ABSTRACT. This work addresses the observer design for linear hybrid systems, which are eventually observable when some linear system does not fulfill the typical observability propositions. Nevertheless, it is possible to establish an observer design. The present article proposes a method for detecting the real eigenvalues contained in the output of each linear system. In the proposed method, each linear system is decomposed into a Jordan form, then entered into an algorithm that determines the real eigenvalues of the measured output.

ABSTRACT. Point cloud object classification has many challenges related to the quality of the data used to perform the task. The quality of the data is related to the sensor calibration, data acquisition methodology and noise or perturbances on the measurement process. It is required for real time practical applications a solution that performs well even with medium quality data. In this paper, it is presented the design and implementation of a geometric convolutional system that works using the mathematical framework of conformal algebra to reduce the impact of having object point clouds that are incomplete, occluded, or noisy, which causes deformations on the objects to classify. We accomplish this by designing three preprocessing layers in our convolutional system, that use conformal geometric space to perform transformations of the input cloud point: a mapping from 3D to conformal space, a search for the best object perspective and an adjustment of the distance between sampling planes that describe the object.

ABSTRACT. The Internet of Things (IoT) is a technological paradigm which has the capability to interconnect electronic devices capable of communicating machines to machines, machines to people and people to people. These devices are useful in industry to monitor the health of machines in production lines in order to avoid down-times. These down-times can cost a great deal of money. In this paper, we present the develop of an IoT System to detect promptly incipient failures of the machines which operate in lines production for the automotive industry. Particularly for the automotive industry which manufacture electrical harnesses. In this paper, we propose the ESP32 NodeMCu V2 module for the monitoring the health conditions for Komax Alpha 550 cutting machine. The IoT architecture allow to connect our IoT System with the Andon System.

ABSTRACT. Generally speaking, design methodologies are system oriented. To the best of our knowledge theres is not a design methodology for IoT systems in the application domain of agriculture. The closest methodologies were conceptualized for broader areas such as software engineering, network design, cyber-physical systems, and IoT from a cross and indepentent domain perspective. Initial steps have been done to provide specific design methodologies for other domains including Industry 4.0, health and intelligent transportation systems. However, as expected they only capture and address the specifics of their domain. We believe that the same engineering design approach should be followed for the other IoT domains. In this paper we propose a design methodology for IoT Systems in the application domain of agriculture.

ABSTRACT. Speech recognition is a common task in various everyday user systems; however, its effectiveness is limited in noisy environments such as moving vehicles, homes with ambient noise, mobile phones, among others. This work proposes to combine deep learning techniques with domain adaptation and filtering based on Wavelet Transform to eliminate both stationary and non-stationary noise in speech signals in automatic speech recognition (ASR) and speaker identification tasks. It demonstrates how a deep neural network model with domain adaptation, using Optimal Transport, can be trained to mitigate different types of noise. Evaluations were conducted based on Short-Term Objective Intelligibility (STOI) and Perceptual Evaluation of Speech Quality (PESQ). The Wavelet Transform (WT) was applied as a filtering technique to perform a second processing on the speech signal enhanced by the deep neural network, resulting in an average improvement of 20% in STOI and 9% in PESQ compared to the noisy signal. The process was evaluated on a pre-trained ASR system, achieving a general decrease in WER of 14.24%, while an average 99% accuracy in speaker identification. Thus, the proposed approach provides a significant improvement in speech recognition performance by addressing the problem of noisy speech.

ABSTRACT. An alternative to estimate the actual resonant frequency in induction heating systems is presented. The output current is measured and processed by a digital device in order to obtain the amplitude of the first and third harmonic components. The proposed analysis and solving equation rely on the equivalent impedance relationship at two different frequencies. Sampling rates in the signal processing are discussed while simulation results show the feasibility of the proposal.

ABSTRACT. This document presents the simulation results of a new inverse kinematics-based controller for path tracking applied to a mobile robot, specifically a car-like robot. The control law design addresses the limitations of steering rotation and the limited speed of the robot. It also takes into account that the reference point is located at an arbitrary position inside or outside the robot’s body. The trajectory is obtained through a planning process that takes into consideration the limitation in steering rotation. In this context, the simulations demonstrate excellent performance of the controller both in steering control and robot velocity.

