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Dr. J.C. Hernandez
Electrical Engineering department, University of Jaen, Campus Las Lagunillas, s/n, 23071, Jaen, Spain

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Research Keywords & Expertise

0 Electric Vehicles
0 Power Electronics
0 microgrids
0 Power quality analysis and optimization
0 power systems simulation and analysis

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Electric Vehicles
renewable systems

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Short Biography

J. C. Hernandez received the M.S. degree in Industrial Engineering from the University of Seville (Spain), in 1995 and Ph.D. degree from the University of Jaen (Spain), in 2003. Nowadays he is an Associate Professor since 1995 in the Department of Electrical Engineering, University of Jaen. He is author of more than 50 papers publish in reviews as Journal Citation Reports of Science Citation Index, and has attended multiple conferences and international research meetings.

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Journal article
Published: 27 July 2021 in Energies
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The problem of optimal phase-balancing in three-phase asymmetric distribution networks is addressed in this research from the point of view of combinatorial optimization using a master–slave optimization approach. The master stage employs an improved sine cosine algorithm (ISCA), which is entrusted with determining the load reconfiguration at each node. The slave stage evaluates the energy losses for each set of load connections provided by the master stage by implementing the triangular-based power flow method. The mathematical model that was solved using the ISCA is designed to minimize the annual operating costs of the three-phase network. These costs include the annual costs of the energy losses, considering daily active and reactive power curves, as well as the costs of the working groups tasked with the implementation of the phase-balancing plan at each node. The peak load scenario was evaluated for a 15-bus test system to demonstrate the effectiveness of the proposed ISCA in reducing the power loss (18.66%) compared with optimization methods such as genetic algorithm (18.64%), the classical sine cosine algorithm (18.42%), black-hole optimizer (18.38%), and vortex search algorithm (18.59%). The IEEE 37-bus system was employed to determine the annual total costs of the network before and after implementing the phase-balancing plan provided by the proposed ISCA. The annual operative costs were reduced by about 13% with respect to the benchmark case, with investments between USD 2100 and USD 2200 in phase-balancing activities developed by the working groups. In addition, the positive effects of implementing the phase-balancing plan were evidenced in the voltage performance of the IEEE 37-bus system by improving the voltage regulation with a maximum of 4% in the whole network from an initial regulation of 6.30%. All numerical validations were performed in the MATLAB programming environment.

ACS Style

Oscar Montoya; Jorge Alarcon-Villamil; Jesus Hernández. Operating Cost Reduction in Distribution Networks Based on the Optimal Phase-Swapping including the Costs of the Working Groups and Energy Losses. Energies 2021, 14, 4535 .

AMA Style

Oscar Montoya, Jorge Alarcon-Villamil, Jesus Hernández. Operating Cost Reduction in Distribution Networks Based on the Optimal Phase-Swapping including the Costs of the Working Groups and Energy Losses. Energies. 2021; 14 (15):4535.

Chicago/Turabian Style

Oscar Montoya; Jorge Alarcon-Villamil; Jesus Hernández. 2021. "Operating Cost Reduction in Distribution Networks Based on the Optimal Phase-Swapping including the Costs of the Working Groups and Energy Losses." Energies 14, no. 15: 4535.

Journal article
Published: 30 April 2021 in Electric Power Systems Research
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This paper presents a model for stabilizing multi-terminal high voltage direct-current (MT-HVDC) networks with constant power terminals (CPTs) interfaced with power electronic converters. A hierarchical structure of hierarchical control is developed, which guarantees a stable operation under load variations. This structure includes a port-Hamiltonian formulation representing the network dynamics and a passivity-based control (PBC) for the primary control. This control guarantees stability according to Lyapunov’s theory. Next, a convex optimal power flow formulation based on semidefinite programming (SDP) defines the control’s set point in the secondary/tertiary control. The proposed stabilization scheme is general for both point-to-point HVDC systems and MT-HVDC grids. Simulation results in MATLAB/Simulink demonstrate the stability of the primary control and the optimal performance of the secondary/tertiary control, considering three simulation scenarios on a reduced version of the CIGRE MT-HVDC test system: (i) variation of generation and load, (ii) short-circuit events with different fault resistances and (iii) grid topology variation. These simulations prove the applicability and efficiency of the proposed approach.

ACS Style

Oscar Danilo Montoya; Walter Gil-González; Alejandro Garces; Federico Serra; Jesus C. Hernández. Stabilization of MT-HVDC grids via passivity-based control and convex optimization. Electric Power Systems Research 2021, 196, 107273 .

AMA Style

Oscar Danilo Montoya, Walter Gil-González, Alejandro Garces, Federico Serra, Jesus C. Hernández. Stabilization of MT-HVDC grids via passivity-based control and convex optimization. Electric Power Systems Research. 2021; 196 ():107273.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Gil-González; Alejandro Garces; Federico Serra; Jesus C. Hernández. 2021. "Stabilization of MT-HVDC grids via passivity-based control and convex optimization." Electric Power Systems Research 196, no. : 107273.

