| 1. |
- Heydari, Rasool, et al.
(författare)
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Model-Free Predictive Control of Grid-Forming Inverters With LCL Filters
- 2022
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Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 37:8, s. 9200-9211
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Tidskriftsartikel (refereegranskat)abstract
- With the increasing penetration of distributed energy resources into islanded microgrids, a grid-forming inverter (GFI) has become the key element interfacing renewable energy sources. Usually, the GFI is employed with an output filter to minimize the harmonic content achieving high-quality output voltage regulation. To this end, model-predictive control (MPC) has been widely proposed to control the output voltage of GFI systems due to the high-quality performance, fast control response, and straightforward handling of constraints. However, an accurate model of the system is required for the conventional MPC to avoid a suboptimal performance under uncertainties. To overcome this known drawback, a novel model-free predictive control is proposed in this article. Consequently, the output voltage of an LC L-filtered GFI is regulated without the knowledge of the physical model.
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| 2. |
- Rodriguez-Deniz, Hector, et al.
(författare)
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Urban Network Travel Time Prediction via Online Multi-Output Gaussian Process Regression
- 2017
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Ingår i: 2017 IEEE 20TH INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC). - : IEEE. - 9781538615263
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Konferensbidrag (refereegranskat)abstract
- The paper explores the potential of Multi-Output Gaussian Processes to tackle network-wide travel time prediction in an urban area. Forecasting in this context is challenging due to the complexity of the traffic network, noisy data and unexpected events. We build on recent methods to develop an online model that can be trained in seconds by relying on prior network dependences through a coregionalized covariance. The accuracy of the proposed model outperforms historical means and other simpler methods on a network of 47 streets in Stockholm, by using probe data from GPS-equipped taxis. Results show how traffic speeds are dependent on the historical correlations, and how prediction accuracy can be improved by relying on prior information while using a very limited amount of current-day observations, which allows for the development of models with low estimation times and high responsiveness.
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| 3. |
- Suau-Sanchez, P., et al.
(författare)
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An assessment of the potential for self-connectivity at European airports in holiday markets
- 2017
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Ingår i: Tourism Management. - : Elsevier Ltd. - 0261-5177 .- 1879-3193. ; 62, s. 54-64
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Tidskriftsartikel (refereegranskat)abstract
- In a context of intense airport and airline competition, a few European airports have recently started offering self-connection services to price-sensitive holiday passengers travelling with a combination of tickets where the airline/s involved do not handle the transfer themselves. This paper provides an exploratory analysis of the potential and implications of self-connectivity for European airports and airlines using a case study of air travel routes to holiday destinations in the Mediterranean. With the help of a forecasting model based on a zero-inflated Poisson regression, we identify the airports and airlines that have the highest potential to facilitate self-connections in the selected markets. The results also explore some implications of the widespread development of self-connection services in Europe.
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| 4. |
- Suau-Sanchez, P., et al.
(författare)
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Benchmarking worldwide airport connectivity with demand data : Global hub competition, new players, and the hidden potential of self-connectivity
- 2017
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Ingår i: Volume 6 - The Economics of Airport Operations. - : Emerald Group Publishing Ltd.. - 9781787144989 ; , s. 387-423
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Bokkapitel (refereegranskat)abstract
- The connectivity provided by full-service network carriers under the umbrella of airline alliances is increasingly challenged by the services of Middle Eastern airlines via their own hubs, and the rise of new passenger strategies like self-connectivity. While these two developments can potentially benefit consumers with more services and lower fares, the rise of Middle East carriers has been met with opposition by EU and US airlines that call for increased protectionism. In addition, only a few airports in the world actively support self-connections. In this context, this study aims to investigate (1) the markets in which Middle East carriers exert a stronger dominance in terms of the number of passenger connections, (2) whether EU, US, or Asian hubs provide a competitive quality of connectivity in terms of travel time, and (3) whether a significant potential for self-connections is hidden at major airports worldwide. To that end, several datasets of passenger bookings (MIDT), airline schedules, and minimum connecting times between 2012 and 2015 are combined in a connections-building methodology that delivers six market-specific airport connectivity indicators for our benchmarking exercise. Our findings show that although European and some Asian hubs have lost traffic in global markets, they remain competitive from a quality perspective. US hubs have maintained their market share and competitive position. Finally, we identify the airports and airlines with the highest potential to provide self-connecting travel options, which can become an attractive new source of revenue for the parties involved.
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| 5. |
- Voltes-Dorta, Augusto, et al.
(författare)
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Vulnerability of the European air transport network to major airport closures from the perspective of passenger delays : Ranking the most critical airports
- 2017
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Ingår i: Transportation Research Part A. - : Elsevier. - 0965-8564 .- 1879-2375. ; 96, s. 119-145
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Tidskriftsartikel (refereegranskat)abstract
- This paper analyzes the vulnerability of the European air transport network to major airport closures from the perspective of the delays imposed to disrupted airline passengers. Using an MIDT dataset on passenger itineraries flown during February 2013, full-day individual closures of the 25 busiest European airports are simulated and disrupted passengers then relocated to minimum-delay itineraries. Aggregate delays are used to rank the criticality of each airport to the network, with the possibility of disaggregating the impact across geographical markets. The results provide useful reference values for the development of policies aimed at improving the resilience of air transport networks.
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| 6. |
- Young, Hector, et al.
(författare)
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Model-free Predictive Torque Control of an Induction Machine Based on Parameter Estimation
- 2021
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Ingår i: 6Th IEEE International Conference On Predictive Control Of Electrical Drives And Power Electronics (PRECEDE 2021). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 725-731
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Konferensbidrag (refereegranskat)abstract
- The uncertainty or variation of the electric machine parameters in predictive torque control (PTC) has a noticeable impact on the controller's performance. This paper proposes a model-free PTC strategy based on the estimation of the prediction model parameters using input and output data of the controlled system, applied to an induction machine. This approach has the advantage of not requiring a detailed previous knowledge of the system, with a high robustness to mismatch in the inductance parameters of the machine. The stator resistance is identified as a critical parameter for PTC, therefore an adaptation mechanism based on support vector regression is proposed to increase the robustness of the system. Simulation tests are carried out to validate the effectiveness of the proposed strategy.
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