ABSTRACT. This paper presents the application of a Super Twisting Controller (STC) based on state and disturbance observers that allow the efficient operation of the boost converter under load variations. The state estimation allows the elimination of sensors in the system which reduces its cost, while the perturbation estimation allows through a rearrangement of the system to adjust to changes in the converter load. A STC is proposed to reduce the chattering in the control signal since a high value, outside permissible limits, leads to deterioration of the actuators. A Lyapunov stability analysis of the proposed observer-based controller is performed. Finally, to verify the proper operation of the proposed scheme, simulation tests are presented and the results are compared with a conventional technique based on PI-controllers.

ABSTRACT. The evolution of modern electrical networks, with bidirectional power flow and interconnected renewable energy sources, presents challenges for traditional automatic capacitor banks in effectively correcting the power factor. In some scenarios, industrial installations may experience nearly zero power consumption periods due to high power generation levels. As a result, the steps in automatic banks can become disproportionately large, making it difficult to achieve proper compensation. To address this issue, a proposed 63-level asymmetric capacitor bank offers a high-resolution solution without discharge resistors and reduced transients. By significantly increasing the number of steps, the bank provides greater resolution in power factor correction, even during periods of near-zero power consumption. Its intelligent startup systems enable controlled connection and disconnection, eliminating the need for discharge resistors and minimizing voltage and current transients. This adaptive solution ensures improved power factor correction and network stability in industrial settings with fluctuating power generation and consumption. Moreover, the bank's ability to accommodate bidirectional power flow and interconnection of renewable energy sources, such as photovoltaic panels, further enhances its suitability for modern electrical grids.

ABSTRACT. This paper shows the Takagi-Sugeno convex compensator design for a class of nonlinear system, that consist of liquid level system of a two-tanks interconnected for which the levels are controlled through two electro-valves, by means of the convex controller; for the purpose of further work to perform fault diagnosis, the design of a Takagi-Sugeno convex observer is tested. The gain scheduling functions used are Gaussian Functions. For the stability analysis of the linear subsystems and the computation of the compensator gains, the interior point method is used in the solution of Linear Matrix Inequalities (LMI's), including a proposal to bound the gains. The contribution of the present work is that the design of the compensator was successfully tested in real-time experimentation using Arduino-Matlab and in simulation in Matlab-Simulink.

ABSTRACT. Power-voltage characteristic curves are a widely used tool for determining voltage stability margins in a power system. They are typically used for steady state and offline studies, for system expansion objectives and voltage collapse evaluation; however, the higher growth in load demand and insufficient infrastructure to transmit energy, has caused the voltage collapse phenomenon to be common in power grids. In this regard, this article presents the performance of the pseudo arc length continuation power flow method, for the tracing of PV curves in an industrial controller in real time. The objective is to evaluate whether current industrial devices have the ability to perform the tracing of PV curves and, consequently, use this power system analysis tool in real time. The performance evaluation of the continuation method is performed on a SEL- 3555, for the 39 buses benchmark of New England. In addition, to prove the reliability of the results, a comparison is made with professional simulation software such as PSS/E.

ABSTRACT. This paper presents a methodology to design under-frequency load shedding (UFLS) schemes in power systems, which is supported by transient studies of critical contingencies related to primary load/generation imbalances that deplete the system primary reserve. The load shedding and frequency set points of each stage related to the UFLS scheme are determined based on the power system inertial and primary responses. The present methodology can be applied to power grids with both conventional and intermittent renewable generation power plants. To showcase the usefulness of the developed UFLS scheme, this was implemented in PSS/E Explore v35 and applied to the 39-bus New England test system including two renewable power plants.

ABSTRACT. This paper presents the application of a time-domain (TD) method for the solution of equations of discrete equivalent models. This approach consists in the substitution of a discrete equivalent Norton model (DNEM) for electric components, which allows obtaining a reduction through companion-circuit branches. The companion-circuit branch is obtained from numerical integration rules, e.g. backward Euler (BE) and trapezoidal rule (TR). This formulation is based on companion-circuit analysis (CCA). The CCA is of general application regardless of the size of the system and consists of algebraic equations, whose solution can be obtained by sparse matrix factorization using a LU decomposition process. The efficiency of the sparse CCA-BE-LU and CCA-TR-LU methods is demonstrated through the determination of the periodic steady-state solution of small, medium and large-scale power systems under different states of operation, such as harmonic distortion and the presence of faults. These methods allow fast and accurate, computational solutions, whose performance is compared against the obtained results with the PSCAD/EMTDC® simulator.