Journal article
Published: 25 April 2021 in Electronics
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This paper proposes adaptive virtual inertia for the synchronverter model implemented in a wind turbine generator system integrated into the grid through a back-to-back converter. A linear dynamic system is developed for the proposed adaptive virtual inertia, which employs the frequency deviation and the rotor angle deviation of the synchronverter model as the state variables and the virtual inertia and frequency droop gain as the control variables. In addition, the proposed adaptive virtual inertia uses a linear quadratic regulator to ensure the optimal balance between fast frequency response and wind turbine generator system stress during disturbances. Hence, it minimizes frequency deviations with minimum effort. Several case simulations are proposed and carried out in MATLAB/Simulink software, and the results demonstrate the effectiveness and feasibility of the proposed adaptive virtual inertia synchronverter based on a linear quadratic regulator. The maximum and minimum frequency, the rate change of the frequency, and the integral of time-weighted absolute error are computed to quantify the performance of the proposed adaptive virtual inertia. These indexes are reduced by 46.61%, 52.67%, 79.41%, and 34.66%, in the worst case, when the proposed adaptive model is compared to the conventional synchronverter model.

ACS Style

Walter Gil-González; Oscar Montoya; Andrés Escobar-Mejía; Jesús Hernández. LQR-Based Adaptive Virtual Inertia for Grid Integration of Wind Energy Conversion System Based on Synchronverter Model. Electronics 2021, 10, 1022 .

AMA Style

Walter Gil-González, Oscar Montoya, Andrés Escobar-Mejía, Jesús Hernández. LQR-Based Adaptive Virtual Inertia for Grid Integration of Wind Energy Conversion System Based on Synchronverter Model. Electronics. 2021; 10 (9):1022.

Chicago/Turabian Style

Walter Gil-González; Oscar Montoya; Andrés Escobar-Mejía; Jesús Hernández. 2021. "LQR-Based Adaptive Virtual Inertia for Grid Integration of Wind Energy Conversion System Based on Synchronverter Model." Electronics 10, no. 9: 1022.

Journal article
Published: 22 April 2021 in Electronics
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The problem of the optimal operation of battery energy storage systems (BESSs) in AC grids is addressed in this paper from the point of view of multi-objective optimization. A nonlinear programming (NLP) model is presented to minimize the total emissions of contaminant gasses to the atmosphere and costs of daily energy losses simultaneously, considering the AC grid complete model. The BESSs are modeled with their linear relation between the state-of-charge and the active power injection/absorption. The Pareto front for the multi-objective optimization NLP model is reached through the general algebraic modeling system, i.e., GAMS, implementing the pondered optimization approach using weighting factors for each objective function. Numerical results in the IEEE 33-bus and IEEE 69-node test feeders demonstrate the multi-objective nature of this optimization problem and the multiple possibilities that allow the grid operators to carry out an efficient operation of their distribution networks when BESS and renewable energy resources are introduced.

ACS Style

Federico Molina-Martin; Oscar Montoya; Luis Grisales-Noreña; Jesus Hernández; Carlos Ramírez-Vanegas. Simultaneous Minimization of Energy Losses and Greenhouse Gas Emissions in AC Distribution Networks Using BESS. Electronics 2021, 10, 1002 .

AMA Style

Federico Molina-Martin, Oscar Montoya, Luis Grisales-Noreña, Jesus Hernández, Carlos Ramírez-Vanegas. Simultaneous Minimization of Energy Losses and Greenhouse Gas Emissions in AC Distribution Networks Using BESS. Electronics. 2021; 10 (9):1002.

Chicago/Turabian Style

Federico Molina-Martin; Oscar Montoya; Luis Grisales-Noreña; Jesus Hernández; Carlos Ramírez-Vanegas. 2021. "Simultaneous Minimization of Energy Losses and Greenhouse Gas Emissions in AC Distribution Networks Using BESS." Electronics 10, no. 9: 1002.

Journal article
Published: 09 March 2021 in IEEE Transactions on Power Electronics
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Cascade H-bridge multilevel (CHB-ML) inverters are an attractive alternative for supplying power to ac grids as they have high reliability and offer an acceptable quality of voltage at their output terminals. In order to achieve efficient operation in these CHB-ML inverters, they must work at low switching frequencies. The finite-control set model predictive control (FCS-MPC) scheme is a very intuitive strategy for controlling this type of converter, but traditional FCS-MPC algorithms generally have a steady-state error when operating at low sampling frequencies and/or if there are parameters mismatch in the prediction model, regarding those of the real system. In this paper, a grid-connected CHB-ML inverter that uses an improved FCS-MPC scheme is proposed. The proposed strategy eliminates the steady-state error in an MPC operating at low sampling frequencies and maintains correct operation when a change in the control reference occurs. Experimental results from a grid-connected CHB-ML inverter with three units (seven levels) demonstrate the feasibility of the proposal.

