Publications resulting from the project
Publications resulting from the project
Embedded Files
Inspection of Visual Corona Discharge in New and Used Electrical Components
Pradeep Kumar Gupta, Jordi-Roger Riba, Kaur Tuttelberg, Jako Kilter, Milad Soltany,
IEEE International Conference on Diagnostics in Electrical Engineering (Diagnostika) (CDEE), 2 - 4 SEP 2026, Pilsen, Czech Republic.
A. Soni, J.-R. Riba and M. Moreno-Eguilaz,
24th International Conference on Renewable Energies and Power Quality (ICREPQ'26), 10-12 June, 2026, Santander, Spain.
M. Soltany, J.-R. Riba, P. Canalda and S. Bogarra,
24th International Conference on Renewable Energies and Power Quality (ICREPQ'26), 10-12 June, 2026, Santander, Spain.
On the Formulas Used To Determine Fair Weather Corona Losses in Transmission Line Conductors
J.-R. Riba, M. Soltany, and S. Bogarra,
24th International Conference on Renewable Energies and Power Quality (ICREPQ'26), 10-12 June, 2026, Santander, Spain.
An Electric Field Energy Harvesting System Prototype for the Smart High-Voltage Transmission Grids
M. Moreno-Eguilaz, S. Bogarra and J.R. Riba,
24th International Conference on Renewable Energies and Power Quality (ICREPQ'26), 10-12 June, 2026, Santander, Spain.
Calculation of the AC Resistance of Single-Layer Steel-Core Conductors for DLR Applications
Ankit Soni, Jordi-Roger Riba, Manuel Moreno-Eguilaz,
IEEE I2MTC 2026, Instrumentation and Measurement for a Sustainable Future, 25-28 May 2026, Nancy, France.
Unmodified DSLR Camera Sensitivity Determination for Partial Discharges Detection
Milad Soltany, Jordi-Roger Riba, Santiago Bogarra,
IEEE I2MTC 2026, Instrumentation and Measurement for a Sustainable Future, 25-28 May 2026, Nancy, France.
Jordi-Roger Riba, Technologies, Technologies 2026, 14(5), 255. 24/04/2026.
Abstract
For high-voltage power transmission, the surface voltage gradient (SVG) of the conductor plays a crucial role in meeting corona performance requirements. The SVG is greatly impacted by the smoothness of the conductor’s surface. Under identical conditions, the SVG of smooth, round conductors differs from that of stranded conductors with the same outer radius. This paper uses Finite Element Analysis (FEA) to study the effect of different stranded conductor geometries and three-phase line topologies with stranded conductor bundles on the SVG. Although industry standards and the scientific literature often rely on simplified smooth-cylinder approximations, this research demonstrates that surface irregularities significantly increase electrical stress compared to idealized smooth surfaces. Through simulating various three-phase configurations, the study reveals a nearly constant field enhancement factor across diverse stranded designs. These results enable us to apply formulas developed for smooth conductors to more realistic power line applications involving stranded conductor bundles. Consequently, this FEA approach offers engineers a precise, versatile method for designing high-voltage transmission lines. The findings presented here facilitate a deeper understanding of the SVG surrounding stranded conductors, particularly with regard to its influence on corona phenomena.
Assessment of Two Methods for On-Line Measurement of the AC Resistance of Conductors
Jordi-Roger Riba, Ankit Soni and Manuel Moreno-Eguilaz, Engineering Research Express (Wiley), Accepted 10/04/2026.
Abstract
The alternating current (AC) of power system components has a major impact on their thermal behavior, current carrying capacity. Despite of its importance, most international standards are still based on the direct current (DC) resistance, since it is easy to measure. However, the AC resistance and the AC power losses are typically greater than the DC resistance and power losses, due to the effect of the eddy currents, and in the case of components including ferromagnetic cores, due to the magnetizing effect of the core. This paper assesses the accuracy and the measurement uncertainty of two experimental methods to determine the AC resistance of power system components. The first method is based on the phase shift between the voltage drop across one meter of conductor and the current flowing through it. The second method is based on the instantaneous power over the same length. Both methods were validated through laboratory experiments using copper and aluminum conductors. Results indicate that while both methods yield similar AC resistance estimates, the phase shift method is superior, reducing uncertainty by 50% compared to the instantaneous power method. The presented approaches are generalizable to a wide array of power system components, including but not limited to insulated cables, connectors, or transformer, motor and generator windings. They can be applied for laboratory purposes such as product optimization, qualification and quality control or for on-line monitoring and maintenance purposes.
