Photovoltaic Electric Scooter Charger Dock for the Development of Sustainable Mobility in Urban Environments

[EN] Means and modes of transport in urban environments are changing. The emergence of new means of personal transport, such as e-scooters or e-bikes, combined with new concepts such as `vehicle sharing' are changing urban transport. A greater social awareness of the harmful effects of polluting gases is leading to the adoption of new e-mobility solutions. A sustainable e-scooter recharging dock has been designed, built, and put into operation in a small town north of the city of Valencia (Spain). In the proposed novel solution, a stand-alone PV system is built for the free recharge of e-scooters using an original system that supports new sustainable means of transport. The design of the PV system considers the size limitations of the equipment, where a single PV module must generate the energy needed to recharge the e-scooters. A battery is used to store the energy and adjust power generation and consumption profiles. A commercial electronic converter adjusts the various electrical characteristics of generation, storage, and consumption. As a result of the system analysis, the surplus autonomy provided for the e-scooter recharging dock is calculated. Potential stakeholders in the use of the proposed system and their reasons for adopting this sustainable solution are identified. Experimental results of the first months of operation are included and these demonstrate the correct operation of the proposed system.Martinez-Navarro, A.; Cloquell Ballester, VA.; Segui-Chilet, S. (2020). Photovoltaic Electric Scooter Charger Dock for the Development of Sustainable Mobility in Urban Environments. IEEE Access. 8:169486-169495. https://doi.org/10.1109/ACCESS.2020.3023881S169486169495

Instantaneous approach to IEEE Std. 1459 power terms and quality indices

Based on an instantaneous analysis approach to the IEEE Std. 1459, the authors demonstrated in previous works that the effective apparent power should not be calculated including the rms neutral current and the rms line to line voltage terms. The use of these terms drives to expressions of power magnitudes that are overvaluated and disagree with well-accepted definitions. By using the instantaneous approach, new power terms are proposed. Based on these terms, new power quality indices and new expressions of the unbalanced power terms are presented in this paper. An experimental case is used to compare the power magnitudes and power quality indices obtained with both approaches. Results demonstrate than the most significant power terms are over evaluated when IEEE Std. 1459 power definitions are used.The authors wish to thank the support offered by the "Estrategia de sostenibilidad 2014-2015" University of Antioquia (Colombia), as well as the support of the Ministerio de Economia y Competitividad of Spain (grant DPI2011-28606).Muñoz-Galeano, N.; Alfonso Gil, JC.; Orts-Grau, S.; Segui-Chilet, S.; Gimeno Sales, FJ. (2015). Instantaneous approach to IEEE Std. 1459 power terms and quality indices. Electric Power Systems Research. 125:228-234. https://doi.org/10.1016/j.epsr.2015.04.01222823412