ACS Style

Carlos R. Baier; Roberto O. Ramirez; Esteban Ignacio Marciel; Jesus de la Casa Hernandez; Pedro E. Melin; Eduardo Enrique Espinosa. FCS-MPC Without Steady-State Error Applied to a Grid-Connected Cascaded H-Bridge Multilevel Inverter. IEEE Transactions on Power Electronics 2021, 36, 11785 -11799.

AMA Style

Carlos R. Baier, Roberto O. Ramirez, Esteban Ignacio Marciel, Jesus de la Casa Hernandez, Pedro E. Melin, Eduardo Enrique Espinosa. FCS-MPC Without Steady-State Error Applied to a Grid-Connected Cascaded H-Bridge Multilevel Inverter. IEEE Transactions on Power Electronics. 2021; 36 (10):11785-11799.

Chicago/Turabian Style

Carlos R. Baier; Roberto O. Ramirez; Esteban Ignacio Marciel; Jesus de la Casa Hernandez; Pedro E. Melin; Eduardo Enrique Espinosa. 2021. "FCS-MPC Without Steady-State Error Applied to a Grid-Connected Cascaded H-Bridge Multilevel Inverter." IEEE Transactions on Power Electronics 36, no. 10: 11785-11799.

Editorial
Published: 03 March 2021 in Electronics
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The use of renewable energy sources (RESs) is a need of global society. This editorial, and its associated Special Issue “Grid-Connected Renewable Energy Sources”, offer a compilation of some of the recent advances in the analysis of current power systems composed after the high penetration of distributed generation (DG) with different RESs. The focus is on both new control configurations and novel methodologies for the optimal placement and sizing of DG. The eleven accepted papers certainly provide a good contribution to control deployments and methodologies for the allocation and sizing of DG.

ACS Style

Jesus Hernández. Grid-Connected Renewable Energy Sources. Electronics 2021, 10, 588 .

AMA Style

Jesus Hernández. Grid-Connected Renewable Energy Sources. Electronics. 2021; 10 (5):588.

Chicago/Turabian Style

Jesus Hernández. 2021. "Grid-Connected Renewable Energy Sources." Electronics 10, no. 5: 588.

Journal article
Published: 02 March 2021 in Applied Sciences
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The problem of reactive power compensation in electric distribution networks is addressed in this research paper from the point of view of the combinatorial optimization using a new discrete-continuous version of the vortex search algorithm (DCVSA). To explore and exploit the solution space, a discrete-continuous codification of the solution vector is proposed, where the discrete part determines the nodes where the distribution static compensator (D-STATCOM) will be installed, and the continuous part of the codification determines the optimal sizes of the D-STATCOMs. The main advantage of such codification is that the mixed-integer nonlinear programming model (MINLP) that represents the problem of optimal placement and sizing of the D-STATCOMs in distribution networks only requires a classical power flow method to evaluate the objective function, which implies that it can be implemented in any programming language. The objective function is the total costs of the grid power losses and the annualized investment costs in D-STATCOMs. In addition, to include the impact of the daily load variations, the active and reactive power demand curves are included in the optimization model. Numerical results in two radial test feeders with 33 and 69 buses demonstrate that the proposed DCVSA can solve the MINLP model with best results when compared with the MINLP solvers available in the GAMS software. All the simulations are implemented in MATLAB software using its programming environment.

ACS Style

Oscar Montoya; Walter Gil-González; Jesus Hernández. Efficient Operative Cost Reduction in Distribution Grids Considering the Optimal Placement and Sizing of D-STATCOMs Using a Discrete-Continuous VSA. Applied Sciences 2021, 11, 2175 .

AMA Style

Oscar Montoya, Walter Gil-González, Jesus Hernández. Efficient Operative Cost Reduction in Distribution Grids Considering the Optimal Placement and Sizing of D-STATCOMs Using a Discrete-Continuous VSA. Applied Sciences. 2021; 11 (5):2175.

Chicago/Turabian Style

Oscar Montoya; Walter Gil-González; Jesus Hernández. 2021. "Efficient Operative Cost Reduction in Distribution Grids Considering the Optimal Placement and Sizing of D-STATCOMs Using a Discrete-Continuous VSA." Applied Sciences 11, no. 5: 2175.

Editorial
Published: 17 February 2021 in Sustainability
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Renewable energies increase their participation in the electricity markets year by year

ACS Style

Jesus Hernández; Carlos Baier. Photovoltaic Power. Sustainability 2021, 13, 2123 .

AMA Style

Jesus Hernández, Carlos Baier. Photovoltaic Power. Sustainability. 2021; 13 (4):2123.

