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A novel adaptive heart rate monitoring and filtering system based on algebraic distance minimization has been designed. This system uses frequency-modulated continuous-wave radar for non-contact monitoring of parameters such as respiration, heart rate, and heart rate variability (HRV). By employing an improved algebraic distance minimization technique, the system suppresses static noise from the environment, enhances the signal-to-noise ratio of the intermediate-frequency signal, and reduces the complexity of subsequent signal processing. To address issues such as low-frequency interference from radar signals reflecting off fixed targets around the subject and the impact of respiratory harmonics on heart rate measurement, this study introduces a respiratory harmonic filter and an adaptive notch filter to eliminate higher-order respiratory harmonic interference. This approach allows for the adaptive decomposition and reconstruction of vital sign signals and final estimation of respiratory heart rate based on the relationship between harmonics. Comparative experiments with intensive care unit medical equipment have validated the superiority and robustness of the proposed algorithm. Experimental results show that the RMSE and MRE of the method are 2.66% and 2.7%, respectively. After multiple measurements across various subjects, the method achieved an average accuracy of 96.5%, demonstrating higher measurement accuracy than other methods in all cases. Additionally, the algorithm also enables the detection of heart rate variability.

Power quality (PQ) has taken center stage in contemporary discussions owing to the escalating usage of power electronic gadgets. This paper throws light on the unified power quality conditioner (UPQC), an instrumental tool for load current balancing, voltage regulation, harmonics mitigation, sag and swell mitigation, and load-reactive power demand compensation within a three-phase, three-wire distribution structure catering to a variety of combinations of non-linear and unbalance loads. In scenarios devoid of UPQC, phenomena such as voltage sag, swell, and supply voltage distortion pose a potential threat to the sensitive equipment connected to the system. UPQC ingeniously amalgamates a series active power filter (APF) with a shunt APF, thereby addressing a majority of PQ issues. The control over the shunt APF is achieved via synchronous reference frame (SRF) theory, while the series APF is governed by the power angle control (PAC) technique. The application of SRF-PAC techniques manifests a high degree of robustness, effectively counterbalancing the VA loading imbalance in both series and shunt APFs within the UPQC system. This equilibrium is attained through the fair distribution of reactive load power between the two APFs. The simulation outcomes convincingly illustrate that UPQC minimizes the impact of supply voltage variations and harmonic currents on the power line under diverse loads, with the total harmonic distortion (THD) of load voltages and source currents generated being confined to less than 5%. [ABSTRACT FROM AUTHOR]

This paper proposes a new multifunctional control technique for a grid-connected hybrid distributed generation system composed of a photovoltaic system and a wind power system based on a voltage source converter (VSC). Indeed, aside from the generation and the injection of energy into the grid, the proposed system deals with power quality issues caused by harmonics generated by non-linear loads in order to keep the source current uncontaminated. The VSC serves to first ensure that the power generated from the hybrid renewable energy source is fed to the utility grid and acts as a shunt active power filter in case an abnormal increase in the THD of the source current above the standard permissible values is detected due to the non-linear load connection. The two sources of the hybrid system are connected to a common DC bus to simplify the control and reduce the cost of the system, and a maximum power point tracking controller is used for both sources. The major advantage of this novel proposed multifunctional control technique is its ability to inject harvested power into the grid while simultaneously ensuring the compensation of the harmonics and reactive power. The proposed multifunctional control technique is validated through an extensive simulation analysis using MATLAB/Simulink. [ABSTRACT FROM AUTHOR]

In this paper, a novel integrated SHE-NLC control is proposed for the mitigation of unwanted lower-order harmonics in the cascaded H-bridge multilevel inverter. The proposed algorithm has been developed by hybridizing the NLC and SHE methods, in an attempt to keep the merits of both the individual control. The switching angles and nearest levels are calculated by applying the Genetic Algorithm (GA). The proposed technique reduces the calculation time and implementation complexity, thus can be a viable alternative to the real time implementation for SHE. Integrated NLC-SHE control is tested by varying the modulation index and load dynamics. This technique resulted in the reduction in Total Harmonic Distortion (THDs) in load voltage and current. Comparative analysis of NLC, SHE and Integrated NLC-SHE technique is also performed on the CHB nine-level inverter. There is significant reduction in voltage and current THD values and power losses. Efficiency of the inverter is increased. The efficacy of the proposed control CHB nine-level is tested on MATLAB Simulink environment and further validated by experimental results.