One-Cycle Zero-Integral-Error Current Control for Shunt Active Power Filters

[EN] Current control has, for decades, been one of the more challenging research fields in the development of power converters. Simple and robust nonlinear methods like hysteresis or sigma-delta controllers have been commonly used, while sophisticated linear controllers based on classical control theory have been developed for PWM-based converters. The one-cycle current control technique is a nonlinear technique based on cycle-by-cycle calculation of the ON time of the converter switches for the next switching period. This kind of controller requires accurate measurement of voltages and currents in order achieve a precise current tracking. These techniques have been frequently used in the control of power converters generating low-frequency currents, where the reference varies slowly compared with the switching frequency. Its application is not so common in active power filter current controllers due to the fast variation of the references that demands not only accurate measurements but also high-speed computing. This paper proposes a novel one-cycle digital current controller based on the minimization of the integral error of the current. Its application in a three-leg four-wire shunt active power filter is presented, including a stability analysis considering the switching pattern selection. Furthermore, simulated and experimental results are presented to validate the proposed controller.Orts-Grau, S.; Balaguer-Herrero, P.; Alfonso-Gil, JC.; Martínez-Márquez, CI.; Gimeno Sales, FJ.; Segui-Chilet, S. (2020). One-Cycle Zero-Integral-Error Current Control for Shunt Active Power Filters. Electronics. 9(12):1-16. https://doi.org/10.3390/electronics9122008S116912Orts-Grau, S., Gimeno-Sales, F. J., Abellan-Garcia, A., Segui-Chilet, S., & Alfonso-Gil, J. C. (2010). Improved Shunt Active Power Compensator for IEEE Standard 1459 Compliance. IEEE Transactions on Power Delivery, 25(4), 2692-2701. doi:10.1109/tpwrd.2010.2049033Orts-Grau, S., Gimeno-Sales, F. J., Segui-Chilet, S., Abellan-Garcia, A., Alcaniz-Fillol, M., & Masot-Peris, R. (2009). Selective Compensation in Four-Wire Electric Systems Based on a New Equivalent Conductance Approach. IEEE Transactions on Industrial Electronics, 56(8), 2862-2874. doi:10.1109/tie.2009.2014368Trinh, Q.-N., & Lee, H.-H. (2013). An Advanced Current Control Strategy for Three-Phase Shunt Active Power Filters. IEEE Transactions on Industrial Electronics, 60(12), 5400-5410. doi:10.1109/tie.2012.2229677Bosch, S., Staiger, J., & Steinhart, H. (2018). Predictive Current Control for an Active Power Filter With LCL-Filter. IEEE Transactions on Industrial Electronics, 65(6), 4943-4952. doi:10.1109/tie.2017.2772176Balasubramanian, R., Parkavikathirvelu, K., Sankaran, R., & Amirtharajan, R. (2019). Design, Simulation and Hardware Implementation of Shunt Hybrid Compensator Using Synchronous Rotating Reference Frame (SRRF)-Based Control Technique. Electronics, 8(1), 42. doi:10.3390/electronics8010042Imam, A. A., Sreerama Kumar, R., & Al-Turki, Y. A. (2020). Modeling and Simulation of a PI Controlled Shunt Active Power Filter for Power Quality Enhancement Based on P-Q Theory. Electronics, 9(4), 637. doi:10.3390/electronics9040637Panigrahi, R., Subudhi, B., & Panda, P. C. (2016). A Robust LQG Servo Control Strategy of Shunt-Active Power Filter for Power Quality Enhancement. IEEE Transactions on Power Electronics, 31(4), 2860-2869. doi:10.1109/tpel.2015.2456155Herman, L., Papic, I., & Blazic, B. (2014). A Proportional-Resonant Current Controller for Selective Harmonic Compensation in a Hybrid Active Power Filter. IEEE Transactions on Power Delivery, 29(5), 2055-2065. doi:10.1109/tpwrd.2014.2344770Panigrahi, R., & Subudhi, B. (2017). Performance Enhancement of Shunt Active Power Filter Using a Kalman Filter-Based ${{{\rm H}}_\infty }$ Control Strategy. IEEE Transactions on Power Electronics, 32(4), 2622-2630. doi:10.1109/tpel.2016.2572142Jiang, W., Ding, X., Ni, Y., Wang, J., Wang, L., & Ma, W. (2018). An Improved Deadbeat Control for a Three-Phase Three-Line Active Power Filter With Current-Tracking Error Compensation. IEEE Transactions on Power Electronics, 33(3), 