Articles de revista
http://hdl.handle.net/2117/3541
2024-03-29T14:36:47Z
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A novel three-dimensional sigma–delta modulation for high-switching-frequency three-phase four-wire active power filters
http://hdl.handle.net/2117/403061
A novel three-dimensional sigma–delta modulation for high-switching-frequency three-phase four-wire active power filters
Lumbreras Carrasco, David; Zaragoza Bertomeu, Jordi; Lamich Arocas, Manuel; Berbel Artal, Néstor; Romero Cadaval, Enrique
This article presents a new modulation technique called three-dimensional sigma–delta (3D-S¿ ) modulation for high-frequency three-leg four-wire voltage source converters (VSCs) that use wide-bandgap (WBG) semiconductors. These WBG devices allow for the use of high switching frequencies with a greater efficiency than silicon devices. The proposed 3D-S¿ technique enables operation at a variable switching frequency, resulting in a significant reduction in switching losses compared to classical pulse-width modulation (PWM) techniques. Moreover, the 3D-S¿ technique uses a fast-processing 3D quantiser that simplifies implementation and considerably reduces computational costs. The behaviour of the 3D-S¿ modulation is analysed using MATLAB/Simulink and PLECS. The experimental results performed on an active power filter that uses silicon carbide (SiC) MOSFETs demonstrate an improvement in converter efficiency compared to the conventional SPWM technique. Additionally, the experimental results show how 3D-S¿ allows for the compensation of harmonics and homopolar currents, thereby balancing the electrical grid currents. The experiments also show that the proposed 3D-S¿ modulation outperforms an SPWM technique in terms of power quality, since the former achieves a larger reduction in the harmonic content of the power grid. In conclusion, the proposed modulation technique is an attractive option for improving the performance of four-wire converters in active power filter applications.
2024-02-23T15:02:11Z
Lumbreras Carrasco, David
Zaragoza Bertomeu, Jordi
Lamich Arocas, Manuel
Berbel Artal, Néstor
Romero Cadaval, Enrique
This article presents a new modulation technique called three-dimensional sigma–delta (3D-S¿ ) modulation for high-frequency three-leg four-wire voltage source converters (VSCs) that use wide-bandgap (WBG) semiconductors. These WBG devices allow for the use of high switching frequencies with a greater efficiency than silicon devices. The proposed 3D-S¿ technique enables operation at a variable switching frequency, resulting in a significant reduction in switching losses compared to classical pulse-width modulation (PWM) techniques. Moreover, the 3D-S¿ technique uses a fast-processing 3D quantiser that simplifies implementation and considerably reduces computational costs. The behaviour of the 3D-S¿ modulation is analysed using MATLAB/Simulink and PLECS. The experimental results performed on an active power filter that uses silicon carbide (SiC) MOSFETs demonstrate an improvement in converter efficiency compared to the conventional SPWM technique. Additionally, the experimental results show how 3D-S¿ allows for the compensation of harmonics and homopolar currents, thereby balancing the electrical grid currents. The experiments also show that the proposed 3D-S¿ modulation outperforms an SPWM technique in terms of power quality, since the former achieves a larger reduction in the harmonic content of the power grid. In conclusion, the proposed modulation technique is an attractive option for improving the performance of four-wire converters in active power filter applications.
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Multi-layer smart fault protection for secure smart grids
http://hdl.handle.net/2117/398495
Multi-layer smart fault protection for secure smart grids
Bakkar, Mostafa; Bogarra Rodríguez, Santiago; Córcoles López, Felipe; Al Hanaineh, Wael Hasan Ahmad
The trend toward Smart grid (SG) is increasing significantly by incorporating Distributed Generators (DGs), which leads to new challenges, especially in protection systems. SGs should strengthen robust environments against cybersecurity threats. So, the cybersecurity of future SGs is essential. This paper proposes a multi-layer protection scheme for the Medium Voltage (MV) Distribution System (DS), especially with reconfigurable SGs. The main protection algorithm is based on Artificial Intelligence (AI), utilizing the communication between all protective devices (PDs) in the grid, whereas as backup protection, another AI algorithm employs the communication between the PDs in the same line. Then, as alternative protection to provide the protection system with another level of security in case of communication issues or cyberattacks, a third algorithm based on the local data of each PDs is proposed. Both simulations using MATLAB SIMULINK and experimental results utilizing a scaled physical grid validated the protection algorithms. The scaled grid has been designed for the smart grid in order to test the behavior of the protection scheme experimentally.