Pooya Parvizi, Milad Jalilian, Alireza Mohammadi Amidi, Mohammad Reza Zangeneh, Jordi-Roger Riba, Energy Technology, Accepted 18/02/2026
Abstract
Although power losses in electricity systems have been widely studied, most research remains focused on the transmission and distribution stages, leaving the generation stage largely overlooked. Thermodynamic, operational, and resource-variability factors at this stage play a decisive role in determining overall energy system efficiency. This article, for the first time, provides a comprehensive and integrated review of loss mechanisms, identifying and categorizing the key contributors to generation-stage losses across all major technologies, including fossil fuel plants, nuclear reactors, and renewable energy sources. Drawing on authoritative international datasets, the review analyzes the environmental and operational implications of these losses and demonstrates how neglecting the generation stage can lead to biased efficiency assessments and suboptimal energy-policy decisions. Furthermore, the article provides forward-looking recommendations, presenting emerging technologies, such as advanced energy cycles, artificial intelligence-based optimization, next-generation storage systems, and digital-twin platforms as promising pathways toward lower generation-stage losses and a more efficient, low-carbon energy future, while also serving as a roadmap for future research by other scholars.
Paschen’s Law for Non-uniform Fields Using a Rod-Plane Gap
Jordi-Roger Riba, Milad Soltany, Adrià Cabello, European Journal of Physics, 47 (2026) 025803, Online 05/03/2026.
Abstract
Paschen’s law describes the breakdown voltage of a gas as a function of gap distance and gas pressure. This fundamental principle of high-voltage physics and engineering significantly impacts the operation, design, and safety of various electrical and plasma-based technologies, including air ionizers, aircraft, and satellites. Originally developed for uniform electric fields, such as those between two parallel plates or spheres, Paschen’s law determines the voltage required to initiate an electric arc. It predicts that the breakdown voltage is a unique function of the pressure-distance product p·d, with a minimum value occurring at a specific p·d. This work proposes a practical laboratory session or guided project for physics or engineering courses to determine Paschen’s law based on laboratory measurements for non-uniform electrode geometries under a 50 Hz sinusoidal supply. A rod-plane gap geometry produces a highly non-uniform electric field distribution, enabling corona discharges to occur before complete breakdown of the air gap. The experimental results presented here indicate that partial discharges tend to occur at higher p·d values for a rod-plane geometry than predicted by Paschen’s law. However, the results approach Paschen’s values as the p·d product decreases. Additionally, the results show that corona discharges occur well before complete air gap breakdown at high p·d values, and that each pressure has a unique curve relating breakdown voltage to the p·d product. Therefore, the results deviate from original Paschen’s law. This paper analyzes the concepts of partial discharges and complete breakdown and discusses the conditions leading to one or the other. The discharges were detected by remotely controlling a smartphone camera via open-source software. A complete dataset is provided that can be used directly for developing practical or guided projects. Students also have the option of acquiring their own data using the simple experimental setup outlined in this paper.
On the scaling of digital cameras to quantify the intensity of corona discharges
M. Soltany, J.-R. Riba, and S. Bogarra, Measurement, Volume 265, 17 March 2026, 120343, Accepted 06/01/2026.
Abstract
Corona and surface discharges emit ultraviolet and visible light. Therefore, imaging sensors can be used to detect and locate such discharges. These sensors offer many advantages, including high sensitivity, high resolution, high immunity to electromagnetic noise, low cost, and direct localization of discharge points. However, information about their scaling is lacking, i.e., how to relate the optical response of the sensor to the electrical charge involved in the discharge process. Using adequately scaled sensors is essential for making informed engineering and maintenance decisions.
