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1

Kim, Mihyang, Su-Il Kim, Jaehong Han, Xiu-Ling Wang, Dae-Geun Song, and Soo-Un Kim. "Stereospecific Biotransformation of Dihydrodaidzein into (3S)-Equol by the Human Intestinal Bacterium Eggerthella Strain Julong 732." Applied and Environmental Microbiology 75, no. 10 (March 20, 2009): 3062–68. http://dx.doi.org/10.1128/aem.02058-08.

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ABSTRACT Stereochemical course of isoflavanone dihydrodaidzein (DHD) reduction into the isoflavan (3S)-equol via tetrahydrodaidzein (THD) by the human intestinal anaerobic bacterium Eggerthella strain Julong 732 was studied. THD was synthesized by catalytic hydrogenation, and each stereoisomer was separated by chiral high-performance liquid chromatography. Circular dichroism spectroscopy was used to elucidate the absolute configurations of four synthetic THD stereoisomers. Rapid racemization of DHD catalyzed by Julong 732 prevented the substrate stereospecificity in the conversion of DHD into THD from being confirmed. The absolute configuration of THD, prepared by reduction of DHD in the cell-free incubation, was assigned as (3R,4S) via comparison of the retention time to that of the authentic THD by chiral chromatography. Dehydroequol (DE) was unable to produce the (3S)-equol both in the cell-free reaction and in the bacterial transformation, negating the possible intermediacy of DE. Finally, the intermediate (3R,4S)-THD was reduced into (3S)-equol by the whole cell, indicating the inversion of stereochemistry at C-3 during the reduction. A possible mechanism accounting for the racemization of DHD and the inversion of configuration of THD during reduction into (3S)-equol is proposed.
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Raharja, Lucky Pradigta Setiya, Ony Asrarul Q., Zainal Arief, and Novie Ayub Windarko. "Reduction of Total Harmonic Distortion (THD) on Multilevel Inverter with Modified PWM using Genetic Algorithm." EMITTER International Journal of Engineering Technology 5, no. 1 (July 23, 2017): 91–118. http://dx.doi.org/10.24003/emitter.v5i1.174.

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In this research, modified PWM has been applied to the multilevel inverter (MLI) single-phase three-level diode clamp full bridge. Modified PWM is performed to produce minimum Total Harmonic Distortion (THD) the voltage because the quality of the good voltage is indicated by small THD. The THD indicates the quality of AC voltage source. The THD standard by the IEEE STD 519-1992 Harmonic Voltage Limits is 5% and the Pacific Corp standard is 8%, if the THD value is greater than the THD standard it can cause the electronic load to be damaged due to the damaged waveform. Modified PWM is applied by adding a 50 Hz sinusoidal reference signal with a sinusoidal signal which has a certain amplitude, frequency and phase shift angle. The frequency of the adder signal is the frequency at which the value of the individual harmonic voltage appears (n harmonic). To get maximum result, optimization using Genetic Algorithm (GA) method to determinate amplitude & phase shift angle done. The result of implementation hardware with modified PWM shows smaller THD voltage compared to the THD voltage with Sinusoidal Pulse Width Modulation (SPWM) switching up to 0.19 or decrease 65,51 % for modified PWM of harmonic injection n = 7 with GA optimization ma= 0.8 (A=0.0936 and ø = 0 rad) and up to 0.08 or decrease 12,30 % for modified PWM of harmonic injection n = 22 with GA optimization ma = 0.4 (A=0.1221 and ø = 0 rad).
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Fedin, Ihor Serhiiovych, Tetiana Oleksandrivna Tereshchenko, and Yuliia Serhiivna Yamnenko. "THD Reduction of Inverters in Photovoltaic Power Systems." Microsystems, Electronics and Acoustics 25, no. 2 (August 31, 2020): 18–24. http://dx.doi.org/10.20535/2523-4455.mea.207543.

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4

El Mehdi Belkacem, Riadh, Redha Benzid, and Noureddine Bouguechal. "Multilevel inverter with optimal THD through the firefly algorithm." Archives of Electrical Engineering 66, no. 1 (March 1, 2017): 141–54. http://dx.doi.org/10.1515/aee-2017-0010.

