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Nowadays the efficient use of energy is a major issue in applications such as electric vehicles. However, there are some phenomena that affect electric vehicle performance. One of those phenomena is the torque ripple of electric motors, which interferes with traction and the suspension system (causing vibration that stresses this system), and it can also introduce electric current harmonics into the battery, reducing its life, since torque ripple is partly a consequence of non-sinusoidal back EMF. For those reasons this is a topic worth investigating. The torque ripple of permanent magnets (PM) motors can be reduced in design or through control. Since control techniques have been reviewed and design methods have not, this paper presents a comparison of several design techniques to reduce torque ripple by different approaches and categorize them to show the characteristics of each group. A discussion is then made about the advantages and disadvantages of the designs, in general, as well as some comments about the missing, but important information, in the papers, such as the effects on efficiency. The study shows that a combination of methods provide the best results, although it complicates fabrication and suggests that this is a promising line of future investigation on torque ripple reduction methods. [ABSTRACT FROM AUTHOR]

Enhancing energy efficiency in commercial buildings is crucial for reducing energy consumption. Achieving this goal requires careful monitoring and analysis of the energy usage patterns exhibited by different devices. Nonetheless, gathering data from individual appliances in commercial buildings presents difficulties due to the large number of appliances, complex installations, and costs. This paper presents the Circuits-Level Electrical Measurements Dataset (CLEMD). The measurement was conducted at the main switchboard to a set of distribution boards instead of measuring at the individual loads. The data is gathered from an institutional setting. It consists of 42 records of vital electrical parameters including voltage, current, frequency, real power, reactive power, apparent power, power factor, and odd harmonics for electrical currents. The device deployed in the measurement were industry-grade and had a high sampling rate of 200 kHz. The measurements were done over a 40-day period, from September 16 2023 to October 25 2023. CLEMD is the first Malaysian public dataset on circuit-level electricity consumption and offers analysis opportunities in different research areas such as electricity load disaggregation at circuit level, circuit identification, load profile forecasting, and pattern recognition. [ABSTRACT FROM AUTHOR]

Partial discharge (PD) diagnostics test is a reliable solution for estimating insulation health conditions in power system components. During laboratory PD diagnostics, the effect of harmonic components in the voltage waveform generated by variable frequency drives (VFD) fed electric motors (EMs) is often overlooked. As VFD‐fed EMs operate at low speeds, the harmonic concentration in the voltage increases. It has been found that PD activity in VFD‐fed EM is significantly affected by the addition of harmonic components in the voltage, thus making it necessary to consider their impact when performing true PD diagnostics. This paper investigates the influence of voltage harmonic distortion produced in VFD‐fed EM on PD severity and the subsequent insulation degradation. Eight VFD‐fed EM are used to study the PD behaviour under different levels of harmonic pollution. The PD characteristics, such as inception voltage, pulse repetition rate, accumulated apparent charge, average discharge current, discharge power, and quadratic rate, are determined. Using probability distribution functions, PD activity and severity at various voltage harmonic levels are estimated. The proposed technique can be used to plan the maintenance activities that ensure the reliability for industrial applications dealing with the voltage harmonic distortion. [ABSTRACT FROM AUTHOR]

Modern electric grid usages extensive non-linear loads leading to the increased harmonic current injection in the system. This paper proposes a data-driven algorithm based on a sparse decomposition approach with the Overcomplete Hybrid Dictionary (OHD) and provides in-depth mathematical analysis to detect and mitigate harmonics in emerging electric power systems. The sparse decomposition method is widely used in image processing applications with significant advantages to big-data applications. However, its application is not properly addressed in electric grids’ applications despite massive data generation in a smart grid environment. Hence, in this paper, the performance evaluation of a sparse decomposition-based algorithm using a greedy approach is proposed and carried out in a real-time simulation environment for Distribution Static Compensator (DSTATCOM) application for the real-time detection, classification, and mitigation of PQ events to show its suitability and effectiveness. Finally, the experimental results on a small-scale laboratory setup are presented to validate the effectiveness of the proposed sparse-based control algorithm for DSTATCOM in real-time applications. The comparative result shows that the proposed sparse-based method is advantageous for off-line PQ signal processing and capable of real-time detection, classification, and control of the power apparatus for harmonics mitigation. [ABSTRACT FROM AUTHOR]

