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Abstract Conventional single‐vector model predictive control (MPC) can suffer from low control accuracy, while multi‐vector MPC is often criticized for its complexity and heavy computational burden. In order to address these issues, an adjacent vector‐based MPC is investigated in this paper for an electric vehicle battery charging and discharging converter. The voltage vector selection table based on the principle of using adjacent vectors has been designed and this reduces the number of iterations and thus the computational burden. A threshold is used in the adjacent vector‐based MPC to coordinate the use of the single and multi‐vector MPCs considering a balance between the control accuracy and computational burden. In addition, to enhance the robustness of MPC to parameter changes, an extended state observer for active disturbance rejection control has been used to derive the predictive model, and an adjacent vector‐based MPC using extended state observer is studied. The method does not need accurate system parameters. Instead, it only requires the system input and output measurements to calculate the predicted current. The robustness of the controller against the parameter mismatch is enhanced compared to alternative approaches and the experimental results verify the feasibility and effectiveness of the proposed strategy.

Matrix converters (MC) have been considered for applications in renewable power generation and microgrids. However, similar to other power electronic converter-interfaced power generation systems, the MC-interfaced system cannot provide inertia or damping effect to support the grid’s frequency or voltage. To improve the inertia and damping effect of the MC-interfaced distributed generation system and realize the grid-friendly connection of new energy power generation, a virtual synchronous generator (VSG) control strategy suitable for the MC-interfaced system is proposed. Aiming at the problem that the system frequency in the traditional VSG cannot be restored to the nominal value after the load power fluctuations, the VSG secondary frequency control strategy is introduced. To ensure a smooth grid connection, a synchronization control strategy based on virtual power has been designed. An experimental validation platform was built and the experimental results verify the correctness and effectiveness of the proposed control strategies for a grid-forming MC.

This paper presents a model predictive control (MPC) strategy to regulate output voltages in a multi-modular matrix converter topology for isolated loads. The converter system harnesses power from a six-phase permanent magnet synchronous generator (PMSG) to deliver sinusoidal voltages to a three-phase load, with LC filters positioned at the output of each MC module within the multi-modular scheme. The proposed MPC approach ensures that the output voltages remain within acceptable ranges of magnitude, phase, and frequency, even under load variations and system faults. This control strategy is particularly suitable for uninterruptible power supply systems, microgrids or other applications where voltage regulation is critical. Experimental studies validate the effectiveness of the control strategy under various load conditions, reference voltage changes, and simulated system fault scenarios. The results highlight the robustness and reliability of the proposed voltage control using the multi-modular matrix converter.

La reiterada aplicación de prácticas agrícolas convencionales ha conducido al deterioro de los suelos, lo que se evidencia por la reducida fertilidad y productividad. Por otro lado, se ha observado que la siembra directa y la rotación de cultivos tienen efectos positivos sobre las propiedades físicas, químicas y biológicas del suelo, por lo que se constituyen en restauradores edáficos. Adicionalmente, los microorganismos y la biomasa microbiana son considerados indicadores de la salud del suelo. En este contexto, con la finalidad de evaluar a largo plazo el efecto de estas prácticas de conservación, la Facultad de Ciencias Agrícolas de la Universidad Central del Ecuador estableció un ensayo en el Campo Docente Experimental “La Tola”, que al momento se encontraba en su segundo ciclo de evaluación. El objetivo de la presente investigación fue determinar la influencia de dos sistemas de labranza (convencional y siembra directa) y la rotación de tres especies vegetales (maíz, fréjol y cebada), en el segundo ciclo de aplicación, sobre la biomasa microbiana y la abundancia y diversidad de hongos y bacterias. El ensayo fue dispuesto en un diseño de parcela dividida, donde la parcela grande albergó el esquema de rotación de cultivos y la parcela pequeña los sistemas de labranza. A la cosecha, se tomaron muestras de suelo en cada unidad experimental, en las cuales se midió la biomasa microbiana. Para medir la diversidad y abundancia de microorganismos, las muestras individuales fueron unidas para obtener una sola muestra por tratamiento. La biomasa microbiana se determinó por el método de fumigación-incubación; y la abundancia y diversidad de microorganismos mediante análisis metagenómico, por secuenciación de amplicones de PCR de los genes 16S e ITS (región intergénica transcrita). Se calculó el ADEVA y las pruebas de significación de Tukey 5 % para biomasa microbiana y el índice de Chao y Shannon para abundancia y diversidad de microorganismos. Se encontró un efecto altamente significativo de los sistemas de labranza sobre la biomasa microbiana, siendo la SD la de mejor respuesta. Además, las rotaciones también presentaron un efecto significativo, con R4 (fréjol-fréjol) en el rango de significancia superior. En cuanto a la abundancia microbiana se observó que en SD predominan hongos y bacterias benéficos, mientras que en LC predominan microorganismos fitopatógenos como Fusarium sp. Para rotaciones, los resultados más favorables se evidenciaron en la R4, existiendo mayor presencia de bacterias fijadoras de nitrógeno y hongos micorrícicos; por el contrario, la R2 (cebada-cebada) presenta una mayor cantidad de hongos y bacterias fitopatógenas. El índice de Shannon es mayor en SD, tanto para hongos como para bacterias, en tanto que no hay diferencias para rotaciones.