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Abstract Reduction of the Total Harmonic Distortion (THD) in multilevel inverters requires resolution of complex nonlinear transcendental equations; in this paper we propose a combination of one of the best existing optimized hardware structures with the recent firefly algorithm, which was used to optimize the THD, through finding the best switching angles and guaranteeing the minimization of harmonics within a user defined bandwidth. The obtained THD through the simulation of the thirteen-level symmetric inverter has been reduced down to 5% (FFT of 60 harmonics). In order to validate the simulation results, a thirteen-level symmetric inverter prototype has been made, and practically experimented and tested with different loads. Consequently, the measured THD with resistive load was 4.7% on a bandwidth of 3 kHz. The main advantage of the achieved work is the reduction of the THD.
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5

Sood, Rajbir, and Geena Kalpesh. "THD Reduction and Power Quality Improvement in Grid Connected PV System." International Journal of Trend in Scientific Research and Development Volume-1, Issue-4 (June 30, 2017): 429–33. http://dx.doi.org/10.31142/ijtsrd173.

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6

Apelfröjd, S., and S. Eriksson. "Evaluation of Harmonic Content from a Tap Transformer Based Grid Connection System for Wind Power." Journal of Renewable Energy 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/190573.

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Simulations done in MATLAB/Simulink together with experiments conducted at the Ångströms laboratory are used to evaluate and discuss the total harmonic distortion (THD) and total demand distortion (TDD) of a tap transformer based grid connection system. The grid connection topology can be used with different turbine and generator topologies and is here applied on a vertical axis wind turbine (VAWT) with a permanent magnet synchronous generator (PMSG) and its operational scheme. The full variable-speed wind conversion system consists of a diode rectifier, DC link, IGBT inverter, LCL-filter, and tap transformer. The full variable-speed operation is enabled by the use of the different step-up ratios of the tap transformer. In the laboratory study, a full experimental setup of the system was used, a clone of the on-site PMSG driven by a motor was used, and the grid was replaced with a resistive load. With a resistive load, grid harmonics and possible unbalances are removed. The results show a TDD and THD below 5% for the full operating range and harmonic values within the limits set up by IEEE-519. Furthermore, a change in tap, going to a lower step-up ratio, results in a reduction in both THD and TDD for the same output power.
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7

Lee, Chung-Seong, and Hae-Joong Kim. "Induced EMF THD Reduction Design of Permanent Magnet Synchronous Generators for Diesel Engine Generators." Processes 9, no. 6 (June 3, 2021): 986. http://dx.doi.org/10.3390/pr9060986.

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This paper deals with design of permanent magnet synchronous generators (PMSG) for diesel engine generators. The PMSG is required to reduce the total harmonic distortion (THD) reduction of the induced electromotive force (EMF) for the enhancement of power quality. In this paper, a design method is proposed to reduce the THD of the induced EMF for power quality enhancement in the PMSG. First, the selection process for the number of poles and slots is described. Second, the rotor shape design is proposed using an eccentric curve and slit shape. Based on the results of the first process, the optimal rotor shape is selected to achieve the additional THD reduction of the induced EMF. Finally, the performance for the optimal rotor shape is verified through a 2-dimensional finite element analysis (2D FEA) and prototype.
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8

Moriano, Javier, Mario Rizo, Emilio Bueno, J. Rafael Sendra, and Raul Mateos. "Distortion-Free Instantaneous Multifrequency Saturator for THD Current Reduction." IEEE Transactions on Industrial Electronics 66, no. 7 (July 2019): 5310–20. http://dx.doi.org/10.1109/tie.2018.2868317.

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9

Mathew, Megha Jess. "THD Reduction in Multilevel Inverters Using Real-Time Algorithm." IOSR Journal of Computer Engineering 8, no. 2 (2012): 01–12. http://dx.doi.org/10.9790/0661-0820112.

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10

Alves de Lima Henn, Gustavo, Paulo Peixoto Praça, R. N. A. L. Silva, Demercil de Souza Oliveira Júnior, Luiz Henrique Silva Colado Barreto, and Edison Roberto Cabral da Silva. "Adapted Modulation For Thd Performance Improvement And Losses Reduction On Multilevel Inverters." Eletrônica de Potência 16, no. 2 (May 1, 2011): 103–9. http://dx.doi.org/10.18618/rep.2011.2.103109.

