Topic Editors

Department of Automation Engineering, Electronics, Architecture and Computer Networks, University of Cádiz, Cádiz, Spain
Dr. Olivia Florencias-Oliveros
Department of Automation Engineering, Electronics, Architecture and Computer Networks, Research Group in Computational Instrumentation and Industrial Electronics (ICEI) (PAIDI-TIC-168), Engineering School of Algeciras, University of Cádiz, 11003 Cádiz, Spain
Department of Electrical and Electronic Engineering, University of Cagliari, 09123 Cagliari, Italy

Power Quality

Abstract submission deadline
closed (25 July 2023)
Manuscript submission deadline
closed (25 October 2023)
Viewed by
22887

Topic Information

Dear Colleagues,

Power quality (PQ) refers to a set of characteristics related to electricity transport and delivery to end consumers, assuring the balance between network performance and customer satisfaction. Two main normative frames have been traditionally adopted by technicians and researchers. Firstly, the UNE-EN 50160 standard defines the characteristics of a common power system service that could be considered secure, continuous and constant. Secondly, the IEC 61000-4-30 standard summarizes the methodologies that must be incorporated within the measurement equipment, regarding their technology and class of precision, to ensure that previously established requirements or measurement characteristics are met.

However, electricity networks and the market are continuously changing and adapting to new technologies and concepts of energy usage emerging within two incipient frames: the smart grid (SG) and the industrial digital revolution (the Industry 4.0). This conception is based on the new capabilities of system production by non-conventional means (e.g., structural issues) with numerous distributed energy resources and loads, whose highly fluctuating demands alter the ideal power delivery conditions. Thus, modern instrumentation and computational intelligence should inform energy behavior and its dynamics almost in real time, and, specifically in the field of PQ, smart instruments should track the continuity and reliability of supply, i.e., perform continuous and permanent monitoring, including short-term forecasting. The aim is to provide customers and industrial managers with new tools capable of interpreting measurements more accurately and flexibly according to the smart grid framework demands.

As a direct consequence of the introduction of new technologies, massive operational data (big data) generated by the measurement equipment deployed during monitoring campaigns are usually difficult or tricky to interpret and manage due to, among other factors, their complex hardware structures and communication protocols, which hinder accessibility to storage units, and the limited possibilities of monitoring equipment, based on dare-to-say obsolete regulations that do not reflect current real-life operation. Consequently, a new conception of data handling is required based on time, frequency and space domain compression techniques, with the goal of offering more robust measurement solutions under real conditions.

Furthermore, PQ problems have serious economic, human and technological consequences. More and more works demand customer-oriented PQ assessment solutions and measurement equipment. Differences in load sensitivity make necessary several specific contractual conditions, introducing thresholds that allow for claims against eventual contractual breaches. Indeed, in the industrial sector, companies request ad hoc PQ assessment, which in fact reflects the real situation, or the “PQ mapping”, of the company facilities and manufacturer process. Industry research benchmarking reports would allow performance comparison of PQ metrics. Hence, quantifying losses and the proposal of compensation strategies are key factors.

Moreover, domestic easy-to-handle instruments should incorporate elements of indication and visualization that do not require extensive technical knowledge and aid in end customers’ understanding of PQ reports (smart indicators).

It can be concluded that keeping PQ in the grid assures human safety and equipment life. This can be achieved by implementing flexible monitoring solutions that can accomplish data management while accounting for temporal and spatial scalability.

Considering this introduction, it is of high interest to classify research literature on PQ into the following flourishing topics or branches that are directly and transversely addressed in multidisciplinary work teams:

