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Special Issue "Power Electronics and Power Quality"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (28 February 2018)

Special Issue Editor

Guest Editor
Dr. José Gabriel Oliveira Pinto

Departamento de Electrónica Industrial, Universidade do Minho, Campus de Azurém, 4800-058, Guimarães, Portugal
Website | E-Mail
Interests: power electronics; power quality; active power conditioners; renewable energy systems; electric vehicles; digital control of power electronics converters

Special Issue Information

Dear Colleagues,

The first studies on power quality were published in the sixties of the last century; however, the evolution of electric power systems, and especially the advances in power electronics, highlighted the significance of this matter in modern power systems. Nowadays, power systems are experiencing new challenges: the decentralized generation, the integration of renewable energy systems, the widespread of plug-in electric and hybrid-electric vehicles, the electrification of railway systems, the distributed control in smart grids, and the interconnected or islanded operation of microgrids brings to a higher level the importance of power quality. This scenario stimulates the research and development in monitoring technologies and power electronics solutions to ensure the power quality of the future power systems. This Special Issue of Energies intends to collect and disseminate the latest research and developments related to “Power Electronics and Power Quality”. The topics of interest include, but are not limited to:

  • advanced power quality monitoring (smart meters, advanced metering infrastructure, phasor measurement unit, signal processing technics, event classification)
  • active power conditioners (active power filters, hybrid filters, unified power quality conditioners (UPQCs))
  • control techniques for power quality improvement (power theories, signal processing technics, artificial neural networks)
  • power quality in smart grids and microgrids (islanding detection, grid synchronization, voltage control, frequency control)
  • energy storage systems with power quality ancillary services (energy storage technologies, voltage support, reactive power control, active damping control)
  • electric vehicle battery chargers with smart operation modes (grid-to-vehicle, vehicle-to-grid, vehicle-to-home, home-to-vehicle)
  • integration of renewable energy systems with power quality ancillary services (voltage control, harmonics compensation)

Dr. José Gabriel Oliveira Pinto
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 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

  • power electronics
  • power quality
  • power quality monitoring
  • power quality mitigation
  • power quality conditioners
  • control theories
  • smart grids
  • microgrids
  • energy storage systems
  • distributed generation
  • renewable energy systems
  • electric vehicles

Published Papers (18 papers)

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Research

Open AccessFeature PaperArticle
Reactive Power and Current Harmonic Control Using a Dual Hybrid Power Filter for Unbalanced Non-Linear Loads
Energies 2018, 11(6), 1392; https://doi.org/10.3390/en11061392
Received: 25 April 2018 / Revised: 25 May 2018 / Accepted: 28 May 2018 / Published: 30 May 2018
Cited by 1 | PDF Full-text (6758 KB) | HTML Full-text | XML Full-text
Abstract
An important power quality issue is related to current harmonic components demanded by non-linear loads. A solution to mitigate this issue is to use hybrid power filters (HPFs), that apply low power active filters with passive filters. Some dual-converter topologies have been shown [...] Read more.
An important power quality issue is related to current harmonic components demanded by non-linear loads. A solution to mitigate this issue is to use hybrid power filters (HPFs), that apply low power active filters with passive filters. Some dual-converter topologies have been shown to be attractive due to a better compensation performance compared with single filters, where the HPFs give a reactive power support (an extra feature) together with harmonic compensation. On the other hand, the drawback of dual converters is the high number of active switches. Besides that, due to the high number of unbalanced non-linear loads connected to the electrical grid, triplen harmonics can appear. However, traditional HPFs do not compensate triplen harmonics, which usually have considerable values. Therefore, in this paper, a dual HPF based on the nine-switch inverter (DHPF-NSI) is proposed to compensate current harmonics and to provide reactive power support. The NSI presents a reduced number of switches when compared with classical dual topologies. The compensation of the third harmonic caused by unbalanced nonlinear loads was also inserted in the control system. Experimental results are presented for the DHPF-NSI in order to demonstrate the reactive power and harmonic compensation performances. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Hybrid HVDC (H2VDC) System Using Current and Voltage Source Converters
Energies 2018, 11(6), 1323; https://doi.org/10.3390/en11061323
Received: 27 April 2018 / Revised: 18 May 2018 / Accepted: 21 May 2018 / Published: 23 May 2018
Cited by 3 | PDF Full-text (3205 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an analysis of a new high voltage DC (HVDC) transmission system, which is based on current and voltage source converters (CSC and VSC) in the same circuit. This proposed topology is composed of one CSC (rectifier) and one or more [...] Read more.