Recent years saw increasing of harmonic distortion at transmission grids caused partly by a growing system undergrounding, leading to resonances at lower frequencies. Presently, the estimation of the harmonic distortion through simulations after significant grid changes is not sufficiently accurate, and the understanding of harmonics propagation is a topic under research. This hinders grid development by system operators, as it is not possible to assess fully the impact of new lines. This paper presents and analyses four harmonic-related phenomena: (1) impact of line asymmetry in long HVAC cables; (2) harmonic peak voltage/current along a line; (3) harmonic propagation between voltage levels; (4) fillter location. The paper summarizes the root causes and consequences of each phenomenon, together with tools and recommendations that can ease the assessment of harmonic propagation. [ABSTRACT FROM AUTHOR]

This paper elucidates the working of shunt active filters in dynamically varying grid conditions. The accuracy of harmonics eliminated is based on the harmonic extraction technique and the switching techniques used. The harmonics of the electrical system are computed and based on the various harmonics produced; the shunt active filter has to supply a compensating current in opposition at the point of common coupling. Space Vector Pulse Width modulation (SVPWM) is an effective switching technique used but its performance is not satisfactory in the over-modulation regions. In this paper, optimised switching technique using a neural network for SVPWM is used which has lesser computation time and computes the gating pulses effectively in the over-modulation regions. Shunt active filter mitigates the impact of harmonics even in the over-modulation regions. The hardware is implemented using FPGA Spartan 6 controller, which utilises fewer hardware resources. The optimised switching topology results with improved harmonic reduction even in the over-modulation regions with unbalanced loading conditions is presented in this paper. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present our research into the reduction of vibrations in induction motors. The use of power inverters results in the generation of electrical harmonics, which increase the level of the mechanical vibrations of electrical machines. To reduce these harmonics, we present a discontinuous pulse-width modulation (PWM) control strategy based on carrier-wave modulation applied to multilevel inverters. Using the proposed modulation technique, the amplitude of the electrical harmonics is reduced, as compared to other conventional techniques. These current harmonics produce the MMF (magnetomotive force) harmonics in the air gap, which are one of the main sources of vibrations. The control strategy makes it possible to vary the electrical spectrum at the output of a multilevel inverter by modifying a control parameter of the carrier wave in the PWM, thus avoiding the natural frequencies of mechanical resonance. The proposed technique also has the feature of attenuating the total harmonics distortion of the voltage of the multilevel inverters, as well as the achievement of a higher RMS value of the output voltage for the same DC level. Laboratory results for an induction motor with different modulation strategies, applied in a multilevel inverter and compared to the strategy presented, are attached. [ABSTRACT FROM AUTHOR]

Multilevel converter plays an important role in high- and medium-power applications, such as renewable energy generation systems and power transmission. One of the most known problems of power electronics converter is harmonics. Furthermore, optimization algorithms can solve complex issues in electrical engineering such as the harmonics in power converters. In this paper, the optimization of total harmonic distortion using genetic algorithm is performed for three-phase three, five, seven, and nine levels inverter for several numbers of switching angles and different modulation index values. The best values of the total harmonic distortion of the three-level inverter were less than 23.60% and about 5% for the nine levels inverter in this study. The results obtained in the optimization process have been applied to a neutral point clamped multilevel inverter. Another challenge for this inverter is the DC-link capacitors voltage unbalance; thus, the multilevel boost DC–DC converter is proposed as a solution. The proposed system is validated experimentally using a three-phase three-level neutral point clamped inverter and four-Level (or two-Level) DC–DC boost converter. [ABSTRACT FROM AUTHOR]