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11

Salgado-Herrera, Nadia Maria, David Campos-Gaona, Olimpo Anaya-Lara, Aurelio Medina-Rios, Roberto Tapia-Sánchez, and Juan Ramon Rodríguez-Rodríguez. "THD Reduction in Wind Energy System Using Type-4 Wind Turbine/PMSG Applying the Active Front-End Converter Parallel Operation." Energies 11, no. 9 (September 16, 2018): 2458. http://dx.doi.org/10.3390/en11092458.

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In this paper, the active front-end (AFE) converter topology for the total harmonic distortion (THD) reduction in a wind energy system (WES) is used. A higher THD results in serious pulsations in the wind turbine (WT) output power and several power losses at the WES. The AFE converter topology improves the capability, efficiency, and reliability in the energy conversion devices; by modifying a conventional back-to-back converter, from using a single voltage source converter (VSC) to use pVSC connected in parallel, the AFE converter is generated. The THD reduction is achieved by applying a different phase shift angle at the carrier of digital sinusoidal pulse width modulation (DSPWM) switching signals of each VSC. To verify the functionality of the proposed methodology, the WES simulation in Matlab-Simulink® (Matlab r2015b, Mathworks, Natick, MA, USA) is analyzed, and the experimental laboratory tests using the concept of rapid control prototyping (RCP) and the real-time simulator Opal-RT Technologies (Montreal, QC, Canada) is achieved. The obtained results show a type-4 WT with a total output power of 6 MVA, generating a THD reduction up to 5.5 times of the total WES current output by Fourier series expansion.
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12

Rabelo Joca, Davi, Luiz Henrique Silva Colado Barreto, Demercil de Souza Oliveira Júnior, Gustavo Alves de Lima Henn, and Ranoyca Nayana Alencar Leão e Silva. "Modulation Technique Applied For Thd Reduction In 3-level Flying Capacitor Multilevel Inverter." Eletrônica de Potência 19, no. 2 (May 1, 2014): 173–81. http://dx.doi.org/10.18618/rep.2014.2.173181.

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13

., S. Kalaivani. "COMPARISON OF THD REDUCTION FOR ASYMMETRICAL CASCADED H-BRIDGE INVERTER." International Journal of Research in Engineering and Technology 03, no. 05 (May 25, 2014): 242–47. http://dx.doi.org/10.15623/ijret.2014.0305046.

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14

Mondal, Santanu, and Madhurima Chattopadhyay. "Comparative study of three different bridge-less converters for reduction of harmonic distortion in brushless DC motor." Indonesian Journal of Electrical Engineering and Computer Science 20, no. 3 (December 1, 2020): 1185. http://dx.doi.org/10.11591/ijeecs.v20.i3.pp1185-1193.

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<p>This paper represents a comparative study of three different types of DC-DC<br />converter that can be used for reduction of Total Harmonic Distortion (THD)<br />in stator current, back electromotive force (EMF) and torque of brush less<br />DC motor. In addition, the topologies of these converters are analysed, and<br />the THD of the output characteristics have also been studied. In this work,<br />SEPIC, Zeta and Flyback converters are considered and their outputs are fed<br />to the BLDCM with the help of universal bridge or six step inverter.<br />Moreover the THD of the output voltages are not only measured for three<br />converters but also reduced by tuning the parameters. At first these three<br />converters are modeled in MATLAB/ Simulink based simulation platform<br />and studied the performance individually and further executed with hardware<br />circuitry. Finally the output parameters from both software simulation and<br />real time hardware are compared for these three converters separately and got<br />satisfactory similar results. Again we studied the performance with these<br />converters in terms of efficiency while fed in the commutation drive circuitry<br />of BLDCM by considering minimum THD. From this comparative<br />simulation results, it has been observed that Zeta converter showed maximum<br />efficiency. Therefore, in real time hardware implementation, the<br />commutation drive circuitry of BLDCM is studied with Zeta converter. With<br />this configuration, a comparatively low THD of stator current, back EMF and<br />electromagnetic torque have been achieved in BLDCM with PID controller.</p>
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15

Ha, Eunyoung, Mikyung Kim, Jaemoo Chun, Chang-Seob Seo, YouMee Ahn, and Jeeyoun Jung. "Tongqiaohuoxue Hinders Development and Progression of Atherosclerosis: A Possible Role in Alzheimer’s Disease." Biology 9, no. 11 (October 27, 2020): 363. http://dx.doi.org/10.3390/biology9110363.

