# J. C. HernándezUniversidad de Jaén | UJAEN · Department of Electric Engineering

J. C. Hernández

Ph.D. Industrial Engineering

## About

126

Publications

30,884

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2,144

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Introduction

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 70 papers publish in reviews as Journal Citation Reports of Science Citation Index, and has attended multiple conferences and international research meetings.

## Publications

Publications (126)

Renewable energy and, in particular, solar PV power, will play a crucial role in achieving net-zero emissions scenarios over the coming decades. Increasing the share of renewables in countries’ energy mixes is therefore a major challenge that must be urgently addressed. Within this context, the present work proposes an innovative tool that may acce...

The integration of new renewable power capacity into the grid constitutes an important challenge. Control issues become more complex, and the behavior of the new installations must be carefully assessed. In this sense, countries are establishing strict technical requirements when integrating new generation facilities into networks. Within this fram...

Currently, with the quick increase in global population, the energetic crisis, the environmental problematic, and the development of the power electronic devices generated the need to include new technologies for supporting and potentiating electrical distributions systems; Distribution Static Compensators (D-STATCOMs) are highly used for this task...

Bipolar direct current (DC) networks are emerging electrical systems used to improve the distribution capabilities of monopolar DC networks. These grids work with positive, negative, and neutral poles, and they can transport two times the power when compared to monopolar DC grids. The distinctive features of bipolar DC grids include the ability to...

This paper presents an integrated methodology applied to photovoltaic (PV) plants for improving the dynamic performance of electric power systems. The proposed methodology is based on primary frequency control, which adds an ancillary signal to the voltage reference of the DC-link for the voltage source converter (VSC) in order to reduce power osci...

The optimal integration of photovoltaic generation systems is a challenge for distribution utilities since these devices have a direct impact on company finances due to the large amount of investment required at the beginning of the planning project. In this investigation, the problem regarding the optimal siting and sizing of photovoltaic resource...

Smart meter (SM) deployment in the residential context provides a vast amount of data that allows diagnose the behavior of household inhabitants. However, the conventional methods to analyze household-consumption load profiles based on time-series techniques, such as Fourier and Wavelet transform, have problems with nonlinear and nonstationary proc...

This paper analyzes the power flow solution in bipolar direct current networks with radial structures considering multiple monopolar and bipolar constant power loads. The electrical configuration of the bipolar DC grid considers that the reference pole is non-grounded along the feeder, which produces important neutral currents and voltage imbalance...

This paper contributes with a new two-stage optimization methodology to solve the problem of the optimal placement and sizing of solar photovoltaic (PV) generation units in medium-voltage distribution networks. The optimization problem is formulated with a mixed-integer nonlinear programming (MINLP) model, where it combines binary variables regardi...

This paper discusses the minimization of the total annual operative cost for a planning period of 20 years composed by the annualized costs of the energy purchasing at the substation bus summed with the annualized investment costs in photovoltaic (PV) sources, including their maintenance costs in distribution networks based on their optimal siting...

Nowadays, the development, implementation and deployment of smart meters (SMs) is increasing in importance, and its expansion is exponential. The use of SMs in electrical engineering covers a multitude of applications ranging from real-time monitoring to the study of load profiles in homes. The use of wireless technologies has helped this developme...

The problem of optimal siting and sizing of distribution static compensators (STATCOMs) is addressed in this research from the point of view of exact mathematical optimization. The exact mixed-integer nonlinear programming model (MINLP) is decoupled into two convex optimization sub-problems, named the location problem and the sizing problem. The lo...

The stabilization problem of multi-terminal high-voltage direct current (MT-HVDC) systems feeding constant power loads is addressed in this paper using an inverse optimal control (IOC). A hierarchical control structure using a convex optimization model in the secondary control stage and the IOC in the primary control stage is proposed to determine...

Purpose
The lightning phenomenon is one of the main threats in photovoltaic (PV) applications. Suitable protection systems avoid major damages from direct strikes but also nearby strikes may induce overvoltage transients in the module itself and in the power conditioning circuitry, which can permanently damage the system. The effects on the PV syst...

