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Measurements, Predictions, and Control in Microgrids and Power Electronic System

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Intelligent Sensors".

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 26942

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Special Issue Editors

Dr. Jesus C. Hernandez

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Guest Editor

Electrical Engineering Department, University of Jaen, Campus Las Lagunillas, S/N, 23071 Jaen, Spain
Interests: power electronics; renewable systems; microgrids; electric vehicles; power quality; power systems simulation; metaheuristic optimization
Special Issues, Collections and Topics in MDPI journals

Dr. Carlos R. Baier

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Guest Editor

Department of Electrical Engineering, University of Talca, Curicó 3340000, Chile
Interests: power electronic; power converter; power quality; power conversion; harmonics
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Pat Wheeler

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Guest Editor

Department of Electrical and Electronic Engineering, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK
Interests: power electronics; matrix converters; multi-level converters/multi-cellular converters; more electric aircraft
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microgrids and power electronic systems have been key to the large-scale integration of renewable energy sources in electrical utility systems. In this context, measurements of voltages, currents, and/or powers associated with the microgrids, inverters, and converters have played a leading role in the path traveled, particularly to control the associated systems. Real-time estimations of electrical variables can become a challenge when there are electronic switching and high electromagnetic interference levels. New research and emerging algorithms to improve these real-time estimations allow engineers to reduce the number of sensors in a system and, thus, the total control systems costs, as well as increasing reliability. Furthermore, predictions and real-time data treatment have become increasingly relevant, particularly in renewable systems with energy storage.

This Special Issue seeks to present new relevant research related to new measurement methods, new estimation methods, or new prediction algorithms applied to control systems either in microgrids or power electronic systems.

Topics of interest include, but are not limited to, the following:

Measurement, estimations and control in microgrids applications.
Observers and reduced sensor control of grid-connected converters.
Artificial Intelligence applied to sensors in microgrids and power electronics applications.
Kalman filter-based microgrid state estimation and control.
Low-cost sensors and digital processing systems for power electronics.
Sensors in power electronics.
New algorithms and Estimations in predictive control applied to power electronics.
Sensorless control in power electronic applications.
Sensorless control applied to fault tolerant electrical and electronic systems.
Predictions and data managements for renewable energy systems.
Prediction algorithms to determine the lifespan of energy storage systems.

Dr. J. C. Hernandez
Dr. Carlos R. Baier
Prof. Pat Wheeler
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. Sensors 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.

Published Papers (11 papers)

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Editorial

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3 pages, 176 KiB

Open AccessEditorial

Measurements, Predictions, and Control in Microgrids and Power Electronic Systems

by Carlos R. Baier, Jesus C. Hernández and Patrick Wheeler

Sensors 2023, 23(8), 4038; https://0-doi-org.brum.beds.ac.uk/10.3390/s23084038 - 17 Apr 2023

Cited by 1 | Viewed by 1104

Abstract

The systems used to distribute electricity are currently undergoing a series of changes that are aiding in the development of smart grids Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

Research

Jump to: Editorial, Review

17 pages, 7453 KiB

Open AccessArticle

Stability Analysis of Two Power Converters Control Algorithms Connected to Micro-Grids with Wide Frequency Variation

by Jaime Rohten, Felipe Villarroel, Esteban Pulido, Javier Muñoz, José Silva and Marcelo Perez

Sensors 2022, 22(18), 7078; https://0-doi-org.brum.beds.ac.uk/10.3390/s22187078 - 19 Sep 2022

Cited by 3 | Viewed by 1665

Abstract

Distributed power generation, micro-grids, and networks working in islanding mode have strong deviations in voltage quantities. These deviations can be divided into amplitude and frequency. Amplitude deviations are well-known and studied, as they are common in small and big grids. However, deviations on the ac mains frequency have not been widely studied. The literature shows control schemes capable of bearing these variations, but no systematic analysis has been performed to ensure stability. As the majority of power converters are designed for big grids, their analysis and design neglect frequency disturbances, therefore those devices allow a very small frequency operating window. For instance, in power converters that need to be synchronized to the grid, the standard deviation does not go beyond 0.5 Hz, and for grid-tied inverters it does not go beyond 1 Hz, whereas variations of around 8 Hz can be expected in micro-grids. This work presents a comprehensive analysis of the control system’s stability, where two different control schemes for a back-to-back static converter topology are implemented and studied under a wide variable grid frequency. Because the behavior of power converters is nonlinear and coupled, dynamic and static decouplers are usually introduced in the controller, being a key element on the scheme according to the findings. The results show that using just a static decoupler does not guarantee stability under frequency variations; meanwhile, when a dynamic decoupler is used, the operating window can be greatly extended. The procedure shown in this paper can also be extended to other control algorithms, making it possible to carefully choose the control system for a variable frequency condition. Simulated and experimental results confirm the theoretical approach. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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16 pages, 2890 KiB