This paper focuses on this issue by proposing a method to scale digital camera responses by establishing a relationship between digital image intensity and the charge involved in electrical discharge phenomena. Though not a standard method, it allows for simple, direct localization of the discharge region and objective quantification of discharge severity. The proposed scaling method is applied to three electrode geometries—needle-plane, rod-plane, and sphere-plane—that generate discharge pulses between 20 pC and 1200 pC. Despite the wide variation in electrode geometries, the scaling results presented in this work prove to be consistently reliable and accurate. The fitted scaling curves achieve coefficients of determination greater than 0.998.
Modified Paschen Curves for Non-uniform Fields In Air Based on a Rod-Plane Electrode Geometry
Jordi-Roger Riba and Milad Soltany, Plasma Sources Science and Technology, Volume 34, Number 12, 125002 (11pp), 2025.
Abstract
As more-electric and all-electric aircraft concepts are developed, there is a growing research interest in the effects of electrical discharges under low-pressure conditions due to the associated damaging effects and safety concerns. Paschen curves allow understanding how gas insulation systems behave in uniform field gaps under different pressure conditions. However, most real-world insulation systems generate non-uniform fields, which behave differently. For example, corona discharges (PDs) occur at lower voltages than those required for complete air gap breakdown. Although conventional Paschen curves for uniform field gaps show that the complete breakdown voltage Ub is a unique function of the pressure–distance product (p·d), this paper shows that under non-uniform field conditions, PDs under 50 Hz sinusoidal supply can occur at significantly lower voltages than those required for complete air gap breakdown, particularly at high p·d values. It also demonstrates that each pressure has a unique curve relating the breakdown voltage to the p·d product. The results presented here demonstrate that, due to the non-uniformity of the electric field distribution at high p·d values, partial discharge activity may occur at much lower voltage levels than those predicted by conventional Paschen curves. However, as the p·d product decreases, due to the uniformity of the electric field, the obtained curves tend to overlap with the Paschen curves based on uniform field gaps. Additionally, this paper shows that complete breakdown discharges can occur in non-uniform fields well below the voltage value predicted by the original Paschen curve. However, such differences diminish as p·d values approach the quasi-uniform field condition.
Emissivity-Temperature Dependence of Cu and Al Conductors up to about 250°C and its effects
Jordi-Roger Riba, Ankit Soni, Manuel Moreno-Eguilaz, Sensors and Actuators A Physical, Volume 396, 16 December 2025, 117168.
Abstract
Accurate thermal-electric models of power line conductors and busbars require knowledge of surface emissivity and absorptivity, especially when operating at temperatures significantly different from ambient temperatures. Although emissivity tends to increase with conductor temperature, this temperature dependence is often overlooked in conductor models. This paper focuses on measuring this dependence by using two solid copper and aluminum rods with a round cross-section. The rods are heated by passing an alternating current of a known magnitude through them under controlled laboratory conditions. The results show an evident increase in emissivity with temperature, though it differs for copper and aluminum due to their inherent differences and different oxidation behaviors. The data presented show a significant increase in emissivity for aluminum and copper when the temperature ranges from 50°C to over 200°C. This paper also shows the impact of varying emissivity values on the final temperature of the conductors. These results can be useful for accurately modeling electrical conductors and can be directly applied to dynamic line rating (DLR) applications.
Low Wind Speed Heat Loss Analysis for DLR Applications
Jordi-Roger Riba, IEEE Access, Vol. 13, pp. 175781-175790, 2025, DOI: 10.1109/ACCESS.2025.3619510, Published 09/10/2025.
Abstract
Dynamic line rating (DLR) is a technology that maximizes the capacity of the power system by dynamically adjusting the system capacity to the actual weather conditions. In DLR approaches, line capacity or ampacity is calculated using thermoelectric conductor models, which are highly sensitive to the effect of wind, especially at low wind speeds, which have the strongest effect on conductor temperature reduction. Due to its powerful cooling effect, wind speed plays an important role in determining conductor temperature. In this paper, experimental tests are conducted to analyze the thermal behavior of four transmission line conductors, i.e., two aluminum alloy conductors (AAAC), one aluminum conductor steel-reinforced conductor (ACSR), and one high-temperature, low-sag conductor (HTLS). The tests were performed in a laboratory environment under controlled temperature and wind conditions. International standards such as IEEE, Cigré and IEC propose formulations for both natural and forced convection, which are evaluated and compared in this paper using experimental laboratory data. The results show that while the proposed natural
convection formulations found in the standards give very similar results, forced convection formulations can lead to significant differences in conductor temperature and ampacity prediction. Since forced convection plays an important role in determining the conductor temperature, the results presented in this paper are useful to better understand the effects of forced convection and to avoid miscalculations.
