ABSTRACT. Genetic improvement uses computational search to improve existing software with respect to a user-defined objective function, while retaining some existing behavior, usually captured by testing. Work on genetic improvement has already resulted in several awards. This includes work on automated program repair. GI has been used, for instance, to automate the process of software specialization, optimize program efficiency, and to minimize memory and energy consumption. GI has also been used to transplant functionality from one software to another in an automated way. I will give an overview of the genetic improvement area and present key components of a GI framework.

ABSTRACT. This article describes the application of a time-domain (TD) procedure based on companion-circuits analysis (CCA) combined with a Newton method of extrapolation to the Limit Cycle (based on a Numerical Differentiation (ND) process). The particular application is aimed at the dynamic and periodic steady state solution of single-phase distributed generation systems with PV units under harmonic distortion conditions. Fundamentally, the applied methodology is based on the representation of linear elements, using Norton equivalents and non-linear elements as variable resistors. The application determines a set of discrete differential equations obtained by nodal analysis. The associated case study is related to the evaluation of harmonic distortion, in terms of individual and total harmonic distortion (THD) at the point of common coupling (PCC) between the PV system and the electrical system. The results obtained have been validated against the PSCAD/EMTDC® simulator.

ABSTRACT. Traditionally, vulnerability is the level of degradation caused by failures or disturbances, and resilience is the ability to recover after a high-impact event. This paper presents a topological procedure based on graph theory to evaluate the vulnerability and resilience of power grids. A cascading failures model is developed by eliminating lines both deliberately and randomly, and four restoration strategies inspired by the network approach are proposed. In the two cases, the degradation and recovery of the electrical infrastructure are quantified through four centrality measures. Here, an index called flow-capacity is proposed to measure the level of network overload during the iterative processes. The developed sequential framework was tested on a graph of 600 nodes and 1196 edges built from the 400 kV high-voltage power system in Spain. The conclusions obtained show that the statistical graph indices measure different topological aspects of the network, so it is essential to combine the results to obtain a broader view of the structural behaviour of the infrastructure.

ABSTRACT. This article presents a strategy for coordinating directional overcurrent relays (DOCRs) for on-line applications by using non-conventional time curves. The off-line coordination is degraded due to the increase of dynamic conditions by generation and topology changes of the electrical network. In meshed systems, when the same time curve for overcurrent relays is used results in numerous violations of coordination constraints. Instead, when the time curve is determined for each coordination pair non-conventional curves are obtained, this improves coordination times. The Grey Wolf Optimizer (GWO) and Differential Evolution (DE) algorithms have been adapted to solve the highly complex and non-linear optimization problem, a comparison is made between both algorithms to analyze their performance. Tests have been carried out on the IEEE systems and show that the proposal is feasible, obtaining the desired results.

ABSTRACT. This paper presents an analysis of the fault ride through requirements established in some grid codes around the world, that conventional power plants should comply, in order to be able to be connected to the transmission network. It describes the causes of this requirement, the way it is currently applied in most electric utilities, and the effect that power plant auxiliaries have in the assessment of this important characteristic. It was corroborated that auxiliaries have a very important effect in the fault ride-through capability of the power plant, and should be therefore explicitly represented in these studies. In addition, it was observed that, in the way this requirement is currently verified, it can be contradictory to stability criteria, and this requires improving the methods of verifying the fault ride-through capability of the plant, so as to conciliate this aspect with stability criteria.

ABSTRACT. A novel approach is proposed in this paper to calculate the total transfer capability through tie-lines considering the problems of transient stability and short-term voltage stability into a unified framework. From a transiently unstable operating point for a given contingency scenario, a multiobjective transient stability-constrained optimal power flow is proposed to obtain a transiently stable operating point, where the total transfer capability is maximized. The stabilization process is performed by sequentially solving the optimization and the transient stability problems until a suitable generation dispatch is obtained. At the resulting operating point, the system is able to withstand the specified contingency. In this proposal, the multiobjective optimization problem is formulated by using the physical programming method, which allows prioritizing the different objective functions according to the operational needs of the system. Finally, the effectiveness of the proposed approach is demonstrated on the WSCC 3-machine-9 bus test system.