2023-12-21T12:03:12Z
Bakkar, Mostafa
Bogarra Rodríguez, Santiago
Córcoles López, Felipe
Al Hanaineh, Wael Hasan Ahmad
The trend toward Smart grid (SG) is increasing significantly by incorporating Distributed Generators (DGs), which leads to new challenges, especially in protection systems. SGs should strengthen robust environments against cybersecurity threats. So, the cybersecurity of future SGs is essential. This paper proposes a multi-layer protection scheme for the Medium Voltage (MV) Distribution System (DS), especially with reconfigurable SGs. The main protection algorithm is based on Artificial Intelligence (AI), utilizing the communication between all protective devices (PDs) in the grid, whereas as backup protection, another AI algorithm employs the communication between the PDs in the same line. Then, as alternative protection to provide the protection system with another level of security in case of communication issues or cyberattacks, a third algorithm based on the local data of each PDs is proposed. Both simulations using MATLAB SIMULINK and experimental results utilizing a scaled physical grid validated the protection algorithms. The scaled grid has been designed for the smart grid in order to test the behavior of the protection scheme experimentally.
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Radial thermoelectric model for stranded transmission line conductors
http://hdl.handle.net/2117/396919
Radial thermoelectric model for stranded transmission line conductors
Riba Ruiz, Jordi-Roger
Bare-stranded conductors play a critical role in the efficiency and safe operation of transmission lines. The heat generated in the interior of the conductor is conducted radially to the outer surface, creating a radial thermal gradient. The radial temperature gradient between the core and the surface depends on multiple factors, such as stranding, number of layers, current level, electrical resistance and the effective radial thermal conductivity. Therefore, the radial temperature model must be considered when developing accurate conductor models. Such models are particularly important in the development of dynamic line rating (DLR) approaches to allow the full current carrying capacity of the conductor to be utilized while ensuring safe operation. This paper develops a radial one-dimensional thermoelectric model for bare-stranded conductors used in transmission lines. The accuracy of the proposed model is determined by experimental tests performed on three conductors.
2023-11-22T15:20:14Z
Riba Ruiz, Jordi-Roger
Bare-stranded conductors play a critical role in the efficiency and safe operation of transmission lines. The heat generated in the interior of the conductor is conducted radially to the outer surface, creating a radial thermal gradient. The radial temperature gradient between the core and the surface depends on multiple factors, such as stranding, number of layers, current level, electrical resistance and the effective radial thermal conductivity. Therefore, the radial temperature model must be considered when developing accurate conductor models. Such models are particularly important in the development of dynamic line rating (DLR) approaches to allow the full current carrying capacity of the conductor to be utilized while ensuring safe operation. This paper develops a radial one-dimensional thermoelectric model for bare-stranded conductors used in transmission lines. The accuracy of the proposed model is determined by experimental tests performed on three conductors.
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Smart switching in single-phase grid-connected photovoltaic power systems for inrush current elimination
http://hdl.handle.net/2117/396570
Smart switching in single-phase grid-connected photovoltaic power systems for inrush current elimination
Martínez Figueroa, Gerardo de Jesús; Bogarra Rodríguez, Santiago; Córcoles López, Felipe
Grid-connected photovoltaic (PV) power systems are one of the most promising tech- nologies to address growing energy demand and ecological challenges. This paper proposes smart switching to mitigate inrush currents during the connection of single-phase transformers used in PV systems. An effective inrush current mitigation contributes to the reliability of PV systems. The inrush current severity is influenced by the pseudorandom residual flux at the transformer core and the energization point-on-wave. The most common approach to avoid inrush currents is controlled connection, which requires prior knowledge of the residual flux. However, the residual flux can differ in each case, and its measurement or estimation can be impractical. The proposed smart switching is based on a comprehensive analysis of the residual flux and the de-energization trajectories, and only requires two pieces of data (fRM and f0, flux values of the static and dynamic loops when the respective currents are null), calculated from two simple no-load tests. It has a clear advantage over common approaches: no need to estimate or measure the residual flux before each connection, avoiding the need for expensive equipment or complex setups. Smart switching can be easily im- plemented in practical settings, as it considers different circuit breakers with distinctive aperture features, making it cost-effective for PV systems.