A Taxonomy of Robust Control Techniques for Hybrid AC/DC Microgrids: A Review
Pooya Parvizi, Milad Jalilian, Alireza Mohammadi Amidi, Mohammad Reza Zangeneh, Jordi-Roger Riba, Eng 2025, 6, 267. DOI: https://doi.org/10.3390/eng6100267, Published 06/10/2025.
Abstract
Hybrid AC/DC microgrids have emerged as a promising solution for integrating diverse renewable energy sources, enhancing efficiency, and strengthening resilience in modern power systems. However, existing control schemes exhibit critical shortcomings that limit their practical effectiveness. Traditional linear controllers, designed around nominal operating points, often fail to maintain stability under large load and generation fluctuations. Optimization-based methods are highly sensitive to model inaccuracies and parameter uncertainties, reducing their reliability in dynamic environments. Intelligent approaches, such as fuzzy logic and ML-based controllers, provide adaptability but suffer from high computational demands, limited interpretability, and challenges in real-time deployment. These limitations highlight the need for robust control strategies that can guarantee reliable operation despite disturbances, uncertainties, and varying operating conditions. Numerical performance indices demonstrate that the reviewed robust control strategies outperform conventional linear, optimization-based, and intelligent controllers in terms of system stability, voltage and current regulation, and dynamic response. This paper provides a comprehensive review of recent robust control strategies for hybrid AC/DC microgrids, systematically categorizing classical model-based, intelligent, and adaptive approaches. Key research gaps are identified, including the lack of unified benchmarking, limited experimental validation, and challenges in integrating decentralized frameworks. Unlike prior surveys that broadly cover microgrid types, this work focuses exclusively on hybrid AC/DC systems, emphasizing hierarchical control architectures and outlining future directions for scalable and certifiable robust controllers. Also, comparative results demonstrate that state of the art robust controllers—including H∞-based, sliding mode, and hybrid intelligent controllers—can achieve performance improvements for metrics such as voltage overshoot, frequency settling time, and THD compared to conventional PID and droop controllers. By synthesizing recent advancements and identifying critical research gaps, this work lays the groundwork for developing robust control strategies capable of ensuring stability and adaptability in future hybrid AC/DC microgrids.
Riba, J.-R., Measurement, 258 (2026) 119184, pp. 1-9. DOI: 10.1016/j.measurement.2025.119184. Accepted 28/09/2025.
Abstract
Corona discharges have many industrial applications, but in high-voltage systems, they often create unwanted effects that need to be addressed. Therefore, design engineers need simple tools to control their effects and, when they do occur, to determine the potential impact. Since the mean free path and mean energy of corona-generated electrons are key indicators of plasma characteristics and the efficiency of various processes occurring within the discharge, these parameters provide important information about the intensity and performance of the discharge. In this work, an easy-to-apply method is developed to determine the mean free path and mean energy of corona-generated electrons once the local electric field is known, which can be determined from finite element method simulations. The mean electron free path and mean electron energy can then be determined from published experimental data relating the total electron collision cross sections with air molecules to the mean electron energy and the mean electron energy to the reduced electric field. The method presented here is applied to experimental data obtained at different supply frequencies and different pressures typical of aircraft systems, which, due to the imperative need for electrification, are exposed to a higher risk of discharges due to the higher operating voltages, higher supply frequencies, and low pressure environment.
Technical Losses in Power Networks: Mechanisms, Mitigation Strategies, and Future Directions
Pooya Parvizi, Milad Jalilian, Alireza Mohammadi Amidi, Mohammad Reza Zangeneh, Jordi-Roger Riba, Electronics 2025, 14, 3442. DOI: 10.3390/electronics14173442, Published 28/08/2025.