ABSTRACT. A mobile manipulation system is a robotic system consisting of having a manipulator robot mounted on a holonomic or non-holonomic mobile robot. These types of systems provide the dexterity of the manipulator robot and the extension of the mobile robot's workspace and are capable of reaching and working on objects that are initially outside the workspace of the manipulator robot, therefore, these prototypes are attractive to many applications. In this work, the complete kinematic modeling of a mobile manipulation system is carried out, obtained as a result of coupling the kinematic model of an anthropomorphic manipulator robot with three degrees of freedom and a four-wheel mobile robot of differential configuration in which it considers the longitudinal slippage of the wheels as a part of their modeling.

ABSTRACT. Abstract – In this paper, we propose a low-cost arbitrary waveform generator to simulate battery voltage transients specified by ISO 16750-2 voltage profiles. The proposed methodology is based on the technique of direct digital synthesis (DDS) implemented in a microcontroller. The proposed approach allows reducing the amount of Flash memory used by the lookup table. The device generates several types of waveforms and uses a sequencer to combine them into the desired voltage profile. For testing purposes, emulations of the variations on the cranking voltage and the superimposed A.C. voltage are used to validate the proposed solution.

ABSTRACT. Sliding Mode Control is a successful control approach inducing an attractive dynamic condition by switching between control structures. However, switching also induces parasitic dynamics that disturbs its performance with high frequency oscillations becoming a major drawback of being accepted as the common design tools in industry. In this paper, to provide a better understanding of the induction of the sliding condition to improve the control design, the author, reviews the basic ideas behind undesired dynamics and introduces designing criteria for a better performance of the closed loop system, in particular, dynamics of a switched transition and ambiguity of the control action on the thick-less switching surface. Then, the Sliding Surface is introduced as an intermediate control structure defined by the equivalent control, and integrated into a unique soft and continuous controller with the other control structures by a Fuzzy like algorithm, and finally, these improvements are implemented in a simple continuous controller whose description and analysis are included in a companion paper also submitted to this conference. Discussions are based using a second order linear systems as a generic plant containing the main dynamic behaviours -inertia, dissipation and restitution forces- whose simulation shows the suppression of chattering keeping the main properties of the sliding controllers.

ABSTRACT. In a Vegetable and fruit farmers are using new methods to produce more efficiently, and many have adopted the use of temperature and humidity monitoring systems of the ground substrate as well as of the environment. Since data-loggers tend to be expensive and wire systems are not flexible, new flexible wireless monitoring systems have to be developed to improve the greenhouses micro-climate controls. This paper presents a wireless real-time monitoring system based on the XBee protocol. The proposed system allows to sample, to monitor, and to save data of temperature and humidity of the greenhouse environment and ground. A graphical interface which accepts a real-time user monitoring is designed, in which the LabView software was used as development platform. Moreover, a low-cost data-logger is implemented, and data is saved *.txt file that can be later analyzed. The feasibility of the proposed system was experimentally tested and verified in a tomato greenhouse.

ABSTRACT. Sliding Mode Control is a robust approach based on a variable structure controller inducing an exponential attractive behavior that has proved to be an effective design technique for complex electronic and electro-mechanical systems. However, discontinuous control is inherently related to the presence of parasitic dynamics excited by the switching action and its general performance is affected by undesired high frequency oscillations around the sliding surface. In this paper, the author, proposes an improved Sliding Mode controller that preserves the dynamic properties of the Sliding Mode but inducing a continuous convergent flow to the sliding surface without chattering. The proposed controller applies redefined design criteria concerning the control structures and the transition between them by introducing the Sliding surface as an intermediate third control structure with an improved equivalent control and integrating them in a soft and continuous controller. Performance of the close loop system is illustrated with numerical simulation using a Mass/Spring/Damper system as a generic plant and comparing the obtained results with those of the basic Sliding Mode Controller. The aim of this work is to provide control engineers of new ideas about basic concepts of the Sliding Mode Control to improve it as a design technique.