2023-11-17T08:11:16Z
Martínez Figueroa, Gerardo de Jesús
Bogarra Rodríguez, Santiago
Córcoles López, Felipe
Grid-connected photovoltaic (PV) power systems are one of the most promising tech- nologies to address growing energy demand and ecological challenges. This paper proposes smart switching to mitigate inrush currents during the connection of single-phase transformers used in PV systems. An effective inrush current mitigation contributes to the reliability of PV systems. The inrush current severity is influenced by the pseudorandom residual flux at the transformer core and the energization point-on-wave. The most common approach to avoid inrush currents is controlled connection, which requires prior knowledge of the residual flux. However, the residual flux can differ in each case, and its measurement or estimation can be impractical. The proposed smart switching is based on a comprehensive analysis of the residual flux and the de-energization trajectories, and only requires two pieces of data (fRM and f0, flux values of the static and dynamic loops when the respective currents are null), calculated from two simple no-load tests. It has a clear advantage over common approaches: no need to estimate or measure the residual flux before each connection, avoiding the need for expensive equipment or complex setups. Smart switching can be easily im- plemented in practical settings, as it considers different circuit breakers with distinctive aperture features, making it cost-effective for PV systems.
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Transformer modelling considering power losses using an inverse Jiles-Atherton approach
http://hdl.handle.net/2117/395998
Transformer modelling considering power losses using an inverse Jiles-Atherton approach
Badri Barberán, José Antonio; Riba Ruiz, Jordi-Roger; García Espinosa, Antonio; Trujillo, S; Marzàbal, Albert
Power transformers are devices with non-linear behavior due to the saturation of the ferromagnetic core. When modelling such devices, the saturation effect must be taken into account because it greatly affects their performance and efficiency. In this paper, an electromagnetic model for power transformers is proposed and experimentally validated using an electrical T-model coupled with a reluctance network to model the magnetic part. The electrical circuit and the reluctance network are linked by two B–H approaches. The B–H relationships are modelled by the full hysteresis cycle based on the inverse Jiles-Atherton theory and by the initial magnetization curve. The results obtained with the inverse Jiles-Atherton theory model reproduce the magnetic core behavior with more accuracy than the one based on the initial magnetization curve, especially at low load conditions where saturation plays a more prominent role on the no-load current. The proposed model can be applied to other magnetic devices such as inductors for power electronic applications or electromechanical relays, among others.
2023-11-08T12:11:01Z
Badri Barberán, José Antonio
Riba Ruiz, Jordi-Roger
García Espinosa, Antonio
Trujillo, S
Marzàbal, Albert
Power transformers are devices with non-linear behavior due to the saturation of the ferromagnetic core. When modelling such devices, the saturation effect must be taken into account because it greatly affects their performance and efficiency. In this paper, an electromagnetic model for power transformers is proposed and experimentally validated using an electrical T-model coupled with a reluctance network to model the magnetic part. The electrical circuit and the reluctance network are linked by two B–H approaches. The B–H relationships are modelled by the full hysteresis cycle based on the inverse Jiles-Atherton theory and by the initial magnetization curve. The results obtained with the inverse Jiles-Atherton theory model reproduce the magnetic core behavior with more accuracy than the one based on the initial magnetization curve, especially at low load conditions where saturation plays a more prominent role on the no-load current. The proposed model can be applied to other magnetic devices such as inductors for power electronic applications or electromechanical relays, among others.
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Experimental validation of the adiabatic assumption of short-circuit tests on bare conductors
http://hdl.handle.net/2117/394723
Experimental validation of the adiabatic assumption of short-circuit tests on bare conductors
Riba Ruiz, Jordi-Roger; González Farré, David; Bas Calopa, Pau; Moreno Eguilaz, Juan Manuel
According to various international standards, many high-voltage devices must withstand short-circuit tests. Due to the enormous power and current requirements, they have to be tested in very specialized and expensive power laboratories, which are scarce and not affordable for the vast majority of electrical product manufacturers. It is proposed to break the time limit of about one second imposed by the standards by using a lower current to heat for a longer time, requiring more affordable equipment and thus reducing the cost for testing. This work analyzes the limits of the adiabatic assumption in short-circuit tests in order to quantify how the duration of these tests can be extended to reduce the power required and the current applied, while obtaining almost the same results, i.e., the same temperature at the end of the heating phase of the tests. For this purpose, bare cylindrical conductors are analyzed and the temperature dependence of the properties of the conductor material is considered. Experimental and simulation results presented in this paper suggest that by applying this approach, short-circuit tests intended for product design, verification and quality control can be performed in much less demanding and affordable laboratory facilities.