In this paper, a three-phase shunt active power filter (SAPF) controller with a fully digital implementation is presented. The main goal of this contribution is to implement a digital direct power control (DDPC) algorithm without phase-locked-loop (PLL) for SAPF. This algorithm is intended for power quality improvement and current harmonic elimination. The controller introduced in this paper is cost-effective, has a fast-dynamic response, and has a simple hardware implementation. In order to comply with the above specifications, a dedicated controller has been conceived and fully implemented within a field-programmable gate array (FPGA) device. This FPGA-based controller integrates the whole signal-processing functions needed to drive the SAPF, as well as an original method for sector identification. The intended controller provides the desired power references to select the optimal switching sequences. The switching orders follow the grid reference to drive the voltage source inverter (VSI), so the SAPF achieves good performances while ensuring balanced overall supply currents, unity power factor, and reduced harmonic load currents. The proposed digital implementation achieves a valuable compromise between fast dynamic response, minimum execution time, and reduced FPGA resources, through a simple hardware design implementation. The entire system is developed and simulated using VHDL and VHDL-AMS languages.

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. [ABSTRACT FROM AUTHOR]

This article proposes a decoupled control scheme for the modular multilevel converter (MMC) to reduce the total harmonic distortion (THD) and eliminate one specific harmonic. First, to realize the decoupled control between the ac and dc paths of the MMC, an improved nearest level control (INLC) method is proposed. It applies the round function to generate the ac output voltage levels, instead of the arm output voltage levels. Thus, a staircase wave is generated by the INLC method. Then, by adding an additional pulse to each quarter of the staircase wave, one specific harmonic can be eliminated without optimizing each conduction angle. Furthermore, a decoupled circulating current fuzzy control method is proposed to suppress the second-order harmonic and balance the arm energy. By this decoupled control structure, the output voltage and the circulating current can be controlled independently. Taking the fifth-order harmonic as an example, simulation and experimental results validate that the proposed scheme can simultaneously realize THD reduction and one specific harmonic elimination in the MMC output voltage. [ABSTRACT FROM AUTHOR]

The interphase reactor (IPR) is one of the most important components of the passive harmonic reduction circuit (HRC), and the optimum turns ratio design of the IPR is of great significance to ensure the effect of the passive HRC. In combination with the pulse number multiplication methods, the configuration of the multipulse rectifiers (MPRs) with single/dual/triple-passive HRCs are constructed, respectively. The general optimum turns ratio design method for the IPRs is proposed, which contains most of the realizable combinations of the HRCs. The relationship between the turns ratio of the IPR and the phase number of the bridge rectifier in the main circuit is established, the influence of the turns ratio selection on the power quality of the MPRs is presented. In addition, this article takes N equal to five as an example to verify the effectiveness of the proposed general optimum turns ratio design method of IPR. The power quality of the MPRs with different HRCs or phase number are compared. All the research can provide a useful guideline and theoretical foundation for the MPR selection and the HRC design under the specific occasions. [ABSTRACT FROM AUTHOR]

In order to eliminate the harmonics of the grid connected inverters accurate harmonic detection is essential. Though there are many kinds of different harmonic detection methods are available, it can hardly be achieved without the help of grid frequency detection of the fundamental component. In this paper a novel Lock-In Amplifier based Frequency Locked Loop (LIA-FLL) is proposed for the improved harmonic elimination of the grid-connected three phase inverters. Due to the outstanding performance of the LIA-FLL, the harmonics can be detected and compensated accurately under the grid frequency variation. To demonstrate the superiority of the proposed method, it is applied to a 10 kW three phase grid connected inverters. The results obtained by the proposed method are compared with those obtained by the harmonic elimination method with no FLL. The principle of LIA-FLL is discussed and its performance for the harmonic elimination is proved by the simulation and experiments with a 10KW three phase grid connected inverter under the highly polluted grid condition.

This paper proposes a new multifunctional control technique for a grid-connected hybrid distributed generation system composed of a photovoltaic system and a wind power system based on a voltage source converter (VSC). Indeed, aside from the generation and the injection of energy into the grid, the proposed system deals with power quality issues caused by harmonics generated by non-linear loads in order to keep the source current uncontaminated. The VSC serves to first ensure that the power generated from the hybrid renewable energy source is fed to the utility grid and acts as a shunt active power filter in case an abnormal increase in the THD of the source current above the standard permissible values is detected due to the non-linear load connection. The two sources of the hybrid system are connected to a common DC bus to simplify the control and reduce the cost of the system, and a maximum power point tracking controller is used for both sources. The major advantage of this novel proposed multifunctional control technique is its ability to inject harvested power into the grid while simultaneously ensuring the compensation of the harmonics and reactive power. The proposed multifunctional control technique is validated through an extensive simulation analysis using MATLAB/Simulink.

