2021
Autores
Bot, K; Ruano, A; Ruano, MD;
Publicação
INVENTIONS
Abstract
Accurate photovoltaic (PV) power forecasting is crucial to achieving massive PV integration in several areas, which is needed to successfully reduce or eliminate carbon dioxide from energy sources. This paper deals with short-term multi-step PV power forecasts used in model-based predictive control for home energy management systems. By employing radial basis function (RBFs) artificial neural networks (ANN), designed using a multi-objective genetic algorithm (MOGA) with data selected by an approximate convex-hull algorithm, it is shown that excellent forecasting results can be obtained. Two case studies are used: a special house located in the USA, and the other a typical residential house situated in the south of Portugal. In the latter case, one-step-ahead values for unscaled root mean square error (RMSE), mean relative error (MRE), normalized mean average error (NMAE), mean absolute percentage error (MAPE) and R-2 of 0.16, 1.27%, 1.22%, 8% and 0.94 were obtained, respectively. These results compare very favorably with existing alternatives found in the literature.
2021
Autores
Ruano, A; Bot, K; Ruano, MG;
Publicação
Lecture Notes in Electrical Engineering
Abstract
Home Energy Management Systems (HEMS) are becoming progressively more researched and employed to invert the continuously increasing trend in (electrical) energy consumption in buildings. One of the critical aspects of any HEMS is the real-time monitoring of all variables related to the management system, as well as the real-time control of schedulable electric appliances. This paper describes a data acquisition system implemented in a residential house in the South of Portugal. With the small amount of data collected, a Radial Basis Function (RBF) model, designed by a Multi-objective Genetic Algorithm (MOGA) framework, to forecast total electric consumption was developed. Results show that, even with these little data, the model can be used in a predictive control scheduling mechanism for HEMS. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021.
2021
Autores
VIERA, LAB; PASCOAL, PG; RECH, C; MEZAROBA, M;
Publicação
Proceedings of the 13th Seminar on Power Electronics and Control (SEPOC 2021)
Abstract
2021
Autores
Godinho, X; Bernardo, H; de Sousa, JC; Oliveira, FT;
Publicação
APPLIED SCIENCES-BASEL
Abstract
Nowadays, as more data is now available from an increasing number of installed sensors, load forecasting applied to buildings is being increasingly explored. The amount and quality of resulting information can provide inputs for smarter decisions when managing and operating office buildings. In this article, the authors use two data-driven methods (artificial neural networks and support vector machines) to predict the heating and cooling energy demand in an office building located in Lisbon, Portugal. In the present case-study, these methods prove to be an accurate and appealing alternative to the use of accurate but time-consuming multi-zone dynamic simulation tools, which strongly depend on several parameters to be inserted and user expertise to calibrate the model. Artificial neural networks and support vector machines were developed and parametrized using historical data and different sets of exogenous variables to encounter the best performance combinations for both the heating and cooling periods of a year. In the case of support vector regression, a variation introduced simulated annealing to guide the search for different combinations of hyperparameters. After a feature selection stage for each individual method, the results for the different methods were compared, based on error metrics and distributions. The outputs of the study include the most suitable methodology for each season, and also the features (historical load records, but also exogenous features such as outdoor temperature, relative humidity or occupancy profile) that led to the most accurate models. Results clearly show there is a potential for faster, yet accurate machine-learning based forecasting methods to replace well-established, very accurate but time-consuming multi-zone dynamic simulation tools to forecast building energy consumption.
2021
Autores
Reiz, C; Leite, JB;
Publicação
IEEE TRANSACTIONS ON POWER DELIVERY
Abstract
The sustainable development of power distribution systems must evolve into smart grids, where advanced automation with fast communication channels is essential. The analysis of their behavior uses the Hardware-In-the-Loop simulation for studying normal and critical operating conditions. In this work, we propose a hybrid technique for transient simulation in distribution systems by combining the high sample rate of the time domain models for voltage profile and electrical current monitoring with the processing speed of algorithms that operate the quasi-stationary, or permanent, phasor models. The proposed simulation platform is also based on the state of the art of standardized communication protocols of the power system. Its evaluation is performed using the comparison with specialized commercial software to assess the transient simulation. The time overcurrent protection function and the verification of messages exchanged between the simulator and the tested device highlights the applicability of the proposed methodology.
2021
Autores
Reiz C.; Leite J.B.;
Publicação
2021 IEEE PES Innovative Smart Grid Technologies Conference - Latin America, ISGT Latin America 2021
Abstract
Integration of distributed generation in power distribution networks provides many advantages and challenges to electric power system. Among challenges are the increase in levels of short-circuit currents and changes of power flow direction. These characteristics can interfere in the interruption capacity of protection devices, which are responsible for maintaining the integrity of distribution networks. Therefore, it is essential to understand the effects of distributed generation on protection systems to determine strategies that aim to solve the challenges imposed by this technology. The present work, first, proposes the mathematical formulation to coordinate overcurrent relays and fuse links, considering permanent and temporary faults. The solution is obtained through a dedicated genetic algorithm. Subsequently, this solution method is analyzed under different levels of penetration of distributed generators, allowing to identify points most susceptible to loss of coordination.
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