  • Statistical Signal Processing (SSP) and intelligent methods for PQ analysis.
    • Statistical planning and characterization in PQ campaigns,
    • Higher-Order Statistics (HOS) for PQ characterization,
    • Intelligent methods for PQ analysis,
    • New estimators for PQ monitoring
  • Power Quality and Reliability characterization.
    • PQ indices and thresholds,
    • Customized PQ for utilities, customers and specific geographical areas,
    • Industry research benchmark reports on PQ metrics,
    • New types of electrical perturbations
  • Management of PQ Big Data in the Smart Grid.
    • Spatial and temporal compression of measurements,
    • Spatial and temporal scalability of measurements,
    • Modelling and forecasting of PQ time-series,
    • Graphical visualization of PQ: plots, diagrams and trajectories,
    • PQ and Information Theory
  • PQ monitoring systems: architectures and communications.
    • New tendencies in smart instruments for PQ,
    • Uncertainty in PQ instruments,
    • Sensors networks for PQ monitoring,
    • Non-intrusive load monitoring,
    • PQ for renewable energy systems,
    • Low-cost measurement equipment.
  • PQ losses and mitigation assessment.
    • Energy efficiency and PQ,
    • Economic impact and losses due to poor PQ,
    • PQ maintenance strategies in networks,
    • PQ mitigation.
  • New PQ monitoring norms and standards.
    • PQ indices,
    • PQ norms,
    • PQ standardized measurements for PMUs
    • PQ monitoring in the industry 4.0.

With all of these precedents, all in all, this second edition of the Special Issue in Analysis for Power Quality Monitoring aims to gather research and review manuscripts dealing with the last advances in PQ analysis and measurement solutions, comprising ad hoc signal processing techniques, artificial intelligence and soft computing, big data analytics and cloud computing for the smart grid, development of new PQ indices, monitoring with newly PQ graphical representations, and their practical implementation in distributed measurement equipment. As a novelty, this issue also pays special attention to the human, technological and financial consequences of a bad PQ, welcoming economic and techno-economic works focusing on losses and the financial effects of PQ mitigation plans. Topics of interest for publication include, but are not limited to:

  • Power Quality and Reliability,
  • Statistical signal processing applied to PQ,
  • Intelligent methods for PQ analysis,
  • PQ indices and thresholds,
  • Soft Computing for PQ,
  • Information Theory and PQ,
  • Customized PQ for utilities, customers and specific areas,
  • Big Data in the Smart Grid: format, compression, and temporal and spatial scalability,
  • Modelling and forecasting of PQ time-series,
  • PQ monitoring systems: architectures and communications,
  • Distributed Measurement Systems,
  • New tendencies in smart instruments for PQ,
  • Sensors networks for PQ monitoring,
  • Graphical visualization of PQ: new displays and hand-held instruments,
  • PQ losses assessment and mitigation,
  • Economic impact of bad PQ losses,
  • PQ maintenance strategies in networks,
  • Industry research benchmark reports on PQ metrics,
  • Prospective introduction of new PQ monitoring norms and standards.

Dr. Juan-José González de la Rosa
Dr. Olivia Florencias-Oliveros
Dr. Sara Sulis
Topic Editors

Keywords

  • power quality (PQ) and reliability monitoring systems
  • statistical signal processing
  • intelligent methods for PQ analysis
  • PQ indices and thresholds
  • customized PQ for utilities and customers
  • big data in the smart grid: temporal and space compression and scalability
  • graphical PQ
  • PQ mitigation
  • PQ losses assessment
  • economic impact of bad PQ losses
  • PQ maintenance strategies in networks
  • new tendencies in smart instruments for PQ
  • PQ norms

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Energies
energies
3.2 6.2 2008 16.1 Days CHF 2600
Applied Sciences
applsci
2.7 5.3 2011 16.9 Days CHF 2400
Electronics
electronics
2.9 5.3 2012 15.6 Days CHF 2400
Sensors
sensors
3.9 7.3 2001 17 Days CHF 2600
Sci
sci
- 4.5 2019 47.7 Days CHF 1200

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Published Papers (15 papers)

