Effect of Symmetrically Switched Rectifier Topologies on the Frequency Regulation of Standalone Micro-Hydro Power Plants

Micro-hydro power plants (μHPPs) are a major energy source in grid-isolated zones because they do not require reservoirs and dams to be built. μHPPs operate in a standalone mode, but a continuously varying load generates voltage unbalances and frequency fluctuations which can cause long-term damage to plant components. One method of frequency regulation is the use of alternating current-alternating current (AC-AC) converters as an electronic load controller (ELC). The disadvantage of AC-AC converters is reactive power consumption with the associated decrease in both the power factor and the capacity of the alternator to deliver current. To avoid this disadvantage, we proposed two rectifier topologies combined with symmetrical switching. However, the performance of the frequency regulation loop with each topology remains unknown. Therefore, the objective of this work was to evaluate the performance of the frequency regulation loop when each topology, with a symmetrical switching form, was inserted. A MATLAB® model was implemented to simulate the frequency loop. The results from a μHPP case study in a small Cuban rural community called ‘Los Gallegos’ showed that the performance of the frequency regulation loop using the proposed topologies satisfied the standard frequency regulation and increased both the power factor and current delivery capabilities of the alternator.This contribution is a result of a cooperation between the APlied Electronic Research Team (APERT) at the University of the Basque Country (UPV/EHU), supported by the Department of Education of the Basque Government, within the fund for research groups of the Basque university system IT978-16, the Power Electronics Control in Energy and Motion Systems group (PECEM) at the University of Oriente, and the IRIS project for Cuban energy transformation. Integration of Renewable Intermittent Sources in the power system (IRIS, 2019-2022) is financed by Academy of Science in Finland, Grant/Award Number 320229. The authors of this article gratefully acknowledge these financers and project partners

High-Voltage Stations for Electric Vehicle Fast-Charging: Trends, Standards, Charging Modes and Comparison of Unity Power-Factor Rectifiers

Emission of greenhouse gases and scarcity of fossil fuels have put the focus of the scientific community, industry and society on the electric vehicle (EV). In order to reduce CO2 emissions, cutting-edge policies and regulations are being imposed worldwide, where the use of EVs is being encouraged. In the best of scenarios reaching 245 million EVs by 2030 is expected. Extensive use of EV-s requires the installation of a wide grid of charging stations and it is very important to stablish the best charging power topology in terms of efficiency and impact in the grid. This paper presents a review of the most relevant issues in EV charging station power topologies. This review includes the impact of the battery technology, currently existing standards and proposals for power converters in the charging stations. In this review process, some disadvantages of current chargers have been identified, such as poor efficiency and power factor. To solve these limitations, five unidirectional three-phase rectifier topologies have been proposed for fast EV charging stations that enhance the current situation of chargers. Simulation results show that all the proposed topologies improve the power factor issue without penalizing efficiency. The topologies with the best overall performance are the Vienna 6-switch and the Vienna T-type rectifier. These two converters achieve high efficiency and power factor, and they allow a better distribution of losses among semiconductors, which significantly increase the life-cycle of the semiconductor devices and the reliability of the converter.This work was supported in part by the Government of the Basque Country through the Fund for Research Groups of the Basque University System under Grant IT978-16, in part by the Research Program ELKARTEK under Project ENSOL2-KK-2020/00077 and Project HARVESTGEN-KK-2020/00113, in part by the Ministerio de Ciencia e Innovacion of Spain under Project PID2020-115126RB-I00, and in part by the FEDER Funds. Documen

Potentzia-bihurgailu matriziala: teknologia eraginkor eta konpaktua

Gaur egun potentzia-elektronikaren erabilera oso hedatuta dago. Teknologia mota hau nonahi aurki daiteke: ibilgailu elektrikoetan, ur-ponpaketako sistemetan, hegazkinetan, haize-errotetan, etab. Potentzia-bihurgailuen artean, bihurgailu matriziala (MC, matrix converter) nabarmentzen da, honek azaltzen dituen ezaugarriak direla-bide. Bihurgailu horrek AC/AC bihurketa era zuzenean egiten du, eta hainbat aplikaziotan erabil daiteke, oso konpaktua eta eraginkorra baita. Gainera, bihurgailu horren bidez sintetizatutako seinaleen kalitatea oso ona da. Lan honetan, MCaren ezaugarriak, aplikazioak, erronkak, arkitektura eta modulazio-printzipioak azaltzen dira. Ondoren, adibide modura, bihurgailu hau haize-errota txikietan ezartzean lortzen diren emaitzak erakutsiko dira. Azkenik, Euskal Herriko Unibertsitatean eraikitako MC prototipo batean lortutako zenbait emaitza esperimentalen berri emango dugu, bihurgailuaren funtzionamendu erreala azaltzeko

Mikrosare elektrikoak: energia berriztagarriak integratzeko aukera

Egun, sorkuntza sakabanatua da energia elektriko eraginkorra eta kalitate onekoa lortzeko gailentzen ari den aukera. Sorkuntza sakabanatua energia berriztagarrietan oinarritzen denez, faktore kontrolaezinen menpe dago, adibidez haizearen eta eguzki-irradiazioaren menpe. Hori dela eta, sistema horiek sare elektrikoan integratzea ez da erraza. Eragozpen hori gainditze aldera, oso eraginkorra gertatzen da mikrosareak erabiltzea, sorkuntza sakabanatuaren integrazio ona bermatzen delako, erabiltzeen hornikuntza elektrikoa hobetzeaz gain. Alde horretatik, mikrosareen ikerkuntza asko hedatu da munduan zehar, tankera honetako sareek dituzten abantailak direla-eta. Artikulu honetan, mikrosareen ezaugarri nagusiak aurkeztuko dira. Ondoren, AC eta DC mikrosareen arteko aldeak azalduko dira, haien funtsezko abantailak eta desabantailak aipatuz. Azkenik, munduan zehar eraikitako hainbat mikrosare zerrendatuko dira, eta Euskal Herriko energia berriztagarrien eta mikrosareen egoera deskribatuko da

