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Power Quality in Power Systems with High-Power PWM Converters: Existing Problems and Their Solutions

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Special Issue Editors

Dr. Aleksandr A. Nikolaev

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Guest Editor

Department of Automatic Electric Drive and Mechatronics, Nosov Magnitogorsk State Technical University, Magnitogorsk, Russia
Interests: electric drives; power quality; power systems; power electronic converters

Dr. Alexandr S. Maklakov

E-Mail Website
Guest Editor

Department of Electric Drive and Mechatronics, South Ural State University, Chelyabinsk, Russia
Interests: power electronic converters; electric drive; pulse-width modulation
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The Special Issue is devoted to providing and sharing a comprehensive review of the relevant power quality problems and their solutions in power systems with high-power PWM converters. A lot of applied scientific research around the world is aimed at its solution, which is non-trivial and has an interdisciplinary nature associated with the grid configurations, algorithms, and automatic control systems of high-power PWM converters, as well as the operating modes of consumers. The Special Issue summarizes research in universities, research institutes, large industrial enterprises, scientific and industrial associations, as well as research results obtained thanks to the personal initiative of the authors.

We hope you will contribute your high-quality research, and we welcome you to submit your articles.

Dr. Aleksandr A. Nikolaev
Dr. Alexandr S. Maklakov
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.

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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 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

power systems
power converters
electric drive
PWM methods
electromagnetic compatibility
power quality

Published Papers (2 papers)

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Research

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16 pages, 3871 KiB

Open AccessArticle

Waveform Quality Evaluation Method of Variable-Frequency Current Based on Curve Fitting

by Shengquan Zhao and Yaozong Liu

Energies 2022, 15(20), 7594; https://0-doi-org.brum.beds.ac.uk/10.3390/en15207594 - 14 Oct 2022

Viewed by 887

Abstract

Since total harmonic distortion (THD) is mainly used as the evaluation index for the waveform quality of periodic signals, it cannot be applied to variable-frequency signals. However, there is scarce research on the evaluation methods and indicators of variable-frequency signals in the literature. In this paper, an evaluation method of the waveform distortion (WD) of variable-frequency signals based on curve fitting is proposed. First, the variable-frequency current expression of the coefficients to be optimized is obtained through theoretical derivation. Second, the coefficients are optimized by curve fitting in the time domain through the nonlinear least-squares method. Then, the waveform distortion of the variable-frequency current (I_WDVF) is calculated. In order to validate the proposed evaluation method, the simulation model of a synchronous motor driven by a cascaded H-bridge five-level inverter is built. The simulation results show that, for the same constant-frequency current, the current THD (I_THD) obtained by the FFT method is the same as the current WD (I_WD) obtained by the curve fitting method, which verifies the equivalence of the two methods. The influence of different sampling frequencies on the I_WD and I_THD is compared. The higher the sampling frequency, the more sampling points, and the more accurate the results. For the linear variable-frequency current, the I_WDVF obtained by the curve fitting method is close to the average value of the I_THD obtained by FFT, which indicates that the time-domain curve fitting method is reasonable to solve the I_WDVF. For nonlinear variable-frequency current waveforms, the curve fitting method can also reasonably calculate the I_WDVF. The curve fitting method can solve the evaluation problem of the variable-frequency current, and provide an evaluation means for the optimal design of a modulation strategy aiming at the optimal waveform quality of the variable- frequency current. Full article

(This article belongs to the Special Issue Power Quality in Power Systems with High-Power PWM Converters: Existing Problems and Their Solutions)

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Review

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29 pages, 12159 KiB

Open AccessReview

Current Electromagnetic Compatibility Problems of High-Power Industrial Electric Drives with Active Front-End Rectifiers Connected to a 6–35 kV Power Grid: A Comprehensive Overview

by Aleksandr Nikolaev, Aleksandr Maklakov, Mikhail Bulanov, Ildar Gilemov, Aleksandr Denisevich and Maksim Afanasev

Energies 2023, 16(1), 293; https://0-doi-org.brum.beds.ac.uk/10.3390/en16010293 - 27 Dec 2022

Cited by 11 | Viewed by 1619

Abstract

Today, electric drive systems based on frequency converters with active front-end rectifiers (FC-AFEs) are widespread across industries. In the course of the upgrade of production facilities, such systems replace the conventional converters with thyristor- and diode-based rectifiers. FC-AFEs have the following advantages: the capacity to regenerate the power to the grid and the capacity to operate at the set power factor. The manufacturers of FC-AFEs also claim that their products have the best electromagnetic compatibility (EMC) with the power grid. The best EMC shall be achieved via a multilevel FC-AFE topology and specialized pulse-width modulation (PWM) algorithms for AFE rectifiers. However, the experience of operating mid-voltage high-power electric drives with an FC-AFE in 6–35 kV factory distribution grids with non-linear frequency response due to resonant phenomena refutes the claims of the FC-AFE manufacturers. Resonant phenomena in 6–35 kV grids are caused by the interaction of the inductance of grid components (transformers, reactors) and the capacitance of output cable lines. If the resonance frequency at a sufficient amplitude corresponds to the harmonic frequency of the current consumed by the FC-AFE, the distribution grid will feature high-frequency voltage distortions. This may lead to failures in voltage quality-sensitive electrical consumers. This problem recurred at various metallurgical companies. The purpose of this research is to make a comprehensive overview of the EMC problems during the operation of FC-AFEs at active production facilities, as well as the analysis of the technical solutions aimed at the improvement of the EMC of high-power FC-AFEs with the power grid. Full article

(This article belongs to the Special Issue Power Quality in Power Systems with High-Power PWM Converters: Existing Problems and Their Solutions)

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