Abstract
Technical losses (TLs) in power systems are an inevitable outcome of energy dissipation in components such as conductors, transformers, and transmission lines. These losses arise from the combined effects of material properties, operational conditions, and environmental factors, creating ongoing challenges for energy efficiency and grid sustainability. Their reduction requires a coordinated approach that integrates material improvements, smart grid technologies, and optimized operational practices. Reducing TLs not only improves economic efficiency but also contributes significantly to global sustainability efforts by enabling more efficient energy use and reducing carbon emissions associated with power generation. A review of recent publications shows that the literature on network losses is heavily skewed toward non-technical losses (NTLs), with TL-focused studies being fewer, often dated, and lacking comprehensive scope. This paper addresses the existing research gap by presenting a comprehensive, section-oriented taxonomy of TL mechanisms in power systems, accompanied by precise definitions for each category and a direct linkage between these categories and applicable loss mitigation measures. In addition, selected real-world projects and global initiatives aimed at reducing TLs, together with current regulatory approaches, emerging trends in this domain, and an assessment of the maturity level of technologies employed for TL reduction, are analyzed. This study aims to serve as a scientific reference to support future research and to guide policymakers, regulators, and utilities in developing more effective strategies for minimizing TLs.
On the Calculation of the Mean Free Path and Electron Energy in Atmospheric Corona Discharges
Riba, J.-R., European Journal of Physics, 2025. 2025 Eur. J. Phys. 46 045804 DOI: 10.1088/1361-6404/adeb12 Published 22/07/2025.
Abstract
This work proposes a practical or guided project for graduate physics or electrical engineering courses to determine the mean free path and the mean energy of electrons in atmospheric air. To this end, concepts such as the total scattering cross section of the electrons with air particles, the electric field strength at which corona occurs for given electrode geometries, and on the electron energy distribution function are analyzed. In addition, this paper provides a complete set of data that can be used directly to develop the practical or guided project, or depending on the extension of the practical or guided project, the students can also acquire their own data using a simple setup similar to the one described in this paper.
Riba, J.-R., Electric Power Systems Research, Volume 247, October 2025, 111794. DOI: 10.1016/j.epsr.2025.111794, Volume 247, October 2025, 111794, Accepted 29/04/2025.
Abstract
The surface voltage gradient (SVG) is probably the most important factor in determining the likelihood of a corona discharge occurring on the surface of round conductors or tubular substation busbars. There are several standards that propose simple formulas to determine the SVG of various configurations involving round conductors. However, such formulas are not exact, so this paper analyzes their accuracy by comparing the results provided by such formulas with the results obtained by Finite Element Method (FEM) models. This comparison highlights the difficulty in accurately calculating the average and maximum SVG of round conductors and tubular busbars using simple formulas.
Analysis of the Relationship between Light Intensity and Electrical Power of Corona Discharges
Riba, J.-R., European Journal of Physics, 46(1), 015202, 12/12/2024, DOI: 10.1088/1361-6404/ad955a.
Abstract
This work analyzes the intensity of the light emitted by corona discharges using a smartphone camera, which is compared to the electrical power associated with the corona discharges. The raw images from the camera provide essential information for the experiment. Data at different atmospheric pressures are also provided to help students understand that at lower pressures, due to the increased mean free path of the electrons, they are more efficient at ionizing neutral air molecules. An analysis of the data obtained also makes it possible to estimate the values of the energy of the electrons involved in the discharge process, the mean free path of the electrons and the cross section for electron collision, using much simpler equipment compared to other studies. The data and approach presented in this paper can be adapted for a group project or a guided practical session for both undergraduate and graduate courses.
Analyzing the effect of corona losses on dynamic line rating models for overhead transmission lines
Riba, J.-R.; Moreno-Eguilaz, M., International Journal of Electrical Power & Energy Systems,
Volume 166, 2025, 110546, ISSN 0142-0615, https://doi.org/10.1016/j.ijepes.2025.110546.