ABSTRACT. This work presents a technique for grape bunches detection within Images. The approach is based on a pixel-wise classification boosted with a morphology operator. Color indices, commonly used for plant segmentation in image processing are proposed here for separating grape pixels from background, along with color components from color spaces. These color features are the input for the classification process. The proposed pipeline achieves an accuracy of 0.928 on images similar to the ones used for training, and 0.887 on images from a different dataset. Finally, we use an area filtering for noise-handling, outputting the grape bunches localization.

ABSTRACT. In recent years, most digital capture devices have been designed with several post capture processing functions such as histogram modulation, based on this an Imperceptible-Visible Watermarking (IVW) scheme has been proposed to deliver auxiliary information and claim the ownership of digital images. In this paper an improved versión of imperceptible-visible watermarking is introduced, where the just noticeable distortion is used in the embedding stage to improve the watermark readability through a novel histogram binarization function in the exhibition stage. The experimental results show that the proposed strategies can improve the performance of several IVW schemes in the context of watermark imperceptibility and readability, which are similar with the most recent IVW schemes reported until now. The benchmarking performance of the proposed strategies is done through of the Peak Signal to Noise Ratio, Structural Similarity Index Measure, and the Bit Error Rate.

ABSTRACT. This paper presents an ontological design to locate learning services semantically, facilitating collaboration, and user customization. A semantic-based online laboratory is presented, which gives students and instructors a common access point to laboratory resources, such as videos, documents, instruments, devices, etc., that can be accessed anytime, anywhere, and which can be customized for user preferences, profile privileges, and access limitations. The use of ontologies is the basic mechanism which allows devices and instruments to be defined semantically, rather than by the use of technical concepts. This model can be used in any teaching laboratory. A case study in a networking course is presented; in this, undergraduate students can remotely control instruments and devices. The effectiveness of our approach has been measured and evaluated through usability methods.

ABSTRACT. A common factor in road accidents is due to inattention in the driving task (drowsiness, distraction, etc.). Therefore, areas such as intelligent transportation systems are in continuous development to provide greater security. An example are the assistance systems that focus on improving occupant safety by merging information from sensors that recognize the environment, processing with methods and algorithms that detect risk situations that are addressed with the activation of actuators and/or recommendations to the driver. This article proposes an assistance system that detects the driver’s inattention level and displays a series of alerts. The system obtains information through computer vision and performs the inference with fuzzy logic, the system is implemented on the embedded NVIDIA Jetson TX2 platform. Real-time experiments show that the proposed system is highly efficient to find drowsiness and alert the driver, obtaining a detection rate > 0.90 and a precision > 0.88.

ABSTRACT. As eye tracking studies are becoming more common, eye behavior is being explored in different scientific fields as it can be analyzed to detect changes in the mental state of users. In this way the development of new products or technologies could include eye tracking as an objective way of obtaining feedback from users. This paper presents an experiment that compares the eye behavior of users' blinks during interaction with two different levels of difficulty in a video game. The results of the experiment show that the participants' blink rate per minute was significantly reduced, according to the state-of-the-art normal blink behavior, during the two tasks. However, it is also shown that there is no significant difference between the samples taken, which is attributable to the fact that interaction with video games, in any difficulty, represents high cognitive load.

ABSTRACT. The solar harvest in static concentration systems is limited by the angle of acceptance which limits the collection time. The increase in acceptance angle usually can only be achieved at the expense of the concentrating factor. Many systems have been proposed using primary and secondary optical systems with different degree of complexity in the optical devices. In this work a double static concentrating system, with a simple geometry, based on a funnel type reflective concentration system with an ontop prism as primary optics is proposed. This device shows an acceptance angle of 60° with an effective maximum concentration factor of 3.3X. The mean optical efficiency is of 66%, having its best performance for incidence angles between ±41:25°, allowing 5.5 hours of use. The design has the additional benefit of its ease to build as it does not have any spherical or parabolic surfaces.

ABSTRACT. The introduction of intermittent Renewable Energy Power Plants based on power converters, such as wind and PV power plants, to Bulk Power Systems has changed the way in which their operation and expansion is being done. The operation and expansion of Bulk Power Systems is carried out based on a series of studies that determine voltage control strategies, transmission limits, reactive compensation needs, etc. The objective of this paper is to evaluate the voltage profile of a power system considering different levels of Renewable Energy Power Plants penetration and their reactive droop control, to determine operation strategies for voltage control across the Bulk Power System.