This paper presents an analysis of a new high voltage DC (HVDC) transmission system, which is based on current and voltage source converters (CSC and VSC) in the same circuit. This proposed topology is composed of one CSC (rectifier) and one or more VSCs (inverters) connected through an overhead transmission line in a multiterminal configuration. The main purpose of this Hybrid HVDC (H2VDC), as it was designed, is putting together the best benefits of both types of converters in the same circuit: no commutation failure and system’s black start capability in the VSC side, high power converter capability and low cost at the rectifier side, etc. A monopole of the H2VDC system with one CSC and two VSCs—here, the VSC is the Modular Multilevel Converter (MMC) considered with full-bridge submodules—in multiterminal configuration is studied. The study includes theoretical analyses, development of the CSC and VSCs control philosophies and simulations. The H2VDC system’s behavior is analyzed by computational simulations considering steady-state operation and short-circuit conditions at the AC and DC side. The obtained results and conclusions show a promising system for very high-power multiterminal HVDC transmission. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Nonlinear Robust Control for Low Voltage Direct-Current Residential Microgrids with Constant Power Loads
Energies 2018, 11(5), 1130; https://doi.org/10.3390/en11051130
Received: 21 March 2018 / Revised: 21 April 2018 / Accepted: 27 April 2018 / Published: 3 May 2018
Cited by 5 | PDF Full-text (793 KB) | HTML Full-text | XML Full-text
Abstract
A Direct Current (DC) microgrid is a concept derived from a smart grid integrating DC renewable sources. The DC microgrids have three particularities: (1) integration of different power sources and local loads through a DC link; (2) on-site power source generation; and (3) [...] Read more.
A Direct Current (DC) microgrid is a concept derived from a smart grid integrating DC renewable sources. The DC microgrids have three particularities: (1) integration of different power sources and local loads through a DC link; (2) on-site power source generation; and (3) alternating loads (on-off state). This kind of arrangement achieves high efficiency, reliability and versatility characteristics. The key device in the development of the DC microgrid is the power electronic converter (PEC), since it allows an efficient energy conversion between power sources and loads. However, alternating loads with strictly-controlled PECs can provide negative impedance behavior to the microgrid, acting as constant power loads (CPLs), such that the overall closed-loop system becomes unstable. Traditional CPL compensation techniques rely on a damping increment by the adaptation of the source or load voltage level, adding external circuitry or by using some advanced control technique. However, none of them provide a simple and general solution for the CPL problem when abrupt changes in parameters and/or in alternating loads/sources occur. This paper proposes a mathematical modeling and a robust control for the basic PECs dealing with CPLs in continuous conduction mode. In particular, the case of the low voltage residential DC microgrid with CPLs is taken as a benchmark. The proposed controller can be easily tuned for the desired response even by the non-expert. Basic converters with voltage mode control are taken as a basis to show the feasibility of this analysis, and experimental tests on a 100-W testbed include abrupt parameter changes such as input voltage. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Single-Phase Shunt Active Power Filter Based on a 5-Level Converter Topology
Energies 2018, 11(4), 1019; https://doi.org/10.3390/en11041019
Received: 14 March 2018 / Revised: 12 April 2018 / Accepted: 16 April 2018 / Published: 22 April 2018
Cited by 1 | PDF Full-text (11067 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a single-phase Shunt Active Power Filter (SAPF) with a multilevel converter based on an asymmetric full-bridge topology capable of producing five distinct voltage levels. The calculation of the SAPF compensation current is based on the Generalized Theory of Instantaneous Reactive [...] Read more.