An appropriate pulse-coding algorithm is the key to achieving an efficient switched-mode power amplification in all-digital transmitters. A five-level RF-PWM method with third and fifth harmonic elimination is proposed to relax the requirements of the filter and to reduce the control complexity of the SMPA for all-digital transmitters. By controlling the pulse width and the center position of three-level sub-pulses, third and fifth harmonic elimination is achieved. Meanwhile, the control complexity of the SMPA is reduced by the decrease in the output-signal-level number. Finally, the feasibility of the method is verified by simulation. For the 16QAM signal with a carrier frequency of 200 MHz, the proposed method can achieve third harmonic suppression of −46.24 dBc and fifth harmonic suppression of −54.05 dBc when coding efficiency reaches 77.51%. [ABSTRACT FROM AUTHOR]

Steel production worldwide continues to grow and, consequently, also the energy consumption of the steel sector. With the applications of the electric arc furnace route in the steelmaking process, the concern with aspects of power quality and overload of the transmission grid lines increases. This work presents the zero harmonic distortion (ZHD) converter static synchronous compensator (STATCOM), which makes it possible to increase the displacement power factor of an electric arc furnace (EAF) application from 0.88 to 0.98 with total demand distortion in the grid around 1.44% with the ZHD prototype operation, this being accomplished without using high-order sinusoidal filters and with consolidated components in the industry. [ABSTRACT FROM AUTHOR]

With the increased usage of power electronics at the source and load ends of modern power systems, power quality issues like harmonic control and total harmonic distortion (THD) minimization are being given considerable attention. Selective harmonic elimination and mitigation (SHE and SHM) are well-known effective techniques to control the low-order harmonics in the voltage and current waveforms generated by DC–AC converters, which otherwise pollute the grid waveforms and lead to undesired losses. As these methods also result in lower switching losses, they are mostly beneficial for high-power applications like medium-voltage electric drives and grid-connected systems. This work presents an over-the-decade overview of the enhancements in the SHE and SHM pulse width modulation (PWM) techniques of two-level and multilevel DC–AC converters, discussing various problem formulations and the solving methods of the resulting transcendental expressions. The exclusive use of metaheuristic techniques, neural networks, and predictive control structures in expression solving and controller architecture are discussed. The current and future research directions are presented with a focus on optimization, digitalization, real-time implementation, and low-power application avenues. • The manuscript emphasizes the heightened focus on harmonic controls. • SHE and SHM as effective techniques for controlling low-order harmonics. • SHE and SHM techniques reduce switching losses alongside harmonic control. • Highlighting advancements in pulse width modulation techniques. • Showcases the metaheuristic techniques, NNs, and MPC for designing controller architectures. [ABSTRACT FROM AUTHOR]

The double-phase-shift filtering method, which is based on the traditional pure-phase-shift filtering method, is a novel approach to harmonic elimination that can be applied to more complicated signals such as white noise and slip-sweep. Nonetheless, any type of phase-shift filtering method necessitates a relationship between the frequency of fundamental sweep and time, which may cost necessitate an enormous amount of human and physical resources to achieve inaccurate results with low efficiency. This paper combines deep learning with harmonic elimination to produce a double-phase-shift filtering method based on AR2U-Net, a type of U-Net with attention gates structure and recurrent residual blocks for improving accuracy and function while simplifying computational complexity. The input of the AR2U-Net structure in this paper is seismic data of slip-sweep signals in vibroseis, and the output is signal frequency variation with the time of the fundamental waves, which are required to eliminate the harmonic waves and adjacent signals using a double-phase-shift method to obtain the fundamental sweep. The training sets and test sets are formed by forward models, and a Log-Cosh loss function is used to monitor the process, during which the results of AR2U-Net and traditional U-Net are compared to demonstrate the eminent function of AR2U-Net. Following that, the outcomes' Log-Cosh loss functions and accuracy are also compared to validate the conclusion. AR2U-Net, when applied to raw data and combined with the double-phase-shift method, tends to polish the filtering effects and is worth promoting. [ABSTRACT FROM AUTHOR]

When suffering the grid voltage distortion, the phase-locked loop (PLL) should equip with the fast response filter to precisely extract the fundamental voltage information for proper grid integration. To shorten the time delay induced by filters, this article proposes a new three-sample filter (TSF) to fast eliminate the harmonics of sampled grid voltage. Theoretically, it can filter out arbitrary individual harmonic with short time delay which could be as small as only two sampling periods. Moreover, TSF can reject a group of harmonics simultaneously within the specifically set time interval. The implementation issues of TSF as in-loop filter or prefilter for both three- and single-phase applications are demonstrated in synchronous reference frame PLL (SRF-PLL) SRF-PLL. Simulation and experimental results verified its advanced performance. [ABSTRACT FROM AUTHOR]

