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Emerging Topics in Power Electronic Converters of Microgrids

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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A1: Smart Grids and Microgrids".

Deadline for manuscript submissions: closed (28 February 2023) | Viewed by 14840

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Special Issue Editors

Prof. Dr. Javier Muñoz Vidal

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Guest Editor

Department of Electrical Engineering, Universidad de Talca, Curicó 3340000, Chile
Interests: digital control of modular multi-level converters to improve power quality and photovoltaic microinverters
Special Issues, Collections and Topics in MDPI journals

Dr. Jaime Rohten

E-Mail Website
Guest Editor

Department of Electrical and Electronic Engineering, Universidad del Bío-Bío, Concepción 4051381, Chile
Interests: renewable energies; digital nonlinear, resonant, and predictive control for voltage or current source converters; microgrids; power converter control
Special Issues, Collections and Topics in MDPI journals

Dr. David Dewar

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Guest Editor

Department of Electrical and Electronic Engineering, The University of Nottingham, Nottingham, UK
Interests: optimal control; microgrid optimisation; system decentralisation and grid identification techniques

Special Issue Information

Dear Colleagues,

Renewable energy (RE) prices have dropped significantly, making it possible for them to be included in microgrids, where now, power converters need to be adjusted in order to properly work under the conditions dictated by microgrids. The main issues of microgrids are due to the low inertia, lower stability, and the bidirectional energy flow, which entails variation on the voltage amplitude and/or frequency for AC or DC lines. Thus, the control of power converters may deal with these disturbances, help to increase the electric system stability, and transform the energy from REs to the network. In addition, the microgrid system’s power quality, reliability, and resilience are achieved by power converters and their respective control. In this context, other aspects need to be considered, such as energy production, power delivery, structure security, special policies, loads capacity to deal with variations on the power supply, and include different types of generators and a combination of them, such as solar, wind, heat, etc.

Thus, this Special Issue aims to present and disseminate the most recent advances in power electronics for microgrids in aspects such as theory, modelling, control, new topologies, and algorithms to make the microgrid system work.

The topics of interest for publication include, but are not limited to, the following:

Power converter modelling for AC, DC, and AC–DC hybrid microgrids;
Power converters control for AC, DC, and AC–DC hybrid microgrids;
New topologies for power converters applied to microgrids;
Grid integration through power electronics;
Storage systems;
Bidirectional DC/DC converters in DC microgrids;
Renewable isolated microgrids;
Power quality, reliability, and resilience;
Trends in power converters;
Predictive control for power converters in microgrids;
Linear control for power converters in microgrids;
Nonlinear control for power converters in microgrids;
Green hydrogen systems;
Trends in solar, wind, and marine energy power system;
Electromobility and their impact on microgrids;
Novel renewable energies and power topologies for microgrid applications.

Prof. Dr. Javier Muñoz Vidal
Dr. Jaime Rohten
Dr. David Dewar
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

microgrids
power converters
renewable energies
microgrids stability
design
control
modelling
new topologies

Related Special Issue

Emerging Directions in Power Converter Control for Renewable Energy Systems and Microgrids in Energies (1 article)

Published Papers (10 papers)

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Research

22 pages, 7668 KiB

Open AccessArticle

Extended Operating Region Algorithm for PV Array Connected to Microgrids for Wide Frequency and Amplitude Variations

by Matías Garbarino, Jaime Rohten, Rodrigo Morales, José Espinoza, Javier Muñoz, José Silva and David Dewar