This paper presents a single-phase Shunt Active Power Filter (SAPF) with a multilevel converter based on an asymmetric full-bridge topology capable of producing five distinct voltage levels. The calculation of the SAPF compensation current is based on the Generalized Theory of Instantaneous Reactive Power (p-q theory) modified to work in single-phase installations, complemented by a Phase-Locked Loop algorithm and by a dedicated algorithm to regulate the voltages in the DC-link capacitors. The control of the SAPF uses a closed loop predictive current control, followed by a multilevel Sinusoidal Pulse-Width Modulation technique with two vertical distributed carriers, which were specially conceived to deal with the asymmetric nature of the converter legs. Along the paper, some simulation results are used to show the main characteristics of the 5-level converter and control algorithms, and the hardware topology and control algorithms are described in detail. In order to demonstrate the feasibility and performance of the proposed SAPF based on a 5-level converter, a laboratory prototype was developed and experimental results obtained under diverse conditions of operation, with linear and non-linear loads, are presented and discussed in this paper. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Evaluation of Harmonics Impact on Digital Relays
Energies 2018, 11(4), 893; https://doi.org/10.3390/en11040893
Received: 28 February 2018 / Revised: 2 April 2018 / Accepted: 4 April 2018 / Published: 11 April 2018
Cited by 1 | PDF Full-text (39050 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the concept of the impact of harmonic distortion on a digital protection relay. The aim is to verify and determine the reasons of a mal-trip or failure to trip the protection relays; the suggested solution of the harmonic distortion is [...] Read more.
This paper presents the concept of the impact of harmonic distortion on a digital protection relay. The aim is to verify and determine the reasons of a mal-trip or failure to trip the protection relays; the suggested solution of the harmonic distortion is explained by a mathematical model in the Matlab Simulink programming environment. The digital relays have been tested under harmonic distortions in order to verify the function of the relays algorithm under abnormal conditions. The comparison between the protection relay algorithm under abnormal conditions and a mathematical model in the Matlab Simulink programming environment based on injected harmonics of high values is provided. The test is separated into different levels; the first level is based on the harmonic effect of an individual harmonic and mixed harmonics. The test includes the effect of the harmonics in the location of the fault point into distance protection zones. This paper is a new proposal in the signal processing of power quality disturbances using Matlab Simulink and the power quality impact on the measurements of the power system quantities; the test simulates the function of protection in power systems in terms of calculating the current and voltage values of short circuits and their faults. The paper includes several tests: frequency variations and decomposition of voltage waveforms with Fourier transforms (model) and commercial relay, the effect of the power factor on the location of fault points, the relation between the tripping time and the total harmonic distortion (THD) levels in a commercial relay, and a comparison of the THD capture between the commercial relay and the model. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Application of a Continuous Particle Swarm Optimization (CPSO) for the Optimal Coordination of Overcurrent Relays Considering a Penalty Method
Energies 2018, 11(4), 869; https://doi.org/10.3390/en11040869
Received: 28 February 2018 / Revised: 27 March 2018 / Accepted: 29 March 2018 / Published: 9 April 2018
Cited by 3 | PDF Full-text (8530 KB) | HTML Full-text | XML Full-text
Abstract
In an electrical power system, the coordination of the overcurrent relays plays an important role in protecting the electrical system by providing primary as well as backup protection. To reduce power outages, the coordination between these relays should be kept at the optimum [...] Read more.