Integrated low capacity renewable energy sources with storage technologies are called micro grids. These sources can operate independently or by being connected to main grid. This paper deals with Proportional Integral (PI)/Artificial Neural Network (ANN)-based control algorithm for voltage frequency regulation in an isolated micro grid with its hardware implementation. Isolated micro grid is formed by using three SEIGs driven small hydro turbine feeding three-phase four-wire consumer load. The battery storage system is connected parallel to the DC link of the converter to facilitate the instantaneous power balance under dynamic condition and to maintain the reliability of the system. The system with PI/ANN controllers is tested under load variations and when a micro source suddenly gets disconnected due to a fault. The conventional PI controller has shown limitations to load variations and source resynchronization. The ANN-based controller on the other hand has less settling time and also improves the dynamic response of the micro grid as per IEEE 1547 standards. Micro grid is modeled with MATLAB Sim power tool and simulation results are produced considering nonlinear load. Simulated results are validated with a laboratory prototype using dPACE 1104. [ABSTRACT FROM AUTHOR]

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.

Modulation using a higher sided polygonal space vector structure (SVS) is an elegant method to increase the linear modulation range and to eliminate the undesired lower order harmonics from motor phase voltage. This article presents the generation of a dense 15-concentric 30-sided multilevel SVS using a single dc-link for an open end induction motor (OEIM) drive. The proposed scheme eliminates lower order harmonics till 25th order from motor phase voltage throughout the modulation range. The $dv/dt$ stress in the phase voltage applied to the motor will also be highly reduced owing to the multilevel structure. The pulsewidth modulation scheme employed utilizes the denseness of SVS and avoids iterative searches to find the triangle, which encompasses the tip of reference voltage vector, which are typical in multilevel polygonal SVS. The topology consists of an active dc-link fed three-level primary inverter and a capacitor fed five-level secondary inverter connected to either end of an OEIM. The primary inverter acts as the active power supplier for the drive and the secondary inverter filters out the undesirable lower order harmonics from motor phase voltage. The proposed scheme is experientially validated and the results are included in this article. [ABSTRACT FROM AUTHOR]

A novel space vector-based approach is introduced in this brief to selectively eliminate the lower order harmonics from the DC-AC converter output waveform by making use of double switching clamping sequences. This technique uses a volt-second balance for control of fundamental voltage while using the dwell time rearrangement of the active vector in a sub-cycle to obtain the elimination of fifth or seventh harmonics. Further, the closed-form expression of the dwell time-division coefficient (DTDC) for the active vector dwell time division rearrangement is expressed. The proposed PWM technique is compared with other space vector-based PWM techniques in terms of voltage weighted total harmonic distortion, switching power loss, and lower order harmonic magnitudes. Further, the experimental results are presented to show the effectiveness of the proposed PWM techniques in terms of harmonic elimination. [ABSTRACT FROM AUTHOR]

The dynamics of a machine tool have an important influence on the quality and efficiency of the machining process. In this paper, the modal parameters identification method of machine tools under normal cutting excitation is proposed based on the fact that the random components in the cutting force can provide an effective excitation. However, the generated cutting force during machining contains strong periodic components and does not satisfy the white noise assumption. Directly applying the operational modal analysis (OMA) method will face serious harmonic interference. Therefore, it is difficult to ensure the accuracy of the identified parameters. The cepstrum editing method is proposed to eliminate the periodic component. And the modal parameters are extracted from the remaining signal by using the OMA method. The experimental results show that the proposed method works well under normal cutting conditions.

This work introduces a 49-level Asymmetrical Inverter (AMLI) with boosted output based on the cascaded operation of two 7-Level Modified Packed U-Cell inverters (MPUC-7). The converter is capable of operation with a boosted voltage of up to 1.714 times the maximum DC voltage employed. It requires only 12 active switches and 4 voltage sources. With the sources set in the ratio of 14:7:2:1, the 7-level output of the two converters is so utilized that the 72 = 49-level output voltage is generated across the load. A detailed explanation of level formation is discussed. This converter is operated using an Artificial Neural Network (ANN) which is trained for the harmonic elimination in the output voltage waveform. For the calculation of optimum angles, a meta-heuristic based Genetic Algorithm (GA) technique is employed. The generation of 49-level output requires 24 transitions in one quarter of a cycle. All these angles are generated for various desired output voltages, and the ANN is trained offline for the same. The converter and its control are simulated in MATLAB/Simulink® environment, and the results are verified on the experimental setup. The multilevel output thus obtained is nearly sinusoidal and the Total Harmonic Distortion (THD) thus produced is under the specified limit of IEEE.