ABSTRACT. In this article, the commissioning of an Intellirupter by S&C Electric Company in the medium voltage network of a primary distribution feeder belonging to the Electric Company Azogues, is explained. The feeder 124, operating at 22kV with a maximum demand of 2.04MVA, has been taken as a case study. The commissioning of the equipment was carried out after coor- dinating protections based on fault parameters, parameterizing the different analog and digital signals to be controlled, and integrating it into the SCADA system of the Electric Company. By implementing this equipment, it is expected to reduce power supply interruption times and improve reliability indices. These results will be reflected in the long term through a comparative analysis with historical FMIK and TTIK indices.

ABSTRACT. In this paper, we consider the problem of voltage regulation of a proton-exchange membrane fuel cell (PEMFC) connected to an uncertain load through a boost converter. We show that, in spite of the inherent nonlinearities in the current-voltage behavior of the fuel cell (FC), the voltage of an FC/boost converter system can be regulated with a simple proportional-integral (PI) action designed following the passivity-based control (PBC) approach. We show that for all positive values of the controller gains, the voltage converges to its setpoint. An Immerse & Invariance parameter estimator is afterward proposed which enables the voltage regulation of the PI passivity-based control when the load varies.

ABSTRACT. In this paper the simulation of a mechanical coupled of two permanent magnet machines is realized, one of them acts as a traction machine in a traction system, the other one generates the opposite torque according to the vehicle electric dynamic equation. Although the regenerative braking system is a trend in electric traction systems, a dynamic braking system is simulated because this paper does not contemplate the bidirectional DC/DC converter for regenerative braking. Additionally, the mathematical model of the permanent magnet machine is obtained, allowing to apply the field-oriented control, moreover the space vector modulation pulse width technique is applied on the inverters used. Finally, the simulation is done with the SAEJ227 driving cycle that contains a constant acceleration period, a constant speed period and a braking period allowing obtain the vehicle behavior on these stages, showing the results as the speed response, the opposite torque developed by the electric vehicle emulator and the action of the dynamic brake.

ABSTRACT. This paper presents a comparative analysis of transformerless power converters based on the conventional fullbridge converter. The comparison is aimed at Transformerless converters to mitigate leakage ground currents in PV systems. The converters compared in this paper are the H5, HERIC, and DD-Buck converters, which are controlled under three different modulation schemes to evaluate their performance indexes. The main performance indices analyzed in this work are efficiency, Total Harmonic Distortion in current and voltage, and Leakage Ground Currents. Finally, experimental and numerical results are performed to assess the proposed study.

ABSTRACT. In this paper, the design of a control strategy for DC battery charger employing a high-gain boost converter is presented. The electronic converter topology used for battery charging is composed of two inductors activated by two power switches. Hence, the power converter achieves a high-gain output voltage compared with the traditional boost converter. The control scheme proposed is based on the charging profile constant current-constant voltage; thus, the control law is divided into two feedback loops. During the constant current stage, a proportional-integral control law provides adequate current tracking injection, while the battery voltage increases to reach a desired reference value. During the constant voltage stage, the control objective is to guarantee a constant output voltage; meanwhile, the battery current decreases to a minimum value. Finally, in order to evaluate the proposed control scheme performance, numerical results are presented.

ABSTRACT. This work presents the development of a small signal model for buck-boost four port DC-DC converter (BB-FPC), which can be used to integrate distributed energy sources (DES) and energy storage systems (ESS). This converter integrates four ports, three for sources and one for an isolated load. Power flow between the sources is bidirectional allowing them to work as sources or sinks to integrate storage systems, which are controlled by two duty cycles and a phase angle. The manuscript presents a small-signal model that describes the interaction between the three controllable inputs and the voltage and currents in each port.

ABSTRACT. Data-driven, reduced-order models of power system frequency control are becoming important analytics tools to obtain fast assessments of dynamic security in power systems. However, these models are commonly associated with low precision in terms of representing more complex phenomena, such as intentional islanding or load and generation shedding schemes. In this way, its applicability to predict or study extreme frequency events has been questioned. This work presents a data-driven algorithm to represent load/generation shedding events using a reduced-order model of frequency dynamics. The applicability of the model is examined by considering an actual case of a cascade load/generation shedding event in the Chilean power system.