Chicago/Turabian Style

Jesus Hernández; Carlos Baier. 2021. "Photovoltaic Power." Sustainability 13, no. 4: 2123.

Journal article
Published: 12 February 2021 in Journal of Energy Storage
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Service complementarity between a frequency containment reserve and PV self-consumption can increase incomes for household-prosumers. Moreover, battery/supercapacitor-based hybrid energy storage systems (HESSs) play a major role. Fitting power and energy management improve HESS performance, and therefore increase the profitability of the asset. Furthermore, component sizing is critical. To achieve both targets, we developed a hybrid meta-heuristic optimization algorithm that deals with the management strategies and sizing. Accordingly, a four-dimensional, non-linear, non-convex, and mixed-integer optimization problem was formulated, and a cost function was minimized by combining the Haar wavelet (WT) transform and the teaching-learning-based optimization (TLBO) method. The algorithm has a flexible design, which is adapted in terms of a number of discrete states to suit input profiles defined according to different time discretizations. The effectiveness of the algorithm was proved by using different data granularity for a PV prosumer in Spain in various service scenarios. The simulations performed in this study reflected both technical and economic impacts. The results suggest that for optimization purposes, high-resolution data should be used to consider the full range of input fluctuations. However, these results largely depend on the service scenario setup. Indeed, in some scenarios, accurate results were obtained by using coarse-grained data, which entailed a lower computational burden. In contrast, in other scenarios, it was preferable to use data with a higher resolution. The optimal combination of services significantly increased the profitability of the asset.

ACS Style

J.C. Hernández; M. Gomez-Gonzalez; F. Sanchez-Sutil; F. Jurado. Optimization of battery/supercapacitor-based photovoltaic household-prosumers providing self-consumption and frequency containment reserve as influenced by temporal data granularity. Journal of Energy Storage 2021, 36, 102366 .

AMA Style

J.C. Hernández, M. Gomez-Gonzalez, F. Sanchez-Sutil, F. Jurado. Optimization of battery/supercapacitor-based photovoltaic household-prosumers providing self-consumption and frequency containment reserve as influenced by temporal data granularity. Journal of Energy Storage. 2021; 36 ():102366.

Chicago/Turabian Style

J.C. Hernández; M. Gomez-Gonzalez; F. Sanchez-Sutil; F. Jurado. 2021. "Optimization of battery/supercapacitor-based photovoltaic household-prosumers providing self-consumption and frequency containment reserve as influenced by temporal data granularity." Journal of Energy Storage 36, no. : 102366.

Journal article
Published: 14 January 2021 in Electronics
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The problem of the optimal placement and dimensioning of constant power sources (i.e., distributed generators) in electrical direct current (DC) distribution networks has been addressed in this research from the point of view of convex optimization. The original mixed-integer nonlinear programming (MINLP) model has been transformed into a mixed-integer conic equivalent via second-order cone programming, which produces a MI-SOCP approximation. The main advantage of the proposed MI-SOCP model is the possibility of ensuring global optimum finding using a combination of the branch and bound method to address the integer part of the problem (i.e., the location of the power sources) and the interior-point method to solve the dimensioning problem. Numerical results in the 21- and 69-node test feeders demonstrated its efficiency and robustness compared to an exact MINLP method available in GAMS: in the case of the 69-node test feeders, the exact MINLP solvers are stuck in local optimal solutions, while the proposed MI-SOCP model enables the finding of the global optimal solution. Additional simulations with daily load curves and photovoltaic sources confirmed the effectiveness of the proposed MI-SOCP methodology in locating and sizing distributed generators in DC grids; it also had low processing times since the location of three photovoltaic sources only requires 233.16s, which is 3.7 times faster than the time required by the SOCP model in the absence of power sources.

ACS Style

Federico Molina-Martin; Oscar Danilo Montoya; Luis Fernando Grisales-Noreña; Jesus C. Hernández. A Mixed-Integer Conic Formulation for Optimal Placement and Dimensioning of DGs in DC Distribution Networks. Electronics 2021, 10, 176 .

AMA Style

Federico Molina-Martin, Oscar Danilo Montoya, Luis Fernando Grisales-Noreña, Jesus C. Hernández. A Mixed-Integer Conic Formulation for Optimal Placement and Dimensioning of DGs in DC Distribution Networks. Electronics. 2021; 10 (2):176.

Chicago/Turabian Style

Federico Molina-Martin; Oscar Danilo Montoya; Luis Fernando Grisales-Noreña; Jesus C. Hernández. 2021. "A Mixed-Integer Conic Formulation for Optimal Placement and Dimensioning of DGs in DC Distribution Networks." Electronics 10, no. 2: 176.