Una importante área de los suelos de Ecuador son ácidos, condición que limita la productividad de los cultivos. La acidez se controla aplicando materiales alcalinizantes a través de la práctica agrícola denominada encalado. A pesar de que el encadado es una práctica común en los suelos del país, todavía se requiere determinar cuáles serían los cambios en los parámetros químicos del suelo inducidos por la aplicación de cal y cuál sería la dosis adecuada para controlar la acidez; especialmente en suelos con prevalencia de coloides de carga variable. Se presentan los resultados de dos ensayos independientes, uno realizado en invernadero (E-1) y otro en laboratorio (E-2), que se establecieron para evaluar el efecto del encalado sobre las propiedades químicas de suelos ácidos del Ecuador, que definen en buena medida su fertilidad. Se tomaron muestras de suelo del horizonte superficial y se analizó pH, capacidad de intercambio catiónico (CIC), saturación de bases (SB), densidad de carga en la superficie de los coloides (DCC), contenido de acidez intercambiable (Al3++H+1) y aluminio intercambiable (Al+3), calcio (Ca+2), magnesio (Mg+2) y potasio (K+), luego de un periodo de incubación. Se evaluaron suelos ácidos provenientes de diversos sitios de Ecuador, en el E-1 se utilizaron siete suelos y en el E-2 cinco. Se aplicaron nueve dosis de carbonato de calcio (0 - 12 t ha-1) en el E-1 y ocho dosis (0 - 10 t ha-1) para el E-2. Se utilizó un diseño de bloques completos al azar en arreglo factorial (7 x 9) con tres repeticiones en el E-1; mientras que, en el E-2 un diseño completamente al azar con ocho tratamientos y tres observaciones. Los resultados indicaron una relación directa entre las dosis crecientes de cal y el aumento progresivo de pH, CIC, SB y el contenido de Ca+2, pero se detectó una reducción en Al3++H+1, Al+3, Mg+2 y K+ en todos los suelos evaluados en los dos ensayos. Se encontró una consistente mayor capacidad tampón para pH (resistencia a cambio de pH) asociada con los suelos derivados de cenizas volcánicas y con mayor contenido de materia orgánica (suelos de carga variable). Todos los suelos estudiados en el E-2 mostraron predominancia de coloides con alta densidad de carga superficial y punto de carga neta cero (PZNC) por debajo de su pH natural, condiciones que favorecen la CIC, particularidad inherente a los suelos de carga variable. Se concluye que la magnitud del efecto del encalado sobre las propiedades químicas del suelo y su fertilidad guarda relación directa con el tipo de suelo que se refleja en un mayor incremento de la densidad de carga negativa y, consecuentemente, más alta capacidad de retención de cationes en suelos con predominio de coloides de carga variable. Por otro lado, se determinó que en los suelos de carga variable la dosis adecuada de cal depende de la capacidad tampón.

In a scenario of energy inequality, countries require stability for development and quality of life for their inhabitants. This paper addresses the reality of access to electrical energy and the effect of climate change on the potential of renewables to propose strategies related to generation and transmission in Argentina, Chile, Colombia and Paraguay. This is done by analysing quantitative and qualitative aspects of the electrical energy matrix: installed capacity and technology for generation and transmission together with the penetration of renewable energies. Among the results, actions address energy poverty, energy efficiency, smart investment in energy, and the readaptation of transmission infrastructure.

The objective of this work is to analyze and compare AC microgrid (ACMG) solutions to introduce the topic to new researchers. The methodology used to achieve this goal is a systematic literature review using five questions: (1) How have ACMGs evolved in five years? (2) What are the standards for ACMGs? (3) What are the different schemes for connecting MGs to the utility grid? (4) What are the different control schemes in ACMGs? (5) What is an appropriate way to compare results when working with ACMGs? The articles were published in Q1/Q2 journals as based on either the Scimago Journal Rank (SJR) and/or the Journal Citation Report (JCR) between 2018 and 2022 and were from three databases: (1) Web of Science (WoS), (2) Scopus, and (3) IEEE Xplore. Publications not describing pure ACMGs, review papers, publications not related to the questions, and papers describing work that did not meet a quality assessment were excluded, resulting in 34 articles being included in this review. Results show: (1) the energy sources and AC bus nature of microgrids over five years, (2) the identification and quantification of cited standards for microgrids, (3) the pros and cons of different schemes for connecting an AC microgrid to the main grid, (4) the control schemes, classified in a hierarchical control structure, and (5) the simulation tools and experimental benches used in microgrids. Most studies considered a generic energy source and a low-voltage three-phase AC bus, 16 standards were found, and the most cited standard was IEEE Standard 1547. The most common connection scheme to the utility grid was a direct connection, most of the works proposed a modification to a hierarchical control system scheme, and the most common simulation tool was MATLAB. The preferred experimental setup consisted of parallel inverters for testing a control scheme, a prototype when proposing a power electronic system, and a laboratory microgrid for testing fault detection methods.

Abstract This paper investigates space‐vector‐modulation (SVM) technique that uses only rotating space vectors to drive a direct matrix converter (DMC) with zero common‐mode voltage (CMV). Two methods for controlling grid power factor have been proposed in the literature for such a drive. Until now, analysis has been limited to balanced grid conditions. However, total harmonic distortion (THD) of grid currents significantly increases under unbalanced conditions. Hence, the aims of this paper are: (1) derivation of DMC model consisting of general equations for output voltages and input currents, written in the complex form. (2) Analysis and comparison of two existing methods for grid power factor control under balanced grid conditions, by using the previously derived model. (3) Proposal of extended versions of both methods in order to improve converter's performance under unbalanced grid conditions. The proposed control strategy aims to achieve sinusoidal currents and maintain the same power factor on the grid side while completely compensating grid unbalance on the load side. (4) Determination of the maximum transfer ratio under balanced and unbalanced grid conditions. Experimental results with Hardware In the Loop (HIL) are provided to verify the theoretical analysis and effectiveness of the proposed control strategy.