ABSTRACT. This paper adopts a methodology to assess and rank the severity of the most frequent disturbances, 3 types in particular, that occur in the Mexican Interconnected System (MIS) when wind power plants (WPPs) are integrated. This is done by combining three stability indices from which an overall performance measure can be derived. In this way, it is possible to assess the severity of the disturbances such as generation tripping, line tripping and disconnection of loads. The indices under consideration include measures such as maximum amplitude, speed variation, and the Lyapunov exponent. For ranking the severity, a general index value is used. To confirm the effectiveness and performance of the proposed methodology, this paper investigates the 190-bus and 46-generator MIS equipped with an 8 % of wind generation to quantitatively evaluate the severity of disturbances, resulting in 66 % of unstable disturbances which are associated with the disconnection of loads.

ABSTRACT. This paper adopts a power system stabilizer (PSS) con- trol structure-based design method to damp out inter-area modes in power systems through non-conventional equipment such as static Var compensator (SVC) and wind turbine generator (WTG). The PSS controller is designed using up to 2 lead/lag stages and is tuned by making stable all trajectories of the dominant modes. Compar- isons of different combinations of feedback signals and actuator control actions are exhibited achieving different damping levels. The correct operation of the controller is analyzed when both actua- tors are added to the system, thus the oscillatory mode is mitigated in case of large disturbances, adding up to 20% of damping. Small- signal analysis (SSA) and time domain simulations are provided to evaluate the effectiveness of the controller under disturbances

ABSTRACT. Power Hardware in the Loop (P-HIL) systems and Battery Energy Storage Systems (BESS) are essential tools in the transition to a more sustainable and efficient energy matrix. These systems work together to analyze the integration of intermittent renewable energy sources to improve the stability and reliability of electrical grids. This, in turn, contributes to the reduction of greenhouse gas emissions and the development of a low-carbon economy. This paper presents an experimental working platform and real-time simulation based on P-HIL technology and scaled power electronics prototypes. The platform allows the analysis of the interaction of BESS devices in electrical distribution grids. A case study is presented to demonstrate the combination of two main qualities of a BESS: improving voltage stability and reducing peak demand. To this end, an experimental 1 kW BESS consisting of a Dual Active Bridge (DAB) and a Voltage Source Converter (VSC) is connected to a 13-bus IEEE distribution network. The attained results demonstrate the ability of the platform to bridge two areas of electrical engineering and highlight its significant advantages.

ABSTRACT. This work presents the design and implementation of a low-cost current source based on power electronics for testing a power current relay. The topology for the system considers a three-phase two-level inverter working as three individual half- bridge single-phase converters. Additionally, a passive filter based on the LCL topology mitigates the high-frequency components of the current signals. The inverter uses the wide bandgap transistors GaN (Gallium Nitrite) type, which allows working with high efficiencies and switching frequencies to achieve low values passive components. The validation for the proposal considers experimental testing, taking quality measurements of the current signals, and testing the power relay SEL-451, by setting the protections 50 and 51.

ABSTRACT. Social Human-Robot Interaction is a research field focused on studying how should be the behavior of a robot when sharing the environment with human users. This way, the socially appropriate motion in mobile robots is an important objective to achieve in control tasks such as autonomous navigation, simultaneous localization and mapping, person-following robot, and so on. Thus, this paper presents some simulation results of our strategies to achieve the socially acceptable robot motion under the task of the person-following robot from the control theory point of view. A differential drive mobile robot with an onboard camera is used to model the task. The simulation results show a good performance when the proposed task is achieved.

ABSTRACT. The deep of hypnosis regulation has been studied for several years to help and assist the anesthesiologist in various general surgery processes. The present contribution presents a scheme for automating this process considering the infusion of two drugs, remifentanil, and propofol, as control variables and the bispectral index as the output variable. A description of virtual compartment-based dynamical modeling for both drugs is presented. Using this model, a proposal for closed-loop regulation based on a discrete model predictive control is presented. The proposed algorithm is tested in twelve virtual male patients, where the controller simulates and rejects two types of disturbances.