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2023-10-06T14:50:59Z
Riba Ruiz, Jordi-Roger
González Farré, David
Bas Calopa, Pau
Moreno Eguilaz, Juan Manuel
According to various international standards, many high-voltage devices must withstand short-circuit tests. Due to the enormous power and current requirements, they have to be tested in very specialized and expensive power laboratories, which are scarce and not affordable for the vast majority of electrical product manufacturers. It is proposed to break the time limit of about one second imposed by the standards by using a lower current to heat for a longer time, requiring more affordable equipment and thus reducing the cost for testing. This work analyzes the limits of the adiabatic assumption in short-circuit tests in order to quantify how the duration of these tests can be extended to reduce the power required and the current applied, while obtaining almost the same results, i.e., the same temperature at the end of the heating phase of the tests. For this purpose, bare cylindrical conductors are analyzed and the temperature dependence of the properties of the conductor material is considered. Experimental and simulation results presented in this paper suggest that by applying this approach, short-circuit tests intended for product design, verification and quality control can be performed in much less demanding and affordable laboratory facilities.
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Exploring the limitations of electric field energy harvesting
http://hdl.handle.net/2117/394719
Exploring the limitations of electric field energy harvesting
Riba Ruiz, Jordi-Roger; Arbat Carandell, Ricard; Ndong, Yaye Oumy; Moreno Eguilaz, Juan Manuel
Energy harvesting systems are key elements for the widespread deployment of wireless sensor nodes. Although many energy harvesting systems exist, electric field energy harvesting is a promising choice because it can provide uninterrupted power regardless of external conditions and depends only on the presence of AC voltage in the grid, regardless of the magnitude of the line current, even under no-load conditions. However, it also has some disadvantages, such as low power availability, the need for storage, or reliance on capacitive coupling, which is a complex phenomenon that depends on parasitic capacitances. This paper aims to provide useful and practical information on the possibilities of electric field energy harvesting for both high- and low-voltage applications. Since the objective of this paper is to quantify the physical limit of the harvested energy, it considers only the physical harvester itself and not the electronic circuitry required to transfer the harvested energy to the load. Theoretical, simulation, and experimental results show the feasibility of this energy source for low-power applications such as wireless sensor nodes.
2023-10-06T13:58:45Z
Riba Ruiz, Jordi-Roger
Arbat Carandell, Ricard
Ndong, Yaye Oumy
Moreno Eguilaz, Juan Manuel
Energy harvesting systems are key elements for the widespread deployment of wireless sensor nodes. Although many energy harvesting systems exist, electric field energy harvesting is a promising choice because it can provide uninterrupted power regardless of external conditions and depends only on the presence of AC voltage in the grid, regardless of the magnitude of the line current, even under no-load conditions. However, it also has some disadvantages, such as low power availability, the need for storage, or reliance on capacitive coupling, which is a complex phenomenon that depends on parasitic capacitances. This paper aims to provide useful and practical information on the possibilities of electric field energy harvesting for both high- and low-voltage applications. Since the objective of this paper is to quantify the physical limit of the harvested energy, it considers only the physical harvester itself and not the electronic circuitry required to transfer the harvested energy to the load. Theoretical, simulation, and experimental results show the feasibility of this energy source for low-power applications such as wireless sensor nodes.
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Energy crisis in Europe: the European Union’s objectives and countries’ policy trends—new transition paths?
http://hdl.handle.net/2117/393610
Energy crisis in Europe: the European Union’s objectives and countries’ policy trends—new transition paths?
Urbano González, Eva María; Kampouropoulos, Konstantinos; Romeral Martínez, José Luis
Amidst the ongoing European energy crisis, the EU has proposed a legislative package to enhance gas independence from Russia, diversify energy supplies, and increase renewable energy targets. However, the urgency for energy security has led some countries to prioritise gas independence over decarbonisation, potentially sacrificing or delaying EU targets. Considering this framework, this article contributes to the body of knowledge by examining the electricity mix of the six most significant EU countries in terms of generation capacity, considers their alignment with 2025 energy transition goals, and analyses the latest legislative trends to evaluate their compatibility with EU objectives. The findings from these analyses indicate that EU members are currently prioritising gas independence, which has led to re-starting or extending the lifespan of coal-fired power plants and an increasing interest in nuclear energy as a low-carbon alternative. These findings have significant implications as they reveal how countries are being steered away from their pre-crisis energy transition paths, resulting in the formation of new perspectives for both the short and long term.
2023-09-18T12:36:36Z
Urbano González, Eva María
Kampouropoulos, Konstantinos
Romeral Martínez, José Luis
Amidst the ongoing European energy crisis, the EU has proposed a legislative package to enhance gas independence from Russia, diversify energy supplies, and increase renewable energy targets. However, the urgency for energy security has led some countries to prioritise gas independence over decarbonisation, potentially sacrificing or delaying EU targets. Considering this framework, this article contributes to the body of knowledge by examining the electricity mix of the six most significant EU countries in terms of generation capacity, considers their alignment with 2025 energy transition goals, and analyses the latest legislative trends to evaluate their compatibility with EU objectives. The findings from these analyses indicate that EU members are currently prioritising gas independence, which has led to re-starting or extending the lifespan of coal-fired power plants and an increasing interest in nuclear energy as a low-carbon alternative. These findings have significant implications as they reveal how countries are being steered away from their pre-crisis energy transition paths, resulting in the formation of new perspectives for both the short and long term.