ABSTRACT. To improve the wind turbine energy yield and strengthen its reliability, the use of robust control strategies is required. This paper presents a robust fuzzy hybrid controller in the context of overcoming the effect of uncertainties in mechanical parameters of a Wind Energy Conversion System (WECS). The WECS is composed of a Doubly-Fed Induction Generator (DFIG). The Field-Oriented Control technique (FOC) is used to separate between the machine’s flux and the machine’s torque control. In order to demonstrate the efficacy of the proposed controller, a comparison between the fuzzy hybrid controller and a classical PI controller has been carried out. The obtained result shows that the proposed controller is faster to reach the steady state and less sensitive to the parameter uncertainties in comparison to the classical PI controller.

ABSTRACT. In this paper, a residential appliance scheduling problem is addressed. Usually, the householders’ main attention is focused on reducing the amount of money put into the energy suppliers’ pocket without affecting the comfort level. The proposed model aims at scheduling the home appliances in such a way the cost and discomfort are reduced. The problem is formulated as a mixed integer linear programming in which the decision variables are the optimal starting time of the appliances. The model is simulated under a day-ahead electricity pricing for three cases: traditional user, smart user, and smart prosumer. Simulation results show that the proposed technique optimally schedules the appliances resulting in reducing the electricity payments and increasing the user’s comfort.

ABSTRACT. In this work a modeling method for photovoltaic (PV) modules based on statistical analysis is presented. In this sense, the work deals with the determination of the parameters of the non-linear I-V equation, represented by the single-diode model. The parameters estimation of the PV model starts with experimental tests on PV panels under different irradiance and temperature conditions. A database is built with the parameters extracted from the family of experimental curves, where mathematical expressions, through linear regression analysis, are obtained to determine electrical variables of interest, such as: Isc, Voc, Im, Vm and Pm which are dependent of irradiance and/or operating temperature. The parameters of the non-linear I-V equation given by the resistances Rsh, Rs and the ideality factor n, the analysis demonstrate that average values are representative; while the light-generated and diode-saturation currents depend on the incident irradiance. The capacity of the models was validated through the analysis of different statistical criteria, such as: the root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE) and the coefficient of determination (R2). The results were accepted for applications where a high precision is not necessary, or for modeling and/or forecasting purposes.

ABSTRACT. Under the occurrence of a critical disturbance that produces a large load-generation imbalance in an electric power system, the primary regulation control may not be sufficient to bound the steady-state error of the frequency deviation within its normal operating range. This also has an effect on the steady-state operational interdependency of multi-energy systems. To overcome this lack of controllability, this paper proposes a new, practical preventive control action for assessing the steady-state interdependency between gas and electricity infrastructures with a feasible control of the frequency deviation. The proposed approach consists of the solution of two mutually connected subproblems: one related to the gas and power flow problem and the other associated with the economic dispatch problem. These two problems are sequentially solved until a feasible equilibrium point is obtained in which the multi-energy system operates with a value of the electrical frequency within limits. The effectiveness of the proposed control action and the validity of the theoretical concepts on which the proposed approach is based are demonstrated numerically in an integrated multi-energy system consisting of a 15-node gas network and 3-bus electrical system.

ABSTRACT. Traditionally, measurements in a power system were obtained only through the Data Acquisition Supervision and Control System (SCADA); Later, Phasor Measurement Units (PMUs) began to be used. The cost associated with the use of PMUs has led to the search for new ways to include PMU measurements in the state estimation process. The state estimator used in this work consists of two stages: in a first stage, the conventional weighted least squares formulation is used and finally, in the second stage, the estimation process is carried out again with the PMU measurements and the vector of estimated states as a result of the first stage. The execution time of the two-stage state estimation algorithm is optimized through the use of Parallel Computing Based on Graphic Processing Units (GPUs). In this paper, a two-stage state estimation algorithm is presented where operations are performed on a CPU-GPU platform. From this approach, a speed-up of 5.74 is achieved with the 1354 bus system.

