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Publicações

Publicações por CPES

2019

Experimental validation of an equivalent dynamic model for active distribution networks

Autores
Fulgencio, N; Rodrigues, J; Moreira, C;

Publicação
SEST 2019 - 2nd International Conference on Smart Energy Systems and Technologies

Abstract
In this paper a real-time laboratorial experiment is presented, intended to validate a 'grey-box' equivalent model for medium voltage active distribution networks with high presence of converter-connected generation, considering the latest European grid codes requirements, in response to severe faults at the transmission network side. A hybrid setup was implemented at INESC TEC's laboratory (Porto, Portugal), relying on a real-time digital simulator to provide the interface between simulation and physical assets available at the laboratory, in a power-hardware-in-the-loop configuration. The study considered the laboratory's internal network to be operating (virtually) as a medium voltage distribution network with converter-connected generation (fault ride through compliant), connected to a fully-detailed transmission network model. The aggregated reactive power response of the laboratory's network was fitted by the dynamic equivalent model, recurring to an evolutionary particle swarm optimization algorithm. The methodology adopted, testing conditions and respective results are presented. © 2019 IEEE.

2019

Continuous Power Flow Analysis for Micro-Generation Integration at Low Voltage Grid

Autores
Alam, MM; Moreira, C; Islam, MR; Mehedi, IM;

Publicação
2nd International Conference on Electrical, Computer and Communication Engineering, ECCE 2019

Abstract
The integration of micro-generation (µG) in distribution networks faces new challenges concerning the technical as well as commercial management. The µG integration in the Low and medium voltage distribution networks has many advantages for the grid operation, such as voltage profiles improvement, power losses reduction, and branches congestion levels reduction. This paper presents a method for guiding continuation power flow simulation of integrating µG on distribution feeders. A base model is designed with variable capacitor bank, µG unit such as PV and Wind generation are integrated. A control method is used to improve the voltage level of each node as well as improving power factor of the systems. The electricity consumption of a university's substation area where commercial, residential and municipal load are presented are modeled using actual data collected from each single residential hall and commercial buildings. This model allows analyzing the power flow and voltage profile along each distribution feeders on continuing fashion for a 24- hour period at hour-by-hour formulation. By dividing the feeder into load zones based on distance from each load node to distribution feeder head, the impact of integration of different µG operation in different condition has been discussed. © 2019 IEEE.

2019

Developing a framework for assessing teaching effectiveness in higher education

Autores
Miguel, CV; Moreira, C; Alves, MA; Campos, JBLM; Glassey, J; Schaer, E; Kockmann, N; Kujundziski, AP; Polakovic, M; Madeira, LM;

Publicação
EDUCATION FOR CHEMICAL ENGINEERS

Abstract
Evaluating the effectiveness of teaching and learning core knowledge outcomes and professional skills is a highly challenging task that has not yet been satisfactorily addressed at higher education level. The iTeach European project consortium developed a framework for assessing the effectiveness of various pedagogical methodologies in chemical engineering education, including those aiming to promote important core competencies related to employability, in a range of geographical and educational contexts. The framework was firstly implemented in a core chemical engineering area (reaction engineering) to check its usability and robustness, and subsequently was also tested on a range of subject areas from various branches of engineering and other disciplines, one of which is analysed in more detail in this contribution. The results of this broader assessment encompassed a much more diverse student body with varying educational experiences and a wider range of different teaching methodologies. The outcomes of this assessment are highlighted and the benefits of such an objective approach for evaluating teaching effectiveness is discussed. Crown Copyright

2019

Proactive management of distribution grids with chance-constrained linearized AC OPF

Autores
Soares, T; Bessa, RJ;

Publicação
INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS

Abstract
Distribution system operators (DSO) are currently moving towards active distribution grid management. One goal is the development of tools for operational planning of flexibility from distributed energy resources (DER) in order to solve potential (predicted) congestion and voltage problems. This work proposes an innovative flexibility management function based on stochastic and chance-constrained optimization that copes with forecast uncertainty from renewable energy sources (RES). Furthermore, the model allows the decision-maker to integrate its attitude towards risk by considering a trade-off between operating costs and system reliability. RES forecast uncertainty is modeled through spatial-temporal trajectories or ensembles. An AC-OPF linearization that approximates the actual behavior of the system is included, ensuring complete convexity of the problem. McCormick and big-M relaxation methods are compared to reformulate the chance-constrained optimization problem. The discussion and comparison of the proposed models is carried out through a case study based on actual generation data, where operating costs, system reliability and computer performance are evaluated.

2019

Explanatory and Causal Analysis of the MIBEL Electricity Market Spot Price

Autores
Goncalves, C; Ribeiro, M; Viana, J; Fernandes, R; Villar, J; Bessa, R; Correia, G; Sousa, J; Mendes, V; Nunes, AC;

Publicação
2019 IEEE MILAN POWERTECH

Abstract
This paper analyzes the electricity prices of the MIBEL electricity spot market with respect to a set of possible explanatory variables. Understanding the main drivers of the electricity price is a key aspect in understanding price formation and in developing forecasting models, which are essential for the selling and buying strategies of market agents. For this analysis, different techniques have been applied in this work, including standard and lasso regression models, causal analysis based on bayesian networks and classification trees. Results from the different approaches are coherent and show strong dependency of the electricity prices with the Portuguese imported coal for lower non-dispatchable net demands, which has been progressively replaced by gas for larger non-dispatchable net demands. Hydro reservoirs and hydro production are also main explanatory variables of the electricity price for all non-dispatchable net demand levels.

2019

Load Forecasting Benchmark for Smart Meter Data

Autores
Viana, J; Bessa, RJ; Sousa, J;

Publicação
2019 IEEE MILAN POWERTECH

Abstract
Actual integration of high-tech devices brings opportunities for better monitoring, management and control of low voltage networks. In this new paradigm, efficient tools should cope with the great amount of dispersed and considerably distinct data to support smarter decisions in almost real time. Besides the use of tools to enable an optimal network reconfiguration and integration of dispersed and renewable generation, the impact evaluation of integrating storage systems, accurate load forecasting methods must be found even when applied to individual consumers (characterized by the high presence of noise in time series). As this effort becomes providential in the smart grids context, this article compares three different approaches: one based on Kernel Density Estimation, an alternative based on Artificial Neural Networks and a method using Support Vector Machines. The first two methods revealed unequivocal benefits when compared to a Naive method consisting of a simple reproduction of the last available day.

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