In an electrical power system, the coordination of the overcurrent relays plays an important role in protecting the electrical system by providing primary as well as backup protection. To reduce power outages, the coordination between these relays should be kept at the optimum value to minimize the total operating time and ensure that the least damage occurs under fault conditions. It is also imperative to ensure that the relay setting does not create an unintentional operation and consecutive sympathy trips. In a power system protection coordination problem, the objective function to be optimized is the sum of the total operating time of all main relays. In this paper, the coordination of overcurrent relays in a ring fed distribution system is formulated as an optimization problem. Coordination is performed using proposed continuous particle swarm optimization. In order to enhance and improve the quality of this solution a local search algorithm (LSA) is implanted into the original particle swarm algorithm (PSO) and, in addition to the constraints, these are amalgamated into the fitness function via the penalty method. The results achieved from the continuous particle swarm optimization algorithm (CPSO) are compared with other evolutionary optimization algorithms (EA) and this comparison showed that the proposed scheme is competent in dealing with the relevant problems. From further analyzing the obtained results, it was found that the continuous particle swarm approach provides the most globally optimum solution. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Power Quality Event Detection Using a Fast Extreme Learning Machine
Energies 2018, 11(1), 145; https://doi.org/10.3390/en11010145
Received: 9 November 2017 / Revised: 31 December 2017 / Accepted: 3 January 2018 / Published: 7 January 2018
Cited by 6 | PDF Full-text (1760 KB) | HTML Full-text | XML Full-text
Abstract
Monitoring Power Quality Events (PQE) is a crucial task for sustainable and resilient smart grid. This paper proposes a fast and accurate algorithm for monitoring PQEs from a pattern recognition perspective. The proposed method consists of two stages: feature extraction (FE) and decision-making. [...] Read more.
Monitoring Power Quality Events (PQE) is a crucial task for sustainable and resilient smart grid. This paper proposes a fast and accurate algorithm for monitoring PQEs from a pattern recognition perspective. The proposed method consists of two stages: feature extraction (FE) and decision-making. In the first phase, this paper focuses on utilizing a histogram based method that can detect the majority of PQE classes while combining it with a Discrete Wavelet Transform (DWT) based technique that uses a multi-resolution analysis to boost its performance. In the decision stage, Extreme Learning Machine (ELM) classifies the PQE dataset, resulting in high detection performance. A real-world like PQE database is used for a thorough test performance analysis. Results of the study show that the proposed intelligent pattern recognition system makes the classification task accurately. For validation and comparison purposes, a classic neural network based classifier is applied. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Power Quality Improvement in a Cascaded Multilevel Inverter Interfaced Grid Connected System Using a Modified Inductive–Capacitive–Inductive Filter with Reduced Power Loss and Improved Harmonic Attenuation
Energies 2017, 10(11), 1834; https://doi.org/10.3390/en10111834
Received: 5 October 2017 / Revised: 2 November 2017 / Accepted: 6 November 2017 / Published: 10 November 2017
Cited by 3 | PDF Full-text (6816 KB) | HTML Full-text | XML Full-text
Abstract
Recently, multilevel inverters are more researched due to the advantages they offer over conventional voltage source inverters in grid connected applications. Passive filters are connected at the output of these inverters to produce sinusoidal waveforms with reduced harmonics and to satisfy grid interconnection [...] Read more.