2061-2072. doi:10.1109/tpel.2017.2693325Buso, S., Caldognetto, T., & Brandao, D. (2015). Dead-Beat Current Controller for Voltage Source Converters with Improved Large Signal Response. IEEE Transactions on Industry Applications, 1-1. doi:10.1109/tia.2015.2488644Tarisciotti, L., Formentini, A., Gaeta, A., Degano, M., Zanchetta, P., Rabbeni, R., & Pucci, M. (2017). Model Predictive Control for Shunt Active Filters With Fixed Switching Frequency. IEEE Transactions on Industry Applications, 53(1), 296-304. doi:10.1109/tia.2016.2606364Kumar, M., & Gupta, R. (2017). Sampled-Time-Domain Analysis of a Digitally Implemented Current Controlled Inverter. IEEE Transactions on Industrial Electronics, 64(1), 217-227. doi:10.1109/tie.2016.2609840Ho, C. N.-M., Cheung, V. S. P., & Chung, H. S.-H. (2009). Constant-Frequency Hysteresis Current Control of Grid-Connected VSI Without Bandwidth Control. IEEE Transactions on Power Electronics, 24(11), 2484-2495. doi:10.1109/tpel.2009.2031804Wu, F., Feng, F., Luo, L., Duan, J., & Sun, L. (2015). Sampling period online adjusting-based hysteresis current control without band with constant switching frequency. IEEE Transactions on Industrial Electronics, 62(1), 270-277. doi:10.1109/tie.2014.2326992Holmes, D. G., Davoodnezhad, R., & McGrath, B. P. (2013). An Improved Three-Phase Variable-Band Hysteresis Current Regulator. IEEE Transactions on Power Electronics, 28(1), 441-450. doi:10.1109/tpel.2012.2199133Komurcugil, H., Bayhan, S., & Abu-Rub, H. (2017). Variable- and Fixed-Switching-Frequency-Based HCC Methods for Grid-Connected VSI With Active Damping and Zero Steady-State Error. IEEE Transactions on Industrial Electronics, 64(9), 7009-7018. doi:10.1109/tie.2017.2686331Chang, C.-H., Wu, F.-Y., & Chen, Y.-M. (2012). Modularized Bidirectional Grid-Connected Inverter With Constant-Frequency Asynchronous Sigma–Delta Modulation. IEEE Transactions on Industrial Electronics, 59(11), 4088-4100. doi:10.1109/tie.2011.2176693Mertens, A. (1994). Performance analysis of three-phase inverters controlled by synchronous delta-modulation systems. IEEE Transactions on Industry Applications, 30(4), 1016-1027. doi:10.1109/28.297919Morales, J., de Vicuna, L. G., Guzman, R., Castilla, M., & Miret, J. (2018). Modeling and Sliding Mode Control for Three-Phase Active Power Filters Using the Vector Operation Technique. IEEE Transactions on Industrial Electronics, 65(9), 6828-6838. doi:10.1109/tie.2018.2795528Guzman, R., de Vicuna, L. G., Morales, J., Castilla, M., & Miret, J. (2016). Model-Based Control for a Three-Phase Shunt Active Power Filter. IEEE Transactions on Industrial Electronics, 63(7), 3998-4007. doi:10.1109/tie.2016.2540580Pichan, M., & Rastegar, H. (2017). Sliding-Mode Control of Four-Leg Inverter With Fixed Switching Frequency for Uninterruptible Power Supply Applications. IEEE Transactions on Industrial Electronics, 64(8), 6805-6814. doi:10.1109/tie.2017.2686346E. S., S., E. K., P., Chatterjee, K., & Bandyopadhyay, S. (2014). An Active Harmonic Filter Based on One-Cycle Control. IEEE Transactions on Industrial Electronics, 61(8), 3799-3809. doi:10.1109/tie.2013.2286558Wang, L., Han, X., Ren, C., Yang, Y., & Wang, P. (2018). A Modified One-Cycle-Control-Based Active Power Filter for Harmonic Compensation. IEEE Transactions on Industrial Electronics, 65(1), 738-748. doi:10.1109/tie.2017.2682021Jin, T., & Smedley, K. M. (2006). Operation of One-Cycle Controlled Three-Phase Active Power Filter With Unbalanced Source and Load. IEEE Transactions on Power Electronics, 21(5), 1403-1412. doi:10.1109/tpel.2006.880264Hirve, S., Chatterjee, K., Fernandes, B. G., Imayavaramban, M., & Dwari, S. (2007). PLL-Less Active Power Filter Based on One-Cycle Control for Compensating Unbalanced Loads in Three-Phase Four-Wire System. IEEE Transactions on Power Delivery, 22(4), 2457-2465. doi:10.1109/tpwrd.2007.893450Qiao, C., Smedley, K. M., & Maddaleno, F. (2004). A Single-Phase Active Power Filter With One-Cycle Control Under Unipolar Operation. IEEE Transactions on Circuits and Systems I: Regular Papers, 51(8), 1623-1630. doi:10.1109/tcsi.2004.832801Qiao, C., Jin, T., & MaSmedley, K. (2004). One-Cycle Control of Three-Phase Active Power Filter With Vector Operation. IEEE Transactions on Industrial Electronics, 51(2), 455-463. doi:10.1109/tie.2004.82522