Recent advances in high-power applications employing voltage source converters have been primarily fuelled by the emergence of the modular multilevel converter (MMC) and its derivatives. Model predictive control (MPC) has emerged as an effective way of controlling these converters because of its high response. However, the practical implementation of MPC encounters hurdles, particularly in MMCs featuring many sub-modules per arm. This research introduces an approach termed folding model predictive control (FMPC), coupled with a pre-processing sorting algorithm, tailored for modular multilevel converters. The objective is to alleviate a significant part of the computational burden associated with the control of these converters. The FMPC framework combines multiple control objectives, encompassing AC current, DC current, circulating current, arm energy, and leg energy, within a unified cost function. Both simulation studies and real-time hardware-in-the-loop (HIL) testing are conducted to verify the efficacy of the proposed FMPC. The findings underscore the FMPC’s ability to deliver fast response and robust performance under both steady-state and dynamic operating conditions. Moreover, the FMPC adeptly mitigates circulating currents, reduces total harmonic distortion (THD%), and upholds capacitor voltage stability within acceptable thresholds, even in the presence of harmonic distortions in the AC grid. The practical applicability of MMCs, notwithstanding the presence of a large number of sub-modules (SMs) per arm, is facilitated by the significant reduction in switching states and computational overhead achieved through the FMPC approach.

This article presents an alternative ac–ac converter topology and its control for low-speed three-phase induction motor drives fed from single-phase ac mains. The proposed matrix converter based drive system eliminates the dc link capacitor, thus facilitating high power density and system reliability. The primary challenge in controlling a $1\phi$ to $3\phi$ matrix converter is to navigate the discrepancy of instantaneous power across the $1\phi$ grid and $3\phi$ load via a direct ac–ac converter. In order to address this concern, it is proposed to use mathematical modeling of the motor and input LC filter for state selection, in order to deliver improved current waveforms. Enhanced performance is demonstrated through simulations, and further validated using experimental results. Particularly improved power quality performance is achieved at low motor speeds, where precise low-speed sensorless operation is ensured through suitable speed observer.

Solar energy can be captured by Photovoltaics (PV) and converted into electrical power. This electrical power can then be connected to grids by power electronic converters, which can also operate the PV panels at around their maximum power point (MPP), maximizing the harvested energy. When the PV panels are connected in an array, the partial shading effect generates a distortion of the power curve can result in a power loss since tracking algorithms might not be able to detect the MPP. To solve this issue microinverters have been proposed, with a small power electronic converter being connected to each PV panel, this arrangement enables independence for maximum power point tracking and electrical isolation. This paper presents a double output multiport microinverter capable of feeding DC and AC loads or providing connection to a single-phase AC grid and energy storage. The proposed structure can be operated in grid-connected and islanded modes. This paper describes the microinverter controlled with the exact linearization technique on both the DC and AC sides, obtaining a lineal transfer function representation of the nonlinear and coupled power electronic converters. The operation of the proposed topology and its control strategy is validated using a laboratory proof-of-concept prototype.

The use of advanced modulation and control schemes for power converters, such as a Feedback Quantizer and Predictive Control, is widely studied in the literature. This work focuses on improving the closed-loop modulation scheme called Feedback Quantizer, which is applied to a three-phase voltage source inverter. This scheme has the natural behavior of mitigating harmonics at low frequencies, which are detrimental to electrical equipment such as transformers. This modulation scheme also provides good tracking for the voltage reference at the fundamental frequency. On the other hand, the disadvantage of this scheme is that it has a variable switching frequency, creating a harmonic spectrum in frequency dispersion, and it also needs a small sampling time to obtain good results. The proposed scheme to improve the modulation scheme is based on a Discrete Space Vector with virtual vectors to obtain a better approximation of the optimal vectors for use in the algorithm. The proposal improves the conventional scheme at a high sampling time (200 μs), obtaining a THD less than 2% in the load current, decreases the noise created by the conventional scheme, and provides a fixed switching frequency. Experimental tests demonstrate the correct operation of the proposed scheme.

The Scholander-type pressure chamber to measure midday stem water potential (MSWP) has been widely used to schedule irrigation in commercial vineyards. However, the limited number of sites that can be evaluated using the pressure chamber makes it difficult to evaluate the spatial variability of vineyard water status. As an alternative, several authors have suggested using the crop water stress index (CWSI) based on low-cost thermal infrared (TIR) sensors to estimate the MSWP. Therefore, this study aimed to develop a low-cost wireless infrared sensor network (WISN) to monitor the spatial variability of MSWPs in a drip-irrigated Cabernet Sauvignon vineyard under two levels of water stress. For this study, the MLX90614 sensor was used to measure canopy temperature (Tc), and thus compute the CWSI. The results indicated that good performance of the MLX90614 infrared thermometers was observed under laboratory and vineyard conditions with root mean square error (RMSE) and mean absolute error (MAE) values being less than 1.0 °C. Finally, a good nonlinear correlation between the MSWP and CWSI (R2 = 0.72) was observed, allowing the development of intra-vineyard spatial variability maps of MSWP using the low-cost wireless infrared sensor network.

The Dual–Vector model predictive control (DV–MPC) method can improve the steady–state control performance of motor drives compared to using the single–vector method in one switching cycle. However, this performance enhancement generally increases the computational burden due to the exponential increase in the number of vector selections, lowering the system’s dynamic response. Alternatively, limiting the vector combinations will sacrifice system steady–state performance. To address this issue, this paper proposes an enhanced DV–MPC method that can determine the optimal vector combinations along with their duration time within minimized calculation times. Compared to the existing DV–MPC methods, the proposed enhanced technique can achieve excellent steady–state performance while maintaining a low computational burden. These benefits have been demonstrated in the results from a 2.5k rpm permanent magnet synchronous motor drive.