ABSTRACT. sEMG (surface electromyography) is the de-facto biopotential medical instrumentation solution for non-invasive detection of limb motion EMG activation signals, which in turn provides important information regarding intentional and reactive muscle activity. Thus, sEMG data analysis plays an essential role in rehabilitation. However, sEMG delivers information of electrical activity mainly due to superficial muscles over a wide sensing field. Additional physiological processes may be elucidated by combining sEMG data with other measurements, such as Electrical Impedance Tomography (EIT) imaging, to assess muscular activity due to increased vascularization of the muscle. In particular for multimodal measurement systems and, as with any biomedical instrumentation system, the sensing electrode array influences the quality of data measured and requires careful examination of the signal properties to be studied in order to select the appropriate type of electrode set. It is common to find that “wet”, AG/AgCl electrodes are used for sEMG measurements, whereas “dry”, (i. e. stainless steele, copper-nickel) electrodes are preferred for electrical impedance measurements since the conducting layer of wet sensors introduces a low-pass filter effect in the β-dispersion frequency range. Here, the authors examine sEMG data obtained for electrodes of different materials in comparison with the preferred Ag/AgCl sEMG electrodes, towards selecting a multimodal wearable measurement setup for assessment of upper limb motion. sEMG data was obtained for 10 healthy volunteers. The datasets were analyzed using STFT (Short Time Fourier Transform), PCSA (Principal Component Spectral Analysis) for PCR (Principal Component Regression and PLSR (Partial Least Squares Regression). The results indicate that Steele Electrodes perform closer to the preferred Ag/AgCl electrodes.

ABSTRACT. Abstract—Cervical cancer is one of the leading causes of cancer-related deaths in women worldwide. Despite advances in early detection and treatment, it remains a significant public health issue, especially in countries with limited resources. Cervical cytology, such as the Pap smear, has been a fundamental tool in the early detection of cervical lesions and the prevention of cervical cancer. However, the accurate and reliable detection of abnormal regions in cytological samples can be challenging, especially in cases of low-quality and low-definition images. In the field of cervical cytology, precise detection of regions of interest is crucial for the early and effective diagnosis of cervical cancer. In this study, we propose the use of the Difference of Gaussians method to enhance blob detection in cytological samples. This method allows for the identification and delineation of areas of interest, even in images with poor quality and definition. By adjusting the values of the standard deviation, the detection sensitivity can be tailored to the specific characteristics of each sample. This promising methodology has the potential to significantly improve the diagnostic process and contribute to earlier and more accurate detection of cervical cancer.

ABSTRACT. Both the transition from grid-tied mode (GTM) to islanded mode (ISM), denoted as GTM-ISM transition, and the transition from ISM to GTM, denoted as ISM-GTM transition, are one of the main topics in AC electrical microgrid (MG) research. Within the MG, the grid-forming power converter (GFRC) is responsible to carry out both the GTM-ISM and ISM-GTM transitions. Usually, the GFRC includes a power supply source at the DC bus; in most cases, this DC source is a battery pack. In abnormal mains conditions, the MG must operate in ISM, then, the GFRC uses the battery power to generate the voltage at the point of common coupling (PCC) during the GTM-ISM transition; in the same way, the GFRC uses the power from the battery pack to sustain the PCC voltage during ISM and for synchronizing it when the nominal conditions of the mains are recovered. The transition of MG operating modes with a battery-less GFRC in the literature has not been reported. Thus, this paper presents a control scheme proposal to perform both GTM-ISM and ISM-GTM transitions with a battery-less GFRC. The results showed the capacity of the battery-less GFRC to operate as smart load during both GTM-ISM and ISM-GTM transitions. This battery-less GFRC proposal highlights a contribution within the research of GFRC units, since the GFRC operation has always been reported using a power supply source at the DC bus, mainly battery packs, but not using a battery-less GFRC working as a smart load for the generation of the PCC voltage.

ABSTRACT. In an islanded microgrid, the grid-forming (GFM) converters are used to stablish an AC voltage whereas the grid-following (GFL) converters rely on the formed AC voltage to supply the loads. This paper presents a system consisting of a GFM converter with a battery pack and a GFL converter with a photovoltaic (PV) array. For this work, it is assumed that the microgrid is in islanded mode. The proposed control strategy allowed the GFM converter to form a stable AC voltage, regulate its DC voltage, and simultaneously charge or discharge the batteries without being affected by load changes. An outstanding capability for the GFM converter was proposed as part of the control strategy, which is carrying out the charging of the batteries during islanded mode while the AC voltage is being formed. This is suitable for the case when there is surplus energy in a microgrid, and the demand is less than the available energy. It also enabled the GFL converter to extract the required power from the PV array, for the loads and for the battery charging process. The proposed GFL converter control strategy is simple and easy to implement, avoiding the use of complex PV power extraction algorithms. The simulation tests demonstrated that the microgrid was not significantly affected by load changes nor by fluctuations of irradiance.

