Desenvolupament i implementació d'un emulador fotovoltaic amb interfície HMI per a inversors de gran potència en el seu rang de funcionament habitual.

Premi al millor Projecte de Fi de Carrera presentat durant el curs 2009-2010 en l'àmbit d'Inovació en Energia Elèctrica que atorga la CÀTEDRA ENDESA REDEn els últims anys, la indústria de les energies renovables ha experimentat un fort creixement i una implantació amb tendència a l’augment en la societat. Concretament, el sector de les energies solars ha desenvolupat una forta evolució, fent-se servir cada cop més en múltiples aplicacions. Molts governs aposten, promouen i inciten a l’explotació de recursos renovables com a fonts d’energia per al col·lectiu de la societat, provocant, al seu torn, la necessitat de dur a terme investigacions amb la finalitat d’aconseguir millores en el rendiment de les tecnologies actuals i de la realització de bancades de proves per a determinar les característiques dels nous productes que apareixen. Així doncs, aquest projecte neix de la necessitat de disposar d’una plataforma que permeti testejar inversors fotovoltaics sense haver de recórrer a l’ús de plaques fotovoltaiques reals o d’emuladors de llum solar. Les principals desavantatges d’aquestes darreres opcions resideixen en la dependència de les condicions atmosfèriques, en el primer cas, o en la gran quantitat d’energia requerida per a recrear la intensitat llumínica, en el segon. D’aquesta forma l’estudi realitzat es basa la implementació d’una bancada que permeti emular el comportament d’un conjunt de panells fotovoltaics fent ús d’un convertidor de potència a través de la seva corba característica tensió-corrent, amb la finalitat que fabricants o muntadors d’inversors fotovoltaics puguin provar els sues equips. Per a la realització d'aquesta tasca s'implementarà una interfície gràfica que permeti treballar amb diferents corbes al llarg del temps. El sistema que es proposa per a l’emulador té el seu fonament en un convertidor de potència de fins a 10 kVA amb una topologia de rectificador trifàsic actiu d’IGBTs. Es farà ús d’una placa de control gestionada per un DSP en la qual s’implementarà el control de les variables desitjades del sistema, el dispar dels IGBTs i la corba característica del sistema fotovoltaic a emular. L’ús d’aquesta topologia presenta el principal inconvenient que no permet recórrer tota la corba fotovoltaica, ja que es tracta d’un elevador de tensió. No obstant, els tests que es realitzen sobre els equips inversors responen, en la majoria dels casos, a un rang de funcionament proper al màxim de les seves prestacions, com ara la determinació del correcte funcionament d’algorismes MPPT. En una primera part del projecte, s’ha realitzat un estudi de les especificacions que hauria de complir el convertidor juntament amb un estudi de mercat, per tal de veure l’actualitat d’aquest. Seguidament, es presenta un anàlisi de possibles alternatives, definició de les característiques del convertidor triat, descripció del software necessari per al control i gestió de l’emulador. Posteriorment, s’han realitzat unes simulacions, les proves sobre la bancada real i, finalment, l’anàlisi econòmic i mediambiental.Award-winnin

Desenvolupament i implementació d'un emulador fotovoltaic amb interfície HMI per a inversors de gran potència en el seu rang de funcionament habitual.

Premi al millor Projecte de Fi de Carrera presentat durant el curs 2009-2010 en l'àmbit d'Inovació en Energia Elèctrica que atorga la CÀTEDRA ENDESA REDEn els últims anys, la indústria de les energies renovables ha experimentat un fort creixement i una implantació amb tendència a l’augment en la societat. Concretament, el sector de les energies solars ha desenvolupat una forta evolució, fent-se servir cada cop més en múltiples aplicacions. Molts governs aposten, promouen i inciten a l’explotació de recursos renovables com a fonts d’energia per al col·lectiu de la societat, provocant, al seu torn, la necessitat de dur a terme investigacions amb la finalitat d’aconseguir millores en el rendiment de les tecnologies actuals i de la realització de bancades de proves per a determinar les característiques dels nous productes que apareixen. Així doncs, aquest projecte neix de la necessitat de disposar d’una plataforma que permeti testejar inversors fotovoltaics sense haver de recórrer a l’ús de plaques fotovoltaiques reals o d’emuladors de llum solar. Les principals desavantatges d’aquestes darreres opcions resideixen en la dependència de les condicions atmosfèriques, en el primer cas, o en la gran quantitat d’energia requerida per a recrear la intensitat llumínica, en el segon. D’aquesta forma l’estudi realitzat es basa la implementació d’una bancada que permeti emular el comportament d’un conjunt de panells fotovoltaics fent ús d’un convertidor de potència a través de la seva corba característica tensió-corrent, amb la finalitat que fabricants o muntadors d’inversors fotovoltaics puguin provar els sues equips. Per a la realització d'aquesta tasca s'implementarà una interfície gràfica que permeti treballar amb diferents corbes al llarg del temps. El sistema que es proposa per a l’emulador té el seu fonament en un convertidor de potència de fins a 10 kVA amb una topologia de rectificador trifàsic actiu d’IGBTs. Es farà ús d’una placa de control gestionada per un DSP en la qual s’implementarà el control de les variables desitjades del sistema, el dispar dels IGBTs i la corba característica del sistema fotovoltaic a emular. L’ús d’aquesta topologia presenta el principal inconvenient que no permet recórrer tota la corba fotovoltaica, ja que es tracta d’un elevador de tensió. No obstant, els tests que es realitzen sobre els equips inversors responen, en la majoria dels casos, a un rang de funcionament proper al màxim de les seves prestacions, com ara la determinació del correcte funcionament d’algorismes MPPT. En una primera part del projecte, s’ha realitzat un estudi de les especificacions que hauria de complir el convertidor juntament amb un estudi de mercat, per tal de veure l’actualitat d’aquest. Seguidament, es presenta un anàlisi de possibles alternatives, definició de les característiques del convertidor triat, descripció del software necessari per al control i gestió de l’emulador. Posteriorment, s’han realitzat unes simulacions, les proves sobre la bancada real i, finalment, l’anàlisi econòmic i mediambiental.Award-winnin