Small Wind Turbine Emulator Based on Lambda-Cp Curves Obtained under Real Operating Conditions

[EN] This paper proposes a new on-site technique for the experimental characterization of small wind systems by emulating the behavior of a wind tunnel facility. Due to the high cost and complexity of these facilities, many manufacturers of small wind systems do not have a well knowledge of the characteristic lambda-Cp curve of their turbines. Therefore, power electronics converters connected to the wind generator are usually programmed with speed/power control curves that do not optimize the power generation. The characteristic lambda-Cp curves obtained through the proposed method will help manufacturers to obtain optimized speed/power control curves. In addition, a low cost small wind emulator has been designed. Programmed with the experimental lambda-Cp curve, it can validate, improve, and develop new control algorithms to maximize the energy generation. The emulator is completed with a new graphic user interface that monitors in real time both the value of the lambda-Cp coordinate and the operating point on the 3D working surface generated with the characteristic lambda-Cp curve obtained from the real small wind system. The proposed method has been applied to a small wind turbine commercial model. The experimental results demonstrate that the point of operation obtained with the emulator is always located on the 3D surface, at the same coordinates (rotor speed/wind speed/power) as the ones obtained experimentally, validating the designed emulator.Martínez-Márquez, CI.; Twizere-Bakunda, JD.; Lundbäck-Mompó, D.; Orts-Grau, S.; Gimeno Sales, FJ.; Segui-Chilet, S. (2019). Small Wind Turbine Emulator Based on Lambda-Cp Curves Obtained under Real Operating Conditions. Energies. 12(13):1-17. https://doi.org/10.3390/en12132456S1171213Nichita, C., Luca, D., Dakyo, B., & Ceanga, E. (2002). Large band simulation of the wind speed for real time wind turbine simulators. IEEE Transactions on Energy Conversion, 17(4), 523-529. doi:10.1109/tec.2002.805216Pillay, P., & Krishnan, R. (1988). Modeling of permanent magnet motor drives. IEEE Transactions on Industrial Electronics, 35(4), 537-541. doi:10.1109/41.9176Tanvir, A., Merabet, A., & Beguenane, R. (2015). Real-Time Control of Active and Reactive Power for Doubly Fed Induction Generator (DFIG)-Based Wind Energy Conversion System. Energies, 8(9), 10389-10408. doi:10.3390/en80910389Martinez, F., Herrero, L. C., & de Pablo, S. (2014). Open loop wind turbine emulator. Renewable Energy, 63, 212-221. doi:10.1016/j.renene.2013.09.019Castelló, J., Espí, J. M., & García-Gil, R. (2016). Development details and performance assessment of a Wind Turbine Emulator. Renewable Energy, 86, 848-857. doi:10.1016/j.renene.2015.09.010Kojabadi, H. M., Chang, L., & Boutot, T. (2004). Development of a Novel Wind Turbine Simulator for Wind Energy Conversion Systems Using an Inverter-Controlled Induction Motor. IEEE Transactions on Energy Conversion, 19(3), 547-552. doi:10.1109/tec.2004.832070Choy, Y.-D., Han, B.-M., Lee, J.-Y., & Jang, G.-S. (2011). Real-Time Hardware Simulator for Grid-Tied PMSG Wind Power System. Journal of Electrical Engineering and Technology, 6(3), 375-383. doi:10.5370/jeet.2011.6.3.375Wasynczuk, O., Man, D. T., & Sullivan, J. P. (1981). Dynamic Behavior of a Class of Wind Turbine Generators during Random Wind Fluctuations. IEEE Power Engineering Review, PER-1(6), 47-48. doi:10.1109/mper.1981.5511593Dai, J., Liu, D., Wen, L., & Long, X. (2016). Research on power coefficient of wind turbines based on SCADA data. Renewable Energy, 86, 206-215. doi:10.1016/j.renene.2015.08.02

Switching Pattern Improvement for One-Cycle Zero-Integral-Error Current Controller

The one-cycle current control is a non-linear technique based on the cycle-by-cycle calculation of the ON time of the power converter switches. Its application is not common in tracking fast-changing reference currents, due to the necessity of fast and accurate measurements, and high-speed computing. In a previous study, a one-cycle digital current controller based on the minimization of the integral error of the current was developed and applied to the control of a three-phase shunt active power filter. In the present work, the one-cycle controller has been improved by proposing a new switching pattern. It allows an easy implementation that reduces the critical computational cost and avoids the main drawbacks of the previous implementation. The controller has been applied in a three-leg four-wire shunt active power filter, including a stability analysis considering the proposed switching pattern. Simulated and experimental results are presented to validate the proposed controller