This paper presents a comparative analysis of six different iterative power flow methods applied to AC distribution networks, which have been recently reported in the scientific literature. These power flow methods are (i) successive approximations, (ii) matricial backward/forward method, (iii) triangular-based approach, (iv) product linearization...

The problem of voltage regulation in unknown constant resistive loads is addressed in this paper from the nonlinear control point of view for second-order DC-DC converters. The converters’ topologies analyzed are: (i) buck converter, (ii) boost converter, (iii) buck-boost converter, and (iv) non-inverting buck-boost converter. The averaging modelin...

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...

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-Hamiltoni...

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...

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, consid...

Conventional power plants that run on synchronous machines are gradually being replaced by renewable generation systems, largely with photovoltaic (PV) solar technology. For the electric power systems, this change implies a reduction in inertia since PV technology does not provide dynamic grid support. This reduction negatively influences the trans...

Nearby lightning strikes are prone to induce overvoltage transients in Photovoltaic (PV) modules and in their power conditioning circuitry, which can permanently damage the PV system. Using a recently introduced 3D semi-analytical method to study the electromagnetic transients caused in PV modules by nearby lightning strikes, we analyse in this pap...

Service complementarity between a frequency containment reserve and PV selfconsumption
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. Furt...

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...

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 fo...

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...

Renewable energies increase their participation in the electricity markets year by year [...]

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-int...

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...

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:...

Combining complementarity services such as frequency containment reserve (FCR) and photovoltaic self-consumption
(PV SFC) can increase revenues for household-prosumers supported by battery/supercapacitor-based hybrid energy
storage systems (HESSs). Nonetheless, to calculate the best financial profitability, optimization algorithms should be
applied...

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, considerin...

Most of the studies that can be found in the literature for analysing self-consumption systems with storage focus on global self-consumption and self-sufficiency indices and it may be very difficult to define the role of the array power and battery. In this sense, a new approach to analysing this type of systems is provided where direct and battery...

Three‐phase electric vehicle (EV) battery chargers are expected to not impact the unbalance of distribution networks; moreover, using active power factor correction topologies they are expected to behave like resistive loads not affecting the system harmonic distortion. In this study, unexpected unbalance characteristics of fundamental and harmonic...

This paper proposes a proportional-integral passivity-based controller (PI-PBC) for supporting voltage in linear loads integrated with Ćuk converters. An adaptive load estimator is also employed to avoid current measurements at the load point. This estimator permits an on-line estimation of the load conductance for maintaining the output voltage as...

This paper explores the controller's design for charging batteries for electric vehicle applications using the direct power representation of the system. These controllers' design is made via passivity-based control (PBC) theory by considering the open-loop port-Hamiltonian representation of the converter. The usage of PBC theory allows designing c...

Nearby Lightning Strikes (LS) are prone to induce dangerous overvoltage transients in Photovoltaic (PV) arrays, which can permanently damage the PV system. A method for the simulation of such transients can help designing suited protections. We propose here a simulation model based on a lumped circuit model of single PV panels, able to estimate the...

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 g...

This study provides a methodology to assess the techno-economic performance of photovoltaic household-prosumers that jointly provide self-consumption/sufficiency enhancement (SCSE) and frequency containment reserve (FCR). It thus addresses the following issues: (i) battery aging; (ii) supercapacitors joined to batteries building hybrid storage syst...

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,...

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 t...

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, thereb...

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, cooperati...

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-worl...

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 w...

This paper deals with the optimal reconfiguration problem of DC distribution networks by proposing a new mixed-integer nonlinear programming (MINLP) formulation. This MINLP model focuses on minimising the power losses in the distribution lines by reformulating the classical power balance equations through a branch-to-node incidence matrix. The gene...