A major part of the adjustable speed drive system is the converters fed by switched-mode power supplies with a bridge pulse topology. This bridge produces in the supply network currents with harmonic components. Thus, it is mandatory to map the time-varying harmonic distortion index caused by the controllers. This paper analyzes through computational simulations the influence of a sensor-less field-oriented control system in the generation of harmonics in time. Through the sliding window recursive-discrete, Fourier Transforms currents were decomposed into harmonic time-varying harmonics signals. Total time-varying harmonic distortions were calculated according to the IEEE 1459 standard. The total harmonic distortion function was obtained applying a curve fitting technique. Total harmonic distortion varying in time of grid currents showed values of less than 3%. The harmonic distortion increases in stator currents due to the action of the torque controllers. Engineers and researchers can use this total time-varying harmonic distortions to improve adjustable speed drive control systems minimizing the injection of harmonics the electric power system. [ABSTRACT FROM AUTHOR]

The excessive use of nonlinear load causes electric current harmonics that ultimately downgrades the electrical power quality. If a failure exists due to internal integration of a power system in any one of the internal networks, it causes uncomplimentary consequences to the entire power system's performance. This paper proposed a hybrid shunt active harmonic power filter (HSAHPF) design to reduce harmonic pollution. A digital controller HIL simulator has been modeled using a three-phase voltage source inverter to test the efficiency of HSAHPF and the performance of control algorithms. Moreover, the instantaneous active and reactive current theory (Id − Iq) and instantaneous active and reactive power theory (Pq0) control algorithms are implemented for the reference current generation in HSAHPF, resulting in reduced harmonic distortions, power factor improvement for a balanced nonlinear load. The control algorithms are further employed in Arduino MEGA to keep the factor of cost-effectiveness. The simulation of the proposed design has been developed in Simulink. The validation and testing of HSAHPF using controller HIL simulation prove the control algorithms' ability to run in a portable embedded device. The statistical analysis of the proposed system response provides a minimum total harmonic distortion (THD) of 2.38 from 31.74 that lies in IEEE 519-1992 harmonic standards with an improved stability time of 0.04 s. The experimental verification and provided results of the HIL approach validate the proposed design. Significant mitigation of harmonics can be observed, consequently enhancing the power quality with power factor near unity. [ABSTRACT FROM AUTHOR]

Introduction. Nowadays, electrical energy is indispensable in industrial, tertiary and domestic appliances. However, its efficiency is becoming affected by the presence of the disturbances that appear in the electrical networks such as harmonics, unbalance, sags/swells, flickers …etc. Indeed, the disturbances cause a decrease in the power factor and an increase in the power losses. In this paper, the harmonic disturbance is considered and a 3-level shunt active power filter powered by a hybrid fuel-cell/battery DC is applied to mitigate current harmonic components from the electrical feeder. Aim. Studying the energy efficiency of a system based on a 3-level shunt active filter powered by a hybrid fuel-cell / battery DC bus. Methodology. It is a matter of finding the suitable formulas that express the efficiency and the relative power losses according to the load factor (which is the ratio between the short-circuit active power and the load active power) and the load power factor. The DC bus energy is controlled using an energy management algorithm that contributes in generating the required reference input currents and output voltages of the fuel-cell and the battery. The DC/DC converters control circuits are performed in a closed loop by means of regulated duty cycles. Results. The simulation results carried-out under MATLAB/Simulink environment show better filtering quality if compared with the case of open loop control of the DC/DC converters and lesser differences between the fuel-cell power, the battery power and their respective reference powers. Which concerns the energy efficiency, the results demonstrate that higher efficiency and lower relative power losses can be achieved only when higher load factor and load power factor are attained. Therefore, the compensating system of the power factor is very important to improve the energy efficiency. [ABSTRACT FROM AUTHOR]

The spread of harmonics in electric power systems causes deviations in voltage and current waveforms from the ideal sinusoidal form and, consequently, the traditional power calculation is unsuitable. One of the power theories defined for non-sinusoidal conditions is the IEEE Standard 1459-2010, based on Fourier Transform (FT). However, when applied to non-stationary signals, the FT leads to miscalculation due to spectral leakage, being unsuitable for non-stationary waveforms. In this paper, a new approach for the IEEE Standard 1459-2010 definitions is proposed using Stockwell Transform (ST). The ST provides a time-frequency resolution which retains magnitude and phase information of signals over time. The performance of the proposed method was evaluated in three scenarios including stationary waveforms, a non-linear circuit, and real measured data. The results were compared to the IEEE Standard 1459-2010 using the FT and the Stationary Discrete Wavelet Packet Transform (SDWPT) approaches. In the three scenarios studied, the proposed method presented a good estimation for each quantity defined in IEEE Standard 1459-2010 and provided more accurate results than FT-based and SDWPT-based methods. [ABSTRACT FROM AUTHOR]