Abstract
High-voltage transmission lines tend to generate corona activity. The value of corona losses is highly dependent on several parameters such as line configuration, conductor geometry, surface condition, operating voltage and weather conditions. International guidelines and standards such as Cigré, IEEE and IEC recommend that corona losses should not be considered when developing thermal conductor models, so such losses are typically omitted when developing dynamic line rating (DLR) applications. DLR is a set of techniques based on dynamically changing the thermal ratings of transmission lines based on changes in environmental conditions (wind, temperature, etc.). To develop accurate DLR models that include corona losses, a large amount of line data is required, including operating voltage, complete conductor information (materials, dimensions, etc.), bundle and line geometry, phase layout, and ground clearance, among others. To validate the accuracy of such models, part of the complete line data, long-term measurements of instantaneous corona losses in existing lines, operating voltage and weather conditions are required. However, the development of DLR approaches and the inclusion of corona losses in such models is severely limited by the lack of experimental work that includes a complete description of all this information. Based on experimental corona losses already published in the literature, this paper uses an accurate conductor model that accounts for radial heat transfer to show that, under certain conditions, corona losses are comparable to and even greater than Joule losses, which are usually the main source of conductor heating, suggesting that corona losses should be included in the development of accurate thermal conductor models. It has also been shown that for conductors in a normal condition, operating in fair weather conditions and at rated line load, corona losses are typically less than 2% of the Joule losses, resulting in a reduction of the maximum current carrying capacity of less than 1%. However, for heavily contaminated conductors, the reduction in current carrying capacity due to the effect of corona losses can be as high as 15%.
Quantification of Corona Discharge Intensity Applied to Sphere-Plane Configurations
Pradeep Kumar Gupta, Pau Bas-Calopa, Jordi-Roger Riba, Kaur Tuttelberg, Jako Kilter,
IEEE Transactions on Dielectrics and Electrical Insulation, DOI: 10.1109/TDEI.2025.3562196.
Abstract
This paper proposes several experimental methods for the quantification of the intensity of corona discharges under alternating current (AC) and positive and negative direct current (+DC and –DC) power supplies. These methods are based on the measurement of voltage and corona current, the energy associated with the corona pulses using high-frequency probes and a high-frequency oscilloscope, the apparent charge using a partial discharge (PD) detector coupled to a coupling capacitor, and the intensity of images taken with a digital camera. The experimental results presented are based on a sphere-plane electrode. However, many other electrode geometries can be studied based on the developments made in this work. In addition, an analysis of the advantages and disadvantages of the different methods is presented.
The Role of AC Resistance of Bare Stranded Conductors for Developing Dynamic Line Rating Approaches
Jordi-Roger Riba,
Applied Sciences 2024, 14(19), 8982. https://doi.org/10.3390/app14198982.
Abstract
Overhead transmission line conductors are usually helically stranded. The current-carrying section is made of aluminum and/or aluminum alloys. Several factors affect their electrical resistance, such as the conductivity of the conductor material, the cross-sectional area, the lay length of the different layers of aluminum, and the presence of a steel core used to increase the mechanical strength of the conductor. The direct current (DC) and alternating current (AC) resistances per unit length of stranded conductors are different due to the effect of the eddy currents. In steel-reinforced conductors, there are other effects, such as the transformer effect due to the magnetization of the steel core, which make the AC resistance dependent on the current. Operating temperature also has an important effect on electrical resistance. Resistive losses are the main source of heating in transmission line conductors, so their temperature rise is highly dominated by such power losses, making it critical to know the value of the AC resistance per unit length when applying dynamic line rating (DLR) methods. They are of great interest especially in congested lines, as by applying DLR approaches it is possible to utilize the full line capacity of the line. This paper highlights the difficulty of accurately calculating the electrical resistance of helically stranded conductors, especially those with a magnetic core, and the importance of accurate measurements for the development of conductor models and DLR approaches.
Milad Jalilian, Jordi-Roger Riba, Pooya Parvizi,
Materials 2024, 17, 4536. https://doi.org/10.3390/ma17184536.