Journal article
Published: 11 January 2021 in Applied Sciences
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The optimal placement and sizing of distributed generators is a classical problem in power distribution networks that is usually solved using heuristic algorithms due to its high complexity. This paper proposes a different approach based on a mixed-integer second-order cone programming (MI-SOCP) model that ensures the global optimum of the relaxed optimization model. Second-order cone programming (SOCP) has demonstrated to be an efficient alternative to cope with the non-convexity of the power flow equations in power distribution networks. Of relatively new interest to the power systems community is the extension to MI-SOCP models. The proposed model is an approximation. However, numerical validations in the IEEE 33-bus and IEEE 69-bus test systems for unity and variable power factor confirm that the proposed MI-SOCP finds the best solutions reported in the literature. Being an exact technique, the proposed model allows minimum processing times and zero standard deviation, i.e., the same optimum is guaranteed at each time that the MI-SOCP model is solved (a significant advantage in comparison to metaheuristics). Additionally, load and photovoltaic generation curves for the IEEE 69-node test system are included to demonstrate the applicability of the proposed MI-SOCP to solve the problem of the optimal location and sizing of renewable generators using the multi-period optimal power flow formulation. Therefore, the proposed MI-SOCP also guarantees the global optimum finding, in contrast to local solutions achieved with mixed-integer nonlinear programming solvers available in the GAMS optimization software. All the simulations were carried out via MATLAB software with the CVX package and Gurobi solver.

ACS Style

Walter Gil-González; Alejandro Garces; Oscar Danilo Montoya; Jesus C. Hernández. A Mixed-Integer Convex Model for the Optimal Placement and Sizing of Distributed Generators in Power Distribution Networks. Applied Sciences 2021, 11, 627 .

AMA Style

Walter Gil-González, Alejandro Garces, Oscar Danilo Montoya, Jesus C. Hernández. A Mixed-Integer Convex Model for the Optimal Placement and Sizing of Distributed Generators in Power Distribution Networks. Applied Sciences. 2021; 11 (2):627.

Chicago/Turabian Style

Walter Gil-González; Alejandro Garces; Oscar Danilo Montoya; Jesus C. Hernández. 2021. "A Mixed-Integer Convex Model for the Optimal Placement and Sizing of Distributed Generators in Power Distribution Networks." Applied Sciences 11, no. 2: 627.

Journal article
Published: 08 January 2021 in Electronics
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Photovoltaic (PV) systems are subject to nearby lightning strikes that can contribute to extremely high induced overvoltage transients. Recently, the authors introduced a 3D semi-analytical method to study the electromagnetic transients caused by these strikes in a PV module. In the present paper we develop an improved model of the PV module that: (a) takes into account high-frequency effects by modelling capacitive and inductive couplings; (b) considers the electrical insulation characteristics of the module; (c) includes the connection to a DC/DC converter. The whole process involves three major steps, i.e., the magnetic-field computation, the evaluation of both common-mode- and differential-mode-induced voltages across the PV module, and the use of the calculated voltages as input to a lumped equivalent circuit of the PV module connected to the DC/DC converter. In such a framework, the influence of the PV operating condition on the resulting electrical stresses is assessed; moreover, the relevance or insignificance of some parameters, such as the module insulation or the frame material, is demonstrated. Finally, results show that the induced overvoltage are highly dependent both on the grounding of the conducting parts and on the external conditions such as lightning current waveforms and lightning channel (LC) geometry.

ACS Style

Alessandro Formisano; Jesus C. Hernández; Carlo Petrarca; Francisco Sanchez-Sutil. Modeling of PV Module and DC/DC Converter Assembly for the Analysis of Induced Transient Response Due to Nearby Lightning Strike. Electronics 2021, 10, 120 .

AMA Style

Alessandro Formisano, Jesus C. Hernández, Carlo Petrarca, Francisco Sanchez-Sutil. Modeling of PV Module and DC/DC Converter Assembly for the Analysis of Induced Transient Response Due to Nearby Lightning Strike. Electronics. 2021; 10 (2):120.

Chicago/Turabian Style

Alessandro Formisano; Jesus C. Hernández; Carlo Petrarca; Francisco Sanchez-Sutil. 2021. "Modeling of PV Module and DC/DC Converter Assembly for the Analysis of Induced Transient Response Due to Nearby Lightning Strike." Electronics 10, no. 2: 120.

Journal article
Published: 09 December 2020 in Electronics
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This paper explores a methodology to locate battery energy storage systems (BESS) in rural alternating current (AC) distribution networks fed by diesel generators to minimize total greenhouse gas emissions. A mixed-integer nonlinear programming (MINLP) model is formulated to represent the problem of greenhouse gas emissions minimization, considering power balance and devices capabilities as constraints. To model the BESS systems, a linear relationship is considered between the state of charge and the power injection/consumption using a charging/discharging coefficient. The solution of the MINLP model is reached through the general algebraic modeling system by employing the BONMIN solver. Numerical results in a medium-voltage AC distribution network composed of 33 nodes and 32 branches operated with 12.66 kV demonstrate the effectiveness of including BESS systems to minimize greenhouse gas emissions in diesel generators that feeds rural distribution networks.