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23 pages, 4395 KiB  
Article
Reactive Power Compensation and Distortion Power Variation Identification in Extended Budeanu Power Theory for Single-Phase Systems
by Zbigniew Sołjan, Maciej Zajkowski and Andrzej Borusiewicz
Energies 2024, 17(1), 227; https://doi.org/10.3390/en17010227 - 31 Dec 2023
Cited by 2 | Viewed by 733
Abstract
This article presents methods of reactive power compensation using passive elements in the form of a capacitor (C) or choke (L) and an LC structure selected in such a way as to lead to the minimization of the reactive current (reactive power) of [...] Read more.
This article presents methods of reactive power compensation using passive elements in the form of a capacitor (C) or choke (L) and an LC structure selected in such a way as to lead to the minimization of the reactive current (reactive power) of a single-phase system. The adaptation of the parameters of a passive compensator, reducing reactive power and/or distortion power, was possible through the extended Budeanu theory. In addition, through the extended Budeanu theory and also through the knowledge of the equivalent parameters of the linear load, the obtained results of the increase in distortion power, depending on the structure of the passive compensator, were analyzed. The values listed in the tables, as well as the waveforms of the component currents of a single-phase linear load, were obtained based on calculations and simulation models in MATLAB/Simulink software R2023a. Full article
(This article belongs to the Topic Power Quality)
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12 pages, 1006 KiB  
Article
Electrophysical Method for Identifying the Causes of Excessive Hydro Generator Vibration
by Aleksei S. Karpov, Vera V. Yaroshevich, Galina P. Fastiy and Elizaveta I. Gubskaya
Appl. Sci. 2023, 13(16), 9152; https://doi.org/10.3390/app13169152 - 11 Aug 2023
Cited by 1 | Viewed by 817
Abstract
This article analyzes the operation of hydro generators based on the operation modes of a hydroelectric power plant operating in the Arctic zone of the Russian Federation. The main load of the hydropower plant is an aluminum smelter. The nonlinear load of the [...] Read more.
This article analyzes the operation of hydro generators based on the operation modes of a hydroelectric power plant operating in the Arctic zone of the Russian Federation. The main load of the hydropower plant is an aluminum smelter. The nonlinear load of the smelter is a powerful source of harmonic disturbances. This load produces current and voltage distortions not only in the electrical networks of the smelter but also in those of the city and in generating voltage busbars of the hydropower plant. As a consequence, higher harmonics cause additional losses in the supply networks and have a negative impact on the hydro generators’ condition. The article analyzes the influence of current impacts of the smelter load on the hydro generators under imbalanced conditions by estimating torsional and tangential vibrations emerging in the generators. The tangential forces of double frequency (100 Hz) have been shown to produce practically no significant vibration displacement when detuning the natural frequency of the basket-type end-winding parts. The values of vibration and surge displacement increase significantly in the near-resonance zone. The intense impact of superimposed surge currents has been shown to result in reduction in the hydraulic turbines’ service life and increase in frequency of repairs. Full article
(This article belongs to the Topic Power Quality)
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39 pages, 9131 KiB  
Article
Novel Harmonic Distortion Prediction Methods for Meshed Transmission Grids with Large Amount of Underground Cables
by Vladislav Akhmatov, Bjarne Søndergaard Bukh, Chris Liberty Skovgaard and Bjarne Christian Gellert
Energies 2023, 16(9), 3965; https://doi.org/10.3390/en16093965 - 8 May 2023
Cited by 2 | Viewed by 1344
Abstract
The tremendous and fast green transition in Denmark has initiated the large-scale grid-integration of renewable energy sources, electrification of energy consumption, and establishment of PtX and Energy Islands, setting goals for transmission grid development—such as the establishment of new connections—and for grid reconstruction—such [...] Read more.
