1,721,063 research outputs found
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
Numerical Dataset Analysis and Sensors Architecture Review for Vehicle Dynamics Application
No full textModern vehicles are nowadays largely equipped with sensors sampling several physical quantities in order to monitor the status of on-board subsystems and more in general give all the information needed on the vehicle dynamics to Electronic Control Units (ECUs). Sensors mounted are featured by different nature as far as the working principles and its techniques of fabrication are concerned. However, it can happen that the actual sensor architecture is not sufficiently robust to prompt the correct behaviour of the vehicle itself. If some physical quantities are not adequately monitored by dedicated sensors, the sampled dataset can be incomplete or not correlated with the real vehicle dynamics. In order to provide for the lack of sensors, it is important to consider both the analysis of the problem via numerical and a review of the whole sensor architecture. This paper aims to analyse the dataset sampled by on-board sensors of the vehicle to evaluate the odometry and estimate the physical quantities not monitored because of the absence of such sensors through a numerical model of the vehicle. The numerical model adopted is fitted and tuned on real tests performed. The information recovered contributes to define the dataset with more accuracy. Furthermore, a schematization of an optimal sensors architecture for vehicle dynamics application is provided to reduce the lack of information on the odometry, considering a frequent critical condition due to the interference given by the weather
Totally Green Vehicle? Correlation the RES and Load Curves of CSs
No full textElectric Vehicles (EV) are seen as a possible solution to reduce GreenHouse Gasses (GHGs) emission caused from the transportation sector. This possibility is enabled from Renewable Energy Sources (RESs) that can provide energy with a very low level of CO2 emissions per kWh. Typically, renewable energy sources like photovoltaic and wind are not dispatchable, with hydropower being a partial exception, due to their weather dependency. The scope of this work is to study the trade of between the percentage of energy produced with RESs and the energy absorbed by the public charging system. It is shown the trade-off between the percentage of Renewable Energy (RE) provided to the Charging Infrastructure (CI) and the overproduced energy solving an optimization problem
Surveying PQ Aspects in Italian Industrial Customers
No full textThe paper has the objective to identify levels of Power Quality (PQ) at industrial customers in the various areas of Italian electric system. To this aim, the results of two different questionnaire based surveys performed so far in different Italian Districts have been analyzed in comparison in order to derive general rules and guidelines concerning PQ aspects. The surveys have involved, as a whole, a sample of about 200 industrial customers located in central and northern areas of the Country. The surveys have concerned even some aspects relevant to costs of PQ problems. The main results as obtained from either the surveys are reported and discussed
Make-or-Buy Policy Decision in Maintenance Planning for Mobility: A Multi-Criteria Approach
No full textBackground: The ongoing technical innovation is fully involving transportation sector, converting the usual mass-transit system toward a sustainable mobility. Make-or-buy decision are usually adopted to assess different solutions in terms of costs-benefits to put in place strategic choices regarding in-house production or from an external supplier. This can also be reflected on maintenance operations, thus replicating a similar approach to transport companies involved. Method: A decision-making model by means of a multi-criteria analysis can lead make-or-buy choices adapted to maintenance. A brief introduction into the actual mobility context is provided, evaluating global and national trends with respect to the mobility solutions offered. Then, a focus is set on maintenance approaches in mobility sector and the need of a make-or-buy decision process is considered. The decision-making path is developed through a multi-criteria framework based on eigenvector weighing assessment, where different Key Performance Indicators (KPIs) are identified and exploited to assess the maintenance approach at stake. Results: A comparison among different scenarios considered helped in identify the solution offered to the transport operator. In particular, for the case study of interest a −35% decrease in maintenance specific cost and −44% in cost variability were found. Reliability of the fleet was kept at an acceptable level compared to the reference in-house maintenance (≥90%) while an increase in the Mean Time Between Failure was observed. Conclusions: For the purposes of a small company, the method can address the choice of outsourcing maintenance as the best. Finally, a general trend is then extrapolated from the analysis performed, in order to constitute a decision guideline. The research can benefit from further analysis to test and validate that the selected approach is effective from the perspective of transport operator
Modern Power Quality Improvement Devices Applied to Electric Railway Systems
No full textElectric railway supplying systems (ERSSs) as one of the foremost and critical loads of the grid have been faced with power quality (PQ) issues all around the world. Due to the various PQ distortion types, and planned priorities, different mitigation methods have been introduced by experts over years and they have been updated based on the emergence of new power electronic-based technologies. These methods mainly deal with harmonic issues, low power factor, imbalance situations, transients, and variation phenomena. The main purpose of this paper is to classify and explain these mitigation technologies including their structure, application and features in detail, which can provide a useful perspective to researchers working in this area
Assessment of the Impact of Electric Vehicles on the Design and Effectiveness of Electric Distribution Grid with Distributed Generation
Full text linkThe objective of this paper is to assess the probable effect that electric vehicles (EVs), already in wide circulation and likely to increase exponentially in the near future, will have on distribution networks. Analyses are conducted on the necessary interventions and evolutions that the distribution grid will have to undergo in order to manage this new and progressively increasing heavy load of energy. Thus, in order to understand the technical limitations of the current infrastructure and how transformers and lines will be able to withstand the increasing penetration of EVs, urban and rural grid models have been studied, to highlight the differences between the impacts on high- and low-density networks. In addition, an analysis of fast charging station impact has been carried out. MATLAB software was used to perform the simulations for the creation of scripts, which were then exploited within the DIgSILENT PowerFactory software. This allowed evaluation of the networks under examination and verification of the effectiveness of the proposed solutions. In concluding based on findings, some methods of managing the distribution network to optimise the network parameters analysed in the study and a solution involving electric vehicles are recommended
Comprehensive evaluation of lossless compression algorithms in a real use case for smart grid applications
No full textThe so-called “energy digitalization” is pervading the power and energy industry by providing many state-of-the-art digital technologies to collect, store, and analyze the very heterogeneous information managed in modern power systems. Requirements in terms of sampling frequency, temporal and user aggregation, measured quantities, measurement aggregations, involved players, and applications can be very different. Compression strategies, removing redundancy and over-specification in collected samples, can play a relevant role in efficiently move and store such heterogeneous data. In this work, a reference dataset from a real-world use case has been collected for comparing the performance of 62 lossless compression algorithms derived from the LZ77/LZSS/LZMA strategies. Compression of the six-day long acquisition, including active power measurements of a prosumer's system equipped with a Photovoltaic (PV) and a Battery Energy Storage System, highlights the different obtainable performance when the aggregation interval is changed from 15 min to 24 h. In particular, once the top performing algorithms have been selected, it has been possible to stress the impact of night–day cycle, mainly due to the different sparsity of PV-related data. The obtained results demonstrate that, globally, the compression ratio increases by increasing the aggregation interval, by reaching values close to 9.7. In particular, when offline operation is tolerated, optimal compression schemes can be easily applied, leading to consistent improvement of the compression ratio (up to 24%, depending on the actual algorithm and aggregation interval), which can be very significant when large number of data sources is considered
Power quality analysis in renewable energy systems supplying distribution grids
No full textThe paper deals with power quality case studies conducted on existing renewable sources based systems. Voltage fluctuations determined by a 0.65 MVA wind turbine are analyzed. The impact of photovoltaic systems on steady state voltage variations and current harmonics is investigated. The correlation between the generated power and the main power quality indices is highlighted
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