Hierarchical control is a widely used strategy that can increase resilience and improve the reliability of the electrical network based on microgrid global variables. The large amounts of data required during transitions prompt the use of more reliable and flexible communications to achieve the control objectives. Such communications can involve potential cyber vulnerabilities and latency restrictions, which cannot be always addressed in real-time. To accurately capture the system’s overall operation, this paper proposes a co-simulation framework driven by flexible communications and a resilient control algorithm to regulate the frequency and voltage deviations in a networked microgrid. Model-based predictive control has been implemented, to avoid slow transient response associated with linear hierarchical control. Software-Defined Networking (SDN) is responsible for increasing the communication intelligence during the power-sharing process. The effects of critical communications and overall system performance are reviewed and compared for different co-simulation scenarios. Graphical Network Simulator (GNS3) is used in combination with model-based predictive control and SDN, to provide latency below 100 ms, as defined in IEC 61850. Testing of the proposed system under different cyber attack scenarios demonstrate its excellent performance. The novel control architecture presented in the paper provides a reference framework for future cloud computing-based microgrids.

The inclusion of solar systems in rural microgrids is becoming increasingly important to supply energy for irrigation, electric motors, lighting and other. This paper presents the implementation of an exact linearization technique for the modeling and control of a DC/DC converter for use in a microgrid based on a photovoltaic (PV) generation system where non-linear converters are used. The basic advantage of this technique is in linearizing the converter model, thus allowing different operating points to be considered under different conditions. This paper presents a general description of the implemented microgrid topology. The exact linearization theory adapted for power converters is applied to both a Single-Ended Primary-Inductor converter (SEPIC) to extract energy from PV modules and to a Boost converter to increase the voltage. Experimental results are also presented to validate the effectiveness of the proposed control.

Los parámetros biológicos son usados como indicadores tempranos en la calidad de un suelo (ICS) agrícola, ya que responden rápidamente al manejo antrópico. El objetivo de esta investigación fue determinar el efecto del sistema de labranza: siembra directa (SD) y labranza convencional (LC), y de la fertilización nitrogenada después de los cultivos de fréjol y maíz, sobre ciertos indicadores biológicos de la calidad del suelo. El estudio se realizó sobre un molisol de la región andina del Ecuador. Se determinó la biomasa microbiana (BM), respiración microbiana (RM), y actividad enzimática (fosfatasa ácida, hidrólisis de la fluoresceína-diacetato [FDA], y β-glucosidasa [β-G]). Los resultados mostraron que la fosfatasa presentó la mayor actividad bajo LC, la FDA respondió al efecto de los niveles altos de nitrógeno (N), la actividad de la enzima β-G fue mayor en LC. Adicionalmente, el análisis de componentes principales seleccionó a los indicadores biológicos estudiados, como ICS. Se concluye que los indicadores biológicos del suelo fueron afectados por las prácticas de manejo estudiadas.

This paper proposes a new way of understanding the debate between vulnerability and resilience. We mobilize on the theoretical level the notion of “paradigm” in the sense of Kuhn and, on the methodological level, Foucault’s notion of “apparatus” to understand volcanic risk management practices. Through an interdisciplinary approach, combining management, geography and Earth sciences, we study the evolution of volcanic risk management practice in Arequipa (Peru) from the 1990s to the present. To do this, we look at the history of volcanic risk management in Arequipa, using a qualitative interview methodology based on six in-depth centered interviews from the main actors of this history, supported by a 2-month ethnography which allowed access to large institutional documentation (reports, studies, archives, maps, pictures...). Management practices in Arequipa appear to be centered on the paradigm of vulnerability since the 1990s. Some operations since 2015 named as resilient emerge but they are still inscribed in the vulnerability paradigm. The results show the relevance of the theoretical and methodological framework chosen for Arequipa but also the possibility of using it in a more general way.

There is a global trend to reduce emissions from cars through the adoption of other alternatives, such as electric vehicles (EVs). The increasing popularity of EVs has led to a growing demand for electric vehicle chargers. EV chargers are essential for charging the batteries of EVs. Since the EV charger stays connected to the grid for long periods of time to charge the EV battery, it must be able to handle disturbances in the power grid. The goal of this paper is to present an overview of the impact of grid events on EV battery chargers. As well as the impact of grid unbalances on EV chargers, this paper also provides an overview of the impact of grid faults on other, similar power electronics interfaced resources such as PV and energy storage systems.

Microgrids represent a promising energy technology, because of the inclusion in them of clean and smart energy technologies. They also represent research challenges, including controllability, stability, and implementation. This article presents a dSPACE-control-platform-based implementation of a fixed-switching-frequency modulated model predictive control (M2PC) strategy, as an inner controller of a two-level, three-phase voltage source inverter (VSI) working in an islanded AC microgrid. The developed controller is hierarchical, as it includes a primary controller to share the load equally with the other power converter with its own local modulated predictive-based controller. All details of the implementation are given for establishing the dSPACE-based implementation of the control on a dSPACE ds1103 control platform, using MATLAB/Simulink for the controller design, I/O implementation and configuration with the embedded dSPACE’s real-time interface in Simulink, and then using the ControlDesk software for monitoring and testing of the real plant. The latter consists of the VSI operating with LCL filters, and sharing an RL load with a paralleled VSI with exactly the same controller. Finally, the obtained experimental waveforms are shown, with our respective conclusions representing this work, which is a very valuable tool for helping microgrid researchers implement dSPACE-based real-time simulations.

To reduce the torque ripple in motors resulting from the use of conventional direct torque control (DTC), a model predictive control (MPC)-based DTC strategy for a direct matrix converter-fed induction motor is proposed in this paper. Two new look-up tables are proposed, these are derived on the basis of the control of the electromagnetic torque and stator flux using all the feasible voltage vectors and their associated switching states. Finite control set model predictive control (FCS-MPC) has then been adopted to select the optimal switching state that minimizes the cost function related to the electromagnetic torque. Finally, the experimental results are shown to verify the reduced torque ripple performance of the proposed MPC-based DTC method.