Recently, multilevel inverters are more researched due to the advantages they offer over conventional voltage source inverters in grid connected applications. Passive filters are connected at the output of these inverters to produce sinusoidal waveforms with reduced harmonics and to satisfy grid interconnection standard requirements. This work proposes a new passive filter topology for a pulse width modulated five-level cascaded inverter interfaced grid connected system. The proposed passive filter inserts an additional resistance-capacitance branch in parallel to the filter capacitor of the traditional inductive–capacitive–inductive filter in addition to a resistance in series with it to reduce damping power loss. It can attenuate the switching frequency harmonic current components much better than the traditional filter while maintaining the same overall inductance, reduced capacitance and resistance values. The basic parameter design procedure and an approach to discover the parameters of the proposed filter is introduced. Further, a novel methodology using Particle Swarm Optimization (PSO) is recommended to guarantee minimum damping loss while ensuring reduced peak during resonance. In addition, PSO algorithm is newly employed in this work to maximize harmonic attenuation in and around the switching frequency on the premise of allowable values of filter inductance and capacitance. A comparative discussion considering traditional passive filters and the proposed filter is presented and evaluated through experiments conducted on a 110 V, 1 kW five-level grid connected inverter. The modulation algorithm for the multilevel inverter is implemented using a SPARTAN 6-XC6SLX25 Field Programmable Gate Array (FPGA) processor. The analysis shows that the proposed filter not only provides decreased damping power loss but also is capable of providing considerable harmonic ripple reduction in the high frequency band, improved output waveforms and lesser Total Harmonic Distortion (THD) with improved power quality for the multilevel inverter based grid connected system. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
New Hybrid Static VAR Compensator with Series Active Filter
Energies 2017, 10(10), 1617; https://doi.org/10.3390/en10101617
Received: 7 August 2017 / Revised: 28 September 2017 / Accepted: 10 October 2017 / Published: 16 October 2017
Cited by 4 | PDF Full-text (1832 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a new hybrid static VAR compensator (SVC) with a series active filter (AF). The proposed hybrid SVC consists of a series AF and SVC. The series AF, which is connected in series to phase-leading capacitors in the SVC, performs for [...] Read more.
This paper proposes a new hybrid static VAR compensator (SVC) with a series active filter (AF). The proposed hybrid SVC consists of a series AF and SVC. The series AF, which is connected in series to phase-leading capacitors in the SVC, performs for a resistor for source-side harmonic currents. A sinusoidal source current with a unity power factor is obtained with the series AF, although the thyristor-controlled reactor generates harmonic currents. A digital computer simulation was implemented to confirm the validity and high practicability of the proposed hybrid SVC using PSIM software. The simulation results demonstrate that sinusoidal source currents with a unity power factor are achieved with the proposed hybrid SVC. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
A Digital Hysteresis Current Control for Half-Bridge Inverters with Constrained Switching Frequency
Energies 2017, 10(10), 1610; https://doi.org/10.3390/en10101610
Received: 7 September 2017 / Revised: 9 October 2017 / Accepted: 12 October 2017 / Published: 14 October 2017
Cited by 5 | PDF Full-text (4340 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a new robustly adaptive hysteresis current digital control algorithm for half-bridge inverters, which plays an important role in electric power, and in various applications in electronic systems. The proposed control algorithm is assumed to be implemented on a high-speed Field [...] Read more.
This paper proposes a new robustly adaptive hysteresis current digital control algorithm for half-bridge inverters, which plays an important role in electric power, and in various applications in electronic systems. The proposed control algorithm is assumed to be implemented on a high-speed Field Programmable Gate Array (FPGA) circuit, using measured data with high sampling frequency. The hysteresis current band is computed in each switching modulation period based on both the current error and the negative half switching period during the previous modulation period, in addition to the conventionally used voltages measured at computation instants. The proposed control algorithm is derived by solving the optimization problem—where the switching frequency is always constrained at below the desired constant frequency—which is not guaranteed by the conventional method. The optimization problem also keeps the output current stable around the reference, and minimizes power loss. Simulation results show good performances of the proposed algorithm compared with the conventional one. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Analysis of Voltage Variation in Silicon Carbide MOSFETs during Turn-On and Turn-Off
Energies 2017, 10(10), 1456; https://doi.org/10.3390/en10101456
Received: 5 July 2017 / Revised: 9 September 2017 / Accepted: 16 September 2017 / Published: 21 September 2017
Cited by 2 | PDF Full-text (6274 KB) | HTML Full-text | XML Full-text
Abstract
Due to our limited knowledge about silicon carbide metal–oxide–semiconductor field-effect transistors (SiC MOSFETs), the theoretical analysis and change regularity in terms of the effects of temperature on their switching characteristics have not been fully characterized and understood. An analysis of variation in voltage [...] Read more.