ACS Style

Oscar Danilo Montoya; Walter Gil-González; Jesus C. Hernández. Optimal Selection and Location of BESS Systems in Medium-Voltage Rural Distribution Networks for Minimizing Greenhouse Gas Emissions. Electronics 2020, 9, 2097 .

AMA Style

Oscar Danilo Montoya, Walter Gil-González, Jesus C. Hernández. Optimal Selection and Location of BESS Systems in Medium-Voltage Rural Distribution Networks for Minimizing Greenhouse Gas Emissions. Electronics. 2020; 9 (12):2097.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Gil-González; Jesus C. Hernández. 2020. "Optimal Selection and Location of BESS Systems in Medium-Voltage Rural Distribution Networks for Minimizing Greenhouse Gas Emissions." Electronics 9, no. 12: 2097.

Journal article
Published: 02 November 2020 in Energies
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This paper addresses the voltage stability margin calculation in medium-voltage distribution networks in the context of exact mathematical modeling. This margin calculation is performed with a second-order cone (SOCP) reformulation of the classical nonlinear non-convex optimal power flow problems. The main idea around the SOCP approximation is to guarantee the global optimal solution via convex optimization, considering as the objective function the λ-coefficient associated with the maximum possible increment of the load consumption at all the nodes. Different simulation cases are considered in one test feeder, described as follows: (i) the distribution network without penetration of distributed generation; (ii) the distribution network with penetration of distributed generation; and (iii) the distribution grid with capacitive compensation. Numerical results in the test system demonstrated the effectiveness of the proposed SOCP approximation to determine the λ-coefficient. In addition, the proposed approximation is compared with nonlinear tools available in the literature. All the simulations are carried out in the MATLAB software with the CVX package and the Gurobi solver.

ACS Style

Oscar Danilo Montoya; Walter Gil-González; Andrés Arias-Londoño; Arul Rajagopalan; Jesus C. Hernández. Voltage Stability Analysis in Medium-Voltage Distribution Networks Using a Second-Order Cone Approximation. Energies 2020, 13, 5717 .

AMA Style

Oscar Danilo Montoya, Walter Gil-González, Andrés Arias-Londoño, Arul Rajagopalan, Jesus C. Hernández. Voltage Stability Analysis in Medium-Voltage Distribution Networks Using a Second-Order Cone Approximation. Energies. 2020; 13 (21):5717.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Gil-González; Andrés Arias-Londoño; Arul Rajagopalan; Jesus C. Hernández. 2020. "Voltage Stability Analysis in Medium-Voltage Distribution Networks Using a Second-Order Cone Approximation." Energies 13, no. 21: 5717.

Journal article
Published: 23 October 2020 in Sensors
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Smart meter (SM) deployment in the residential context provides a vast amount of data of high granularity at the individual household level. In this context, the choice of temporal resolution for describing household load profile features has a crucial impact on the results of any action or assessment. This study presents a methodology that makes two new contributions. Firstly, it proposes periodograms along with autocorrelation and partial autocorrelation analyses and an empirical distribution-based statistical analysis, which are able to describe household consumption profile features with greater accuracy. Secondly, it proposes a framework for data collection in households at a high sampling frequency. This methodology is able to analyze the influence of data granularity on the description of household consumption profile features. Its effectiveness was confirmed in a case study of four households in Spain. The results indicate that high-resolution data should be used to consider the full range of consumption load fluctuations. Nonetheless, the accuracy of these features was found to largely depend on the load profile analyzed. Indeed, in some households, accurate descriptions were obtained with coarse-grained data. In any case, an intermediate data-resolution of 5 s showed feature characterization closer to those of 0.5 s.

ACS Style

J. C. Hernandez; F. Sanchez-Sutil; A. Cano-Ortega; C. R. Baier. Influence of Data Sampling Frequency on Household Consumption Load Profile Features: A Case Study in Spain. Sensors 2020, 20, 6034 .

AMA Style

J. C. Hernandez, F. Sanchez-Sutil, A. Cano-Ortega, C. R. Baier. Influence of Data Sampling Frequency on Household Consumption Load Profile Features: A Case Study in Spain. Sensors. 2020; 20 (21):6034.

Chicago/Turabian Style

J. C. Hernandez; F. Sanchez-Sutil; A. Cano-Ortega; C. R. Baier. 2020. "Influence of Data Sampling Frequency on Household Consumption Load Profile Features: A Case Study in Spain." Sensors 20, no. 21: 6034.