Energies 2023, 16(7), 3157; https://doi.org/10.3390/en16073157 - 31 Mar 2023

Viewed by 1034

Abstract

The employment of microgrids and distributed power generation have exponentially increased over recent decades, due in part to the increased inclusion of renewable energies as these technologies become cheaper to install. However, microgrids are highly sensitive to power variation, leading to distortion of the grid voltage (amplitude and frequency changes) which could destabilize the entire microgrid under variation of loads and/or other power sources. In this context, a new control strategy is proposed for a photovoltaic grid connected system, operating under voltage variations typical of a low inertial electric power network. The main problem related to voltage fluctuation is that the variables may take the power converter out of the operating region, and therefore, all controllers, including the maximum power point tracking, will not work as designed. The analysis, based on the mathematical operating region, demonstrates that the control strategy can include overmodulation compensation—to overcome problems related to weak microgrids and systems variations—through the addition of smart power factor imposition and DC-link voltage variation in transient time when the variables are far from the nominal values. The proposal is validated through simulation in PSim^®/Matlab^® and implementation on a laboratory prototype, showing the feasibility of the designed algorithm. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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17 pages, 2217 KiB

Open AccessArticle

Evaluating the Effect of the Communication Link of the Relays on the Operation Time of the Protection System

by Aliakbar Azari, Abass Saberi Noghabi, Farhad Zishan, Oscar Danilo Montoya and Alexander Molina-Cabrera

Energies 2023, 16(6), 2692; https://doi.org/10.3390/en16062692 - 14 Mar 2023

Cited by 1 | Viewed by 1178

Abstract

In case of an error in the power system, it is the duty of the protection relays to isolate the faulty part from the rest of the system as soon as possible. Overcurrent and distance relays are usually used to protect the transmission and super distribution systems. The optimum coordination of these relays is very important. In this article, communication links are used to improve the optimal coordination of overcurrent and distance relays. In the proposed plan, the overcurrent relays on both sides of the line are equipped with a communication link for immediate action in the event of an error. Using this communication link, the complete coverage of the line is also provided by distance relays. The number and place of installation of the communication link greatly affect the operation time of overcurrent relays and the distance and coordination between them. The coordination problem is formulated by considering the location and number of communication links, and to solve it, the combined optimization algorithm of genetics and linear programming will be used. With the help of the genetic algorithm, the location and setting of the second zone of the distance relay, and by using the linear programming algorithm, the setting of the overcurrent relays is determined. The proposed method has been tested on the IEEE 14-bus (the simulation in MATLAB software) network and its results examined, and it will be seen how much the existence of a communication link can improve the performance time of the protection system. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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24 pages, 8117 KiB

Open AccessArticle

Distribution Network Reconfiguration Based on Hybrid Golden Flower Algorithm for Smart Cities Evolution

by Dhivya Swaminathan, Arul Rajagopalan, Oscar Danilo Montoya, Savitha Arul and Luis Fernando Grisales-Noreña

Energies 2023, 16(5), 2454; https://doi.org/10.3390/en16052454 - 4 Mar 2023

Cited by 11 | Viewed by 1549

Abstract

Power losses (PL) are one of the most—if not the most—vital concerns in power distribution networks (DN). With respect to sustainability, distribution network reconfiguration (DNR) is an effective course of action to minimize power losses. However, the optimal DNR is usually a non-convex optimization process that necessitates the employment of powerful global optimization methods. This paper proposes a novel hybrid metaheuristic optimization (MO) method called the chaotic golden flower algorithm (CGFA) for PL minimization. As the name implies, the proposed method combines the golden search method with the flower pollination algorithm to multiply their benefits, guarantee the best solution, and reduce convergence time. The performance of the algorithm has been evaluated under different test systems, including the IEEE 33-bus, IEEE 69-bus, and IEEE 119-bus systems and the smart city (SC) network, each of which includes distributed-generation (DG) units and energy storage systems (ESS). In addition, the locations of tie-switches in the DN, which used to be considered as given information in previous studies, are assumed to be variable, and a branch-exchange adaption is included in the reconfiguration process. Furthermore, uncertainty analysis, such as bus and/or line fault conditions, are studied, and the performance of the proposed method is compared with other pioneering MO algorithms with minimal standard deviations ranging from 0.0012 to 0.0101. The case study of SC is considered and the obtained simulation results show the superiority of the algorithm in finding higher PL reduction under different scenarios, with the lowest standard deviations ranging from 0.012 to 0.0432. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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28 pages, 999 KiB

Open AccessArticle

An Effective Power Dispatch of Photovoltaic Generators in DC Networks via the Antlion Optimizer

by Luis Fernando Grisales-Noreña, Andrés Alfonso Rosales-Muñoz and Oscar Danilo Montoya

Energies 2023, 16(3), 1350; https://doi.org/10.3390/en16031350 - 27 Jan 2023

Cited by 3 | Viewed by 1194

Abstract

This paper studies the problem regarding the optimal power dispatch of photovoltaic (PV) distributed generators (DGs) in Direct Current (DC) grid-connected and standalone networks. The mathematical model employed considers the reduction of operating costs, energy losses, and

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emissions as objective [...] Read more.