ABSTRACT. The main objective of this work is to show how the empirical equation was obtained that quantifies the amount of heat that the cooling unit with mobile elements removes from the drilling fluid (which is the main objective of this device), the amount of heat that is transferred by evaporation of the water contained in the drilling fluid and that mixes with the air, the amount of sensible heat that is transmitted to the air and the amount of heat that is transmitted by convection to the environment. In order to quantify the amount of heat that is transferred by convection to the environment, it was necessary to develop an appropriate equation for the Nusselt number (Nu) as a function of Reynolds (Re) and Prandtl (Pr).

ABSTRACT. A power plant interconnected to the power system must provide reactive power under disturbances or as required by the system operator. Wind parks based on doubly fed induction generators technology can compensate reactive power by voltage control at the wind park terminals from three control modes. This technique is proposed in this paper, in order to the wind park can provide support the voltage of the electrical power system and achieve the reactive power requirements of the Mexican grid code. To this end, different simulations of a 75 MW wind park interconnected to an equivalent power system are carried out, in which different scenarios are used with the three control modes. The results of the simulations are evaluated to verify compliance with the minimum reactive power requirements in agreement with the established of the grid code.

ABSTRACT. With the increasing integration of flexible generation technologies into modern electrical power systems, novel mechanisms and perspectives are essential to ensure system stability. Most flexible generation sources, such as renewable energy systems, are interconnected to the power grid via electronic devices. However, these devices lack inertia, which can lead to grid instability or even collapse during disturbances. In electrical power systems, maintaining stable frequency and voltage is critical. Conventional synchronous generators employ two controls, namely Load Frequency Control (LFC) and Automatic Voltage Regulator (AVR), to keep these parameters within a reliable range. This study focuses on analyzing the interaction between these two controls during system disturbances under low inertia conditions. To address the stability challenges, a virtual inertia control is proposed to provide support to the system. Furthermore, the study examines changes in voltage at the generator terminals following a disturbance, due to the reactive power demand, and evaluates its impact on the LFC control loop. By investigating the interplay of LFC and AVR controls in the presence of disturbances and low inertia conditions, this work contributes to a deeper understanding of maintaining stability in power systems with flexible generation. The findings shed light on the effectiveness of virtual inertia control in enhancing system stability and provide insights into managing voltage variations for improved control loop performance.

ABSTRACT. In this article, electricity demand forecasting is performed by Artificial Intelligence (AI), the technique used was an Artificial Neural Network (ANN). The ANN is created from 2 years of data (17520 hours of operation/supply) of the Mexican National Electric System (SEN), obtained from the system operator (National Energy Control Center, CENACE). In order to increase the accuracy of the network, an exhaustive filtering of atypical values of the raw data was performed. The developed forecasting method was applied to the region of Baja California Sur (BCS), a province of small demand compared to the other areas of the Mexican SEN. The 14-year electricity demand of the region was estimated using ANN. The results obtained are evaluated.

ABSTRACT. This paper shows the settings and evaluation of four protection schemes with four different shunt capacitor bank configurations, also units with external fuses and fuseless. Internal and external faults on shunt capacitor banks (SCB) was taken to evaluate and software PSCAD/EMTDC was used to simulate this. The test systems on this paper are two substations on Mexico electrical system on 23 kV with presence of shunt capacitor banks, called SE Moctezuma and SE Tuzania. The results show critical conditions where protection schemes operate properly. Nevertheless, some scenarios evidence a null operation of protection schemes even with several units or elements faulted. Finally, the evaluation on these schemes demonstrates that methods with voltage operating principle require a less sensitivity than schemes witch current operating principle

ABSTRACT. This work proposes a renewable energy generation system that has a similar behavior has a synchronous generator in terms of reliability in the power supply and inertial response against power changes and grid voltage variations. The main contributions of this work are: (1) the variability absorption by means of a battery energy storage system, whose charge and discharge are determined by a variability calculation algorithm based in Kalman filter estimation, (2) the dynamical modeling of the virtual inertia-based inverter and its corresponding response to power variations and grid voltage disturbance, and (3) the modeling of a nonlinear optimal control for the inertia-based inverter system where the reactive power injection is regulated. Simulations results are presented in order to demonstrate the effectiveness of the proposed methodologies.