Deciduous trees are well known for controlling solar gains in buildings, contributing to energy savings in a sector that consumes 35% of global energy. However, there is still a lack of information about the real thermal impact that deciduous trees have. This work proposes a new method that is cheap and easy to implement to quantify the shading efficiency of different types of deciduous trees in hot seasons. The results can be applied in energy evaluations of buildings. The trees selected belong to the central valley of Chile, which is characterized by hot summers and cold winters. The trees selected can also be found in other parts of the world. A spectrometer is used for measuring the amount of solar radiation (irradiance) that is present in the shadow of trees, measuring wavelengths between 339 nm and 750 nm (mostly within the visible light range). The full referential irradiance spectrum of the site is obtained by calibrating the standard ASTM G-173-03. At the site, the spectrometer is used to obtain the visible light range, while the infrared radiation (IR) and ultraviolet (UV) radiation ranges are obtained from the literature. Our results indicate that the analyzed deciduous trees reduce an average of 82% of the solar radiation. This information will help project designers during the building energy efficiency design phase by representative modeling of the solar radiation gains allowed by deciduous trees.

Pulsed electrolysis has become a promising research topic in recent decades due to advances in solid-state semiconductor devices. These technologies have enabled the design and construction of simpler, more efficient, and less costly high-voltage and high-frequency power converters. In this paper, we study high-voltage pulsed electrolysis considering variations in both power converter parameters and cell configuration. Experimental results are obtained for frequency variations ranging from 10 Hz to 1 MHz, voltage changes from 2 V to 500 V, and electrode separations from 0.1 to 2 mm. The results demonstrate that pulsed plasmolysis is a promising method for decomposing water for hydrogen production.

The effects of partial shading or dust accumulation on the panels of photovoltaic systems connected to the grid can generate a considerable reduction in energy performance, being necessary to provide the appropriate voltage to the grid regardless of the irradiance level. This paper addresses this problem and presents a comprehensive control strategy and its implementation for a grid-connected microinverter composed of a push–pull converter followed by an H-bridge inverter. In the push–pull converter, a hybrid MPPT algorithm and a PI control enable work in the MPP of the PV panel. In the H-bridge inverter, a cascade control consisting of a PI control and a predictive control allows the connection to the grid. A proof-of-concept prototype is implemented in order to validate the proposal. Experimental tests were performed by connecting the microinverter to a PV panel and a programmable photovoltaic panel emulator to check the MPPT performance. Furthermore, partial shading conditions were simulated on the dc source to check if the global maximum power point is reached. Experimental results demonstrate the feasibility of the topology and the control approach, obtaining MPPT performance in the topology above 99% at different power and voltage levels on the MPPT, even in the presence of partial shading conditions.

Software Defined Networking (SDN) is a communication alternative to increase the scalability and resilience of microgrid hierarchical control. The common architecture has a centralized and monolithic topology, where the controller is highly susceptible to latency problems, resiliency, and scalability issues. This paper proposes a novel and intelligent control network to improve the performance of microgrid communications, solving the typical drawback of monolithic SDN controllers. The SDN controller’s functionalities are segregated into microservices groups and distributed through a bare-metal Kubernetes cluster. Results are presented from PLECS hardware in the loop simulation to validate the seamless transition between standard hierarchical control to the SDN networked microgrid. The microservices significantly impact the performance of the SDN controller, decreasing the latency by 10.76% compared with a monolithic architecture. Furthermore, the proposed approach demonstrates a 42.23% decrease in packet loss versus monolithic topologies and a 53.41% reduction in recovery time during failures. Combining Kubernetes with SDN microservices can eliminate the single point of failure in hierarchical control, improve application recovery time, and enhance containerization benefits, including security and portability. This proposal represents a reference framework for future edge computing and intelligent control approaches in networked microgrids.

This article presents a sub-module topology for switched DC source cascaded multilevel inverter configurations that require fewer switching devices and can generate a high number of voltage levels that are suitable for renewable energy sources. The proposed sub-module topology comprises eight semiconductor switches and four DC voltage sources that generate fifteen voltage levels. Furthermore, the cascaded topology is presented to increase the output voltage levels and to minimize the number of components. The proposed sub-module inverter and its cascaded topology are compared with several multilevel inverters to indicate the advantages and drawbacks of the proposal. The comparison studies show that the proposed topologies require fewer switching devices and gate drivers in comparison with other multilevel inverter topologies. In addition, the proposed cascaded topology reduces the cost of the inverter when compared to other multilevel inverter configurations. Furthermore, the power loss calculations and the implementation of the proposed topology in grid-connected photovoltaic applications are simulated and analyzed. Finally, the performance of the proposal is verified by simulation and experimental results for both symmetric and asymmetric sub-module topologies as well as for the proposed cascaded topology.

A variable-speed predictive torque control (PTC) of a six-phase induction machine (SPIM) fed by a multi-modular matrix converter (M-MMC) is presented in this paper. This new system inherits the advantages of both multiphase machines (i.e., inherent fault-tolerance and better distribution of the power/current per phase compared to three-phase machines) and the M-MMC (i.e., smaller size and weight, and has no bulky storage elements). In addition, with the M-MMC topology, it is possible to use two power generation sources of different characteristics instead of a single three-phase source. This article proposes a method that reduces the number of calculations significantly compared to conventional PTC to overcome this issue. Simulation and experimental results are provided for speed control, module failure performance and tolerance to the variation of the magnetization inductance of the SPIM. An experimental test bench on a customized SiC-Mosfets based M-MMC and a 5.5 kW symmetrical SPIM has been used.

Finite Set Model Predictive Control (FS-MPC) is a widely used technique in power electronic converter applications. One challenge in FS-MPC implementation is selecting appropriate weighting factors, as there is currently no established methodology for finding the best values. An alternative approach is to consider cost functions without weighting factors, as used by the Sequential Model Predictive Control (SMPC). In this paper, the performance of SMPC applied to induction motors is analyzed. The SMPC strategy involves sequentially evaluating simple cost functions by considering a limited number of available switching states for the power electronic converter. This number is the control parameter of the SMPC. The parameter’s domains and a selection criteria based on THD were established in this investigation. The power converter topologies studied include the Voltage Source Inverter (VSI) and the Neutral Point Clamped three-level (3L-NPC). Simulations performed in PLECS software and Hardware-in-the-Loop (HIL) tests using an RT Box for valid parameters satisfy the characteristics of the classical predictive control, such as good control variables tracking and high dynamic response. For a VSI converter, increasing the control parameter results in reduced harmonic distortion, while for an NPC converter, optimal results are achieved with control parameter values within a specific range.