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emissions as objective functions, and it integrates all technical and operating constraints implied by DC grids in a scenario of variable PV generation and power demand. As a solution methodology, a master–slave strategy was proposed, whose master stage employs Antlion Optimizer (ALO) for identifying the values of power to be dispatched by each PV-DG installed in the grid, whereas the slave stage uses a matrix hourly power flow method based on successive approximations to evaluate the objective functions and constraints associated with each solution proposed within the iterative process of the ALO. Two test scenarios were considered: a grid-connected network that considers the operating characteristics of the city of Medellín, Antioquia, and a standalone network that uses data from the municipality of Capurganá, Chocó, both of them located in Colombia. As comparison methods, five continuous optimization methods were used which were proposed in the specialized literature to solve optimal power flow problems in DC grids: the crow search algorithm, the particle swarm optimization algorithm, the multiverse optimization algorithm, the salp swarm algorithm, and the vortex search algorithm. The effectiveness of the proposed method was evaluated in terms of the solution, its repeatability, and its processing times, and it obtained the best results with respect to the comparison methods for both grid types. The simulation results obtained for both test systems evidenced that the proposed methodology obtained the best results with regard to the solution, with short processing times for all of the objective functions analyzed. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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35 pages, 1275 KiB

Open AccessArticle

Application of the Generalized Normal Distribution Optimization Algorithm to the Optimal Selection of Conductors in Three-Phase Asymmetric Distribution Networks

by Julián Alejandro Vega-Forero, Jairo Stiven Ramos-Castellanos and Oscar Danilo Montoya

Energies 2023, 16(3), 1311; https://doi.org/10.3390/en16031311 - 26 Jan 2023

Cited by 5 | Viewed by 1533

Abstract

This article addresses the problem of the optimal selection of conductors in asymmetric three-phase distribution networks from a combinatorial optimization perspective, where the problem is represented by a mixed-integer nonlinear programming (MINLP) model that is solved using a master-slave (MS) optimization strategy. In the master stage, an optimization model known as the generalized normal distribution optimization (GNDO) algorithm is proposed with an improvement stage based on the vortex search algorithm (VSA). Both algorithms work with discrete-continuous coding that allows us to represent the locations and gauges of the different conductors in the electrical distribution system. For the slave stage, the backward/forward sweep (BFS) algorithm is adopted. The numerical results obtained in the IEEE 8- and 27-bus systems demonstrate the applicability, efficiency, and robustness of this optimization methodology, which, in comparison with current methodologies such as the Newton metaheuristic algorithm, shows significant improvements in the values of the objective function regarding the balanced demand scenario for the 8- and 27-bus test systems (i.e., 10.30% and 1.40% respectively). On the other hand, for the unbalanced demand scenario, a reduction of 1.43% was obtained in the 27-bus system, whereas no improvement was obtained in the 8-bus grid. An additional simulation scenario associated with the three-phase version of the IEEE33-bus grid under unbalanced operating conditions is analyzed considering three possible load profiles. The first load profile corresponds to the yearly operation under the peak load conduction, the second case is associated with a daily demand profile, and the third operation case discretizes the demand profile in three periods with lengths of 1000 h, 6760 h, and 1000 h with demands of 100%, 60% and 30% of the peak load case. Numerical results show the strong influence of the expected demand behavior on the plan’s total costs, with variations upper than USD/year 260,000.00 between different cases of analysis. All implementations were developed in the MATLAB^® programming environment. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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18 pages, 7172 KiB