ABSTRACT. Distributed Flexible AC Transmission System (D-FACTS) devices are a technology derived from Flexible AC Transmission System devices that provide essential benefits in modern power systems. Their most important feature is that they are small devices compared to FACTS devices, and can be attached directly to power lines to control the conductor impedance. Equally important, they increase system reliability as long as the power system has a large number of D-FACTS. Furthermore, they can be manufactured at a low cost from conventional industrial-grade components. This paper presents a review of three different D-FACTS technologies reported in the literature and the equations governing their steady-state behavior. Each device's mathematical model is included in the study of power flow to improve the voltage profile to the adjacent nodes of these devices. The Mexican equivalent network's numerical results demonstrate the correct operation of the D-FACTS devices but with different operating principles.

ABSTRACT. The increasingly tighter interdependency between natural gas and power systems because of the increasing number of natural gas-fired units for electricity production has motivated research on the operational effects associated with this coupling. To evaluate the effects of this interaction, however, the operating status of the integrated gas and electricity networks must first be estimated. Hence, this paper proposes and implements a static state estimator that assesses the operating state of integrated electricity and natural gas networks. The proposed approach is based on the equality-constrained weighted least squares algorithm, which simultaneously upgrades the estimated values of the state variables associated with both energy infrastructures for a unified solution in a single frame of reference. The effectiveness of the proposed approach is demonstrated in a multi-energy system composed of the 20-bus Belgium gas system and a 3-bus electric power system.

ABSTRACT. To reinforce the lack of physical understanding of phenomena and hands-on experience of the software-based power engineering education is necessary that the student get the opportunity to apply as many of the concepts presented in the theoretical and lecture portions of the course as allowable, and acquire some hands-on experience and receive training in practical aspects of the subject. In this way, the problem of the real implementation of a transmission grid is addressed. The objective of this paper is the development of a physical two-areas power system implemented in a real laboratory and equipped with generators, loads, transmission lines, relays, PMUs, and ancillary equipment for educational purposes. All this together makes it possible to study dynamic phenomena with a real small power system. Thus, with this laboratory implementation, electromechanical swings such as inter-area oscillations after some disturbance can be shown. So, this paper focuses on the identification of low-frequency electromechanical modes in power systems giving a mix of laboratory experiments with a software-based algorithm.

ABSTRACT. Capacitive type wireless power transfer systems, CPT, are becoming a suitable alternative to inductive type transfer systems. However, because their research is relatively recent, they have not achieved the power and efficiency levels of their inductive counterparts. To increase power with high efficiencies, feedback loops are used, but achieving adequate stability is problematic since the resonance frequency of this type of wireless system changes with respect to the distance of the capacitive plates, making it difficult to design the controller that could be used. In this work, the use of multi-resonant schemes to stabilize the resonance frequency is proposed. In particular, the analysis of the multi-resonant tank topology modified to compensate the frequency variation of a capacitive type energy transfer scheme is presented.

ABSTRACT. Titanium dioxide (chemical formula TiO2) is a semiconductor that absorbs electromagnetic radiation in the UV region; According to the type of crystallization, different crystalline distributions will be formed (anatase, rutile and brookite) which have significant differences in their chemical, mechanical and electrical properties; The last mentioned property is currently a little-known field of research, however TiO2 is the most widely used photocatalyst and is currently used to degrade various types of pollutants in the medium. In this work, a methodology is designed and implemented to know the electrical behavior of anatase, rutile and brookite crystalline structures; the study is developed from the simulation in Comsol Multiphysic software; Measurements of electrical properties are made with the technique of electrical impedance spectroscopy in a measurement frequency range of 4Hz to 8MHz. During the process, the particular geometric constants for this investigation are obtained, which are essential to obtain reliable results.

ABSTRACT. Fatigue cracks are one of the most common damages encountered in the civil structures. For this reason, early detection of these types of damages can reduce their accumulation in the elements that conform to a civil structure, preventing its possible collapse. In this sense, this work investigates the usefulness of the statistical time features (STFs) for identifying fatigue cracks in a four-story building exposed to dynamic forced excitations. The effectiveness of the proposal is validated under three fatigue crack levels (i.e., light, moderate, and severe damage), which are artificially generated. Results show that the STFs can determine a building exposed to diverse levels of fatigue cracks with high accuracy using only one sensor placed on the structure

ABSTRACT. An antilock braking system is characterized by nonlinear dynamics, which make more difficult to design a controller for high performance. The problem is even harder due to the uncertainties parametrics that appear in its dynamics. In this paper, it is considered an ABS laboratory setup. An Equivalent Control and a Reaching Controller is proposed to overcome the problem due to the parameter uncertainties. This controller is designed in order to impose a reference value of the tire slip. Also, the Equivalent Control and a Reaching Controller is developed and simulated using the mathematical model of the ABS laboratory.