ABSTRACT. One of the great challenges of HVDC systems is the protection against short-circuit faults. The propagation of the fault effects in DC systems is faster than in AC networks mainly because to the low resistance, so a new breed of detection algorithms is required, much faster and more effective, with operation times to 10 milliseconds. This work proposes a step-forward scheme to detect and classify high and low resistance pole-to-pole and pole-to-ground short circuit faults in a MMC-HVDC system by combining the use of Voltage Controlled Oscillator (VCO) modules with a smoothing reactor. Case studies to verify the effectiveness of the proposed strategy are performed in PSCAD/EMTDC with a point-to-point HVDC system.

ABSTRACT. This paper analyzes the dynamic contribution of doubly fed induction generator (DFIG) type wind turbine unit and energy storage systems (ESS), using super capacitors (CES) and superconducting coils (SMES) for frequency regulation services of the power system in a regulated environment. A generalized mathematical formulation is developed, which is capable of modeling systems in state space for an unlimited number of areas and devices per area from the parameters of the different devices in an automatic way. The control strategy used is realized through the implementation of a proportional-integral (PI) controller which, besides being simple to implement in the generalized mathematical formulation, has also proven to deliver satisfactory results for frequency control problems. The parameters of PI controllers are tuned to the optimum values using a multiobjective genetic algorithm (GA). The DFIG units considered in this work are presented by means of models with virtual inertia control schemes in order to support frequency regulation. Finally, the behavior of the IEEE 24-buses system under different operating conditions is analyzed, demonstrating that the coordinated action of the ESS/DFIG units in each operating area provides a transient benefit by arresting the initial system frequency dip as well as the power flow deviation on the transmission lines. In addition, the analysis demonstrates that the response of the ESS units is better and faster than that of the DFIG units in damping system oscillations.

ABSTRACT. Single-phase non-isolated photovoltaic inverters are widely used to inject electrical power to the mains. In these systems, the leakage ground current is one of the more important issues to be solved. Several topologies have been proposed and studied during last decade contributing to reduce size, improve the efficiency and presenting solutions to the leakage ground current problem. In this paper, a five-level single-phase inverter topology is proposed. It consists in five power controlled semiconductors and five diodes. The converter operation is derive and a pulse width modulation strategy is particularly proposed. An study regarding efficiency and power losses distribution is also performed. The proposed single-phase transformerless multilevel inverter is validated by means of numerical simulations and the results and characteristics are compared with existing solutions.

ABSTRACT. In this paper, a basic boost converter is analyzed and designed as a characterization system for photovoltaic modules, where the energy generated in the characterization process is recovered in a battery. Under the scenario of photovoltaic application and storage, the steady-state operating condition, voltage conversion ratio, design expressions of passive elements and the converter operation mode are derived. The operation of the converter as a characterization device with energy storage is verified through computational simulations.

ABSTRACT. In this paper the approximate mechanical torque method is developed for the study of a wind farm. The response of that method is compared with the response of a detailed wind farm that consist of four variable speed wind turbines with PMSG technology. The detailed description of the involved models for the aggregation method allows easy implementation on different platforms, such as open source simulators. For comparison purposes, in the aggregated and detailed models, a simulation case study considering variable incident wind speed in each turbine was developed. As a result, time responses demonstrate the functionality of the aggregated model, as well as its easy implementation in a commercial simulation software, and their simulation in the open source Python software.

ABSTRACT. Ground leakage currents can occur in transformerless grid-connected photovoltaic inverter systems, posing safety and performance issues. This paper provides a brief overview of recent research efforts focused on reducing or eliminating ground leakage currents in transformerless grid-connected single-phase voltage source inverters. The main objective of this study is to examine and describe the various methods used, including modifications or proposals for topologies, switching schemes, and filters. The paper aims at offering insights into the progress made to address the problem of ground leakage currents and their mitigation strategies in transformerless grid-connected PV inverters.

ABSTRACT. Power electronics converters that conditions electric power in its DC form, and that are capable of reversing power flow are becoming increasingly essential in a variety of applications such as energy storage systems, electric vehicles, and renewable energy systems. Among them, non-isolated DC-DC bidirectional converters may be simpler and have higher power densities than isolated converters. This is because they do not require a transformer and can consist of a single power stage, making them suitable for applications that do not require a high level of safety or galvanic isolation. The fundamental topology of a non-isolated DC-DC bidirectional converter is derived by replacing the unidirectional switches of a basic converter with bidirectional switches. However, modifications, improvements, and new topologies have emerged aimed at reducing weight, volume, losses, and cost, while increasing reliability and power density. This work reviews and compares some reported bidirectional non-isolated power converter topologies and their applications.