Understanding the three and four-leg inverter Space Vector

This paper shows a new point of view of the classical voltage space vectors and its implications on three and four-leg converters. It is easy to find in the literature, authors using bi-dimensional and threedimensional representations of the converter states. Nonetheless, the literature rarely specifies what these spaces represent. Therefore, this paper proposes a wide analysis of the state voltages and its references for three-leg, three-leg four-wire and four-leg inverters, in favour of understanding the space vector behaviour under three and four-wire scenarios.Postprint (published version

Smart grid architecture for rural distribution networks: application to a Spanish pilot network

This paper presents a novel architecture for rural distribution grids. This architecture is designed to modernize traditional rural networks into new Smart Grid ones. The architecture tackles innovation actions on both the power plane and the management plane of the system. In the power plane, the architecture focuses on exploiting the synergies between telecommunications and innovative technologies based on power electronics managing low scale electrical storage. In the management plane, a decentralized management system is proposed based on the addition of two new agents assisting the typical Supervisory Control And Data Acquisition (SCADA) system of distribution system operators. Altogether, the proposed architecture enables operators to use more effectively—in an automated and decentralized way—weak rural distribution systems, increasing the capability to integrate new distributed energy resources. This architecture is being implemented in a real Pilot Network located in Spain, in the frame of the European Smart Rural Grid project. The paper also includes a study case showing one of the potentialities of one of the principal technologies developed in the project and underpinning the realization of the new architecture: the so-called Intelligent Distribution Power Router.Postprint (published version

Review of flux-weakening algorithms to extend the speed range in electric vehicle applications with permanent magnet synchronous machines

This article reviews Flux-Weakening (FW) algorithms for Permanent Magnet Synchronous Machines (PMSMs), focusing on the automotive sector, especially in electric and hybrid electric vehicles. In the past few years, the spread of Electric Vehicles (EVs) has improved the technology of electric machines and their control to achieve more compact and competitive solutions. PMSMs are the most widespread electric machines used in EVs thanks to their high-power density and potential operation at constant power range during high speed. Such high speed implies a high electromotive force. An FW technique is mandatory to reduce the electromagnetic flux generated by the electric machine due to the voltage limits of the traction inverter and the energy source. This article classifies and analyses the state-of-the-art FW control strategies by comparing their main advantages and drawbacks. The Vector Current Control (VCC) method that regulates the modulus of the applied voltage is the most common one in the literature thanks to i) its robustness to parameter modification and model unsureness, ii) low computational complexity, and iii) high dynamic response and control stability.Peer ReviewedPostprint (published version

Fractional proportional-resonant current controllers for Voltage Source Converters

This paper proposes a novel fractional proportional-resonant controller, which applies fractional order calculus to the well-known proportional-resonant controllers. The focus of the study is the current control loop of voltage source converters. The main merit of the proposed fractional controller formulation lies into the use of fractional exponents in the integro-derivative parts obtaining a controller with an extra degree of freedom. This degree of freedom allows the phase delay to be improved for a wide frequency range in comparison with the conventional proportional-resonant controllers. Furthermore, the obtained controller results in a lower order transfer function that reduces the computational burden when multiple current frequencies have to be tracked. As fractional integro-derivative exponents are not directly implementable, five mathematical approaches are explored, selecting the Chareff’s approximation for the fractional controller operator’s implementation. A tuning procedure for such a controller is also addressed. The new controller formulation is validated in a 20 kVA laboratory set-up based on a silicon-carbide converter, and it is implemented in a DSP. Two AC output converter’s configurations are considered to demonstrate the controllers’ tracking capability; short-circuited (balanced fault) output, and grid-connected operation. This last case is evaluated operating as active filter and delivering fundamental component to a non-ideal grid.Postprint (author's final draft