Inverters which convert DC voltage into AC voltage are widely used in the field of power electronics. During the conversion from DC voltage to AC voltage, some of the harmonics can occur. Harmonics which are one of the most important parameters in the field of energy/power systems determine the power quality. Therefore, one of the crucial steps is the elimination/suppression of harmonics in the outputs of the inverters. It is required to solve complex equations with multiple variables in this elimination process. In this study, a software is developed and eight different metaheuristic algorithms/approaches (backtracking search, cuckoo search, electromagnetic field optimization, harmony search, Harris hawks optimization, interior search, vortex search, Yin-Yang-pair optimization) are used for the elimination of the chosen harmonics by determining suitable switching angles. The desired harmonics are eliminated in the chosen inverter circuits via the software with a user-friendly interface easily, fast and effectively, and the results can be observed both numerically and graphically through the this software.

Copyright of Journal of National University of Defense Technology / Guofang Keji Daxue Xuebao is the property of NUDT Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Decaying DC (DDC) current due to impact loads causes detrimental consequences in weak grids. In this paper, the active power filter (APF) is enhanced to simultaneously compensate for the undesired harmonics, negative sequence components and the DDC component in the event of a transient. To this end, first, a novel DDC component detection method is mathematically deduced for single-phase transient current, followed by its extension to the three-phase system. With respect to existing techniques, the proposed method has a significantly reduced detection time from 1 grid cycle to approximately 0.5 grid cycle. By further exploiting the transient signal properties in dq-frame, the three-phase fundamental-frequency current in positive sequence can be separated. Finally, the enhanced APF control scheme is developed based on the proposed detection algorithm. Experiments verified the effectiveness and advancement of the proposed technique. [ABSTRACT FROM AUTHOR]

Renewable energy sources are installed into both distribution and transmission grids more and more with the introduction of smart grid concept. Hence, efficient usage of cascaded H-bridge multilevel inverters (MLIs) for power control applications becomes vital for sustainable electricity. Conventionally, selective harmonic elimination equations need to be solved for obtaining optimum switching angles of MLIs. The objective of this study is to obtain switching angles for MLIs to minimize total harmonic distortion. This study contributes to the solution of this problem by utilizing two recently developed intelligent optimization algorithms: multi-verse optimization algorithm and salp swarm algorithm. Moreover, well-known particle swarm optimization is utilized for MLI optimization problem. Seven-level, 11-level and 15-level MLIs are used to minimize total harmonic distortions. Simulation results with different modulation indexes for seven-, 11- and 15-level MLIs are calculated and compared in terms of the accuracy and solution quality. Numerical calculations are verified by using MATLAB/Simulink-based models. [ABSTRACT FROM AUTHOR]

This paper presents Arduino controller implementation and Simulink model in MATLAB to eliminate a selected number of harmonics in a single phase inverter. A MATLAB code is written to solve the nonlinear trigonometric that arises in the Fourier analysis of the output of the inverter. Newton’s Raphson method is adopted to find the triggering angles for the four electronic switches in the inverter. All possible combinations of these triggering instants are then computed for period of one cycle. To validate the model a practical set using Arduino controller is implemented. Frequency spectrums of the output of the inverter for both the Simulink model and the practical set are shown for the elimination of certain selected harmonics. Any other selected harmonics can be eliminated using the proposed model.

Compared with the conventional three‐phase motors, the dual three‐phase permanent magnet synchronous motors (PMSMs) have many advantages and have been widely used in various drive fields. However, one major disadvantage of these machines is that they are easy to generate large stator current harmonics, which makes it difficult to have an excellent performance in the drive field. To solve this problem, this study introduces a current harmonic elimination method based on a spatial analytical model of flux linkage. The study reconstructed the analytical model of flux linkage from finite element analysis. The analytical model can describe the spatial harmonics of flux linkage by considering the rotor position information. Based on the model, an active feedforward controller was proposed to eliminate current harmonics by actively injecting the corresponding voltage harmonics, the voltage harmonics are calculated by the model of flux linkage. The performance of the proposed method in eliminating current harmonics is verified by simulations and experiments. [ABSTRACT FROM AUTHOR]

This study presents the design and analysis of an adaptive second-order generalised integrator (SOGI) technique for controlling voltage source inverter in a three-phase three-wire distribution system. The function of the proposed shunt active power filter involves compensation of reactive power for power factor correction, harmonic elimination, load balancing, voltage regulation under non-linear load condition. In this study, an effective approach for load compensation is proposed by designing an adaptive SOGI trained using Levenberg–Marquardt technique and compared with conventional techniques which ensure smooth operation under normal and distorted grid condition. An experimental setup is developed and its performance is analysed during different loading conditions. The experimental results are in line with the expected simulation results. Experimental and simulation results are verified and analysed using Bode plot. [ABSTRACT FROM AUTHOR]