ABSTRACT. Phasor measurement units are widely used for monitoring purposes in power grids. Over the years, different phasor estimation algorithms have been studied to obtain more accurate estimations. Following this path, this paper specializes in developing a real-time phasor estimation via the discrete time Taylor-Fourier transform (DTTFT) implemented through their O-splines on a field-programmable gate array (FPGA) board, based on the finite impulse response structure. A digital Taylor-Fourier filter was designed using the O-splines of the DTTFT to deal with the extraction of the dynamic phasor estimates such as amplitude and phase. The description structure was developed using a multiplier accumulator (MAC) structure, which only uses four embedded 9-bit multiplier elements for an 18-bit input-output resolution. To assess the performance of the system, steady-state and real-event scenarios are analyzed by an FPGA-in-the-loop simulation using the Matlab/Simulink software. The results show that the DTTFT-powered phasor estimator could be successfully described using VHSIC hardware description language (VHDL) code and implemented in a D2-115 board by Intel.

ABSTRACT. La corriente de Inrush es un fenómeno transitorio de baja frecuencia que se presenta por las conmutaciones del transformador, ya sean monofásico o trifásico, así como en transformadores de instrumentación, como los Transformadores de potencial (TP´s). La importancia en el estudio de este fenómeno radica en las grandes magnitudes de corriente que se pueden presentar, ocasionando un mal funcionamiento de la protección diferencial, porque la corriente Inrush puede ser mayor a la corriente nominal hasta diez veces dependiendo del ángulo de incepción, siendo similar a la magnitud de una corriente de falla. En este sentido, la corriente de Inrush es un fenómeno que se presenta en cualquier transformador lo que hace importante su análisis y mitigación y así evitar daños importantes a equipos dentro y en el sistema eléctrico. En este trabajo se lleva a cabo un análisis de la corriente de Inrush en un banco de transformadores trifásico de 9 kVA utilizando la técnica Taylor-Fourier para el análisis del contenido armónico de las señales de corriente.

ABSTRACT. In this paper, a real time simulation based on software in the loop (SIL) of a battery energy storage system (BESS) integrated into the distribution electrical networks is presented. The BESS is used for the active and reactive power control, and as an interface between the battery bank, DC-link and voltage source converter (VSC), generating an independent control of the DC voltage and reactive power in the electrical networks. This system allows a bidirectional power flow, so that it can store energy when the generation exceeds the demand, but if the opposite occurs the energy is supplied. The effectiveness is assessed by complete mathematical model, the simulation results are evaluated using MATLAB-Simulink® (Matlab r2018, Mathworks, Natick, MA, USA) and are validated with the real-time simulator Opal-RT Technologies® (Montreal, QC, Canada).

ABSTRACT. The integration of new sources of electricity generation to the General Distribution Networks (RGD), have meant topological changes in the system, such as the change of direction of current flows, resulting in bidirectional flows, likewise, requirements have been set that must be met when distributed generation units (DG) are connected to distribution systems, one of them is the ability for the unit (DG) to remain connected when a fault occurs. The traditional protection schemes that are operating in radial distribution networks tend not to operate correctly with the presence of (GD) units, since they fail to detect or isolate the fault or may act outside their area of operation. For this reason, it is important to make changes in the protection schemes, which is why a more selective protection is necessary. This paper proposes a protection scheme capable of identifying the magnitude of the fault by means of directional relays in the presence of distributed generation that is designed in the ATP/EMTP platform.

ABSTRACT. Detecting disturbances using digital signal processing methods and techniques that allow the correct extraction of their distinctive characteristics to make the classification more effective is necessary for Power Quality monitoring. But developing an automatic detection system to be applied in smart measurement devices is not a trivial task, especially in obtaining a low computational cost method that can be integrated into hardware, due to the need to coordinate the functions of data acquisition, preprocessing, detection, and data exchange in real-time. It has been demonstrated that FPGA is a sufficiently fast hardware platform that allows the detection of disturbances of transient nature. In this work, a methodology for detection and extraction of the distinctive features of seven simple power quality disturbances based on Discrete Wavelet Transform and methods of energy and RMS values extraction, implemented in real-time using the Xilinx Artix-7 FPGA from Xilinx, is proposed. From implementing the proposed methodology on the hardware platform, the result obtained is an algorithm that allows extracting the distinctive features of the analyzed disturbances, making optimal use of memory and processing resources, which makes this procedure efficient for its implementation in real time.