ABSTRACT. The use of the genetic algorithm to obtain the appropriate switching sequence of a multilevel inverter has been increasing during the last years; this algorithm has been implemented through a Matlab solver. However, the choosing of the solver parameters have been by means of trial-and-error or by the user experience. In order to maximize the Matlab genetic algorithm performance, the present work proposes the use of Taguchi design approach to determine the optimal switching sequence of a five-level multilevel inverter to decrease THD in the output voltage.

ABSTRACT. Understandability of class diagrams is a quality attribute that should be evaluated, due to the importance of class diagrams for the design of software products and for product management when continuous improvement is of importance for an organization. However, the evaluation of class diagrams is a difficult task if the understandability concept itself is not understood. Furthermore, software products most of the times are evaluated after the system is finished. This work proposes an understandability quality model that is reusable, extensible and customizable. It may be used as a guide to evaluate the class diagrams before starting the implementation phase of software systems. After the validation of the model, it was found that the model is highly prescriptive so areas for improvement in the class diagrams are detected straightforward.

ABSTRACT. Sensory parameters are crucial for making a purchase decision in meat products. Thus, consumers will guide their choice based on its color. They will seek cherry red meat; when the meat turns brown due to oxidation of the myoglobin, the product is no longer desired. Therefore, it is crucial for the food industry to have a system that could be effective and give just-intime information regarding changes in color to maintain quality during the shelf life that consumers expect. This research has as an objective to present a methodology based on computer vision for analyzing the change of color in meat. We used images taken of different beef cuts and tested on different days. The Euclidean distance on the average of colors could be used. However, the method proposed in this study is the use of Kullback Leibler divergence, which takes the meat not only at one color point but as a cloud of points. The results were obtained with Kullback Leibler divergence demostrated that it is possible to calculate differences in meat images when passing the days. The practical application for this type of analysis would be in the retail industry in order to give just in time information about the quality of meat.

ABSTRACT. Discrete cosine transform (DCT) is commonly used in image and video compression. DCT approximations are excellent alternatives to reduce the computational complexity of exact DCT with good coding performance.In this article we review and compare some of the most interesting multiplication-free approximations in the literature and their hardware cost.

ABSTRACT. Currently the Institute of Standards and Technology (NIST) goes in the second round of the standardization process of asymmetric key post-quantum cryptographic schemes. Such schemes are said to be resistant to attacks from quantum computers. With this, the need to start experimenting and implementing with these schemes has arisen. Nowadays, there is a variety of post-quantum cryptographic schemes libraries written in different programming languages and compiled for different architectures. However, in order to a programmer can integrate them into an Android application, it is necessary to compile the source code, perform the integration and test the integration. As a consequence it is not possible to have a ready-to-use library. Based on the aforementioned, in this paper we present the design of a post-quantum scheme library for Android operating system that has the characteristic to be ready-to-use. Moreover, obtained results shows our library has the three main aspects that make a library good.

ABSTRACT. This work presents an analysis of four regression systems. Two of them are statistical: the widely used Auto-regressive Integrated Moving Average (ARIMA) and the state-of-the-art Facebook Prophet. From deep learning, a Long Short-Term Memory (LSTM) Recurrent Neural Network (RNN) is evaluated, and an optimized Nearest Neighbor model is used as a machine learning approach. The study is carried out over seventeen benchmarks; fifteen coming from M4-Competition and two more power systems time series i.e., electricity demand, and hydropower generation. For all the models, the regression systems are fitted and optimized with a focus of minimizing user intervention. The results show that deep learning models obtained the best performance; nonetheless, the performance difference is not statistically significant with the rest of the systems tested.