The tremendous and fast green transition in Denmark has initiated the large-scale grid-integration of renewable energy sources, electrification of energy consumption, and establishment of PtX and Energy Islands, setting goals for transmission grid development—such as the establishment of new connections—and for grid reconstruction—such as the extensive substitution of overhead lines (OHLs) with underground cables (UGCs). The share of UGCs in the Danish transmission grid is increasing. Presence of UGC has resulted in that resonances of the harmonic impedance characteristics of the transmission grid are brought within the harmonic order range coinciding with the harmonic emission sources and causing systemwide increase of the harmonic voltage distortion in the 400 kV transmission grid. The transformation of the 400 kV transmission grid has given rise to the need to predict harmonic voltage distortion using simulation models to secure an adequate power quality and support investment decisions and harmonic mitigation for the grid stage, which has not yet been established and which differs from the present grid. This paper presents the experiences of Energinet, the Transmission System Operator (TSO) in Denmark, with harmonic distortion in the Danish transmission grid due to the establishment of 400 kV UGCs, and the development of measurement-validated methods for harmonic distortion simulation and prediction. The paper also presents ongoing developments within, and research addressing, the prediction of harmonic distortion in meshed grids; for example, it explores where and how an analytical approach can replace observational studies with many numerical simulations. The methods shall make it possible to predict whether, where in the transmission grid, and for which harmonic orders connections that have not yet been commissioned may cause the violation of the planning levels, and which mitigations are necessary for bringing the harmonic distortion below the planning levels with respect to a given margin. Full article
(This article belongs to the Topic Power Quality)
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19 pages, 6906 KiB  
Article
Unity Power Factor Operation in Microgrid Applications Using Fuzzy Type 2 Nested Controllers
by Hilmy Awad, Amr M. Ibrahim, Michele De Santis and Ehab H. E. Bayoumi
Appl. Sci. 2023, 13(9), 5537; https://doi.org/10.3390/app13095537 - 29 Apr 2023
Cited by 2 | Viewed by 1384
Abstract
The issue of low-power factor operation microgrids was reported for several layouts. Although numerous power factor improvement strategies have been applied and tested, various concerns remain to be addressed such as transient performance, simplicity of implementation, and satisfying the power-quality standards. The presented [...] Read more.
The issue of low-power factor operation microgrids was reported for several layouts. Although numerous power factor improvement strategies have been applied and tested, various concerns remain to be addressed such as transient performance, simplicity of implementation, and satisfying the power-quality standards. The presented research aimed to design and implement controllers that can improve the transient response of microgrids due to changes in the load demand and achieve a near-unity power factor at the AC grid side, to which the DC microgrid is connected. Due to the nonlinear nature of microgrids, as they rely on power electronics converters, a Fuzzy type 2 controller was designed, implemented, and tested. The focus was given to improving the power factor of the DC microgrids. The validation of the proposed technique was verified by comparing its performance with Fuzzy type 1 and autotuned conventional PI controllers. To achieve the set aims, two nested control loops were designed with an inner current loop and an outer voltage loop. Besides MATLAB/Simulink simulations, a 10 kHz-sampling dSPACE platform was used to implement the suggested system. Two operational scenarios were tested: (1) a step change in the DC link voltage and (2) a change in the AC load (increase and decrease) at the output of the power inverter, connected to the DC grid. The simulation and experimental results confirmed that the proposed Fuzzy type 2 controller performed better than the other two techniques regarding the dynamic response, steady-state error, and compliance with power quality standards. Conventional approaches develop controllers using a linearized model, which limits the model accuracy and ignores higher-order variability. The method employs the nonlinear model. Fuzzy type 2 can better approximate high-precision problems than Fuzzy type 1. Full article
(This article belongs to the Topic Power Quality)
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17 pages, 5357 KiB  
Article
Minimization of Voltage Harmonic Distortion of Synchronous Generators under Non-Linear Loading via Modulated Field Current
by Oktay Karakaya, Murat Erhan Balci and Mehmet Hakan Hocaoglu
Energies 2023, 16(4), 1789; https://doi.org/10.3390/en16041789 - 10 Feb 2023
Cited by 1 | Viewed by 2191
Abstract
The synchronous generators (SGs) supplying non-linear loads have harmonically distorted terminal voltages. Hence, these distorted terminal voltages adversely affect the performance parameters of the supplied loads such as the power factor, current distortion, losses, and efficiency. To mitigate the harmonic voltages and currents, [...] Read more.