Due to our limited knowledge about silicon carbide metal–oxide–semiconductor field-effect transistors (SiC MOSFETs), the theoretical analysis and change regularity in terms of the effects of temperature on their switching characteristics have not been fully characterized and understood. An analysis of variation in voltage (dVDS/dt) for SiC MOSFET during turn-on and turn-off has been performed theoretically and experimentally in this paper. Turn-off variation in voltage is not a strong function of temperature, whereas the turn-on variation in voltage has a monotonic relationship with temperature. The temperature dependence is a result of the competing effects between the positive temperature coefficient of the intrinsic carrier concentration and the negative temperature coefficient of the effective mobility of the electrons in SiC MOSFETs. The relationship between variation in voltage and supply voltage, load current, and gate resistance are also discussed. A temperature-based analytical model of dVDS/dt for SiC MOSFETs was derived in terms of internal parasitic capacitances during the charging and discharging processes at the voltage fall period during turn-on, and the rise period during turn-off. The calculation results were close to the experimental measurements. These results provide a potential junction temperature estimation approach for SiC MOSFETs. In SiC MOSFET-based practical applications, if the turn on dVDS/dt is sensed, the device temperature can be estimated from the relationship curve of turn on dVDS/dt versus temperature drawn in advance. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Robustness Improvement of Superconducting Magnetic Energy Storage System in Microgrids Using an Energy Shaping Passivity-Based Control Strategy
Energies 2017, 10(5), 671; https://doi.org/10.3390/en10050671
Received: 15 February 2017 / Revised: 4 May 2017 / Accepted: 9 May 2017 / Published: 11 May 2017
Cited by 6 | PDF Full-text (7563 KB) | HTML Full-text | XML Full-text
Abstract
Superconducting magnetic energy storage (SMES) systems, in which the proportional-integral (PI) method is usually used to control the SMESs, have been used in microgrids for improving the control performance. However, the robustness of PI-based SMES controllers may be unsatisfactory due to the high [...] Read more.
Superconducting magnetic energy storage (SMES) systems, in which the proportional-integral (PI) method is usually used to control the SMESs, have been used in microgrids for improving the control performance. However, the robustness of PI-based SMES controllers may be unsatisfactory due to the high nonlinearity and coupling of the SMES system. In this study, the energy shaping passivity (ESP)-based control strategy, which is a novel nonlinear control based on the methodology of interconnection and damping assignment (IDA), is proposed for robustness improvement of SMES systems. A step-by-step design of the ESP-based method considering the robustness of SMES systems is presented. A comparative analysis of the performance between ESP-based and PI control strategies is shown. Simulation and experimental results prove that the ESP-based strategy achieves the stronger robustness toward the system parameter uncertainties than the conventional PI control. Besides, the use of ESP-based control method can reduce the eddy current losses of a SMES system due to the significant reduction of 2nd and 3rd harmonics of superconducting coil DC current. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Space Vector Modulation for an Indirect Matrix Converter with Improved Input Power Factor
Energies 2017, 10(5), 588; https://doi.org/10.3390/en10050588
Received: 16 February 2017 / Revised: 17 April 2017 / Accepted: 19 April 2017 / Published: 25 April 2017
Cited by 3 | PDF Full-text (6902 KB) | HTML Full-text | XML Full-text
Abstract
Pulse width modulation strategies have been developed for indirect matrix converters (IMCs) in order to improve their performance. In indirect matrix converters, the LC input filter is used to remove input current harmonics and electromagnetic interference problems. Unfortunately, due to the existence of [...] Read more.