Abstract
Industrial development and population growth have increased the need for higher-capacity power transmission lines. Aluminum conductor steel-supported (ACSS) conductors, a type of high-temperature low-sag (HTLS) conductor, are now widely used in new designs and reconductoring applications. ACSS conductors are preferred over traditional aluminum conductor steel-reinforced (ACSR) conductors due to their high strength, low sag, and excellent thermal stability. These attributes have garnered significant interest from researchers, engineers, and manufacturers. This paper provides a comprehensive review of the structure, properties, testing methods, and environmental behavior of ACSS conductors.
Ankit Soni, Jordi-Roger Riba, Manuel Moreno-Eguilaz,
CPE POWERENG 2025, 20-22 May 2025, Antalya, Turkey.
Abstract
Emissivity is an important parameter to consider when analyzing the heat balance of conductors and thus their temperature. Surface emissivity becomes more important at high temperature operation, as it plays a leading role in the radiation loss, since it depends on the fourth power of temperature. This paper analyzes the effect of surface oxidation on the emissivity of a solid copper rod conductor. It is shown that the emissivity changes. For this purpose, the temperature of the copper bar is varied from 20ºC to about 240ºC by applying a current of about 1450 A. A large change in the estimated emissivity value from 0.04 to 0.30 is observed, which is attributed to the oxidation of the surface of the polished copper bar. This significant change in emissivity due to the oxidation process has important consequences for the thermal behavior of copper conductors that cannot be ignored.
Ankit Soni, Jordi-Roger Riba, Manuel Moreno-Eguilaz,
23th International Conference on Renewable Energies and Power Quality (ICREPQ'25), Tenerife 25-27 June, 2025.
Abstract
Transmission conductors used in overhead power lines are typically helically stranded and often have a steel core to give the conductor mechanical strength and outer strands of aluminium or aluminium alloy to provide the current carrying capacity. The presence of a magnetic core has several effects on the behaviour of the conductors, such as the presence of an axial component of the magnetic field which interacts with the current of the different layers of conductive strands wound helically around the magnetic core. This has a major effect on the alternating current (AC) resistance of the conductor, which can be very different from the direct current (DC) resistance. When applying dynamic line rating (DLR) approaches, the surface temperature of the conductor is typically measured due to the inability to measure inside the conductor, but the average temperature determines the true value of the resistance. In this work, a thermal model of the conductor is used to account for the radial temperature distribution to more accurately determine the resistance of the conductor and the temperature coefficient of the resistance. The experimental results presented show the potential of the proposed method.
Evaluation of the sensitivity of measuring circuits for corona discharges detection
M. Soltany, J.-R. Riba, S. Bogarra,
23th International Conference on Renewable Energies and Power Quality (ICREPQ'25), Tenerife 25-27 June, 2025.
Abstract
Partial discharges (PD) play a major role in the degradation of insulation in high voltage equipment. PD occurs when localized electrical breakdowns occur in the presence of a high electric field near an insulator. A critical aspect of PD measurement is the calibration of the measurement system. Calibration results in a scale factor (k), that is used to convert the measured signal to the apparent charge. This paper presents a comparative analysis of five different measurement circuits used for PD detection. The experiments were performed using a sphere-to-plane configuration. In addition to the conversion factor, this study also examines the signal-to-noise ratio (SNR) for each measurement system.
Corona Discharge Pulse Shape Analysis: Sphere Plane Configurations
Pradeep Kumar Gupta, Maninder Choudhary, Pau Bas, Jordi-Roger Riba, Kaur Tuttelberg, Jako Kilter,
IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2025, September 14-17, 2025, Manchester, United Kingdom.
Abstract
This paper proposes the experimental corona discharge pulse shape analysis (PSA) for different sizes of spherical electrode plane configurations at different voltage levels. According to experiments, the corona discharge signal may be assessed by measuring the peak amplitude and the rise and fall times of the pulse edges. This approach might be very useful when corona discharges are being examined and assessed. In addition, the pulse width is studied as the intensity level and discharge gap for different voltage levels are varied. PSA patterns are based on the sequence of discharge occurrences. The study presents PSA simulations and corona discharge analysis on common spherical test configurations for corona discharges, conducted at AC and partially under DC test conditions.
Page updated
Report abuse