In this paper, a fixed-switching-frequency modulated model predictive control (M2PC) is established for a two-level three-phase voltage source inverter (VSI) working in an islanded AC microgrid. These small-scale power systems are composed by two or more VSIs which interface DGs, controlling the voltage amplitude and frequency in the system, and simultaneously sharing the load active and reactive power. Generally, these operational characteristics are achieved using hierarchical linear control loops, but with challenging limitations such as slow transient reaction to disturbances and high proneness to be affected by parameter modifications. Model predictive control may solve these issues. Nevertheless, the most used and developed predictive control scheme, the finite-set model predictive control (FS-MPC), presents the drawback of having the harmonic spectrum spread over all the frequencies. This brings issues with coupling between the different hierarchical control levels of the whole microgrid system, and eventually, when designing the filters for main-grid connection. This paper aims to solve these issues by developing the fixed-switching-frequency M2PC working with higher-level control loops for operation in an islanded AC microgrid. These advantages are proved in an AC microgrid configuration where methodology for paralleling multiple M2PC-regulated VSIs is described, with rapid transient response, inherent stability, and fully decentralised operation of individual VSIs, achieving proper load power sharing, eliminating circular currents, and proper waveforms for output currents and capacitor voltages. All these achievements have been confirmed via simulation and experimental verification.

This article reviews the main methodologies employed for the optimal location, sizing, and operation of Distributed Generators (DGs) and Energy Storage Systems (ESSs) in electrical networks. For such purpose, we first analyzed the devices that comprise a microgrid (MG) in an environment with Distributed Energy Resources (DERs) and their modes of operation. Following that, we examined the planning and operation of each DER considered in this study (DGs and ESSs). Finally, we addressed the joint integration of DGs and ESSs into MGs. From this literature review, we were able to identify both the objective functions and constraints that are most commonly used to formulate the problem of the optimal integration and operation of DGs and ESSs in MGs. Moreover, this review allowed us to identify the methodologies that have been employed for such integration, as well as the current needs in the field. With this information, the purpose is to develop new mathematical formulations and approaches for the optimal integration and operation of DERs into MGs that provide financial and operational benefits.

Power electronic devices play an important role in energy conversion. Among the options, matrix converters, in combination with predictive control, represent a good alternative for the power conversion stage. Although several reviews have been undertaken on this topic, they have been conducted in a non-systematic manner, without indicating how the studies considered were chosen. This paper presents results from a systematic literature review on predictive control applied to matrix converters that included 142 primary papers, which were selected after applying a defined protocol with clear inclusion and exclusion criteria. The study provides a detailed classification of predictive control methods and strategies applied to different matrix converter topologies. Research findings require to be understood in combination to develop a common understanding of the topic and ensure that future research effort is based on solid premises. In light of this, this study identifies and characterizes different predictive control techniques and matrix converter topologies through systematic literature review. The results of the review indicate that interest in the area is increasing. A number of open questions in the field are discussed.

Due to no dc-link energy storage element in the matrix converter (MC), its input and output performances are highly sensitive to the unbalanced grid conditions. In order to mitigate the adverse effects of the unbalanced grid voltages, this paper proposes a simple and effective control strategy based on the finite-control set model predictive control (FCS-MPC). In this case, an extended instantaneous power theory is adapted to generate the source current references. As a result, both sinusoidal source currents and balanced output currents are ensured. Besides, complicated positive and negative sequence decomposition is avoided. Furthermore, an extended state observer (ESO) is designed to eliminate the grid voltages sensors, which not only estimates the grid voltages but also provides the delayed grid voltage information required for the source current reference calculation. The effectiveness of the proposed method is verified by the simulation and experimental results.

The use of controlled power converters has been extended for high power applications, stacking off-the-shelve semiconductors, and allowing the implementation of, among others, AC drives for medium voltages of 2.3 kV to 13.8 kV. For AC drives based on power cells assembled with three-phase diode rectifiers and cascaded H-bridge inverters, a sophisticated input multipulse transformer is required to reduce the grid voltage, provide isolation among the power cells, and compensate for low-frequency current harmonics generated by the diode-based rectifiers. However, this input multipulse transformer is bulky, heavy, and expensive and must be designed according to the number of power cells, not allowing total modularity of the AC drives based on cascade H-bridges. This study proposes and evaluates a control strategy based on a finite control set-model predictive control that emulates the harmonic cancellation performed by an input multipulse transformer in a cascade H-bridge topology. Hence, the proposed method requires conventional input transformers and replaces the three-phase diode rectifiers. As a result, greater modularity than the conventional multicell converter and improved AC overall input current with a THD as low as 2% with a unitary displacement power factor are achieved. In this case, each power cell manages its own DC voltage using a nonlinear control strategy, ensuring stable system operation for passive and regenerative loads. The experimental tests demonstrated the correct performance of the proposed scheme.

The use of renewable energies sources is taking great importance due to the high demand for electricity and the decrease in the use of fossil fuels worldwide. In this context, electricity generation through photovoltaic panels is gaining a lot of interest due to the reduction in installation costs and the rapid advance of the development of new technologies. To minimize or reduce the negative impact of partial shading or mismatches of photovoltaic panels, many researchers have proposed four configurations that depend on the power ranges and the application. The microinverter is a promising solution in photovoltaic systems, due to its high efficiency of Maximum Power Point Tracking and high flexibility. However, there are several challenges to improve microinverter’s reliability and conversion efficiency that depend on the proper control design and the power converter design. This paper presents a review of different control strategies in microinverters for different applications. The control strategies are described and compared based on stability, dynamic response, topologies, and control objectives. One of the most important results showed that there is little research regarding the stability and robustness analysis of the reviewed control strategies.