Secondary radial distribution networks (SRDNs) have been increasingly affected by the uncertainties of harmonic
sources associated with photovoltaic (PV) systems. The quantitative assessment of uncertainty propagation causing
harmonic distortion and voltage unbalance can be successively handled by probabilistic or affine formulations of
harmonic lo...

Load and generation variations and the random nature of harmonics in non-linear devices (NLDs) are the source of
multiple uncertainties that can be handled in harmonic load flows (HLFs) by probabilistic or interval formulations. The
paper presents a new combined analytical technique (CAT) for iterative HLFs in the presence of correlated input
uncer...

In this paper, a proportional-integral passivity-based controller (PI-PBC) is proposed to regulate the amplitude and frequency of the three-phase output voltage in a direct-current alternating-current (DC-AC) converter with an LC filter. This converter is used to supply energy to AC loads in hybrid renewable based systems. The proposed strategy use...

This paper presents a methodology for jointly optimizing the sizing and power management of PV household-prosumers, namely, photovoltaic (PV) power, electric vehicle charging load (EVCL), household consumption load (HCL), battery bank (BB), and power converters. The optimization includes PV self-consumption enhancement and frequency containment res...

Solar irradiation that is received on a terrestrial surface at minor scale of an hour does not have many records, since the current solar irradiation databases generally only have data recorded on a daily (most) and hourly (some less) scale. For places where there are no records of solar irradiation, there are a lot of methods that are used to synt...

Abstract: Smart meter roll-out in photovoltaic (PV) household-prosumers provides easy access to granular meter measurements, which enables advanced energy services. The design of these services is based on the training and validation of models. However, this requires temporal high-resolution data for generation/load profiles collected in real-world...

Batteries of photovoltaic (PV) household-prosumers undergo many fast, partial charge/discharge cycles because of the short-term fluctuations of household load and PV profiles. This negatively affects battery lifetime and can increase project cost involving energy storage systems (ESSs). To address this problem, this research developed an innovative...

Nearby lightning strikes are prone to induce overvoltage transients in Photovoltaic (PV) modules and in their power conditioning circuitry, which can permanently damage the PV system. Therefore, it becomes important to establish a method for accurate assessment of such transients. To this aim, we propose a three-dimensional (3D) semi-analytical num...

The main objective of this paper is to compensate power factor using teaching learning
based optimization (TLBO), determine the capacitor bank optimization (CBO) algorithm, and monitor
a system in real-time using cloud data logging (CDL). Implemented Power Factor Compensation and
Monitoring System (PFCMS) calculates the optimal capacitor combinatio...

This paper presents the theoretical model and the simulation of a cutting edge hybrid power system composed of an externally-fired gas turbine (EFGT) coupled with an organic Rankine cycle (ORC) as a bottoming unit for the maximization of electrical power. The power plant is fed with different biomass sources from olive industry wastes (pruning, dry...

The performance of stand-alone photovoltaic (SAPV) systems can be evaluated by monitoring them in the field using data acquisition systems (DASs). Most SAPV systems use battery charge controllers with pulse width modulation (PWM) to regulate the current into the battery. The PWM signals generated by battery charge controllers imply monitoring chall...

Because of vehicle-to-grid (V2G) growth, the provision of ancillary services by V2Gs is now required in the most recent network codes. A lack of primary frequency control (PFC) and dynamic grid support (DGS) in V2Gs could thus be detrimental to power system stability. This research presents a detailed V2G model with a hybrid energy storage system (...

This paper presents a probabilistic method that accurately verifies the fulfilment of voltage constraints in radial distribution systems (RDSs) with photovoltaic (PV) systems and electric vehicle (EV) charging loads. This problem has not been comprehensively discussed. The proposed probabilistic method (PPM) involves the calculation of input variab...

Feeding biomass-fueled gas engines (BFGEs) with olive tree pruning residues offers new
opportunities to decrease fossil fuel use in road vehicles and electricity generation. BFGEs, coupled
to radial distribution systems (RDSs), provide renewable energy and power that can feed electric
vehicle (EV) charging stations. However, the combined impact of...