Journal article
Published: 14 October 2020 in Electronics
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The problem associated with economic dispatch of battery energy storage systems (BESSs) in alternating current (AC) distribution networks is addressed in this paper through convex optimization. The exact nonlinear programming model that represents the economic dispatch problem is transformed into a second-order cone programming (SOCP) model, thereby guaranteeing the global optimal solution-finding due to the conic (i.e., convex) structure of the solution space. The proposed economic dispatch model of the BESS considers the possibility of injecting/absorbing active and reactive power, in turn, enabling the dynamical apparent power compensation in the distribution network. A basic control design based on passivity-based control theory is introduced in order to show the possibility of independently controlling both powers (i.e., active and reactive). The computational validation of the proposed SOCP model in a medium-voltage test feeder composed of 33 nodes demonstrates the efficiency of convex optimization for solving nonlinear programming models via conic approximations. All numerical validations have been carried out in the general algebraic modeling system.

ACS Style

Oscar Danilo Montoya; Walter Gil-González; Federico Martin Serra; Jesus C. Hernández; Alexander Molina-Cabrera. A Second-Order Cone Programming Reformulation of the Economic Dispatch Problem of BESS for Apparent Power Compensation in AC Distribution Networks. Electronics 2020, 9, 1677 .

AMA Style

Oscar Danilo Montoya, Walter Gil-González, Federico Martin Serra, Jesus C. Hernández, Alexander Molina-Cabrera. A Second-Order Cone Programming Reformulation of the Economic Dispatch Problem of BESS for Apparent Power Compensation in AC Distribution Networks. Electronics. 2020; 9 (10):1677.

Chicago/Turabian Style

Oscar Danilo Montoya; Walter Gil-González; Federico Martin Serra; Jesus C. Hernández; Alexander Molina-Cabrera. 2020. "A Second-Order Cone Programming Reformulation of the Economic Dispatch Problem of BESS for Apparent Power Compensation in AC Distribution Networks." Electronics 9, no. 10: 1677.

Journal article
Published: 13 October 2020 in Sustainability
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In a scenario in which the labour market is increasingly competitive and there is a need to provide students with practical training, Higher Education Institutions (HEIs) must promote the labour integration of students, by building their competences and shaping their skills in accordance with the strategic plans of companies. In the past, cooperation between companies and universities was based on informal agreements. Nowadays, companies are actively involved in the development of educational models. This is not only part of their corporate social responsibility, but also represents a business opportunity. In this context, the research performed to identify collaboration models between companies and HEIs that simplify the integration of training processes in companies is scarce. Therefore, the aim of this research is to identify existing joint educational models between companies and HEIs and to propose a methodology that allows them to select the models most in line with their business. The methodology applies a multi-criteria selection procedure and, in a simple way, enables the businesses to identify how to increase their involvement. Model identification is based on a proposal of common features that uses indicators for involvement quantification. This study selected ten HEI-company cooperation models and subsequently applied the Analytical Hierarchy Process (AHP) method to analyse the level of involvement that these models require of companies. Five models of different involvement levels were selected and detailed by their features.

ACS Style

Angela Medina; Jesus Hernández; Emilio Muñoz-Cerón; Catalina Rus-Casas. Identification of Educational Models That Encourage Business Participation in Higher Education Institutions. Sustainability 2020, 12, 8421 .

AMA Style

Angela Medina, Jesus Hernández, Emilio Muñoz-Cerón, Catalina Rus-Casas. Identification of Educational Models That Encourage Business Participation in Higher Education Institutions. Sustainability. 2020; 12 (20):8421.

Chicago/Turabian Style

Angela Medina; Jesus Hernández; Emilio Muñoz-Cerón; Catalina Rus-Casas. 2020. "Identification of Educational Models That Encourage Business Participation in Higher Education Institutions." Sustainability 12, no. 20: 8421.

Journal article
Published: 20 September 2020 in Sustainability
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Electric vehicles (EVs) presence in the power grid can bring about pivotal concerns regarding their energy requirements. EVs charging behaviors can be affected by several aspects including socio-economics, psychological, seasonal among others. This work proposes a case study to analyze seasonal effects on charging patterns, using a public real-world based dataset that contains information from the aggregated load of the total charging stations of Boulder, Colorado. Our approach targets to forecast and recognize EVs demand considering seasonal factors. Principal component analysis (PCA) was used to provide a visual representation of the variables and their contribution and the correlation among them. Then, twelve classification models were trained and tested to discriminate among seasons the charging load of electric vehicles. Later, a benchmark stage is presented for regression as well as for classification results. For regression models, examined through Mean Absolute Percentage Error (MAPE) and Root Mean Square Error (RMSE), the random Forest provides better prediction than quasi-Poisson model widely. However, it was observed that for large variations in electric vehicles’ charging load, quasi-Poisson fits better than random forest. For the classification models, evaluated through Accuracy and the Area under the Curve, the Lasso and elastic-net regularized generalized linear (GLMNET) model provided the best global performance with accuracy up to 100% when evaluated on the test dataset. The results of this work offer great insights for enhancing demand response strategies that involve PEV charging regarding charging habits across seasons.