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Atherosclerosis is closely associated with Alzheimer’s disease (AD). Tongqiaohuoxue decoction (THD) is a classical herbal prescription in traditional Chinese medicine widely used for the prevention and treatment of cerebrovascular disease. This study aimed to explore the therapeutic effects of THD on atherosclerosis and AD. Eight-week-old C57BL6/J wild-type and ApoE-deficient (ApoE-/-) mice were fed a high-fat and high-cholesterol diet for eight weeks, followed by oral phosphate-buffered saline vehicle or THD treatment for eight weeks further. In ApoE-/- mice, THD attenuated lipid deposition in the aorta and the brain, and abrogated atherosclerotic changes without affecting serum lipid profiles while decreasing amyloid plaque formation. In vitro assays undertaken to understand THD’s effects on lipid clearance in the aorta and brain vessels revealed that THD treatment inhibited the lipid uptake, stimulated by oxidized low-density lipoprotein, resulted in decreased endothelial cell activation through reduction in intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and monocyte chemoattractant protein-1 levels. Serum analysis revealed inhibitory effects of THD on resistin production, which has important roles in the development of both atherosclerosis and AD. In conclusion, the current study demonstrates beneficial effects of THD on the development and progression of atherosclerosis, and a possible protective role against AD.
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Akintade, S. A., Y. Jibril, and A. S. Abubakar. "Development of Shunt Active Power Filter for Harmonic Reduction using Synchronous Reference Frame with Space Vector Pulse Width Modulation." Nigerian Journal of Technological Development 17, no. 2 (July 22, 2020): 104–12. http://dx.doi.org/10.4314/njtd.v17i2.5.

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The work aims at development of Shunt Active Power Filter (SAPF) for harmonic reduction. The current harmonics are being caused by nonlinear characteristic of power electronics based equipments which increase power losses and in turn reduce power quality. Synchronous Reference Frame (SRF) was used as a control strategy and for reference harmonic current generation and Space Vector Pulse Width Modulation (SVPWM) was adopted as switching signal generation. With RL load under balanced input voltage condition, the developed SAPF-SVPWM achieved a reduction of THD of 0.91% as compared to 25.60 before compensation. In addition, the developed SAPF- SVPWM model was compared with SAPF without compensation using RL load under unbalanced voltage and the result shows that the developed SVPWM achieved reduction in THD of 1.74 % as compared to 26.68% after and before compensation. The developed SVPWM model was also compared with SPWM balanced and unbalanced voltage condition. The results show that SVPWM performed better than SPWM. All the results obtained are within IEEE 519 harmonics standard (i.e. THD less than 5%) with nonlinear load under balanced and unbalanced voltage. Keywords: Shunt active filter, input voltage, harmonics, space vector pulse width modulation, nonlinear load.
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17

Alhmoud, Lina. "THD Reduction Using Shunt Active Power Filter: A Real Case Study." Universal Journal of Electrical and Electronic Engineering 6, no. 4 (October 2019): 259–64. http://dx.doi.org/10.13189/ujeee.2019.060407.

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18

Hassan Adel, Ahmed, Salama Abo-Zaid, and Mahmoud Elwany. "Harmonics Reduction using a Modified Controller for Doubly Fed Induction Generator." International Journal of Recent Technology and Engineering 9, no. 5 (January 30, 2021): 45–50. http://dx.doi.org/10.35940/ijrte.e5135.019521.