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Tracking resistance in polymeric insulation materials for high-voltage electrical mobility applications evaluated by existing test methods: identified research needs
http://hdl.handle.net/2117/393456
Tracking resistance in polymeric insulation materials for high-voltage electrical mobility applications evaluated by existing test methods: identified research needs
Riba Ruiz, Jordi-Roger; Moreno Eguilaz, Juan Manuel; Bogarra Rodríguez, Santiago
With the increasing electrification of the transportation and mobility sectors, polymer insulation materials are inevitably exposed to harsher environments, including exposure to contamination, wide temperature ranges, operation at higher voltages and switching frequencies, and low-pressure environments. This paper reviews the tests to characterize the polymeric materials used in insulation systems for electric mobility applications, focusing on resistance to tracking. This paper also reports on the limitations of existing standard test methods and identifies the challenges and research needs to meet the increasing demands of the electric mobility industry. To this end, an evaluation of the scientific and technological state of the art is carried out through the analysis of theses, research articles, technical reports, manufacturers’ datasheets, international standards, and white papers.
2023-09-13T14:26:24Z
Riba Ruiz, Jordi-Roger
Moreno Eguilaz, Juan Manuel
Bogarra Rodríguez, Santiago
With the increasing electrification of the transportation and mobility sectors, polymer insulation materials are inevitably exposed to harsher environments, including exposure to contamination, wide temperature ranges, operation at higher voltages and switching frequencies, and low-pressure environments. This paper reviews the tests to characterize the polymeric materials used in insulation systems for electric mobility applications, focusing on resistance to tracking. This paper also reports on the limitations of existing standard test methods and identifies the challenges and research needs to meet the increasing demands of the electric mobility industry. To this end, an evaluation of the scientific and technological state of the art is carried out through the analysis of theses, research articles, technical reports, manufacturers’ datasheets, international standards, and white papers.
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Linking digital image intensity to carrier density in low-pressure corona discharges
http://hdl.handle.net/2117/388846
Linking digital image intensity to carrier density in low-pressure corona discharges
Riba Ruiz, Jordi-Roger
The electrification of transportation, and aircraft electrification in particular, is experiencing rapid development due to the more efficient use of energy. Since the dielectric strength of air decreases at the cruising altitudes of commercial aircraft due to the reduced pressure environment, there is a need to control and minimize the risks associated with electrical discharges. This paper shows from experimental and computational data that there is a relationship between the electrical and optical phenomena involved in the discharge process. To this end, this paper analyzes corona discharges generated using different electrode geometries under a wide range of pressures from 100 kPa to 10 kPa. It is shown that the densities of charged particles or charge carriers generated during the discharge process are positively correlated with the intensity of corona images acquired with a digital imaging sensor sensitive to the near UV and visible wavelength ranges. Therefore, the intensity of the images can be used as a reliable and accurate indicator of the corona activity, the values of which are related to the ionization processes involved in the discharges. The results presented in this paper can be applied in various physical and engineering fields, such as high voltage engineering, power line monitoring, or ozone generation, among others.
2023-06-16T13:52:53Z
Riba Ruiz, Jordi-Roger
The electrification of transportation, and aircraft electrification in particular, is experiencing rapid development due to the more efficient use of energy. Since the dielectric strength of air decreases at the cruising altitudes of commercial aircraft due to the reduced pressure environment, there is a need to control and minimize the risks associated with electrical discharges. This paper shows from experimental and computational data that there is a relationship between the electrical and optical phenomena involved in the discharge process. To this end, this paper analyzes corona discharges generated using different electrode geometries under a wide range of pressures from 100 kPa to 10 kPa. It is shown that the densities of charged particles or charge carriers generated during the discharge process are positively correlated with the intensity of corona images acquired with a digital imaging sensor sensitive to the near UV and visible wavelength ranges. Therefore, the intensity of the images can be used as a reliable and accurate indicator of the corona activity, the values of which are related to the ionization processes involved in the discharges. The results presented in this paper can be applied in various physical and engineering fields, such as high voltage engineering, power line monitoring, or ozone generation, among others.