In this paper we propose a strategy for real-time detection of interturn shortcircuit faults (ISCF) on three-phase induction motor (IM) by using a Vold-Kalman filter (VKF) algorithm. ISCF produce a thermal stress into the stator winding due to large current that flows through the short-circuited turns. Therefore, incipient fault detection is required in order to avoid catastrophic failures such as phase to phase, or phase to ground faults. The strategy is based on an analytical IM model that includes a ISCF fault in any of the phase windings and considering the h-th harmonic in the voltage supply. Based on equivalent electrical circuits with harmonics in sequence components, we propose a strategy for detection of an ISCF on IM by tracking the 5th harmonic current component using a VKF algorithm. The proposed model is experimentally validated using a three-phase IM with modified stator windings to generate ISCF. Also, the IM is feeded by a programmable voltage source to synthesize distorted voltage supply with the 5th harmonic. The results demonstrated that the positive-sequence magnitude for the 5th harmonic current component is a good indicator of the fault severity once it exceeds a threshold limit value, even under load variations and unbalanced voltages. [ABSTRACT FROM AUTHOR]

Pollution levels in major cities in India are increasing exponentially. According to Air Visual, 22 of the world's 30 most polluted cities are in India. Therefore, there is a need to find an alternative way to operate the conventional vehicles. Recently, the National Electric Mobility Mission Plan 2020 was notified by the Government of India (GoI) to address the environmental challenges posed by conventional motor vehicles and boost the production of reliable, affordable and efficient Electric Vehicles (EVs). Without a charging infrastructure, electric vehicles are supposed to charge the battery in the home. The EV charger is required to charge the batteries. The charger is basically a non-linear device. This paper analyses harmonics generated by electric vehicles and the determination of the total harmonic distortion (THD) at different nodes of the residential distribution network. Decoupled Harmonic Power Flow (DHPF) was developed for residential distribution system to assess the harmonic effects of EV loads. [ABSTRACT FROM AUTHOR]

This paper aims to present a simulation model for the analysis of the operational characteristics of electric motors (EMs). The model was developed on the Simulink platform of the MATLAB program and allows analysis in supply conditions with harmonics and voltage unbalance. The contribution of the model is that it considers the mechanical losses and provides for the study of the effect of each component of the electrical sequence of the harmonics and the voltage unbalance on the electromechanical characteristics of the EM. The model developed was tested in a 37.3 kW EM, operating under four power supply conditions: balanced sinusoidal voltages, balanced non-sinusoidal voltages (i.e., harmonics), unbalanced sinusoidal voltages, and non-sinusoidal unbalanced voltages. The results showed that under the conditions of harmonics and unbalance, the efficiency was reduced by 2%, respectively and that with the combined effects, the efficiency decreased by 4%. The results made it possible to quantify, from the current, voltage, and electrical power values of each sequence, the adverse effects caused by voltage unbalance and harmonics. [ABSTRACT FROM AUTHOR]

In the present-day decade, the world has regarded an expansion in the use of non-linear loads. These a lot draw harmonic nonsinusoidal currents and voltages in the connection factor with the utility and distribute them with the useful resource of the overall performance of it. The propagation of these currents and voltages into the grids have an effect on the electricity constructions in addition to the one of various client equipment. As a result, the electrical strength notable has come to be critical trouble for each client and distributor of electrical power. Active electrical electricity filters have been proposed as environment splendid gear for electrical power pinnacle notch enchantment and reactive electrical strength compensation. Active Power Filters (APFs) have Flipped out to be a possible wish in mitigating the harmonics and reactive electrical electricity compensation in single-phase and three-phase AC electrical energy networks with Non-Linear Loads (NLLs). Conventionally, this paper applied Ant Colony Algorithm (ACO) for tuning PI and reduce Total Harmonic Distortion (THD). The result show reduces THD at 2.33%. [ABSTRACT FROM AUTHOR]