Open AccessArticle

A Global Tracking Sensorless Adaptive PI-PBC Design for Output Voltage Regulation in a Boost Converter Feeding a DC Microgrid

by Walter Gil-González, Oscar Danilo Montoya, Sebastián Riffo, Carlos Restrepo and Javier Muñoz

Energies 2023, 16(3), 1106; https://doi.org/10.3390/en16031106 - 19 Jan 2023

Cited by 5 | Viewed by 1054

Abstract

The problem of the output voltage regulation in a DC-DC boost converter feeding a DC microgrid is addressed in this research via the passivity-based control theory with a proportional–integral action (PI-PBC). Two external input estimators were implemented in conjunction with the proposed controller to make it sensorless and adaptive. The first estimator corresponds to the immersion & invariance (I&I) approach applied to calculate the expected value of the DC load, which is modeled as an unknown DC current. The second estimator is based on the disturbance–observer (DO) approach, which reaches the value of the voltage input. The main advantage of both estimators is that these ensure exponential convergence under steady-state operating conditions, and their parametrization only requires the definition of an integral gain. A comparative analysis with simulations demonstrates that the proposed PI-PBC approach is effective in regulating/controlling the voltage profile in unknown DC loads as compared to the adaptive sliding mode controller. Experimental validations have demonstrated that the proposed PI-PBC approach, in conjunction with the I&I and the DO estimators, allowed regulation of the voltage output profile in the terminals of the DC load with asymptotic stability properties and fast convergence times (1.87 ms) and acceptably overshoots (6.1%) when the voltage input varies its magnitude (from 10 to 12 V and from 10 to 8 V) considering that the DC load changed with a square waveform between 1 and 2 A with 100 Hz. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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20 pages, 626 KiB

Open AccessArticle

Multi-Objective Dispatch of PV Plants in Monopolar DC Grids Using a Weighted-Based Iterative Convex Solution Methodology

by Oscar Danilo Montoya, Luis Fernando Grisales-Noreña and Diego Armando Giral-Ramírez

Energies 2023, 16(2), 976; https://doi.org/10.3390/en16020976 - 15 Jan 2023

Cited by 2 | Viewed by 984

Abstract

The design of an efficient energy management system (EMS) for monopolar DC networks with high penetration of photovoltaic generation plants is addressed in this research through a convex optimization point of view. The EMS is formulated as a multi-objective optimization problem that involves economic, technical, and environmental objective functions subject to typical constraints regarding power balance equilibrium, thermal conductor capabilities, generation source capacities, and voltage regulation constraints, among others, using a nonlinear programming (NLP) model. The main characteristic of this NLP formulation of the EMS for PV plants is that it is a nonconvex optimization problem owing to the product of variables in the power balance constraint. To ensure an effective solution to this NLP problem, a linear approximation of the power balance constraints using the McCormick equivalent for the product of two variables is proposed. In addition, to eliminate the error introduced by the linearization method, an iterative solution methodology (ISM) is proposed. To solve the multi-objective optimization problem, the weighted optimization method is implemented for each pair of objective functions in conflict, with the main advantage that in this extreme the Pareto front has the optimal global solution for the single-objective function optimization approach. Numerical results in the monopolar version of the IEEE 33-bus grid demonstrated that the proposed ISM reaches the optimal global solution for each one of the objective functions under analysis. It demonstrated that the convex optimization theory is more effective in the EMS design when compared with multiple combinatorial optimization methods. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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17 pages, 5893 KiB

Open AccessArticle

Allocation of Renewable Energy Resources in Distribution Systems While considering the Uncertainty of Wind and Solar Resources via the Multi-Objective Salp Swarm Algorithm

by Farhad Zishan, Saeedeh Mansouri, Farzad Abdollahpour, Luis Fernando Grisales-Noreña and Oscar Danilo Montoya