Chatter that occurs between a cutting tool and a workpiece greatly reduces the surface quality and production efficiency. Therefore, it is of great importance to predict and avoid chatter so as to guarantee the stability of the manufacturing process. To realise the accurate prediction of the stability boundary of machine tools, operational modal analysis (OMA) is increasingly receiving attention due to its adequate consideration of variations in working conditions in the industrial environment. However, because of the influence of harmonic components in the response signals, the accuracy in identifying the modal parameters is seriously compromised. In this paper, an adaptive complex Morlet filter (ACMF) is presented to remove the harmonic components by adaptively adjusting the centre frequency and bandwidth according to the local character of the ambient environment in a specific frequency range and filtering out harmonic components that are not strict integer multiples of the fundamental frequency owing to non-rigid periodic motion of the machine tool spindle. In order to show the effectiveness of the proposed method, milling experiments are carried out and experimental modal analysis (EMA) is utilised to make comparisons with the proposed method. Moreover, comparisons between the ACMF and two other typical filtering methods are made. The results indicate that the proposed method performs well in modal parameter recognition for machine tools. [ABSTRACT FROM AUTHOR]

Copyright of Tikrit Journal of Engineering Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, an adaptive normalized least mean fourth (NLMF) control scheme is employed to generate the anti-harmonic currents of photovoltaic (PV) integrated with grid system for harmonic elimination and power factor (PF) correction (PFC). In addition, a fuzzy tuned PID-based adaptive dc voltage regulator is integrated in the proposed scheme to regulate the reference voltage of the dc bus. The proposed FPID-based NLMF control scheme attains the features of power quality (PQ) related issues elimination such as PFC and harmonics elimination with an extraction of photovoltaic (PV) generated maximum power through the grid interfacing converter (VSC) at a unity PF. Moreover, the PV system’s feed-forward (FF) component is included in the control strategy to enrich the aggressive behavior of the system. The NLMF current controller is employed to measure the three-phase calculated currents by extracting the fundamental weight constituents of the load currents for harmonic mitigation in the presence of point of common coupling (PCC). The proposed control topology is developed on MATLAB/SIMULINK software platform under different load and grid transient conditions. A dSPACE based real-time laboratory platform is developed to justify the proposed scheme under different conditions such as steady-state, load dynamic, removed and unbalanced, grid voltage distorted, unbalanced, swell and sag conditions. The presented control scenario’s results are obtained satisfactory and the grid current’s THD are in the IEEE-519 regular limits. [ABSTRACT FROM AUTHOR]

Summary: This article presents a modified whale optimization (MWO) for harmonic mitigation in a three‐phase 11‐level hybrid cascaded multilevel inverter (HC‐MLI). The proposed MWO has improved rate of convergence as compared with conventional whale optimization (WO). This is achieved by improving the exploration‐exploitation feature of the conventional WO. Selective harmonic elimination–pulse width modulation technique is applied through MWO for generating the optimal switching angles of the HC‐MLI so as to eliminate the lower‐order harmonics such as 5th, 7th, 11th, and 13th from the output voltage. In the proposed MWO optimized HC‐MLI, capacitor voltage balance is made possible even at higher modulation indices using the available redundant switching states of HC‐MLI. The proposed work is useful where the HC‐MLI has to work at the low switching frequency and the conversion efficiency is of prime importance such as medium‐ and high‐power motor drives, static synchronous compensators, and active power filters. The performance of the proposed work is validated through simulation and experimentation on a 1.5‐kW prototype. The results obtained show that the MWO algorithm is more efficient and accurate than other reported algorithms such as genetic algorithm, particle swarm optimization, and WO in terms of performance, harmonic mitigation, and rate of convergence. [ABSTRACT FROM AUTHOR]

Active power filters are conventionally utilized to compensate steady-state harmonic currents and reactive power in the utility, yet their capabilities are usually limited if the elimination of undesirable effects associated with decaying dc components during transients is the target, especially under the weak grid condition. In this letter, active cancellation of the typical first-order decaying dc-mode transients is explored. To this end, a real-time detection algorithm of decaying dc component is first developed for a generic single-phase distorted ac signal. Furthermore, fast and robust elimination of both decaying dc transient and harmonics can be performed simultaneously in three-phase grids, by adoption of moving average filters in $d$ – $q$ frame and subsequent calculations. Hardware-in-the-loop experiment results verified the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]