In the new era, the presence of harmonics in electrical traction used in Indian railways has become one of the major concerns in the last decade. The quality of power supply has deteriorated as the voltage and current signals are loaded with unwanted frequency components. The cause of harmonic distortion in these locomotives is due to the traction substations (TSS) of Indian Railways take twophase power (132 or 66 kV) and convert it to single-phase 25 kV power using a step-down transformer (usually in the range of 21.6 MVA capacity). Typically, two transformers are used, with one transformer normally remaining in standby mode. One of the terminals of the secondary side of the transformer is earthed, while the other terminal feeds the substation equipment and also the overhead line. The TSS, more specifically its 25 kV supply, experiences a fluctuating traction load of 50 to 800 ampere. The power factor also varies and can reach a low value of 0.8 at higher loads. The reactive power compensation requirement for such a TSS can reach as high as 4.0 to 7.0 MVAr, depending on the minimum power factor limit set. The second major problem of TSS is the high percentage of current harmonics, especially of lower order, and the associated total distortion Current Harmonic Distortion (ITHD) and total supply voltage distortion / Voltage Harmonic Distortion (VTHD). Due to the presence of a large number of rectifiers and thyristor converters in the electric traction, the current drawn from the 25 kV supply has a high percentage of lower order current harmonics (5, 7, 11, 13......) including the 3rd order current harmonics. Since the short circuit capacity (SCC) is limited at 25 kV, the voltage distortion increases. Both the current and voltage distortions need to be addressed as per the current / prevailing standard (IEEE 519 -2014). This is the problem that is considered and addressed in detail in this paper, considering both reliability and economics of the solution. [ABSTRACT FROM AUTHOR]

This paper presents a harmonic compensation strategy for a 3‐ϕ grid‐tied solar energy conversion system with leakage current attenuation feature. As parasitic capacitance exists between the solar photovoltaic panels with the ground, the deviation in common‐mode voltage compels the probable safety hazards such as electromagnetic interference and harmonics injection in the grid currents. Additionally, the power quality indices of the grid, are exacerbated with the coupling of the non‐linear load. Owing to these issues, a generalized integrator based approach is introduced to ensure the harmonics suppression, power factor correction, leakage current alleviation. Additionally, the grid current distortion limits are ensured within limits in order to comply with the IEEE std. 519. The presented algorithm ensures a robust operation with respect to various anomalies in the grid voltages. Simulation results show the satisfactory response of the harmonics controller even under abnormal operating scenarios including the symmetrical/unsymmetrical faults in the grid side network. In comparison with the traditional algorithms, the harmonic controller suppresses the leakage current and harmonics within restricted limits despite the abnormal conditions. Real‐time simulator results demonstrate the performance of the controller under distinct operating conditions such as load unbalancing, distorted grid voltages, etc. [ABSTRACT FROM AUTHOR]

Modular multilevel converters (MMC)s are promising candidates for large‐scale grid‐connected photovoltaic (PV) systems. Due to their modular structure, MMCs provide a direct connection of the PV arrays to the converter submodules. They also offer scalability, independent maximum power point tracking, and enhanced power quality with internal power flow capabilities. However, the intermittent nature of PV arrays introduces a power unbalance inside the converter, which affects its operation. This paper addresses the issue and proposes an energy balancing strategy for the grid‐connected MMC‐based PV system. It uses the internally generated leg currents to control the power flow inside the converter and inject a three‐phase balanced current to the grid with low total harmonic distortion. Compared to the existing strategies, the proposed strategy can overcome any condition of the power unbalance with minimal submodule voltage fluctuations. A 162‐kW, 9‐kV PV grid‐connected system is modelled and simulated in MATLAB Simulink environment. The corresponding results are presented to demonstrate the effectiveness of the proposed control strategy for grid‐connected PV systems. [ABSTRACT FROM AUTHOR]