Pulse width modulation strategies have been developed for indirect matrix converters (IMCs) in order to improve their performance. In indirect matrix converters, the LC input filter is used to remove input current harmonics and electromagnetic interference problems. Unfortunately, due to the existence of the input filter, the input power factor is diminished, especially during operation at low voltage outputs. In this paper, a new space vector modulation (SVM) is proposed to compensate for the input power factor of the indirect matrix converter. Both computer simulation and experimental studies through hardware implementation were performed to verify the effectiveness of the proposed modulation strategy. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Design and Evaluation of an Efficient Three-Phase Four-Leg Voltage Source Inverter with Reduced IGBTs
Energies 2017, 10(4), 530; https://doi.org/10.3390/en10040530
Received: 4 January 2017 / Revised: 3 April 2017 / Accepted: 10 April 2017 / Published: 13 April 2017
Cited by 2 | PDF Full-text (3697 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a new three-phase four-leg voltage source inverter (VSI), which achieves a high cost effectiveness for mega-watt level system applications. The proposed four-leg inverter adopts the integrated topology with thyristors and insulated-gate bipolar transistors (IGBTs), which aims to reduce the number [...] Read more.
This paper presents a new three-phase four-leg voltage source inverter (VSI), which achieves a high cost effectiveness for mega-watt level system applications. The proposed four-leg inverter adopts the integrated topology with thyristors and insulated-gate bipolar transistors (IGBTs), which aims to reduce the number of IGBTs. In order to handle the zero sequence current, a neutral leg via incorporating IGBTs is artfully integrated with the regular phase legs. Furthermore, the modelling principles are elaborated and analyzed, which emphasizes switching states and voltage vectors in six segments based on the states of thyristors. Finally, by using the carrier-based pulse width modulation (PWM) method, the closed-loop current control of the proposed inverter is verified by both simulation and experimentation. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
A Time-Efficient Approach for Modelling and Simulation of Aggregated Multiple Photovoltaic Microinverters
Energies 2017, 10(4), 465; https://doi.org/10.3390/en10040465
Received: 14 February 2017 / Revised: 26 March 2017 / Accepted: 29 March 2017 / Published: 31 March 2017
PDF Full-text (4577 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a time-efficient modeling and simulation strategy for aggregated microinverters in large-scale photovoltaic systems. As photovoltaic microinverter systems are typically comprised of multiple power electronic converters, a suitable modeling and simulation strategy that can be used for rapid prototyping is required. [...] Read more.
This paper presents a time-efficient modeling and simulation strategy for aggregated microinverters in large-scale photovoltaic systems. As photovoltaic microinverter systems are typically comprised of multiple power electronic converters, a suitable modeling and simulation strategy that can be used for rapid prototyping is required. Dynamic models incorporating switching action may induce significant computational burdens and long simulation durations. This paper introduces a single-matrix-form approach using the average model of a basic microinverter with two power stages consisting of a dc-dc and dc-ac converter. The proposed methodology using a common or intermediate source between two average models of cascaded converters to find the overall average model is introduced and is applicable to many other converter topologies and combinations. It provides better flexibility and simplicity when investigating various power topologies in system-level studies of microinverter and other power electronic systems. A 200 W prototype microinverter is tested to verify the proposed average and dynamic models. Furthermore, MATLAB/Simulink (2010a, Mathworks, Natick, MA, USA) is used to show the improved simulation speed and maintained accuracy of the multiple microinverter configurations when the derived average model is compared to a dynamic switching simulation model. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
A New Method to Monitor the Primary Neutral Integrity in Multi-Grounded Neutral Systems
Energies 2017, 10(3), 380; https://doi.org/10.3390/en10030380
Received: 14 December 2016 / Revised: 26 February 2017 / Accepted: 13 March 2017 / Published: 16 March 2017
Cited by 1 | PDF Full-text (3538 KB) | HTML Full-text | XML Full-text
Abstract
In the three-phase four-wire system, there are usually multiple grounding points in the primary neutral line due to safety and economic considerations. The rising “neutral to earth voltage (NEV)” caused by a broken primary neutral can threaten the safety of nearby facilities and [...] Read more.