This article proposes a modified grey wolf optimization (MGWO) which has improved rate of convergence and avoids local optima stagnation. This is achieved by improving the exploration–exploitation balance in conventional grey wolf optimization (GWO). Moreover, the use of weighted-distance strategy allows quick identification of the global optima in the proposed MGWO. This optimization is then applied for the control of a three-phase, 11-level hybrid cascaded multilevel inverter (HC-MLI). Selective harmonic elimination pulsewidth modulation technique is implemented through MGWO which generates optimal switching angles for the HC-MLI so as to eliminate lower order harmonics such as 5th, 7th, 11th, and 13th from the output voltage. In MGWO optimized HC-MLI, balancing of capacitor voltage is made possible at higher modulation index by making use of the available redundant switching states. The performance of the proposed work is validated through simulation and experimentation on a 1.5 kW prototype. The results obtained through simulation show that the MGWO algorithm is more efficient and accurate than other reported algorithms such as GWO, genetic algorithm, and particle swarm optimization in terms of performance, harmonic reduction, and convergence rate. [ABSTRACT FROM AUTHOR]

This paper proposes a novel polygonal voltage space vector structure (SVS) having 30 sides, for a star-connected induction motor drive. The SVS eliminates the presence of harmonics up to 25th order from motor phase voltage throughout the entire modulation range, providing a torque profile devoid of lower order pulsations. Linear modulation is extended till 99.63% of base speed without exceeding the motor phase voltage rating. Topology consists of a dc-link fed primary inverter and two equal low voltage modular capacitor fed secondary inverters. Here the harmonics generated by the primary inverter is canceled by the secondary inverter which acts as a switched capacitive filter. Detailed description of the SVS generation and timing calculations are provided in this paper. Effectiveness of the proposed scheme is validated using experimental results, inverter loss calculations, and harmonic analysis. [ABSTRACT FROM AUTHOR]

A large number of harmonics will be generated in the process of transforming high frequency and high voltage alternating current (AC) into a constant frequency and constant voltage through a power conversion system when the high-speed motor is used as a generator. The phase-shifting reactor is used to eliminate harmonics for high-speed generator power conversion systems, and LCL filter and adjustable inductance filter are used to eliminate harmonics for high-speed motor power supply system in this paper. The adjustable inductance filter can adjust the inductance value in time according to the change of the output frequency of the inverter. The results verify the effectiveness of the methods used, and provide a theoretical basis for the wide application of high-speed motor by simulation.

A control structure design of a three-phase three-leg four-wire grid-tied Distribution Static Synchronous Compensator (DSTATCOM) based on a combined-step-size real-coefficient improved proportionate affine projection sign algorithm (CSS-RIP-APSA) has been presented. The three-phase four-wire DSTATCOM is used for reactive power compensation along with harmonic current minimization. This strategy also helps in load balancing and neutral current compensation. The affine projection sign algorithm (APSA) is a member of the adaptive filter family, which has a slow convergence rate. The conventional adaptive filter deals with the trade-off between the convergence rate and the steady-state error. In the proposed algorithm, the RIP-APSA adaptive filter with two different step sizes has been designed to decrease the computational burden while achieving the advantages of a fast convergence rate and reduced steady-state error. The proposed controller also makes the inverter function a shunt compensator. The controller primarily evaluates the fundamental weight component of distorted load currents. The aim of the proposed system is to compensate for reactive power and to ensure unity power factor during the faulty conditions as well as for unbalancing grid conditions. The proposed control algorithm of the grid-tied DSTATCOM works effectively on the laboratory prototype as verified from the experimental results.

This paper presents an experimental performance comparison between differential evolution (DE) algorithm and Newton Raphson (NR) method for solving the optimal switching problem for multilevel inverters with the objective of improving the output AC voltage quality. The methods are used to compute optimal switching angles to control a multilevel inverter in such way that allows the elimination of low order harmonics; this control technique is called selective harmonic elimination. The proposed inverter in this article is composed of two H-bridge cells with non-equal DC voltage sources in order to generate seven voltage levels. The differential evolution (DE) optimization and the Newton Raphson (NR) algorithm is used to solve non-linear transcendental equations necessary for the (SHPWM). Computational results obtained from computer simulations presented a good agreement with the theoretical predictions. A laboratory prototype based on STM32F407 microcontroller was built in order to validate the simulation results.

This paper presents an efficient harmonic detection for real-time generation of the reference current fed to a shunt active power filter using the ADALINE neural network. This proposed method is a single layer with 101 nodes generating the coefficients referred to as weights of the reference current model. It effectively overcomes the drawback of the current technology, which is instantaneous power theory (PQ). The proposed method was implemented on the TMS320F28335 DSP board and tested against MATLAB with Simulink as a hardware-in-loop (HIL) structure. This method gives a good performance by producing a precise reference current in a short period with uncomplicated calculation. It also efficiently can eliminate individual harmonic current. The achieved percentage of total harmonic distortion (%THD) in the current is reduced following the IEEE standard, while the power factor can be maintained to unity.