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This paper discusses a control system for the converter of doubly fed induction generator (DFIG) driven by wind energy. The converter of DFIG consists of two main parts; rotor side converter (RSC) and grid side converter (GSC). Two advanced control methods for GSC are presented here in this paper; vector control strategy based on pulse width modulation (PWM) and direct power control (DPC). DPC is based on switching table for voltage vector selection. In addition to grid voltage position, direct and quadrature current components are used here as inputs to the switching table instead of active and reactive powers respectively. This paper proposes a modified switching table for DPC to reduce ripples and total harmonic distortion (THD) of current produced by GSC. A Simulink model for 9 MW wind system based on DFIG is given in this paper. Simulation results are given for PWM, DPC and Proposed system for GSC. In view of THD calculations and simulation results a comparative study and conclusion are given in the end of this paper.
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19

Alhafadhi, Liqaa, Jiashen Teh, Ching-Ming Lai, and Mohamed Salem. "Predictive Adaptive Filter for Reducing Total Harmonics Distortion in PV Systems." Energies 13, no. 12 (June 26, 2020): 3286. http://dx.doi.org/10.3390/en13123286.

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This paper presents a new method for reducing the total harmonic distortion (THD) of photovoltaic (PV) systems by using an adaptive filter based on a predictive model. Instead of reducing the produced THD at each stage of the PV system, a one-step process is implemented at the end stage. The connection topology of the adaptive filter is similar to normal active and passive filters. The main difference is its ability to adjust the filtering coefficients while others cannot. The proposed method is applied to a single-phase standalone PV system by adopting least mean square (LMS), normalized LMS (NLMS) and leaky LMS algorithms to verify the validity of the proposed method. Various values of filter length and step size are evaluated, and results indicate that the proposed method can reduce THD in the current signal of the PV system significantly by using all of the mentioned algorithms. Different step sizes and filter lengths directly influence the effectiveness of the THD reduction, with small step sizes and long filters being the most effective. Amongst the algorithms, NLMS reduces THD the most, and LMS reaches the peak current value the fastest.
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20

Fawzi Mohammed, Mustafa, Ali Husain Ahmad, and AbdulRahim Thiab Humod. "Harmonics reduction of a five-level inverter by unbalanced carriers and over-modulation techniques." International Journal of Engineering & Technology 7, no. 3 (June 23, 2018): 1059. http://dx.doi.org/10.14419/ijet.v7i3.12217.

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The most concerns in the inverter's design are about, how to make the output voltage of the inverter sinusoidal at the desired fundamental frequency with low total harmonic distortion (THD). This paper presents a design and implementation of single-phase five-level inverter which is powered by single dc source and based on T-type multi-level inverters construction. The proposed inverter is built mainly by six IGBTs and two diodes. The used modulation technique is based on using two triangular carriers at 2000 Hz frequency and shifted by phase opposition disposition (POD) method. The carriers are made slightly unbalanced with their amplitudes. The over-modulation method is also introduced in the design to get the lowest possible THD effect without using filters. The inverter is simulated by MATLAB SIMULINK, implemented practically, and tested with the help of LabVIEW software.
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21

Okilly, Ahmed H., Hojin Jeong, and Jeihoon Baek. "Optimal IP Current Controller Design Based on Small Signal Stability for THD Reduction of a High-Power-Density PFC Boost Converter." Applied Sciences 11, no. 2 (January 7, 2021): 539. http://dx.doi.org/10.3390/app11020539.

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This paper presents an optimal design for the inner current-control loop of the continuous current conduction mode (CCM) power factor correction (PFC) stage, which can be used as the front stage of the two-stage AC/DC telecom power supply. The conventional single-phase CCM-PFC boost converter is implemented with proportional–integral (PI) controllers in both the voltage and current-control loops to regulate the output DC voltage to the specified value and to ensure the input current follows the input voltage, which offers a converter with a high-power factor (PF) and low current total harmonic distortion (THD). However, due to the slow dynamic response of the PI controller at the zero-crossing point of the input supply current, the input current cannot fully follow the input voltage, which leads to high THD. In this paper, we investigate a digitally controlled PFC converter with an optimally designed inner current-control loop using a doubly-fed control loops integral-proportional (IP) controller to reduce the THD and to offer an input current with a unity PF. For the economic design of a digitally controlled PFC converter, two isolated AC and DC voltage sensors are designed for interfacing with the microcontroller unit (MCU). PSIM software as well as experimental prototype was used to test the converter performance using the proposed designed current controllers and isolated voltage sensors. We achieved a high-power-density, digitally controlled, telecom PFC stage with a power factor more than 99% and THD of about 5.50%.
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Okilly, Ahmed H., Hojin Jeong, and Jeihoon Baek. "Optimal IP Current Controller Design Based on Small Signal Stability for THD Reduction of a High-Power-Density PFC Boost Converter." Applied Sciences 11, no. 2 (January 7, 2021): 539. http://dx.doi.org/10.3390/app11020539.