Energies 2023, 16(1), 474; https://doi.org/10.3390/en16010474 - 1 Jan 2023

Cited by 9 | Viewed by 2275

Abstract

Given the importance of renewable energy sources in distribution systems, this article addresses the problem of locating and determining the capacity of these sources, namely, wind turbines and solar panels. To solve this optimization problem, a new algorithm based on the behavior of salp is used. The objective functions include reducing losses, improving voltage profiles, and reducing the costs of renewable energy sources. In this method, the allocation of renewable resources is considered for different load models in distribution systems and different load levels using smart meters. Due to the fact that these objective functions are multi-objective, the fuzzy decision-making method is used to select the optimal solution from the set of Pareto solutions. The considered objective functions lead to loss reduction, voltage profile improvement, and RES cost reduction (A allocating RES resources optimally without resource limitations; B: allocating RES resources optimally with resource limitations). In addition, daily wind, solar radiation, and temperature data are taken into account. The proposed method is applied to the IEEE standard 33-bus system. The simulation results show the better performance of the multi-objective salp swarm algorithm (MSSA) at improving voltage profiles and reducing losses in distribution systems. Lastly, the optimal results of the MSSA algorithm are compared with the PSO and GA algorithms. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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12 pages, 2426 KiB

Open AccessArticle

Classification of Behavior Profiles for Non-Residential Customers Considering the Variable of Electrical Energy Consumption: Case Study—SAESA Group S.A. Company

by Luis García-Santander, Jerson San Martín-Ayala, Fernando Ulloa-Vásquez, Dante Carrizo, Vladimir Esparza, Jaime Rohten and Carlos Mejias

Energies 2022, 15(18), 6634; https://doi.org/10.3390/en15186634 - 10 Sep 2022

Viewed by 1223

Abstract

This work allows characterizing and classifying the consumption profiles of non-residential customers (without distributed generation) based on the consumption curves obtained from the records reported by 934 smart meters in the period from January to December 2019, and which belong to an electric power distribution company in Chile, SAESA Group S.A. To achieve the characterization and classification of the consumption profiles, three typical days are analyzed and determined, which correspond to working days (Monday to Friday), Saturdays, and Sundays or holidays. These three typical days are analyzed for each trimester of 2019. The data processing is carried out on the Power Bi and Matlab^® platforms. In Power Bi, the data provided by the electricity company are worked, obtaining the average consumption curves for each client in each period of study considered, while in Matlab^®, the visualization and classification of the curves is carried out using the K-means algorithm, to finally obtain the results and conclusions. The results show the existence of seven typical profiles representative of the behavior of non-residential clients, which, in some cases, show similar behaviors, despite being from different categories. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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14 pages, 1535 KiB

Open AccessArticle

Proposal on New Tariffs with a Price Option per Use Time: Application to the Cooperativa Eléctrica San Pedro de Atacama (CESPA) Microgrid in Chile

by Luis García-Santander, Jorge Pérez Martínez, Dante Carrizo, Fernando Ulloa Vásquez, Vladimir Esparza and José Araya

Energies 2022, 15(14), 5151; https://doi.org/10.3390/en15145151 - 15 Jul 2022

Cited by 1 | Viewed by 1542

Abstract

In this paper, a pricing alternative based on the scheme of Time of Use Pricing (TOUP) is proposed for customers connected to the Cooperativa Eléctrica San Pedro de Atacama (CESPA) microgrid, located in the far north of Chile. With this proposal, the promotion of Demand-Side Management, DSM, aims at optimizing both the use of electric energy and the available infrastructure. The pricing proposal replaces the current tariff scheme based on sections of energy consumption and does not give an incentive for customers to efficiently manage their energy consumption. The proposal considers the creation of time bands and their corresponding tariff formulas, to obtain economic benefits both for customers and the electric company. Study cases consider the operation of a photovoltaic plant of 2 MWp in the electric system of CESPA, which is currently underway. The obtained results report benefits for all parts of the electric market. For customers, favorable pricing up to a 19.1% monthly reduction in electric bills is shown, whereas the company presents an increment in their average monthly income of about 7.7%. Full article

(This article belongs to the Special Issue Emerging Topics in Power Electronic Converters of Microgrids)

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