In this paper, a novel active current co‐efficient extraction (ACCE)‐based control method is presented for a three‐phase grid‐interfaced voltage source inverter (VSI). Since the VSI performance largely depends on the reference current generation method, it is of significance to identify the active current co‐efficient of the load current contaminated with harmonics, as it is a key governing factor that decides the shape of the compensating current. The proposed ACCE structure functions with minimal mathematical operators like product, sum, and integrators and thereby identifies the fundamental current with computational effectiveness. Besides, in comparison to existing prevalent state‐of‐the‐art methods, the proposed ACCE structure is devoid of any low‐pass filter and zero‐crossing detector, and hence serves the following two distinctive purposes: (i) Ensures minimum steady‐state oscillations and (ii) exhibits improved dynamic performance under disturbances in the grid and load. The proposed structure effectively confronts the various power quality challenges while injecting the active power into the utility grid. Further, the incremental‐conductance‐based maximum power point tracking algorithm is equipped to extract the maximum possible power from the photovoltaic array. Finally, the effectiveness of the proposed ACCE structure has been investigated through MATLAB/Simulink software studies followed by dSPACE‐1104‐based experimental setup. [ABSTRACT FROM AUTHOR]

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This paper presents a detailed mathematical loss-modelling, design, hardware implementation issues, and experimental verification of high-power isolated single-stage three-phase differential-based flyback inverter (DBFI) for grid-tied photovoltaic applications. In addition, this paper studies the loss-modelling analysis of the DBFI components in terms of time and system parameters, which describes the power loss distribution over the circuit components for efficiency enhancement possibility. Also, it studies the practical design issues of DBFI; power stage design, HFT-based F3CC Nano-Crystalline C-Core design, passive elements selection effects on harmonics compensation of grid current waveforms, and the input DC current ripple for PV applications propriety. In addition, the input DC-voltage variation impact on the grid-current THD, system efficiency, and operational power factor are investigated. Also, continuous modulation scheme (CMS) is used to control the proposed DBFI for low-order harmonic components mitigation. The system is simulated by PSIM computer-aided simulator. Then, the proposed system is verified experimentally using a laboratory prototype controlled by TMS320C6713 DSP controller. [ABSTRACT FROM AUTHOR]

• Two improved types of accurate models based on the Schavemaker model are developed. • Unlike the original Schavemaker model which uses invariant parameters, the time-varying nature of the arc's parameters is considered in the proposed models. • The first improved model has time-varying coefficients. • In the second improved model, a new term has been added to the schavemaker model that includes time-varying coefficients. • A large number of the actual data are used. Electric arc furnace (EAF) is more and more applied in large industrial systems and represent one of the major sources of perturbations for the power system because it is highly non-linear and time-varying. New models are suggested in this research based on instantaneous EAF voltage and current measurements taken from EAFs at the Mobarakeh steel mill in Isfahan, Iran. This paper aims to develop two improved types of accurate models based on the Schavemaker model. The original Schavemaker model has three constant parameters. Unlike the original Schavemaker model which uses invariant parameters, the time-varying nature of the arc's parameters is considered in the proposed models. The first improved model has time-varying parameters. Additionally, to further enhance the model's accuracy, in the second improved model, a term has been added to the schavemaker model that includes time-varying parameters. Compared to the original Schavemaker model, all of the developed Schavemaker models are more precise. Finally, auto-regressive moving average (ARMA) models are used to attain the time variation characteristic of the parameters. [ABSTRACT FROM AUTHOR]

Compared to the classical inverters, the multilevel inverter finds remarkable advantages that can be suitably implemented in green energy power generation. Here, an asymmetric multilevel inverter with fewer components is proposed for renewable energy applications. The proposed inverter is a cross between two H-bridge-style devices. To maximize the output voltage, three different algorithms to fix the amplitude of the DC sources are proposed, and the best among them is chosen for implementation. The recommended inverter can generate 19 levels of output voltage using three DC sources with reduced power components. The nearest-level modulation is used as the control course for the inverter. Here, MATLAB software is used to simulate the proposed inverter, and the performance of the inverter is observed. The proposed inverter is constructed in real time, and the performance of the inverter is studied by testing with fixed and variable reactive loads. A comparative study is made between the simulation model and real-time work results interms of efficiency and harmonics in the load waveforms. [ABSTRACT FROM AUTHOR]