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This paper presents an optimal design for the inner current-control loop of the continuous current conduction mode (CCM) power factor correction (PFC) stage, which can be used as the front stage of the two-stage AC/DC telecom power supply. The conventional single-phase CCM-PFC boost converter is implemented with proportional–integral (PI) controllers in both the voltage and current-control loops to regulate the output DC voltage to the specified value and to ensure the input current follows the input voltage, which offers a converter with a high-power factor (PF) and low current total harmonic distortion (THD). However, due to the slow dynamic response of the PI controller at the zero-crossing point of the input supply current, the input current cannot fully follow the input voltage, which leads to high THD. In this paper, we investigate a digitally controlled PFC converter with an optimally designed inner current-control loop using a doubly-fed control loops integral-proportional (IP) controller to reduce the THD and to offer an input current with a unity PF. For the economic design of a digitally controlled PFC converter, two isolated AC and DC voltage sensors are designed for interfacing with the microcontroller unit (MCU). PSIM software as well as experimental prototype was used to test the converter performance using the proposed designed current controllers and isolated voltage sensors. We achieved a high-power-density, digitally controlled, telecom PFC stage with a power factor more than 99% and THD of about 5.50%.
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23

Usha, S., C. Subramani, and A. Geetha. "Performance Analysis of H-bridge and T-Bridge Multilevel Inverters for Harmonics Reduction." International Journal of Power Electronics and Drive Systems (IJPEDS) 9, no. 1 (March 1, 2018): 231. http://dx.doi.org/10.11591/ijpeds.v9.i1.pp231-239.

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This paper deals with the design of cascaded 11 level H- bridge inverter. It includes a comparison between the 11 level H-bridge and T-bridge multilevel inverter. The cascaded inverter of higher level is a very effective and practical solution for reduction of total harmonic distortion (THD).These cascaded multilevel inverter can be used for higher voltage applications with more stability. As the level is increased the output waveform becomes more sinusoidal in nature. The inverter is designed using multicarrier sinusoidal pulse width modulation technique for generating triggering pulses for the semiconductor switches used in the device. Through this paper it will be proved that a cascaded multilevel H-bridge topology has higher efficiency than a T-bridge inverter, as whichever source input voltage is provided since input is equal to the output voltage. In T-bridge inverter, the output obtained is half of the applied input, so efficiency is just half as compared to H-bridge. The output waveform is distorted and has higher THD. The simulation is performed using MATLAB /Simulink 2013 software.
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24

Esmaeili Jafarabadi, S., and G. B. Gharehpetian. "A new ISPWM switching technique for THD reduction in custom power devices." Renewable Energy and Power Quality Journal 1, no. 05 (March 2007): 197–204. http://dx.doi.org/10.24084/repqj05.250.

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25

Sankararao, Pitta. "Integration of Smart Grids and PV System Total Harmonics Distortion (THD) Reduction." International Journal for Research in Applied Science and Engineering Technology 7, no. 11 (November 30, 2019): 759–67. http://dx.doi.org/10.22214/ijraset.2019.11127.

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26

Saini, Rupendra, and K. T. Chaturvedi. "Voltage THD Reduction for Cascaded Multi-level Converter using Sliding Mode Control." International Journal of Computer Sciences and Engineering 7, no. 5 (May 31, 2019): 1504–7. http://dx.doi.org/10.26438/ijcse/v7i5.15041507.

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27

S. K., Chien. "Enhanced DTC induction motor drives- THD reduction multilevel inverter fed drives control." International Journal of Advanced Trends in Computer Science and Engineering 9, no. 1.4 (September 15, 2020): 269–76. http://dx.doi.org/10.30534/ijatcse/2020/4091.42020.