Impedance measurement and detection frequency bandwidth, a valid island detection proposal for voltage controlled inverters

Anti-islanding detection methods have been part of a secure operation for distributed energy resource inverters, avoiding the creation of non-intentional energization when the mains are lost. These detection mechanisms were conceived historically for current-controlled inverters. New control possibilities have broken ground, and current- or voltage-controlled inverters are a reality; however, special attention must be paid to detection strategies when applied to the latter ones. This paper addresses two topics: it exposes the lack of effectiveness of those detection algorithms based on the voltage/frequency displacement concept under voltage-controlled inverters and evaluates the applicability limits of the others based on the impedance measurement (IM). The IM is presented as a valid mechanism to achieve the islanding detection, but the exploration of its limits drives the concept of detection frequency bandwidth (DFBW), introduced in this paper. The DFBW is suggested as a practical approach to select the proper injection frequency to measure. Therefore, an improved strategy based on the IM and DFBW is proposed to allow achieving the detection towards (non-)resonant loads considering low computational burden. The results were experimentally validated in a 90-kVA four-wire voltage-controlled inverter, offering detection times of less than 100 ms in any case.Postprint (published version

Accurate angle representation from misplaced hall-effect switch sensors for low-cost electric vehicle applications

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis article presents an accurate method to determine the mandatory rotor position to control a permanent magnet synchronous machine from misplaced Hall-effect switch sensors. The main feature of this technique is the estimated speed from two consecutive edge transitions in the same phase to dodge the inaccurate information. Besides, when a new electrical cycle starts, a gradual compensation algorithm corrects the initial speed estimation to cancel the electrical angle error in order to prevent current distortions. Furthermore, a first-order Taylor series approximation estimates the rotor position from the compensated speed calculation, reducing the possible torque ripple and noise due to an inaccurate control strategy. The proposed method has been compared with other state-of-the-art approaches through simulation and experimental results obtained from a low-voltage powertrain, showing more straightforward implementation and delivering the best balance performance during steady-state and transient operation.Peer ReviewedPostprint (author's final draft

Analytical dead-band compensation for ZCS modulation applied to hybrid Si-SiC dual active bridge

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper proposes a triangular modulation with zero current switching (ZCS) for a hybrid Si-SiC isolated bidirectional DC-DC converter (IBDC). Three of the four legs in the IBDC operate at ZCS and use Si IGBTs, while the fourth operates at zero voltage switching (ZVS) and uses SiC MOSFET. In that case, the turn-off switching losses are concentrated regardless of the direction of the power. The main contribution of this paper resides in the proposed dead-band compensation mechanism. This dead-band compensation is crucial when addressing ZCS modulation and improves the overall efficiency of the full operating range. As a co-benefit, the proposed mix of semiconductor technologies can result in an effective cost reduction compared with a full SiC IBDC. The paper contains a detailed explanation of the implemented modulation applied to an IBDC. The paper contributes to deploy a theoretical implementation where the effect of parasitic capacitance on semiconductors during the dead-band is analytically considered. The presented method results are validated on a laboratory set-up using a 20 kW - 40 kHz hybrid Si-SiC IBDC.Postprint (author's final draft

Analytical and Normalized Equations to Implement the Optimized Triple Phase-Shift Modulation Strategy for DAB Converters

A fully normalized algorithm to implement the optimal triple-phase-shift (TPS) modulation strategy of the dual active bridge (DAB) converter is proposed in this article. The algorithm evaluates three simple expressions that fit the optimal solutions obtained in recent works, which allows the algorithm to be implemented in real-time and valid for the whole operating range. As a result, the converter operates under zero voltage switching (ZVS) conditions and minimizes conduction losses. In addition, the algorithm considers the minimum current required to guarantee the ZVS condition that faces the undesired dead-band of switching devices effect. The proposal achieves a soft transition between any operation region and a fast closedloop response with no stability concern, presenting robustness under leakage inductance deviation. Finally, the algorithm presented in this article is verified with a 4-kW experimental prototype. Experimental results show that the algorithm proposed can be evaluated with less than 2.8 µs and allows soft transition between any operation region to be achieved. Besides, fast closedloop changes of 750 µs through all the operating ranges, keeping minimum rms current under ZVS, are shownPeer ReviewedPostprint (published version