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Publicações

2021

Modeling an electric vehicle parking lot with solar rooftop participating in the reserve market and in ancillary services provision

Autores
Osorio, GJ; Lotfi, M; Gough, M; Javadi, M; Espassandim, HMD; Shafie khah, M; Catalao, JPS;

Publicação
JOURNAL OF CLEANER PRODUCTION

Abstract
Electric vehicles (EVs) are seen as a crucial tool to reduce the polluting emissions caused by the transport and power systems (PS) sector and the associated shift to a cleaner and more sustainable energy sector. The com-bination of EVs and solar photovoltaics (PV) in PS, specifically through the aggregation of EVs in parking lots (PLs), may improve the reliability and flexibility of the PS, assisting the power network in critical moments. This work proposes a novel aggregator agent in the energy system which is an EV charging station with an installed PV system. In this work, an optimal operation strategy for the solar-powered EV PL (EVSPL) operation is pre-sented. The model optimizes the EVSPL's participation in various energy and ancillary services markets, including the effects of capacity payments. The results show that the EVSPL leads to higher profits. The EVSPL's participation in ancillary services is highly influenced by the prices. The results of this work show that this novel agent can actively participate in the energy system in an economically viable manner while respecting the technical constraints of the network and providing important ancillary services to the system operator. Superscript/Subscript Available

2021

The Fast Overvoltage Protection Consideration and Design for SiC-Based Matrix Converters

Autores
Costa, LALDC; Fan, BR; Burgos, R; Boroyevich, D; Chen, WR; Blasko, V;

Publicação
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS

Abstract
Matrix converters feature low switching loss, small electromagnetic interference filter, and the potential for achieving high power density. With the employment of wide-bandgap devices, such as silicon carbide devices, the converter performance can be further improved. For a safe operation of matrix converters, an overvoltage protection circuit is necessary to limit the voltage stress of the devices during fault conditions. Due to the high switching speed of silicon carbide devices, the topology and layout design of the overvoltage protection circuit is critical to ensure fast and robust protection for the devices. In this article, a detachable overvoltage protection circuit is designed for each phase leg of the matrix converter. The topology and hardware layout design are elaborated. A 15-kW full silicon carbide implemented matrix converter is built, and the designed overvoltage protection circuits are employed and tested.

2021

Applying Machine Learning for Traffic Forecasting in Porto, Portugal

Autores
Maia, P; Morgado, J; Goncalves, T; Albuquerque, T;

Publicação
MACHINE LEARNING AND PRINCIPLES AND PRACTICE OF KNOWLEDGE DISCOVERY IN DATABASES, PT II

Abstract
Pollutant emissions from passenger cars give rise to harmful effects on human health and the environment. Predicting traffic flow is a challenging problem, but essential to understand what factors influence car traffic and what measures should be taken to reduce carbon dioxide emissions. In this work, we developed a predictive model to forecast traffic flow in several locations in the city of Porto for 24 h later, i.e., the next day at the same time. We trained a XGBoost Regressor with multi-modal data from 2018 and 2019 obtained from traffic and weather sensors of the city of Porto and the geographic location of several points of interest. The proposed model achieved a mean absolute error, mean square error, Spearman's rank correlation coefficient, and Pearson correlation coefficient equal to 80.59, 65395, 0.9162, and 0.7816, respectively, when tested on the test set. The developed model makes it possible to analyse which areas of the city of Porto will have more traffic the next day and take measures to optimise this increasing flow of cars. One of the ideas present in the literature is to develop intelligent traffic lights that change their timers according to the expected traffic in the area. This system could help decrease the levels of carbon dioxide emitted and therefore decrease its harmful effects on the health of the population and the environment.

2021

A bibliometric view on the use of total quality management in services

Autores
Zhang, C; Moreira, MRA; Sousa, PSA;

Publicação
TOTAL QUALITY MANAGEMENT & BUSINESS EXCELLENCE

Abstract
This research aims to highlight the major domains of and address the most prominent topics in the Total Quality Management (TQM) field in the service sector. Although there are numerous studies related to TQM, systematic quantitative reviews on TQM in services are scarce. The objective of this paper is to present a thorough analysis of the current mostly discussed issues related to the use of TQM in services by conducting a bibliometric analysis of the extant literature on TQM collected from Web of Science and Scopus databases. The findings indicate that TQM implementation is not a fading topic. The studies in the field of 'TQM use in services' are growing and becoming more intensive. TQM-related practices are gaining more attention while the TQM implementation framework is still under development. Healthcare is the most researched industry. Top management commitment/leadership is a critical construct and managers should be aware of the obstacle caused by lacking it. TQM professionals and managers in the service sector can benefit from this paper by having a sketch of the latest and most prominent academic findings and thus gaining insights on techniques that fit into TQM implementation. For academic professionals, several research avenues are pointed out.

2021

COVID-19 and the Digitalization Pace

Autores
Almeida, F;

Publicação
Academia Letters

Abstract

2021

Estimation of the Global Amount of Mandatory Investments for Distribution Network Expansion Planning

Autores
Macedo, PM; Fidalgo, JN; Saraiva, JT;

Publicação
2021 IEEE MADRID POWERTECH

Abstract
The financial planning of distribution systems usually includes the prediction of annual mandatory investments, concerning the resources that the DSO is compelled to allocate as a result of new network connections, required by new consumers or new energy producers. This paper presents a methodology to estimate the mandatory investments that the DSO should do in the distribution network. These estimations are based on historical data, load growth expectations and various socioeconomic indices. However, the available database contains very few annual investment examples (one aggregated value per year since 2002) compared to the large number of variables (potential inputs), which is a factor of regression overfitting. Thus, the applicable regression techniques are restrained to simple but efficient models. This paper describes a new methodology to identify the most suitable estimation models. The implemented application automatically builds, selects, and tests estimation models resulting from combinations of input variables. The final forecast is provided by a committee of models. Results obtained so far confirm the feasibility of the adopted methodology.

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