ACS Style

Juan Dominguez-Jimenez; Javier Campillo; Oscar Montoya; Enrique Delahoz; Jesus Hernández. Seasonality Effect Analysis and Recognition of Charging Behaviors of Electric Vehicles: A Data Science Approach. Sustainability 2020, 12, 7769 .

AMA Style

Juan Dominguez-Jimenez, Javier Campillo, Oscar Montoya, Enrique Delahoz, Jesus Hernández. Seasonality Effect Analysis and Recognition of Charging Behaviors of Electric Vehicles: A Data Science Approach. Sustainability. 2020; 12 (18):7769.

Chicago/Turabian Style

Juan Dominguez-Jimenez; Javier Campillo; Oscar Montoya; Enrique Delahoz; Jesus Hernández. 2020. "Seasonality Effect Analysis and Recognition of Charging Behaviors of Electric Vehicles: A Data Science Approach." Sustainability 12, no. 18: 7769.

Journal article
Published: 19 September 2020 in Energies
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This paper deals with the problem of the optimal selection of capacitor banks in electrical AC distribution systems for minimizing the costs of energy losses during a year of operation through a discrete version of the vortex search algorithm (DVSA). This algorithm works with a hypersphere with a variable radius defined by an exponential function where a Gaussian distribution is used to generate a set of candidate solutions uniformly distributed around the center of this hypersphere. This center corresponds to the best solution obtained at the iteration t, which is initialized at the center of the solution space at the iterative search beginning. The main advantage of combining the exponential function with the Gaussian distribution is the correct balance between the exploration and exploitation of the solution space, which allows reaching the global optimal solution of the optimization problem with a low standard deviation, i.e., guaranteeing repeatability at each simulation. Two classical distribution networks composed of 33 and 69 nodes were used to validate the proposed DVSA algorithm. They demonstrated that the DVSA improves numerical reports found in specialized literature regarding the optimal selection and location of fixed-step capacitor banks with a low computational burden. All the simulations were carried out in MATLAB software.

ACS Style

Walter Gil-González; Oscar Danilo Montoya; Arul Rajagopalan; Luis Fernando Grisales-Noreña; Jesus C. Hernández. Optimal Selection and Location of Fixed-Step Capacitor Banks in Distribution Networks Using a Discrete Version of the Vortex Search Algorithm. Energies 2020, 13, 4914 .

AMA Style

Walter Gil-González, Oscar Danilo Montoya, Arul Rajagopalan, Luis Fernando Grisales-Noreña, Jesus C. Hernández. Optimal Selection and Location of Fixed-Step Capacitor Banks in Distribution Networks Using a Discrete Version of the Vortex Search Algorithm. Energies. 2020; 13 (18):4914.

Chicago/Turabian Style

Walter Gil-González; Oscar Danilo Montoya; Arul Rajagopalan; Luis Fernando Grisales-Noreña; Jesus C. Hernández. 2020. "Optimal Selection and Location of Fixed-Step Capacitor Banks in Distribution Networks Using a Discrete Version of the Vortex Search Algorithm." Energies 13, no. 18: 4914.

Journal article
Published: 02 September 2020 in Energy Policy
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This paper surveys and assesses the technical and economic features that are crucial in the provision of frequency control services from aggregated household-prosumers. A framework is presented that allows policy makers to accurately assess these services. Furthermore, the role of the service aggregator in the provision from prosumers is outlined, something that highlights the value of the new distributed framework. Also discussed are the key features within the overall context of the design variables in various European countries, which are representative of different synchronous areas. This finding implies that from a regulatory point of view, important efforts are being made to harmonise the different network codes in the investigated countries. Moreover, this research compares the impact of techno-economic design variables on the financial incomes of providing frequency control services. For this purpose, we used a stochastic model of input variables that involves the statistical analysis of time series. A probabilistic method based on Monte Carlo simulation allowed the assessment of the revenues. The outcomes indicate that the RES penetration in each country together with the ratios of the power availability band and of the power availability band activation, and their associated prices are crucial factors that influence the resulting profitability.

ACS Style

A. Lopez; B. Ogayar; J.C. Hernández; F.S. Sutil. Survey and assessment of technical and economic features for the provision of frequency control services by household-prosumers. Energy Policy 2020, 146, 111739 .

AMA Style

A. Lopez, B. Ogayar, J.C. Hernández, F.S. Sutil. Survey and assessment of technical and economic features for the provision of frequency control services by household-prosumers. Energy Policy. 2020; 146 ():111739.

Chicago/Turabian Style

A. Lopez; B. Ogayar; J.C. Hernández; F.S. Sutil. 2020. "Survey and assessment of technical and economic features for the provision of frequency control services by household-prosumers." Energy Policy 146, no. : 111739.