentials of utilizing regenerative braking energy (RBE). Among different methods of recuperating RBE, adopting reversible/bidirectional substations to feed back the RBE into the upstream grid is a promising solution. In this paper, different methods and configurations regarding the implementation of reversible substations (RSS) with bidirectional power flow capability are discussed and compared. Meanwhile, the challenges of transforming the existing traditional traction substations (TSS) into reversible substations together with their impacts on the energy efficiency of the electric railway system (ERS) are outline
The Evolution of Railway Power Supply Systems Toward Smart Microgrids: The concept of the energy hub and integration of distributed energy resources
No full textIn recent years, the achievement of sustainable energy systems has become one of the foremost challenges of experts around the world. In this context, the reduction of energy consumption while providing optimum power flow to the end users is a substantial challenge in various fields of generation, transmission, and distribution. Environmental concerns like global greenhouse gas emissions and other problems related to fossil fuels, together with deficiency of resources, are other significant aspects
Optimal Integration of Rooftop PV and Wind Powers for Cost-Efficient and Low-Carbon Operation of Sustainable Railway Systems
No full textThis paper focuses on the environmental and economic impact of electric railway systems (ERS) and introduces Railway Energy Management Systems (REMS) as a green solution to reduce greenhouse gas (GHG) emissions and CO2 pollution and reducing the operational cost of the station while allowing surplus electricity sales to the grid market. The research utilizes Mixed Integer Linear Programming (MILP) to optimize the operation cost and GHG reduction of railway station electrical systems in Milan, Italy. The study considers Renewable Energy Resources (RERs), Energy Storage Systems (ESSs), Regenerative Braking Energy (RBE), and the electrical grid. It also incorporates real-time data to account for the probabilistic and stochastic behaviors of these elements, leading to a significant cost reduction of 56.09% in smart railway station operations. MATLAB is employed to solve the model effectively, demonstrating the suitability and effectiveness of the proposed approach with compelling evidence of operational cost and GHG reductions in various scenarios, achieving a reduction of 3458.26 kg/day in the best scenario
Bidirectional Solid-State Circuit Breakers for DC Microgrid Applications
No full textThe aim of this work is to investigate on DC microgrids and to find all the advantages and disadvantages of this type of configuration, in particular to find a solution for the problem of protection devices. In this paper, different types of circuit breaker devices are analyzed in order to find a possible solution to the main criticality of this distribution system. Two different configuration of Solid-State Circuit Breaker (SSCB) are analyzed and simulated in a DC microgrid using Simulink/Matlab
Dual-loop generalized predictive control method for two-phase three-wire railway active power quality controller
No full textOne of the most challenging topics in electric railway networks (ERNs) is power quality (PQ) problems caused by single-phase feeding of time-varying and high-power locomotives. During previous years, many techniques and compensators have been offered to alleviate these problems. Railway active power quality controller (RAPQC) is considered as one of the most efficient approaches. Due to the time-variant, uncertainty and distorted features of ERNs, the controlling of RAPQCs has always been a substantial concern to experts. This paper presents, a new robust control system for two-phase three-wire RAPQC (ThRAPQC) based on generalized model predictive control integrated with modified instantaneous reactive power theory (GMPC-MIRP). A dual-loop balancing system has been adopted in the proposed control system to equalize the active powers of traction power substation (TPSS) adjacent feeders, compensate reactive powers and suppress harmonic simultaneously. The performance of the proposed method in comparison with the conventional Fryze-Buchholz-Depenbrock (FBD)-based current strategy together with hysteresis current controller (FBD-HCC) has been evaluated through the detailed simulations and Opal-RT 5600-based laboratory setup results. The fast response, high precision, lower fluctuation in reference current tracking and high capability of working in distorted conditions are the outstanding privileges of the proposed method that are confirmed by the output results
Impact Analysis of Ultra-Fast Charging Station by Monte Carlo Simulation
No full textElectrification of road transport represents a necessary strategy for reducing oil dependency and hence climate change. As the penetration of electric vehicles on the market becomes more massive, the need of having a charging system, which can emulate the conventional oil fuel station, becomes ever more important; particularly as medium-long distance travels are concerned. To satisfy such need the installation of Ultra-Fast Charging (UFC) stations is increasing. Nevertheless, this type of infrastructure has to face technical, economical and grid-related challenges. This paper presents an impact analysis in terms of peak power consumption of an UFC station on the grid, obtained by the Monte Carlo simulation. Such analysis takes into account some of the main features which influence the charging speed and the absorbed power
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