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28

Salimin, S., S. A. Zulkifli, and M. Armstrong. "Reduction in Current THD of Grid Parallel Inverters Using Randomized PR Control." International Journal of Power Electronics and Drive Systems (IJPEDS) 8, no. 1 (March 1, 2017): 290. http://dx.doi.org/10.11591/ijpeds.v8.i1.pp290-296.

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In grid connected system, unity power factor current injection into the grid is vital. This can be achieved by choosing the right inverter topology, passive filter components, current controllers, and PWM switching scheme. This paper compares the output current harmonics profile between when using the conventional proportional resonant (PR) current controller and when using the modified PR current controller. By applying the latter technique, via experimental validation using TMS320F2812, the THD of the injected grid current in a parallel connected inverters system is improved.
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Firouzi, Mehdi, Gevorg B. Gharehpetian, and Mojtaba Pishvaie. "THD reduction of PCC voltage by using bridge-type fault current limiter." International Transactions on Electrical Energy Systems 23, no. 5 (March 28, 2012): 655–68. http://dx.doi.org/10.1002/etep.1621.

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30

Prasun, Satyam Kumar, Sanjeev Jarariya, and Avinash Kumar. "Compensation Design Using RLS Algorithm for THD Reduction in a Solar PV Hybrid System." SMART MOVES JOURNAL IJOSCIENCE 5, no. 11 (November 19, 2019): 29–38. http://dx.doi.org/10.24113/ijoscience.v5i11.236.

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PV and wind hybrid are found to be the most lucrative solution for the diminishing traditional energy sources. Whereas these alternatives sources of the energy have many remarkable rewards like cost of energy and feasibility etc. The attributes of these sources of being cost effective and stable are possible due to their complementary nature as compared to independent energy systems. Therefore, these systems have admirable capability to meet energy crisis up to some extent. The proposed word has designed a hybrid energy system fit for driving residential loads using MATLAB/SIMULINK software. The work has proposed a compensator with RLS algorithm is place of traditional STATCOM device. The results has sown that the active power output available at the load terminal improved from 400 KW to 700KW. Also the work has analyzed THD level in voltage and current waveforms. The proposed RLS based compensator reduced the THD level in voltage to 0.81% and in current wave form to 1.26% . The model has also been integrated with the grid in order to make the system more reliable and efficient while driving loads
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A. Mahmood, Yasser, Majed S. Al-Hafid, and Dhaiya A. Al-Nimma. "THD Reduction Using Series Transformer Connection In A STATCOM Within Mosul Ring System." AL-Rafdain Engineering Journal (AREJ) 17, no. 5 (October 28, 2009): 15–22. http://dx.doi.org/10.33899/rengj.2009.43378.

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Hwang, Yuh-Shyan, Jian-Hong Shen, Jiann-Jong Chen, Yi-Rong Du, and Cheng-Chieh Yu. "Implementation of THD-reduction stereo audio amplifier using compensators and sigma–delta modulators." Analog Integrated Circuits and Signal Processing 73, no. 1 (December 20, 2011): 243–53. http://dx.doi.org/10.1007/s10470-011-9818-z.

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33

Mahmood, Dana, and Bernd G. Stegmayr. "Haemodialysis with Tinzaparin Versus Dialysate Citrate as Anticoagulation." Blood Purification 46, no. 3 (2018): 257–63. http://dx.doi.org/10.1159/000490409.

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Anticoagulation with citrate-containing haemodialysate (cHD) is an alternative to tinzaparin haemodialysate (tHD). The study investigated whether cHD would differ when changed from tHD. The same 18 patients were their own controls followed up with cHD for 5 months. LDL-cholesterol decreased at the end of a cHD session (p = 0.01). Neutrophils (p = 0.013) and monocytes (p = 0.007) dropped more during a cHD session. During the follow-up period of cHD, approximately 50% needed additional tinzaparin. Before the cHD session could start, there was a lower total cholesterol at 2 weeks (p = 0.014) and LDL-cholesterol at 1 month (p = 0.011) versus an increase of LDL at 5 months (p = 0.02). Only patients without additional tinzaparin had a reduction of ­C-reactive protein (CRP) at 2 months of cHD (p < 0.05) but not later. Solely cHD seems possible only in half of the patients. A greater reduction in granulocytes and monocytes during cHD indicates a more extensive blood membrane interaction, while CRP may be lower.
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34

Durgasukumar, G., and M. K. Pathak. "Induction Motor Drive THD Improvement with Multi-Level Inverter." Advanced Materials Research 403-408 (November 2011): 5045–52. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.5045.