Energy Efficiency Optimization in Battery-Based Photovoltaic Pumping Schemes

[EN] This article deals with the analysis of energy efficiency optimization in battery-based photovoltaic pumping schemes. The study builds on previous findings derived from the comparison between a direct photovoltaic water pumping system (DPVWPS) and the equivalent system including a lithium-ion battery (LIB). The initial experimental results of the battery-based photovoltaic water pumping system (PVWPS+LIB) were obtained with the motor-pump group operating at its rated condition of 50 Hz. In the present work, an analysis of the efficiency and the performance ratio of the variable speed drive (VSD) and the motor-pump group, showed that both parameters improve when operating in the low frequency range of the VSD and far from the rated frequency where the flow rate is maximized. Several fitting models were performed with the data obtained with the monitoring system and it was concluded that an overall energy efficiency optimization can be achieved with a VSD frequency equal to 37 Hz. A comparison of the experimental results obtained with the VSD working in the direct mode and with the battery-based solution (setting different VSD frequencies - 50 Hz, 37 Hz, and a combination of the two frequencies designed as 37/50/37 Hz) was made to determine the efficiency and performance ratios in each case. The results presented in this study also establish criteria for improving efficiencies in the LIB charging and discharging processes.This work was supported in part by the Universitat Politecnica de Valencia (UPV) (Program ADSIDEO-Cooperation 2017 through the Project Characterization of Sustainable Systems for the Pumping of Water for Human Consumption in Developing Regions and/or Refugee Camps in Kenya Through the Implementation of Isolated Photovoltaic Systems With New Generation Lithium-Ion Batteries); and in part by the International Organization for Migration under a contract entitled `Design, Assembly, Testing and Documenting Parameters of Solar and Ion-Lithium Energy Storage Equipment for Powering of Water Pumps under Laboratory Conditions' with funding from the Bureau for Humanitarian Assistance-United States Agency for International Development (USAID).Gasque Albalate, M.; González Altozano, P.; Gimeno Sales, FJ.; Orts-Grau, S.; Balbastre Peralta, I.; Martíne-Navarro, G.; Segui-Chilet, S. (2022). Energy Efficiency Optimization in Battery-Based Photovoltaic Pumping Schemes. IEEE Access. 10:54064-54078. https://doi.org/10.1109/ACCESS.2022.317558654064540781

Photovoltaic Water Pumping: Comparison Between Direct and Lithium Battery Solutions

[EN] This work presents the conversion of a photovoltaic water pumping system (PVWPS) to its corresponding battery-based solution, while maintaining the components of the PVWPS facility and adding the power converter needed to manage the operation of a lithium-ion battery. A complete analysis of the direct PVWPS is performed based on the values obtained by the monitoring system developed for the installation. The efficiencies and performance ratios of the various elements of the facility are calculated, as well as other relevant factors (such as irradiance thresholds). The dependence of some variables on the solar resource is analyzed to model the system. A similar study is carried out in the battery-based solution and a comparative analysis of the two modes of operation is then performed to find which aspects could be improved in the battery-based solution to increase the pumping time and total daily pumped volume. The results presented demonstrate the benefits of including a battery (reduction in start/stop cycles and improved performance on cloudy days). Aspects that can be improved to make the battery-based solution more efficient and achieve better results are suggested.This work was supported in part by the Universitat Politecnica de Valencia (UPV-Program ADSIDEO-cooperation 2017-Project Characterization of sustainable systems for the pumping of water for human consumption in developing regions or refugee camps in Kenya through the implementation of isolated photovoltaic systems with new generation lithium-ion batteries), and in part by the International Organization for Migration under Contract entitled "Design, Assembly, Testing and Documenting Parameters of Solar and Ion-Lithium Energy Storage Equipment for Powering of Water Pumps under Laboratory Conditions'' from the Bureau for Humanitarian Assistance-USAID.Orts-Grau, S.; González Altozano, P.; Gimeno Sales, FJ.; Balbastre Peralta, I.; Martínez Márquez, CI.; Gasque Albalate, M.; Segui-Chilet, S. (2021). Photovoltaic Water Pumping: Comparison Between Direct and Lithium Battery Solutions. IEEE Access. 9:101147-101163. https://doi.org/10.1109/ACCESS.2021.3097246101147101163

Switching Pattern Improvement for One-Cycle Zero-Integral-Error Current Controller