The synchronous generators (SGs) supplying non-linear loads have harmonically distorted terminal voltages. Hence, these distorted terminal voltages adversely affect the performance parameters of the supplied loads such as the power factor, current distortion, losses, and efficiency. To mitigate the harmonic voltages and currents, passive and active filters are generally employed. However, passive filters cause resonance problems, while active filters can cause high costs. On the other hand, in several recent studies to reduce the SG’s terminal voltage harmonic distortion, which depends on the constructional design under the no-loading condition, the conventional DC excitation current has been modulated with AC harmonic components. These field current modulation methods have high computational complexity, and require extra hardware for their implementation. In the present paper, firstly, for the reduction of the terminal voltage harmonic distortion of the SG under non-linear loading conditions, the validity of the field current modulation technique is investigated. The numerical results show that by using the field current modulation method, under rated loading conditions, the total harmonic distortion of the terminal voltage can be reduced from 18% to 11%. Secondly, to provide a computational efficient and low-cost tool for optimal field current modulation, which minimizes the terminal voltage harmonic distortion, an Artificial Neural Network (ANN)-based model is proposed. Finally, with the integration of ANSYS Maxwell, ANSYS Simplorer, and MATLAB/Simulink software, the implementation of the developed model is demonstrated for the construction of the optimally modulated field current. Full article
(This article belongs to the Topic Power Quality)
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18 pages, 4540 KiB  
Article
Harmonic Distortion Reduction of Transformer-Less Grid-Connected Converters by Ellipsoidal-Based Robust Control
by Hisham M. Soliman, Ashraf Saleem, Ehab H. E. Bayoumi and Michele De Santis
Energies 2023, 16(3), 1362; https://doi.org/10.3390/en16031362 - 28 Jan 2023
Cited by 7 | Viewed by 1874
Abstract
A photovoltaic generator connected to a large network and supplying a nonlinear load (source of harmonics) injects distorted current into the grid. This manuscript presents an invariant-ellipsoid set design of a robust controlled active power filter to inject current into the large grid [...] Read more.
A photovoltaic generator connected to a large network and supplying a nonlinear load (source of harmonics) injects distorted current into the grid. This manuscript presents an invariant-ellipsoid set design of a robust controlled active power filter to inject current into the large grid with minimum total harmonic distortion (THD). The nonlinear load current is considered an external disturbance to minimize its effect on the injected grid current. Moreover, the large grid is modeled as a fixed voltage source in a series with a Thevenin impedance whose value changes within an interval. Using the invariant-ellipsoid technique, the problem is cast as a robust disturbance-rejection tracking control. The volume of the ellipsoid is minimized, which results in minimizing the effect of disturbance on system performance and keeping the trajectories as close as possible to the origin. The design is cast into a set of nonlinear matrix inequalities that are linearized by fixing a scalar. The resulting convex optimization is solved iteratively by linear matrix inequalities (LMIs). The simulation and experimental findings show that the proposed design is successful in reducing THD injected into the grid when grid impedance is uncertain and variable loads are applied (balanced and unbalanced cases). Full article
(This article belongs to the Topic Power Quality)
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10 pages, 3718 KiB  
Article
Voltage Sag Mitigation Effect Considering Failure Probability According to the Types of SFCL
by Joong-Woo Shin, Young-Woo Youn and Jin-Seok Kim
Energies 2023, 16(2), 625; https://doi.org/10.3390/en16020625 - 4 Jan 2023
Cited by 1 | Viewed by 1074
Abstract
The development of industrial technology is based on electronic devices that are sensitive to power quality. Thus, the demand for high-quality and reliable power supplies is increasing. Voltage sag results in severe problems in the manufacturing process of power quality-sensitive industrial loads. When [...] Read more.
The development of industrial technology is based on electronic devices that are sensitive to power quality. Thus, the demand for high-quality and reliable power supplies is increasing. Voltage sag results in severe problems in the manufacturing process of power quality-sensitive industrial loads. When a fault occurs in a multi-ground power distribution system, the magnitudes of the fault current and voltage sag in the faulted and nonfaulted feeders become high. Hence, installing a superconducting fault current limiter (SFCL) is an effective method of compensating for fault current limitation and voltage sag. This study evaluates the effects of improving the magnitude, duration, and frequency of the voltage sag according to the type of SFCL used. First, a fault in the power distribution system is analyzed using PSCAD/EMTDC, a power system simulation software, according to the fault current-limiting element (CLE) and the type of SFCL. Second, the expected voltage sag frequency caused by a feeder fault in the power distribution system is assessed. Finally, the voltage sag improvement effect according to the CLE and the type of SFCL are compared. The trigger-type SFCL with a resistor as a CLE has been evaluated and found to be effective in improving voltage sag. Full article