This paper proposes an optimized synchronous PWM method for harmonic elimination in a quasi square wave inverter. The synchronized PWM method enables online harmonic computation and PWM pulse generation in a multitasking digital controller to eliminate lower order harmonics. The multitasking digital controller reduces the look-up table requirement and helps in realizing efficient implementation to eliminate dominant harmonics. This method offers a simple scalable solution for combined fifth and seventh harmonic elimination using two low-cost eight-bit PIC microcontrollers (PIC18F4550, PIC18F452). Experimental results are demonstrated for a single-phase three-level inverter. The proposed method achieves 90% reduction of fifth and seventh harmonic components from a quasi square wave inverter output. [ABSTRACT FROM AUTHOR]

This paper proposes a modified particle swarm optimization (MPSO) for fast convergence and harmonic minimization in three-phase eleven-level hybrid cascaded multilevel inverter (HC-MLI). Selective harmonic elimination pulsewidth modulation (SHE-PWM) technique implemented through MPSO has been used in the proposed work for synthesizing an eleven-level output voltage using two dc sources, a precharged capacitor, and twelve switches. The switching angles of the three-phase eleven-level HC-MLI has been computed for eliminating specified lower order odd harmonics such as 5th, 7th, 11th, and 13th from the output voltage of the HC-MLI. In the proposed MPSO optimized HC-MLI, capacitor voltage balance is also ensured even at higher modulation indices by utilizing the redundant switching states available at different switching instances of the HC-MLI. The performance of the MPSO optimized three-phase eleven-level HC-MLI has been verified through simulation and experimentation on a 1.5-kW prototype using closed-loop control. The results obtained through MPSO are compared with the results obtained through genetic algorithm (GA) and particle swarm optimization (PSO) in terms of convergence rate and harmonic content. It has been found that MPSO gives improved results in comparison to GA and PSO. [ABSTRACT FROM AUTHOR]

A 12-pulse converter has been commonly used for a large-scale power generating system. The arrangement of a delta–delta (Δ–Δ) and a delta–wye (Δ–Y) phase-shift transformer pair in series with the voltage source eliminates undesirable harmonics from nonlinear loads. Recently, a novel front-end for a multi-generator power system was proposed, which utilizes a single Y–Δ transformer to shunt between the two 30° phase-shifted generator outputs and results in the comparable harmonic elimination performance to the conventional 12-pulse rectifier. The shunt-type Y–Δ transformer front-end achieves more than 75% transformer size reduction, making it extremely attractive to large-scale industrial and shipboard applications. However, the exact 30° phase shift between the two rotating generators can drift in a practical system, especially under dynamic conditions. The harmonic performance under the non-ideal 30° phase-shift condition can deteriorate with the Y–Δ shunt-type front-end. To understand the impact of non-ideal phase-shifted generator sources, this paper derives the mathematical models through the use of an equivalent circuit, a square-wave analysis, and the phasor representation to show the harmonic cancellation principle and verifies the results with the computer simulation. [ABSTRACT FROM AUTHOR]

Highlights • The very effective strategy to reject unwanted negative and harmonic components. • No unreal disturbance in the estimated frequency for phase angle jumps. • A wide variability (trade-off between attenuation of unwanted components and speed). • Setting the values of all parameters for the strategy is easy and already well elaborated. • The DSC 2 element for rejection even harmonics (with time delay T /2) can be omitted. Abstract A technique has been developed that incorporates the advantages of the cascaded delayed signal cancellation and dual second order generalized integrator schemes, the first one being used now as a pre-filter for the second element. A reconstructor block is applied as well to prevent unreal changes in the estimated frequency in case of phase angle jumps of the grid voltage. Experimental results are evaluated in terms of quality of the positive voltage sequence, frequency and phase angle identification for the grid voltage disturbed by harmonic and negative sequence components as well as for amplitude, frequency, and phase angle jumps in the voltage. [ABSTRACT FROM AUTHOR]

This paper deals with a parallel 3-phase active filter to eliminate harmonics and to compensate the reactive power of the non-linear loads. A 3-phase voltage source inverter bridge with a dc bus capacitor is used as an active filter (AF). A hysteresis current control and PWM current control is employed to derive the switching signals to the AF. Source reference currents are derived using load currents, dc bus voltage and source voltage. The command currents of the AF are derived using source reference and load currents. A 3- phase diode rectifier with capacitive loading is employed as the non-linear load. [ABSTRACT FROM AUTHOR]