In the three-phase four-wire system, there are usually multiple grounding points in the primary neutral line due to safety and economic considerations. The rising “neutral to earth voltage (NEV)” caused by a broken primary neutral can threaten the safety of nearby facilities and humans; therefore, the integrity of the primary neutral conductor is of vital importance for the multi-grounded neutral (MGN) system. In this paper, a new passive method is proposed to monitor the integrity of the primary neutral line in the MGN system. The method is based on the measured voltage and current data at the service transformer, and there is no need to install any signal generators. Therefore, it causes no disturbance to the utility and customer. In the paper, the equivalent analysis circuit is established and a new parameter is proposed to reflect the neutral condition. The value of the parameter is estimated based on the measured data, and then, the equivalent impedance of the primary neutral groundings can be obtained. On the other hand, the impedance value for the primary neutral under normal operating conditions can be estimated based on the derived analytical formulas. By comparing the monitored primary neutral impedance with its normal value, the broken neutral condition in the primary system can be detected. Different primary neutral broken cases are analyzed in the paper based on the Monte Carlo simulation. The results indicate that the integrity condition in the primary neutral can be accurately monitored by the proposed method. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
An Efficient Phase-Locked Loop for Distorted Three-Phase Systems
Energies 2017, 10(3), 280; https://doi.org/10.3390/en10030280
Received: 6 December 2016 / Accepted: 20 February 2017 / Published: 27 February 2017
Cited by 5 | PDF Full-text (6868 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposed an efficient phase-locked loop (PLL) that features zero steady-state error of phase and frequency under voltage sag, phase jump, harmonics, DC offsets and step-and ramp-changed frequency. The PLL includes the sliding Goertzel discrete Fourier transform (SGDFT) filter-based fundamental positive sequence [...] Read more.
This paper proposed an efficient phase-locked loop (PLL) that features zero steady-state error of phase and frequency under voltage sag, phase jump, harmonics, DC offsets and step-and ramp-changed frequency. The PLL includes the sliding Goertzel discrete Fourier transform (SGDFT) filter-based fundamental positive sequence component separator (FPSCS), the synchronousreference-frame PLL (SRF-PLL) and the secondary control path (SCP). In order to obtain an accurate fundamental positive sequence component, SGDFT filter is introduced as it features better filtering ability at the frequencies that are integer times of fundamental frequency. Meanwhile, the second order Lagrange-interpolation method is employed to approximate the actual sampling number including both integer and fractional parts as grid frequency may deviate from the rated value. Moreover, an improved SCP with single-step comparison filtering algorithm is employed as it updates reference angular frequency according to the FPSC, which promises a zero steady-state error of phase and improves the frequency tracking speed. In this paper, the mathematical model of the proposed PLL is constructed, its stability is analyzed. Also, design procedure of the control parameters is presented. The effectiveness of the proposed PLL is confirmed by experimental results and comparison with advanced pre-filtering PLLs. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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Open AccessArticle
Development of Propulsion Inverter Control System for High-Speed Maglev based on Long Stator Linear Synchronous Motor
Energies 2017, 10(2), 170; https://doi.org/10.3390/en10020170
Received: 19 September 2016 / Revised: 30 December 2016 / Accepted: 20 January 2017 / Published: 3 February 2017
Cited by 2 | PDF Full-text (2328 KB) | HTML Full-text | XML Full-text
Abstract
In the case of a long-stator linear drive, unlike rotative drives for which speed or position sensors are a single unit attached to the shaft, these sensors extend along the guideway. The position signals transmitted from a maglev vehicle cannot meet the need [...] Read more.
In the case of a long-stator linear drive, unlike rotative drives for which speed or position sensors are a single unit attached to the shaft, these sensors extend along the guideway. The position signals transmitted from a maglev vehicle cannot meet the need of the real-time propulsion control in the on-ground inverter power substations. In this paper the design of the propulsion inverter control system with a position estimator for driving a long-stator synchronous motor in a high-speed maglev train is proposed. The experiments have been carried out at the 150 m long guideway at the O-song test track. To investigate the performance of the position estimator, the propulsion control system with, and without, the position estimator are compared. The result confirms that the proposed strategy can meet the dynamic property needs of the propulsion inverter control system for driving long-stator linear synchronous motors. Full article
(This article belongs to the Special Issue Power Electronics and Power Quality)
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