(This article belongs to the Topic Power Quality)
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16 pages, 3693 KiB  
Article
Fast Supraharmonic Estimation Algorithm Based on Simplified Compressed Sensing Model
by Zesen Gui, Qun Zhou, Hui Zhou, Zheng Liao and Ziyi Wang
Electronics 2023, 12(1), 141; https://doi.org/10.3390/electronics12010141 - 28 Dec 2022
Cited by 2 | Viewed by 1444
Abstract
The computational time of compressed sensing algorithms applied to supraharmonic needs to be improved in online applications. In this paper, a simplified supraharmonic compressive sensing model is proposed. The model first detects the supraharmonic raw spectral array to obtain the estimated sparsity and [...] Read more.
The computational time of compressed sensing algorithms applied to supraharmonic needs to be improved in online applications. In this paper, a simplified supraharmonic compressive sensing model is proposed. The model first detects the supraharmonic raw spectral array to obtain the estimated sparsity and the index of supraharmonic emissions, which simplifies the sensing matrix in the iteration according to the index and then shortens the whole iteration time of compressed sensing. The simulation verifies that the model can reduce the computation time to less than half of the original compressed sensing model and does not affect the computation accuracy. Finally, the online application effect of the algorithm is verified by experiments. Full article
(This article belongs to the Topic Power Quality)
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3 pages, 168 KiB  
Editorial
New Power Quality Measurement Techniques and Indices in DC and AC Networks
by Julio Barros
Energies 2022, 15(23), 9192; https://doi.org/10.3390/en15239192 - 4 Dec 2022
Viewed by 1059
Abstract
Currently, we are living through the implementation of the electrical smart grid, a network that can intelligently integrate the actions of all users connected to it in order to efficiently deliver the sustainable, economical and secure supply of electricity [...] Full article
(This article belongs to the Topic Power Quality)
14 pages, 2834 KiB  
Article
Dynamic Voltage Regulation and Unbalance Compensation in a Low-Voltage Distribution Network Using Energy Storage System
by Krzysztof Rafał, Jacek Biskupski, Sebastian Bykuć and Patryk Chaja
Appl. Sci. 2022, 12(22), 11678; https://doi.org/10.3390/app122211678 - 17 Nov 2022
Cited by 5 | Viewed by 2002
Abstract
Modern distribution grids may suffer problems of voltage distortion, especially along radial low-voltage feeders with a high penetration of intermittent, unbalanced and distorted loads and generation sources. It is a challenge to develop an effective voltage-regulation method using a straightforward implementation. This paper [...] Read more.
Modern distribution grids may suffer problems of voltage distortion, especially along radial low-voltage feeders with a high penetration of intermittent, unbalanced and distorted loads and generation sources. It is a challenge to develop an effective voltage-regulation method using a straightforward implementation. This paper proposes a novel method for local voltage control and balancing using a shunt-connected energy storage system. The compensation principles are explained, and a complete controller design is proposed. The algorithm is designed to be implemented in power electronic converters that provide the interface between the storage and the grid. The original contribution is the development of a low-level control method, which includes voltage balancing and a method to minimize the compensator current and is to be implemented in power electronic converters that provide the interface between the storage and the grid. The calculation of active and reactive compensator currents is explained with relation to the estimated grid impedance. The efficacy of the designed controller is verified by laboratory experiments. It is shown that voltage regulation using the proposed method is achieved with less apparent power compared to a system where only reactive power is used. The controller presents a very good dynamic response to rapid voltage variations, such as unbalanced voltage dips. The applicability and constraints of the method are discussed with respect to the present state of the art in low-voltage-grid voltage regulation. Full article
(This article belongs to the Topic Power Quality)
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18 pages, 3536 KiB  
Article