Open AccessArticle

FCS–MPC with Nonlinear Control Applied to a Multicell AFE Rectifier

by Eduardo Espinosa, José Espinoza, Pedro Melín, Jaime Rohten, Marco Rivera and Javier Muñoz

Sensors 2022, 22(11), 4100; https://0-doi-org.brum.beds.ac.uk/10.3390/s22114100 - 28 May 2022

Cited by 2 | Viewed by 1380

Abstract

The use of controlled power converters has been extended for high power applications, stacking off-the-shelve semiconductors, and allowing the implementation of, among others, AC drives for medium voltages of 2.3 kV to 13.8 kV. For AC drives based on power cells assembled with three-phase diode rectifiers and cascaded H-bridge inverters, a sophisticated input multipulse transformer is required to reduce the grid voltage, provide isolation among the power cells, and compensate for low-frequency current harmonics generated by the diode-based rectifiers. However, this input multipulse transformer is bulky, heavy, and expensive and must be designed according to the number of power cells, not allowing total modularity of the AC drives based on cascade H-bridges. This study proposes and evaluates a control strategy based on a finite control set-model predictive control that emulates the harmonic cancellation performed by an input multipulse transformer in a cascade H-bridge topology. Hence, the proposed method requires conventional input transformers and replaces the three-phase diode rectifiers. As a result, greater modularity than the conventional multicell converter and improved AC overall input current with a THD as low as 2% with a unitary displacement power factor are achieved. In this case, each power cell manages its own DC voltage using a nonlinear control strategy, ensuring stable system operation for passive and regenerative loads. The experimental tests demonstrated the correct performance of the proposed scheme. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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13 pages, 741 KiB

Open AccessArticle

Derivative-Free Power Flow Solution for Bipolar DC Networks with Multiple Constant Power Terminals

by Ángeles Medina-Quesada, Oscar Danilo Montoya and Jesus C. Hernández

Sensors 2022, 22(8), 2914; https://0-doi-org.brum.beds.ac.uk/10.3390/s22082914 - 11 Apr 2022

Cited by 14 | Viewed by 1420

Abstract

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 imbalances along the DC grid. The power flow problem is formulated through the triangular-based representation of the grid topology, which generates a recursive formulation that allows determining the voltage values in the demand nodes through an iterative procedure. The linear convergence of the triangular-based power flow method is tested through multiple load variations with respect to the nominal grid operative condition. Numerical results in the 21- and the 85-bus grids reveal the relevant variations in the voltage profiles and total grid power losses when the neutral cable is solidly grounded or not. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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20 pages, 8650 KiB

Open AccessArticle

Application of a Control Scheme Based on Predictive and Linear Strategy for Improved Transient State and Steady-State Performance in a Single-Phase Quasi-Z-Source Inverter

by Manuel Diaz-Bustos, Carlos R. Baier, Miguel A. Torres, Pedro E. Melin and Pablo Acuna

Sensors 2022, 22(7), 2458; https://0-doi-org.brum.beds.ac.uk/10.3390/s22072458 - 23 Mar 2022

Cited by 7 | Viewed by 1809

Abstract

Z and quasi-Z-source inverters (Z/qZSI) have a nonlinear impedance network on their

d c

side, which allows the system to behave as a buck–boost converter in their outputs. The challenges derived from the qZSI topology include (a) the control of the voltage and [...] Read more.

Z and quasi-Z-source inverters (Z/qZSI) have a nonlinear impedance network on their

d c

side, which allows the system to behave as a buck–boost converter in their outputs. The challenges derived from the qZSI topology include (a) the control of the voltage and current on its nonlinear impedance network, (b) the dynamic coupling between the

a c

and

d c

variables, and (c) the fact that a unique set of switches are used to manage the power at

d c

and

a c

side of the system. In this work, a control scheme that combines a PWM linear control strategy and a strategy based on finite control state model predictive control (FCS-MPC) is proposed. The linear approach works during steady state, while the FCS-MPC works during transient states, either in the start-up of the converter or during sudden reference changes. This work aims to show that the performance of this control proposal retains the best characteristics of both schemes, which allows it to achieve high-quality waveforms and error-free steady state, as well as a quick dynamic response during transients. The feasibility of the proposal is validated through experimental results. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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24 pages, 10865 KiB

Open AccessArticle

Modular Single-Stage Three-Phase Flyback Differential Inverter for Medium/High-Power Grid Integrated Applications

by Ahmed Ismail M. Ali, Cao Anh Tuan, Takaharu Takeshita, Mahmoud A. Sayed and Zuhair Muhammed Alaas

