Washington Luiz Araujo Neves

The selection of georeferenced meteorological databases is a critical technical and financial factor in photovoltaic (PV) system sizing. This study evaluates how database choice affects PV generation estimates and economic feasibility by combining bibliometric screening, technical validation, financial indicators, and multicriteria analysis. A bibliometric review of 5,658 documents indexed in Scopus and Web of Science supports the selection of seven databases, which are compared across ten Brazilian locations. PV generation is estimated using both a simplified sizing approach and a higher-temporal-resolution model based on hourly irradiance, ambient temperature, and module thermal coefficients, enabling comparison with measured generation in a three-year case study in João Pessoa. Performance is assessed using MAE, MAPE, RMSE, R2, NPV, payback, and the Analytic Hierarchy Process. NASA POWER shows the strongest overall multicriteria performance, ranking first in seven of the ten locations. Database choice causes variations of up to 4.70 years in payback and BRL 105,709.36 in NPV for the same system, equivalent to USD 21,082.84 at the May 22, 2026 exchange rate. The simplified CRESESB-based method overestimates annual generation by 6.79%–12.64%, whereas NASA POWER reaches a best annual deviation of −1.66% in 2024.

This study presents an innovativeapproach to estimate the operating temperature of photovoltaic modules by incorporating underexplored climatic factors, such as wind direction and precipitation, in addition to commonly analyzed variables, such as ambient temperature, wind speed, solar irradiance, and relative humidity. The research addresses a gap in the literature, improving the predictive accuracy of photovoltaic module temperature estimation models. The developed methodology is designed to integrate measurement data from any location and was validated using data collected from over two years of measurements, demonstrating that the resulting prediction model is both valid and precise. The methodology employs multiple linear regression to derive the predictive model, ensuring adaptability and accuracy across different environmental contexts. Results indicate a significant improvement in prediction performance compared to other models. This advancement supports better design and operation of distributed photovoltaic systems globally.

Este artigo apresenta uma aplicação da Transformada de Hilbert Huang (HHT) para analisar os transitórios de alta frequência em um sistema de transmissão gerado por uma falta em linha de transmissão com o objetivo de determinar sua localização. A metodologia utilizada baseia-se na teoria das ondas viajantes, onde, em função do tempo de propagação dos sinais entre o ponto de falta e os terminais da linha e empregando o HHT, é determinada a localização da falta. A técnica de localização de faltas utiliza dados registrados de um terminal da linha de transmissão. O algoritmo implementado no MATLAB que executa o ATP apresenta resultados promissores para localização de faltas em sistemas de transmissão, não sofrendo interferência significativa na variação de parâmetros de falta como tipo de falta, resistência de falta e ângulo de incidência de falta na linha de transmissão

Coupling capacitor voltage transformers (CCVT) are the predominant devices used in high voltage systems to provide scaled down voltage signals for metering, protection and control devices. The performances of these devices are subject to errors due to the transient behavior of CCVT, so that the use of CCVT digital models is essential for power systems studies in order to predict how the equipment dynamics affect protective relaying performances. In this review paper, the authors put together complete information regarding five realistic CCVT digital models available in literature and perform a detailed sensitivity analysis of their magnitude and angle frequency responses, as well as their influence on phasor estimation, distance protection, and fault location techniques.

In this paper, a closed-form solution for traveling wave (TW)-based fault location on non-homogeneous lines (NHLs) with multiple sections is proposed. It is able to accurately estimate the fault location on NHLs taking into account the different propagation velocities, irrespective of the number of sections, including the effects of line electrical parameters uncertainties. The algorithm can be applied to non-homogeneous transmission networks composed by overhead transmission lines (OHLs), underground cable lines (UCLs), submarine cable lines (SCLs) or by any other line section with considerably different electrical characteristics. A wide variety of fault scenarios were simulated in a 380 kV/50 Hz NHL consisting of multiple OHL, UCL and SCL sections. In each simulation, the proposed algorithm performance was compared against that obtained from an existing two-terminal TW-based fault location approach. The obtained results reveal the proposed closed-form TW-based solution is generalist and reliable, being useful for fault location applications on NHLs.

A new method to numerically estimate the primary voltage waveform of coupling capacitor voltage transformers is presented. The outcome is a simple digital filter suitable for the frequency range from 10 to 60 Hz, enabling to recover the transformer primary voltage waveform from its secondary voltage waveform. Unlike the techniques reported in the literature, the method does not depend directly on the transformer topology nor on the operational characteristics of the protected system, once only the coupling capacitor voltage transformer frequency response is required as input. The evaluation of the technique is performed through digital simulations using transmission line data from the Brazilian National Power System Grid. Frequency and time domain analysis of two coupling capacitor voltage transformers with different topologies and voltage levels are presented. It is shown that the proposed method is effective for the dynamic correction of low frequency disturbances which may improve the speed, reliability and security of the numerical distance relay.

An innovative methodology for protection performance evaluation on transmission networks is presented in this paper. It was developed to overcome difficulties faced by the Brazilian utility Companhia Hidro Elétrica do São Francisco (CHESF) during the preparation of short-circuit reports that must be sent to regulatory organizations whenever transmission-line faults occur. In the proposed methodology, a combination of several algorithms is used to extract from oscillographic records relevant information about short circuits and performance of protection functions. Aiming toward practical applications in CHESF, a software named disturbance analysis and protection performance evaluation has been developed in order to execute the proposed methodology functions, providing reports about the short-circuit characteristics and protection operation. To validate the proposed methodology, digital fault simulations in the Alternative Transients Program (ATP) and in Computer-Aided Protection Engineering (CAPE) software were carried out. Furthermore, real-world fault cases were also analyzed by assessing actual oscillographic fault records provided by CHESF. The obtained results show that the proposed methodology is reliable and quite useful for short-circuit analysis and protection performance evaluation procedures.