Extension and Correction of Budeanu Power Theory Based on Currents’ Physical Components (CPC) Theory for Single-Phase Systems
by Zbigniew Sołjan and Maciej Zajkowski
Energies 2022, 15(21), 8321; https://doi.org/10.3390/en15218321 - 7 Nov 2022
Cited by 6 | Viewed by 1584
Abstract
In 1927, the most recognized power theory in the frequency domain was proposed by Budeanu. The second power theory in the frequency domain, which is currently catching a lot of supporters, is the approach proposed by Czarnecki. Both theories have common features in [...] Read more.
In 1927, the most recognized power theory in the frequency domain was proposed by Budeanu. The second power theory in the frequency domain, which is currently catching a lot of supporters, is the approach proposed by Czarnecki. Both theories have common features in the form of the description of active power and are completely different in terms of the description and interpretation of reactive power. This article presents the possibility of using mutual elements of both approaches: thus, it is possible to interpret the physical meaning of the reactive power (reactive current) proposed by Budeanu and the power before the deformation obtained from the mathematical description. Full article
(This article belongs to the Topic Power Quality)
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19 pages, 4177 KiB  
Article
A Mathematical Approach of Voltage Sag Analysis Incorporating Bivariate Probability Distribution in a Meshed System
by Jagannath Patra and Nitai Pal
Energies 2022, 15(20), 7592; https://doi.org/10.3390/en15207592 - 14 Oct 2022
Cited by 3 | Viewed by 1331
Abstract
In this paper, different mathematical expressions are derived to compute the residual magnitude of voltage caused by faults along the line and on the bus. Symmetrical and unsymmetrical faults are taken into consideration, and the consequences of the various fault distributions are considered. [...] Read more.
In this paper, different mathematical expressions are derived to compute the residual magnitude of voltage caused by faults along the line and on the bus. Symmetrical and unsymmetrical faults are taken into consideration, and the consequences of the various fault distributions are considered. A new way of assessing a sag is proposed that incorporates the method of fault position and mathematical expression based on sequence currents and voltages. The fault impedance is introduced to obtain a better result. A fast and efficient load flow analysis technique produces quick computational results. In addition, the sag analysis is performed using the bivariate joint discrete probability distribution method that gives a clear idea about the probability of occurrence of sag in a meshed network. The suggested approach is applied in the IEEE 39-bus system and with an existing real-time electrical power distribution system in India. Full article
(This article belongs to the Topic Power Quality)
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16 pages, 6223 KiB  
Article
Current Ratio and Stability Issues of Electronically Enhanced Current Transformer Stimulated by Stray Inter-Winding Capacitance and Secondary-Side Disturbance Voltage
by Peter Zajec
Sensors 2022, 22(19), 7565; https://doi.org/10.3390/s22197565 - 6 Oct 2022
Viewed by 1364
Abstract
Electronically enhanced current transformers (EECT) have gained much interest in power quality assessment. Their magnitude and phase angle error, which mainly relates to the properties of the ferromagnetic materials used, the impedance of the secondary load, and the inter-turns capacitance, are thoroughly analyzed. [...] Read more.
Electronically enhanced current transformers (EECT) have gained much interest in power quality assessment. Their magnitude and phase angle error, which mainly relates to the properties of the ferromagnetic materials used, the impedance of the secondary load, and the inter-turns capacitance, are thoroughly analyzed. In contrast, the capacitance between the windings, i.e., inter-winding capacitances and their limiting effects on EECT operation, are rarely analyzed in detail—in particular, no details on the control design of the assisting electronic unit, its tuning recommendations, or both are provided. In this paper, the capacitive coupling between indication and compensating winding of EECT with simplified feedthrough construction is analyzed thoroughly in terms of current ratio error and stability of the implemented configuration of the trans-conductance amplifier. The preliminary assumption about the adverse effect of the inter-winding capacitance shunting both ends of the original amplifier, composed of two series-connected inverting amplifier stages, was confirmed and resolved within a modified amplifier with the help of a simplified simulation model and was experimentally proven with measurements on a custom-built EECT prototype. Furthermore, the analyzed phenomena were linked to trans-conductance amplifier parameters, explicitly with its compensating networks, and summarized in their design guidelines. Throughout the paper, the EECT features obtained with original and modified amplifier designs are compared with the plain composite current transformer to demonstrate the benefits of the modified amplifier, especially its robustness against inter-winding capacitance variations. Full article