Power electronic circuits in modern power supplies have improved the conversion efficiency on the one hand but have also increased harmonic emissions. Harmonic currents from the operation of these units affect the voltage waveforms of the network and could compromise the reliability of the network. Load and source non-linearity can, therefore, limit the renewable source's hosting capacity in the grid, as a large number of inverter units may increase the harmonic distortions. As a result, voltage and current distortions could reach unbearable levels in devices connected to the network. Harmonic estimation modelling often relies on measurement data, and differences may appear in mathematical simulations as the harmonic aggregation or cancellation may generate different results due to the inaccuracies and limitations of the measurement device. In this paper, the effect of harmonic currents cancellation on the aggregation of different load currents is evaluated to show its impact in the network by presenting a comparison between the measurement and mathematical aggregation of harmonics. Furthermore, the harmonic cancellation phenomenon is also qualified for multiple loads connected to the power supply. [ABSTRACT FROM AUTHOR]

Renewable energy sources especially solar energy connected to an electrical grid system by using power electronic devices, known that devices degrade the power quality and especially generate harmonic currents. This article presents the study investigation and propagation of harmonics in the integration system of an electric grid connected to the photovoltaic system in the presence or not of a non-linear load (polluting load). In this study, the perturb and observe type MPPT controller for the boost converter and the PWM control for the three-phase inverter which provides the connection are used. We use a passive filtering technique (single and multiple filters) to mitigate the harmonic currents generated by the non-linear load. In the first case where the integration system is alone, the results obtained show that the values of the total harmonic distortion (THD) rates are within the standard used. But in the case of the presence of the non-linear load, the THD values are higher than the used norm. After using our proposed technique, the values of THD obtained are in the norm used for the application of a tuned filter at the fifth harmonic, and better results find with using of multiple filters (fifth and seventh). [ABSTRACT FROM AUTHOR]

The shift of the world in the past two decades towards renewable energy (RES), due to the continuously decreasing fossil fuel reserves and their bad impact on the environment, has attracted researchers all around the world to improve the efficiency of RES and eliminate problems that arise at the point of common coupling (PCC). Harmonics and un-balance in 3-phase voltages because of dynamic and nonlinear loads cause a lagging power factor due to inductive load, active power losses, and instability at the point of common coupling. This also happens due to a lack of system inertia in micro-grids. Passive filters are used to eliminate harmonics at both the electrical converter's input and output sides and improve the system's power factor. A Synchronous Reference Frame (SRF) control method is used to overcome the problem related to grid synchronization. The sine pulse width modulation (SPWM) technique provides gating signals to the switches of the multilevel inverter. A multi-layer feed forward neural network (ML-FFNN) is employed at the output of a system to minimize mean square error (MSE) by removing the errors between target voltages and reference voltages produced at the output of a trained model. Simulations were performed using MATLAB Simulink to highlight the significance of the proposed research study. The simulation results show that our proposed intelligent control scheme used for the suppression of harmonics compensated for reactive power more effectively than the SRF-based control methods. The simulation-based results confirm that the proposed ML-FFNN-based harmonic and reactive power control technique performs 0.752 better in terms of MAE, 0.52 for the case of MSE, and 0.222 when evaluating based on the RMSE. [ABSTRACT FROM AUTHOR]