This paper proposes an active and reactive power control strategy based on predictive control approaches applied to gridconnected renewable energy systems. To accomplish this a multi-modular matrix converter topologies are used in combination with a simple but efficient grid synchronization strategy. The theoretical performance analysis is performed considering a six-phase wind energy generator system interconnected with the grid. Results based on a MATLAB/Simulink simulation environment are discussed and the most relevant characteristics of the proposed control technique are highlighted considering the total harmonic distortion and the mean squared error as a parameters of performance.

Power converters are essential for the use of renewable energy resources. For example, a photovoltaic system produces DC energy that is transformed into AC by the voltage source inverter (VSI). This power is used by a motor drive that operates at different speeds, generating variable loads. Two parameters, namely, resistance and inductance are essential to correctly adjust the model predictive control (MPC) in a VSI. In this paper, we describe the data from a VSI that incorporates an MPC. We generate four datasets consisting of 399 cases or instances (rows) each one. Two data set comprises the simulations varying the inductance (continuous and discrete versions) and the other two varying the resistance (continuous and discrete versions). The motivation behind this data is to support the design and development of nonintrusive models to predict the resistance and inductance of a VSI under different conditions. Keywords: Voltage source inverter data, Nonintrusive monitoring, High dimensional machine learning

The operation of single-phase Modular Multilevel Converter (MMC) is analyzed in the paper. A mathematical model of the converter is developed and described, based on which the structure and selection of parameters for Classical Control and Optimal Switching State Model Predictive Control (OSS-MPC) are defined. Additionally, the procedure for the determination of circuit parameters, such as submodule capacitance and arm inductance, is described and carried out. The listed control methods are designed and evaluated in Virtual Hardware-in-the-Loop together with single-phase MMC power circuit, regarding three control objectives: AC current control, voltage balancing control and circulating current control. Control methods are evaluated for both steady-state and transient performance and compared based on nine criteria: AC current reference tracking, THD of AC current and voltage, submodule capacitor voltage balancing, total submodule voltage control, circulating current magnitude and THD, number of control parameters and computational complexity. This is the first time that a fair comparison between Classical Control and MPC is considered in literature, resulting in superior performance of both control methods regarding four different criteria and the same performance regarding AC current reference tracking.

The single-phase matrix converter is an AC-AC power topology which consists of six bidirectional switches and it is considered the key unit in cascade or multilevel configurations. In this paper, a comparison between two control techniques is presented, one based on a proportional-integral-derivative control module with a pulse width modulator, and the other known as finite-state model predictive control. Simulation and experimental results are presented and discussed to demonstrate the feasibility and performance of both techniques.

In this paper, a ‘k’-state inverter producing a higher number of voltage levels was designed, and we studied the inverter’s working. Further, a tri-state inverter was derived from the ‘k’-state inverter, which could build a maximum number of output voltage levels with the requirement of fewer components, thereby reducing the cost and size. A single Tri-state architecture generates three direct current (D.C.) voltage levels; therefore, cascading five tri-state architectures can generate 242 levels of DC voltages. Further, the inversion is done via the H bridge, which leads to 485 levels of the output voltage. Algorithms to design the amplitude of voltage sources and the generation of pulses are discussed in this paper. The proposed tri-state inverter takes a significant role in advancing renewable energy systems in utilizing inverter technology. A simulation study validated the operation of the proposed inverter. Moreover, an experimental setup was built for a single-phase 485-level inverter, and the structure’s performance was verified through the experimental results.

The aim of the study was to determine the genotype of 15 ESBL strains of Enterobacteriaceae resistant to beta-lactams, isolated from inanimate surfaces and phenotypically characterized as producing extended-spectrum beta-lactamase. After evaluation and screening of the bacterial strains, a PCR was conducted to amplify fragments of 1078 bp and 544 bp corresponding to type TEM and CTX-M ESBL. Eleven strains presented both fragments at the time and only three had blaCTX-M. In conclusion, the presence of ESBL genes in cultures from the environment was demonstrated, some of which may belong to more than one type. This information could serve as a basis for implementing preventive measures to prevent the transmission of multiresistant bacteria from inanimate surfaces to patients, mainly in critical hospital areas.

Microgrids need control and management at different levels to allow the inclusion of renewable energy sources. In this paper, a comprehensive literature review is presented to analyse the latest trends in research and development referring to the applications of predictive control in microgrids. As a result of this review, it was found that the application of predictive control techniques on microgrids is performed for the three control levels and with adaptations of the models in order to include uncertainties to improve their performance and dynamics response. In addition, to ensure system stability, but also, at higher control levels, coordinated operation among the microgrid’s components and synchronised and optimised operation with utility grids and electric power markets. Predictive control appears as a very promising control scheme with several advantages for microgrid applications of different control levels.

Distributed generation systems are emerging as a good solution as part of the response to the world’s growing energy demand. In this context multi-phase wind generation systems are a feasible option. These systems consist of renewable AC sources which requires efficient and controlled power conversion stages. This work proposes a novel predictive current control strategy that takes advantage of a multi-modular matrix converter topology in the power stage of a six-phase generation system. The proposed method uses a coupling signal between the modules to decrease the error and the total harmonic distortion compared to independent control of each module. Experimental results validate the new control strategy showing the improvement regarding the target parameters.

The bidirectional switch (Bi-Sw) is a power device widely used by power conversion systems. This paper presents a novel modular design of a Bi-Sw with the purpose of providing to beginner researchers the key issues to design a power converter. The Bi-Sw has been designed in modular form using the SiC-MOSFET device. The Bi-Sw uses the advantages of SiC-MOSFET to operate at high switching frequencies. The verification of the module is carried out experimentally by means of the implementation in a voltage regulating converter, where performance analysis, power losses, and temperature dissipation are performed.