(This article belongs to the Topic Power Quality)
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17 pages, 4314 KiB  
Article
An Approach for Determining Voltage Imbalance Contributions Based on Complex Independent Component Analysis
by Márcio Arvelos Moraes, Vinícius Henrique Farias Brito and José Carlos de Oliveira
Energies 2022, 15(19), 7014; https://doi.org/10.3390/en15197014 - 24 Sep 2022
Cited by 2 | Viewed by 1266
Abstract
In the context of power quality problems, the voltage imbalance index is relevant, given its harmful impacts on the networks and loads. Thus, reliable and viable methodologies for practical use are necessary to determine agents’ contributions. This article presents a noninvasive method for [...] Read more.
In the context of power quality problems, the voltage imbalance index is relevant, given its harmful impacts on the networks and loads. Thus, reliable and viable methodologies for practical use are necessary to determine agents’ contributions. This article presents a noninvasive method for sharing responsibility for imbalances based on the principle of superposing the individual voltage imbalance produced by the parties. A procedure based on the Complex Independent Component Analysis (CICA) technique is proposed to meet the parameters required by the superposition method. Based on the measurements of voltages and currents carried out on the point of common coupling (PCC), the negative sequence impedances are determined using the CICA method under the terms needed by the superposition principle. The methodology’s effectiveness is evaluated through performance comparisons carried out over the process, in light of the response from the methods for sharing responsibilities currently published in the literature of this domain. The results obtained through the proposed approach show good adherence to the procedures presented with solid conceptual bases. However, unlike these, this article’s methodology offers practical perspectives for application in the field. Full article
(This article belongs to the Topic Power Quality)
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20 pages, 2222 KiB  
Article
Microgrid Harmonic Mitigation Strategy Based on the Optimal Allocation of Active Power and Harmonic Mitigation Capacities of Multi-Functional Grid-Connected Inverters
by Ning Wang, Shuai Zheng and Weiqiang Gao
Energies 2022, 15(17), 6109; https://doi.org/10.3390/en15176109 - 23 Aug 2022
Cited by 4 | Viewed by 1425
Abstract
Harmonic pollution sources in microgrids have the characteristics of high penetration and decentralization, as well as forming a full network. Local harmonic mitigation is a traditional harmonic mitigation method, which has the disadvantages of complexity and costly operation. Based on the idea of [...] Read more.
Harmonic pollution sources in microgrids have the characteristics of high penetration and decentralization, as well as forming a full network. Local harmonic mitigation is a traditional harmonic mitigation method, which has the disadvantages of complexity and costly operation. Based on the idea of the decentralized autonomy of power quality, this paper establishes a comprehensive optimization model of the active power and harmonic mitigation capacities of grid-connected inverters based on two-layer optimization and realizes harmonic mitigation. Firstly, based on the harmonic sensitivity analysis, the calculation method of harmonic mitigation capacity is given. Secondly, a two-layer model of harmonic mitigation optimization is established. The upper-layer optimization model takes the minimum operation cost of the microgrid as the objective and the active power reduction in the multi-functional grid-connected inverter (MFGCI) as the optimization variable. The lower-layer optimization model offers the best harmonic mitigation effect as the objective and the harmonic current compensation as the optimization variable. According to the relationship between the total remaining capacity of MFGCI and the capacity required for harmonic mitigation, there are three different objective functions in the lower-layer optimization model. Then, the model solving steps are provided. Finally, an example shows that the proposed optimization model can achieve harmonic mitigation at different times. Compared with the case without active power optimization, the operation cost of the whole system can be reduced by up to 14.6%, while ensuring the harmonic mitigation effect. The proposed method has the advantages of a harmonic mitigation effect and economical system operation. Full article
(This article belongs to the Topic Power Quality)
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