Sensors 2022, 22(5), 2064; https://0-doi-org.brum.beds.ac.uk/10.3390/s22052064 - 7 Mar 2022

Cited by 7 | Viewed by 2062

Abstract

This paper proposes a single-stage three-phase modular flyback differential inverter (MFBDI) for medium/high power solar PV grid-integrated applications. The proposed inverter structure consists of parallel modules of flyback DC-DC converters based on the required power level. The MFBDI offers many features for renewable energy applications, such as reduced components, single-stage power processing, high-power density, voltage-boosting property, improved footprint, flexibility with modular extension capability, and galvanic isolation. The proposed inverter has been modelled, designed, and scaled up to the required application rating. A new mathematical model of the proposed MFBDI is presented and analyzed with a time-varying duty-cycle, wide-range of frequency variation, and power balancing in order to display its grid current harmonic orders for grid-tied applications. In addition, an LPF-based harmonic compensation strategy is used for second-order harmonic component (SOHC) compensation. With the help of the compensation technique, the grid current THD is reduced from 36% to 4.6% by diminishing the SOHC from 51% to 0.8%. Moreover, the SOHC compensation technique eliminates third-order harmonic components from the DC input current. In addition, a 15% parameters mismatch has been applied between the flyback parallel modules to confirm the modular operation of the proposed MFBDI under modules divergence. In addition, SiC MOSFETs are used for inverter switches implementation, which decrease the inverter switching losses at high-switching frequency. The proposed MFBDI is verified by using three flyback parallel modules/phase using PSIM/Simulink software, with a rating of 5 kW, 200 V, and 50 kHz switching frequency, as well as experimental environments. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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26 pages, 442 KiB

Open AccessArticle

Optimal Design of PV Systems in Electrical Distribution Networks by Minimizing the Annual Equivalent Operative Costs through the Discrete-Continuous Vortex Search Algorithm

by Brandon Cortés-Caicedo, Federico Molina-Martin, Luis Fernando Grisales-Noreña, Oscar Danilo Montoya and Jesus C. Hernández

Sensors 2022, 22(3), 851; https://0-doi-org.brum.beds.ac.uk/10.3390/s22030851 - 23 Jan 2022

Cited by 27 | Viewed by 3070

Abstract

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 and sizing. This problem is presented using a mixed-integer nonlinear programming model, which is resolved by applying a master–slave methodology. The master stage, consisting of a discrete-continuous version of the Vortex Search Algorithm (DCVSA), is responsible for providing the optimal locations and sizes for the PV sources—whereas the slave stage employs the Matricial Backward/Forward Power Flow Method, which is used to determine the fitness function value for each individual provided by the master stage. Numerical results in the IEEE 33- and 69-node systems with AC and DC topologies illustrate the efficiency of the proposed approach when compared to the discrete-continuous version of the Chu and Beasley genetic algorithm with the optimal location of three PV sources. All the numerical validations were carried out in the MATLAB programming environment. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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28 pages, 10804 KiB

Open AccessArticle

Modelling of SEPIC, Ćuk and Zeta Converters in Discontinuous Conduction Mode and Performance Evaluation

by Emerson Madrid, Duberney Murillo-Yarce, Carlos Restrepo, Javier Muñoz and Roberto Giral

Sensors 2021, 21(22), 7434; https://0-doi-org.brum.beds.ac.uk/10.3390/s21227434 - 9 Nov 2021

Cited by 10 | Viewed by 2870

Abstract

High-order switched DC-DC converters, such as SEPIC, Ćuk and Zeta, are classic energy processing elements, which can be used in a wide variety of applications due to their capacity to step-up and/or step-down voltage characteristic. In this paper, a novel methodology for analyzing the previous converters operating in discontinuous conduction mode (DCM) is applied to obtain full-order dynamic models. The analysis is based on the fact that inductor currents have three differentiated operating sub-intervals characterized by a third one in which both currents become equal, which implies that the current flowing through the diode is zero (DCM). Under a small voltage ripple hypothesis, the currents of all three converters have similar current piecewise linear shapes that allow us to use a graphical method based on the triangular shape of the diode current to obtain the respective non-linear average models. The models’ linearization around their steady-state operating points yields full-order small-signal models that reproduce accurately the dynamic behavior of the corresponding switched model. The proposed methodology is applicable to the proposed converters and has also been extended to more complex topologies with magnetic coupling between inductors and/or an

R C

damping network in parallel with the intermediate capacitor. Several tests were carried out using simulation, hardware-in-the-loop, and using an experimental prototype. All the results validate the theoretical models. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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15 pages, 6471 KiB