In this research work, deep machine learning-based methods together with a novel data augmentation are developed for predicting flicker, voltage dip, harmonics, and interharmonics originating from highly time-varying electric arc furnace (EAF) currents and voltage. The aim with the prediction is to counteract both the response and reaction time delays of active power filters (APFs) specifically designed for electric arc furnaces (EAF). Multiple synchronous reference frame (MSRF) analysis is used to decompose the frequency components of the EAF current and voltage waveforms into dqo components. Then using low-pass filters and prediction of the future values of these dqo components, reference signals for APFs are generated. Three different methods have been developed. In two of them, a low-pass Butterworth filter is used together with a linear finite impulse response (FIR)-based prediction or long short-term memory network (LSTM) for prediction. In the third method, a deep convolutional neural network (CNN) combined with a LSTM network is used to filter and predict at the same time. For a 40-ms prediction horizon, the proposed methods provide 2.06%, 0.31%, 0.99% prediction errors of the dqo components for the Butterworth and linear prediction, Butterworth and LSTM, and CNN with LSTM, respectively. The error of the predicted reconstructed waveforms of flicker, harmonics, and interharmonics resulted in 8.5%, 1.90%, and 3.2% reconstruction errors for the abovementioned methods. Finally, a Simulink and GPU-based implementation of predictive APF using Butterworth filter + LSTM and a trivial APF resulted 96% and 60% efficiency on compensation of EAF current interharmonics. [ABSTRACT FROM AUTHOR]

Beat phenomenon is an important issue for the practical application of electrolytic capacitorless motor drives. In this study, the characteristics of stator current harmonics caused by the voltage sampling delay are analyzed. Further, the beat phenomenon generated from the interaction between the harmonics and the fundamental currents is investigated, and the envelope feature of the stator current is derived mathematically. For the purpose of suppressing the beat phenomenon, a voltage reconstruction strategy is proposed to reduce the influence of dc-link voltage sampling delay at the six times of grid frequency. By utilizing the reconstructed dc-link voltage for calculation of PWM duty ratio, the beat phenomenon can be attenuated significantly. The proposed method can be integrated into motor control system easily. Experimental results show the effectiveness of the proposed strategy in a prototype of electrolytic capacitorless permanent magnet synchronous motor drive. [ABSTRACT FROM AUTHOR]

• Abnormal vibrations of mechanical structures due to electromechanical coupling effects of high-speed train drive systems. • Electrical harmonics in the transmission system increased vibration fatigue damage of mechanical structures. • Vibration suppression using current feedback compensation algorithm mitigated the structural fatigue damage. High-speed train transmission systems operate in a multi-source excitation environment, in which the torque pulsation of the traction motor is an important one. According to the principle of AC/DC/AC transmission, a voltage pulsation in the DC-link causes a torque pulsation in the motor. In this paper, an electromechanical coupling model for the traction drive system of high-speed trains was established, and which was used to analyze the effect of DC voltage pulsations on motor current and torque, and further studied the structural fatigue damage of the drive system under electromechanical coupling vibration. A current compensation algorithm was then used to compensate for the DC voltage pulsations and suppress the motor torque pulsations, thus extending the service life of the structure. [ABSTRACT FROM AUTHOR]

• Proposes a hybrid power amplifier, with parallel LPA and SMPA for machine emulation. • A new current control scheme is presented to reduce the current rating of the LPA. • Control is illustrated for the emulation of a direct-online start-up of an Induction machine. • Control bandwidths and their relation with the machine emulation accuracy are evaluated. Machine Emulation (ME) is one of the main applications of Power-Hardware-In-the-Loop (PHIL) simulations. The performance and cost of an ME system depends heavily on the type of Power Amplifier (PA) it employs. Linear Power Amplifiers (LPAs) produce ripple free outputs and offer high bandwidths but are costly. Switch-Mode Power Amplifiers (SMPAs) are more affordable, with higher power density, but produce switching harmonics that yield distorted waveforms and reduce the closed loop bandwidths. In order to get a compromise between these technologies for ME, this paper proposes an ME based on a Hybrid Power Amplifier (HPA), with parallel LPA and SMPA. A new current control scheme for the HPA, suitable for voltage-in current-out machine models, is proposed to reduce the required current rating, and thus the cost, of the LPA. A design procedure for the control scheme of the HPA is presented and illustrated for the emulation of a direct-online start-up of an Induction Machine (IM). Simulation results evaluate and compare systems built exclusively with SMPA or LPA for ME. Experimental results are shown to validate the proposed control scheme for the parallel HPA in ME systems. Besides, the impact of the bandwidths of the control loops of the LPA and SMPA and the switching frequency of the SMPA, on the accuracy of the ME system and on the current requirement of the LPA are highlighted. [ABSTRACT FROM AUTHOR]