Wide Bandgap semiconductor HF-oscillation attenuation method with tuned gate RLC filter

Wide Bandgap (WBG) transistors provide better switching performance and higher operating temperatures compared to state of the art Si devices and are suited for high frequency applications due to very short switching times. The main obstacle for implementation of WBG transistors at full potential is the high frequency oscillation in voltage and current during switching transients. Oscillations arise from resonance due to parasitic and device inductances and capacitances. Introduction of WBG transistors depends on the elimination of these oscillations and their negative effect on the performance of power converters. Good layout practice is mandatory, but there is a limit to the reduction of these parasitics and, often, slowing of the semiconductor switching time must be applied. This paper presents a simple methodology for the attenuation of the negative effects of WBG transistor high frequency oscillations without increasing rise and fall times. The proposed methodology is based on determination of the source of feedback resonant frequency between gate and power loops using network analyzer measurement on PCB and utilization of tuned RLC filter. Experimental application of the methodology shows direct relationship between loop resonant frequency and voltage and current oscillations. The proposed method reduces power losses, high frequency oscillations and EMI.UPV/EHU IT978-16, GV/EJ (Elkartek) KK-2018/0004

Mikrosare elektrikoak: energia berriztagarriak integratzeko aukera

Egun, sorkuntza sakabanatua da energia elektriko eraginkorra eta kalitate onekoa lortzeko gailentzen ari den aukera. Sorkuntza sakabanatua energia berriztagarrietan oinarritzen denez, faktore kontrolaezinen menpe dago, adibidez haizearen eta eguzki-irradiazioaren menpe. Hori dela eta, sistema horiek sare elektrikoan integratzea ez da erraza. Eragozpen hori gainditze aldera, oso eraginkorra gertatzen da mikrosareak erabiltzea, sorkuntza sakabanatuaren integrazio ona bermatzen delako, erabiltzeen hornikuntza elektrikoa hobetzeaz gain. Alde horretatik, mikrosareen ikerkuntza asko hedatu da munduan zehar, tankera honetako sareek dituzten abantailak direla-eta. Artikulu honetan, mikrosareen ezaugarri nagusiak aurkeztuko dira. Ondoren, AC eta DC mikrosareen arteko aldeak azalduko dira, haien funtsezko abantailak eta desabantailak aipatuz. Azkenik, munduan zehar eraikitako hainbat mikrosare zerrendatuko dira, eta Euskal Herriko energia berriztagarrien eta mikrosareen egoera deskribatuko da

Common-Mode Voltage Elimination in Multilevel Power Inverter-Based Motor Drive Applications

[EN] The industry and academia are focusing their efforts on finding more efficient and reliable electrical machines and motor drives. However, many of the motors driven by pulse-width modulated converters face the recurring problem of common-mode voltage (CMV). In fact, this voltage leads to other problems such as bearing breakdown, deterioration of the stator winding insulation and electromagnetic interferences (EMI) that can affect the lifespan and correct operation of the motors. In this sense, multilevel converters have proven to be a useful tool for solving these problems and mitigating CMV over the past few decades. Among other reasons, because they provide additional degrees of freedom when comparing with two-level converters. However, although there are several proposals in the scientific literature on this topic, no complete information has been reviewed about the CMV issues and the different multilevel alternatives that can be used to solve it. In this context, the objective of this work is to determine how multilevel power converters provide additional degrees of freedom to make the reduction of the CMV possible by using specific modulation techniques, making it easier for engineers and scientists in this field to find solutions to this problem. This document consists of a descriptive study that collects the strengths and weaknesses of most important multilevel power converters, with special emphasis on how CMV affects each of them. In addition, the differences of modulation techniques aimed to the CMV reduction are explained in terms of output voltage, operating linear range, and generated CMV. Considering this last, it is recommended to use those modulation techniques that allow the generation of CMV levels of 0 V in order to be able to completely eliminate said voltage.This work was supported in part by the Government of the Basque Country within the Fund for Research Groups of the Basque University System under Grant IT978-16; in part by the Research Program ELKARTEK under Project ENSOL2-KK-2020/00077; in part by the Secretaria d'Universitats i Recerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya; in part by the Ministerio de Ciencia, Innovacion y Universidades of Spain under Project PID2019-111420RB-I00 and Project PID2020-115126RB-I00; and in part by the FEDER Funds

Olatu-energiaren bilakaera

Olatu-energia edo energia undimotriza1 gero eta arreta handiago erakartzen ari da komunitate zientifikoan eta erakunde publiko zein pribatuetan. Ez da energia-baliabide berri bat; izan ere, jadanik XIII. mendean ere erabiltzen zen energia-iturri hori. Hala ere, historian zehar izan duen bilakaerak hainbat gorabehera izan ditu. Egun, berriz berpizten ari da harekiko jakin-mina, eta horren adierazgarri dira aurrekontu handiko I+G proiektu ugarien onarpena. Bestalde, Iberiar penintsulako ipar kostaldea baliabide honen munduko potentzialik handienetakoen barnean dago, eta haren industria-ustiapen errealitate bihur daiteke epe luze-ertainean