Open AccessArticle

Sensorless Adaptive Voltage Control for Classical DC-DC Converters Feeding Unknown Loads: A Generalized PI Passivity-Based Approach

by Walter Gil-González, Oscar Danilo Montoya, Carlos Restrepo and Jesus C. Hernández

Sensors 2021, 21(19), 6367; https://0-doi-org.brum.beds.ac.uk/10.3390/s21196367 - 24 Sep 2021

Cited by 14 | Viewed by 2249

Abstract

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 modeling method is used to model these converters, representing all these converter topologies with a generalized port-Controlled Hamiltonian (PCH) representation. The PCH representation shows that the second-order DC-DC converters exhibit a general bilinear structure which permits to design of a passivity-based controller with PI actions that ensures the asymptotic stability in the sense of Lyapunov. A linear estimator based on an integral estimator that allows reducing the number of current sensors required in the control implementation stage is used to determine the value of the unknown resistive load. The main advantage of this load estimator is that it ensures exponential convergence to the estimated variable. Numerical simulations and experimental validations show that the PI passivity-based control allows voltage regulation with first-order behavior, while the classical PI controller produces oscillations in the controlled variable, significantly when the load varies. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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21 pages, 33887 KiB

Open AccessArticle

DC Voltage Sensorless Predictive Control of a High-Efficiency PFC Single-Phase Rectifier Based on the Versatile Buck-Boost Converter

by Catalina González-Castaño, Carlos Restrepo, Fredy Sanz, Andrii Chub and Roberto Giral

Sensors 2021, 21(15), 5107; https://0-doi-org.brum.beds.ac.uk/10.3390/s21155107 - 28 Jul 2021

Cited by 9 | Viewed by 2543

Abstract

Many electronic power distribution systems have strong needs for highly efficient AC-DC conversion that can be satisfied by using a buck-boost converter at the core of the power factor correction (PFC) stage. These converters can regulate the input voltage in a wide range with reduced efforts compared to other solutions. As a result, buck-boost converters could potentially improve the efficiency in applications requiring DC voltages lower than the peak grid voltage. This paper compares SEPIC, noninverting, and versatile buck-boost converters as PFC single-phase rectifiers. The converters are designed for an output voltage of 200 V and an rms input voltage of 220 V at 3.2 kW. The PFC uses an inner discrete-time predictive current control loop with an output voltage regulator based on a sensorless strategy. A PLECS thermal simulation is performed to obtain the power conversion efficiency results for the buck-boost converters considered. Thermal simulations show that the versatile buck-boost (VBB) converter, currently unexplored for this application, can provide higher power conversion efficiency than SEPIC and non-inverting buck-boost converters. Finally, a hardware-in-the-loop (HIL) real-time simulation for the VBB converter is performed using a PLECS RT Box 1 device. At the same time, the proposed controller is built and then flashed to a low-cost digital signal controller (DSC), which corresponds to the Texas Instruments LAUNCHXL-F28069M evaluation board. The HIL real-time results verify the correctness of the theoretical analysis and the effectiveness of the proposed architecture to operate with high power conversion efficiency and to regulate the DC output voltage without sensing it while the sinusoidal input current is perfectly in-phase with the grid voltage. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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Review

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35 pages, 2896 KiB

Open AccessReview

Review of Control Techniques in Microinverters

by Diego Rojas, Javier Muñoz, Marco Rivera and Jaime Rohten

Sensors 2021, 21(19), 6486; https://0-doi-org.brum.beds.ac.uk/10.3390/s21196486 - 28 Sep 2021

Cited by 9 | Viewed by 3834

Abstract

The use of renewable energies sources is taking great importance due to the high demand for electricity and the decrease in the use of fossil fuels worldwide. In this context, electricity generation through photovoltaic panels is gaining a lot of interest due to the reduction in installation costs and the rapid advance of the development of new technologies. To minimize or reduce the negative impact of partial shading or mismatches of photovoltaic panels, many researchers have proposed four configurations that depend on the power ranges and the application. The microinverter is a promising solution in photovoltaic systems, due to its high efficiency of Maximum Power Point Tracking and high flexibility. However, there are several challenges to improve microinverter’s reliability and conversion efficiency that depend on the proper control design and the power converter design. This paper presents a review of different control strategies in microinverters for different applications. The control strategies are described and compared based on stability, dynamic response, topologies, and control objectives. One of the most important results showed that there is little research regarding the stability and robustness analysis of the reviewed control strategies. Full article

(This article belongs to the Special Issue Measurements, Predictions, and Control in Microgrids and Power Electronic System)

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