[EN] The one-cycle current control is a non-linear technique based on the cycle-by-cycle calculation of the ON time of the power converter switches. Its application is not common in tracking fast-changing reference currents, due to the necessity of fast and accurate measurements, and high-speed computing. In a previous study, a one-cycle digital current controller based on the minimization of the integral error of the current was developed and applied to the control of a three-phase shunt active power filter. In the present work, the one-cycle controller has been improved by proposing a new switching pattern. It allows an easy implementation that reduces the critical computational cost and avoids the main drawbacks of the previous implementation. The controller has been applied in a three-leg four-wire shunt active power filter, including a stability analysis considering the proposed switching pattern. Simulated and experimental results are presented to validate the proposed controller.Orts-Grau, S.; Balaguer-Herrero, P.; Alfonso-Gil, JC.; Martínez-Márquez, CI.; Martínez-Navarro, G.; Gimeno Sales, FJ.; Segui-Chilet, S. (2022). Switching Pattern Improvement for One-Cycle Zero-Integral-Error Current Controller. IEEE Access. 10:158-167. https://doi.org/10.1109/ACCESS.2021.31377581581671

PV monitoring system for a water pumping scheme with lithium-ion battery using free open-source software and IoT technologies.

[EN] The development of photovoltaic (PV) technology is now a reality. The inclusion of lithium-ion batteries in grid-connected PV systems is growing, and the sharp drop in prices for these batteries will enable their use in applications such as PV water pumping schemes (PVWPS). A technical solution for the monitoring and tracking of PV systems is shown in this work, and a novel quasi-real-time monitoring system for a PVWPS with a Li-ion battery is proposed in which open-source Internet of Things (IoT) tools are used. The purpose of the monitoring system is to provide a useful tool for the operation, management, and development of these facilities. The experimental facility used to test the monitoring system includes a 2.4 kWpk photovoltaic field, a 3.6 kVA hybrid inverter, a 3.3 kWh/3 kW lithium-ion battery, a 2.2 kVA variable speed driver, and a 1.5 kW submersible pump. To address this study, data acquisition is performed using commercial hardware solutions that communicate using a Modbus-RTU protocol over an RS485 bus and open software. A Raspberry Pi is used in the data gateway stage, including a PM2 free open-source process manager to increase the robustness and reliability of the monitoring system. Data storage is performed in a server using InfluxDB for open-source database storage and Grafana as open-source data visualization software. Data processing is complemented with a configurable data exporter program that enables users to select and copy the data stored in InfluxDB. Excel or .csv files can be created that include the desired variables with a defined time interval and with the desired data granularity. Finally, the initial results of the monitoring system are presented, and the possible uses of the acquired data and potential users of the system are identified and described.This research was funded by Universitat Politècnica de València (UPV; Program ADSIDEO-cooperation 2017, project titled ¿Characterization of sustainable systems for the pumping of water for human consumption in developing regions and/or refugee camps in Kenya through the implementation of isolated photovoltaic systems with new generation lithium-ion batteries¿).Gimeno Sales, FJ.; Orts-Grau, S.; Escriba-Aparisi, A.; González Altozano, P.; Balbastre Peralta, I.; Martínez-Márquez, CI.; Gasque Albalate, M.... (2020). PV monitoring system for a water pumping scheme with lithium-ion battery using free open-source software and IoT technologies. Sustainability. 12(24):1-28. https://doi.org/10.3390/su122410651S128122

Contribución a la mejora de la eficiencia y al ahorro energético en y lineales, con neutro

[ES] La tesis doctoral analiza las ineficiencias presentes en sistemas eléctricos a cuatro hilos en los que se conectan receptores lineales asimétricos que provocan un sistema de tensiones y corrientes desequilibradas. La tesis doctoral propone un nuevo método para la compensación total o parcial de las ineficiencias utilizando un convertidor activo de potencia formado por tres semipuentes convencionales. El sistema eléctrico se analiza utilizando las componentes simétricas de las tensiones y corrientes (Transformada de Stokvis-Fortescue). Las componenete directas, inversas y homopolares de las tensiones y corrientes determinan las corrientes de compensación. Debido a las pérdidas de potencia en el compensador, las corrientes de referencia incluyen las corrientes de compensación así como las corrientes necesarias para mantener la tensión del bus de continua en un valor cercano al de referencia. La tesis incluye resultados simulados y experimentales, obtenidos estos últimos con un prototipo. Los resultados muestran como las corrientesde compensación propuestas mejoran la eficiencia del sistema cuando hay presentes tensiones y corrientes desequilibrada.Segui Chilet, S. (2004). Contribución a la mejora de la eficiencia y al ahorro energético en y lineales, con neutro [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/5510