ABSTRACT. This paper presents a robust stability study of a DC nanogrid considering parametric variations, where the system was simplified using the impedance approaches. For the stability analysis, the uncertainties were incorporated into the simplified system under the representation of nonstructured uncertainties, because the impedances change due to the parameters variations. The results point to a way to ensure the robust stability of the overall system.

ABSTRACT. Technological advances have reduced the installation costs of large quantities of photovoltaic solar generation, motivating the penetration of distributed generation in order to satisfy the demand for electrical energy. In this sense, the research focuses its interest in the industrial sector, to take advantage of its existing infrastructure, the geographical location of the equatorial zone and the information on the behavior of demand through the use of data analysis techniques and application of models to the forecasting and optimization of the energy and economic resources of the Industry and the Energy Distribution Company.

ABSTRACT. Several technical challenges are presented with the integration of photovoltaic systems into electrical grids, being output power variability due to transient clouds one the most significant issues. In this paper is tested a variability smoothing approach for a grid-integrated multi-megawatt installation which comprises a photovoltaic system and a battery energy storage system. The approach consists of two algorithms: moving average control, which uses a fixed window size to estimate a smooth power curve; and state of charge control, which aims to preserve the storage flexibility and the state of charge close to a reference value. Simulations performed in an OpenDSS-Python environment, using the IEEE 123 Node Test Feeder, demonstrate the effectiveness of the approach and its suitability for impact alleviation of photovoltaic power integration into distribution networks.

ABSTRACT. The main purpose of this article is to propose a novel definition for the remaining useful life of lithium-ion batteries based on the increase of the inefficiencyrelated to the Joule effect due to the growth on the internal impedance f the battery as it degrades. The applied methodology consists in the cycling of a rechargeable lithium-ion cell at different discharge current rates considering and a defined charging protocol. The experiment was conducted inside an environmental chamber allowing a constant ambient temperature of 25 ◦C, and 50% of relative humidity. The results show that even though that heat generation does not increase significantly as the battery degrades, the evolution of the proportional generated heat in time has a notorious increment since the cycles have a shorter duration. As a consequence, the battery experiences a temperature rise according to the ventilation it has. Finally, the proportion of heat generated in time is proposed as a metric to define the remaining useful life of a lithium-ion battery.

ABSTRACT. In photovoltaic systems, it is necessary to have DC-DC converters topologies with wide transformation ranges that they have the ability to provide output voltages greater or less than the supply voltage provided by the PV modules. Other aspect that the converters must satisfies is associated to the new requirements of the load consumption requirements have been standardized to 48V, 24, 12V and 5V for different applications such as LED lighting, battery banks, among others. An additional requirement in these systems is that the power processing by the converter must be carried out as efficiently as possible. This paper proposes to implement a quadratic buck converter based on the concept of R2P2 as an alternative for photovoltaic applications, where the characteristics of the input current demanded to the panels and the reduction of EMI are improved. In this work the description of the system formed by the quadratic buck converter R2P2 with an input filter is presented where are satisfied the requirements of non-pulsating input current and output voltage regulation. In addition, the design procedure of the elements that form the converter is developed, as well as the description of the operating modes during the switching process of the switches.Also, the linear and non-linear models of the converter are presented, as well as some comparative aspects with some reported topologies. The results obtained by simulation and experimental measurements are presented.

ABSTRACT. The development of renewable energy is fundamentally changing the power grid. While the percentage of electricity produced from renewable sources often receives most public and political attention, the underlying physical transformation of the grid is more profound and creates many technological challenges as well as opportunities for electrical engineers. With converter-based generation from wind and solar replacing conventional power plants, the grid is increasingly dominated by converters. Since the best renewable resources are usually at remove locations, new transmission infrastructures are also required to support large wind and solar projects, and HVDC transmission is often preferred because of its ability to work over long distance and to enhance, or black-start the local grid. This combination of converter-based generation and transmission, coupled with converter-based loads such as electronics, motor drives, and electric vehicles, is creating a future grid that is very different from conventional power systems.

This talk gives an overview of the growing applications of converters in power systems, discusses the fundamental differences between converters and machines, and presents a frequency-domain method for stability study of converter-based power systems.