This paper introduces an approach that applies a digital sampling technique for a sinusoidal pulse width modulation (SPWM) multilevel inverter modulation that reduces the total harmonic contents in the output voltage compared to that of classical regular sampling techniques. This new modulation emulates with a high degree of fidelity a natural sampling pulse width modulation (PWM). The theoretical analysis of this new digital technique compared with natural sampling has been validated by simulations and through experiments with a built prototype that performed five−level inverter modulations with vertically displaced carriers in phase disposition. Both simulation and experimental results generate a SPWM output voltage with higher fidelity than classic regular sampling techniques, allowing a reduction of the filtering demands on the inverter output, which in turn can decrease the converter size and its manufacturing costs. As the presented technique is digital, the resulting modulation is more robust against switching noise, jitter, and other system perturbations and the modulation parameters can be changed easily, even in an automated way. For this reason, the modulation introduced here can be a useful tool to perform spectral analysis for different multilevel modulations and systems.

In applications such as multiphase motor drives, classical predictive control strategies are characterized by a variable switching frequency which adds high harmonic content and ripple in the stator currents. This paper proposes a model predictive current control adding a modulation stage based on a switching pattern with the aim of generating a fixed switching frequency. Hence, the proposed controller takes into account the prediction of the two adjacent active vectors and null vector in the ( α - β ) frame defined by space vector modulation in order to reduce the (x-y) currents according to a defined cost function at each sampling period. Both simulation and experimental tests for a six-phase induction motor drive are provided and compared to the classical predictive control to validate the feasibility of the proposed control strategy.

Pulse width modulation (PWM) strategies for the control of asymmetrical six-phase drives have been widely studied since the beginning of this century. Nevertheless, space vector modulation (SVM) techniques with multifrequency voltage injection for the control of all the degrees of freedom of the multiphase model is still a subject under research. This paper deals with this topic and introduces a generalised PWM method for a two-level voltage source converters. The architecture was derived by extending a three-phase modulator proposed as an alternative to the widely studied SVM. The proposal computes the duty times straightforwardly with a fast algorithm based on an analytical solution of the voltage-time modulation law. Theoretical derivations supported by experimental results demonstrate the proper synthesis of the multifrequency target voltage in the linear modulation region as well as good frequency behaviour of the presented modulation strategy.

OBJETIVO: Comparar un kit ELISA comercial para coproantígenos y la técnica de sedimentación espontánea en tubo (TSET) para el diagnóstico de Giardia lamblia en muestras fecales de niños de una zona endémica peruana. MATERIAL Y MÉTODOS: Fueron analizadas 174 muestras mediante la TSET y el kit Giardia 2nd Generation ELISA. RESULTADOS: Fueron positivas 51 muestras por ELISA y 49 por TSET. CONCLUSIONES: El ELISA resultó ser altamente sensible y específico, sencillo y rápido; sin embargo, la muy buena concordancia, alta precisión, bajo costo y capacidad para detectar otros enteroparásitos hace que la TSET sea recomendable para el diagnóstico en zonas endémicas del Perú.OBJETIVE: To compare a commercial coproantigen ELISA kit and the technique of spontaneous sedimentation in tube (TSET) for the diagnosis of Giardia lamblia in fecal specimens from children in a Peruvian endemic area. MATERIAL AND METHODS: 174 fecal samples were analyzed by TSET and 2nd Generation Giardia ELISA kit. RESULTS: 51 samples were positive by ELISA and 49 by TSET. CONCLUSIONS: The ELISA was highly sensitive and specific, simple and fast. However, the very good agreement, high precision, low cost and ability to detect other intestinal parasites makes use of TSET recommended for laboratory diagnosis in endemic areas of Peru.

Objetivos: Identificar enterobacterias en reservorios intrahospitalarios, evaluar su sensibilidad a betalactámicos y determinar su capacidad de producir betalactamasas de espectro extendido (BLEE), en el Hospital Regional de Cajamarca. Material y métodos: Se obtuvieron muestras mediante hisopado de grifos, lavatorios, mesas, camas y tablillas de historia clínica en las áreas de cirugía y pediatría; se recuperaron, aislaron e identificaron 45 cultivos de importancia clínica: 14 Enterobacter cloacae, 11 Escherichia coli, 5 Citrobacter freundii, 4 Klebsiella pneumoniae y 11 de otros géneros. Se determinó la sensibilidad antimicrobiana a los antibióticos betalactámicos: ampicilina, cefalotina, cefoxitina, ceftazidima, cefotaxima, ceftriaxona, amoxicilina-clavulanato, aztreonam e imipenem. Teniendo en cuenta los diámetros críticos de tamizaje, se realizó el test confirmatorio para BLEE. Para el análisis estadístico se utilizó el programa estadístico SPSS v15. Resultados: De los 45 cultivos aislados 34 fueron resistentes a ampicilina, 34 a cefalotina, 14 a cefoxitina, 12 a cefotaxima, 11 a ceftriaxona, 5 a ceftazidima, 19 a amoxicilina-clavulanato y 15 a aztreonam. Doce cultivos presentaron resistencia por BLEE a cefalosporinas de tercera generación y/o monobactámicos, cuatro E. coli y cuatro E. cloacae fueron los más relevantes. Todos fueron sensibles a imipenem. Conclusiones: Dada la capacidad de algunos de estos cultivos de producir BLEE existe el riesgo de brotes intrahospitalarios que pueden complicarse cuando son originados por microorganismos multirresistentes. La producción de BLEE como mecanismo de resistencia en los cultivos hallados debe ser motivo de preocupación por las implicancias que tiene.(Rev Med Hered 2011;22:69-75).