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Multi-level voltage source inverters offer several advantages such as a better output voltage with reduced total harmonic distortion (THD), reduction of voltage ratings of the power semiconductor switching devices and also the reduced electro-magnetic interference problems etc. This paper presents the application of Fast space vector pulse width modulation (SVPWM) method for multi-level diode clamped inverter feeding a three-phase Induction motor. The algorithm is independent of the number of inverter levels. In this the three vectors nearest to the reference vector are identified and their corresponding duty cycles are found. These values remain same regardless of number of inverter levels and the location of reference vector.
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35

Abdollahi, Rohollah. "Harmonic reduction using a novel multipulse AC-DC converter." World Journal of Engineering 15, no. 4 (August 6, 2018): 520–30. http://dx.doi.org/10.1108/wje-11-2017-0353.

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Purpose For direct torque controlled induction motor drives, an effective solution to eliminate harmonics is the use of multipulse alternating current (AC)-direct current (DC) converters. Many researchers have used different configurations based on 24- and 30-pulse rectifications for improved power quality. However, the total harmonic distortion (THD) of AC mains current with these topology is more than 4 per cent when operating at a light load. For mitigating the THD problems observed in the input currents, Abdollahi propose 40-, 72- and 88-pulse AC-DC converters, while the power quality enhancement was the main concern. It is known that by increasing the number of pulses further results in reduction in current harmonics, but this is accompanied by an increase in cost and complexity. In this context, the purpose of this paper is to design a new delta/hexagon transformer based 36-pulse AC-DC converter for harmonic reduction without increasing the cost and complexity. Design/methodology/approach The proposed converter consists of two paralleled 18-pulse AC-DC converters involving a nine-phase shifted uncontrolled diode bridges with an interphase transformer circuit. Findings In this paper, the proposed scheme is simulated by matrix laboratory (MATLAB)/SIMULINK considering different loading scenarios. The simulation results show that the proposed scheme improves the power quality indices and satisfies the The Institute of Electrical and Electronics Engineers (IEEE)-519 requirements at the point of common coupling. Also, a laboratory prototype is implemented using the proposed design, and the experimental results confirm the simulation results under different loading conditions. Originality/value The proposed solution is a tradeoff among the pulse number, the transformer platform, the complexity of the scheme and the cost. The proposed scheme has an optimized configuration in this regard.
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36

Sadeghi, Hassan, and Navid Ghaffarzadeh. "A Simultaneous Biogeography based Optimal Placement of DG Units and Capacitor Banks in Distribution Systems with Nonlinear Loads." Journal of Electrical Engineering 67, no. 5 (September 1, 2016): 351–57. http://dx.doi.org/10.1515/jee-2016-0050.

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Abstract This paper uses a new algorithm namely biogeography based optimization (BBO) intended for the simultaneous placement of the distributed generation (DG) units and the capacitor banks in the distribution network. The procedure of optimization has been conducted in the presence of nonlinear loads (a cause of harmonic injection). The purpose of simultaneous optimal placement of the DG and the capacitor is the reduction of active and reactive losses. The difference in the values of loss reduction at different levels of the load have been included in the objective function and the considered objective function includes the constraints of voltage, size and the number of DG units and capacitor banks and the allowable range of the total harmonic distortion (THD) of the total voltage in accordance with the IEEE 519 standards. In this paper the placement has been performed on two load types ie constant and mixed power, moreover the effects of load models on the results and the effects of optimal placement on reduction of the THD levels have also been analyzed. The mentioned cases have been studied on a 33 bus radial distribution system.
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Nalina, B. S., and V. J. Vijayalakshmi. "Comparison of Current Control Strategies of Shunt Active Power Filter ." Applied Mechanics and Materials 573 (June 2014): 59–65. http://dx.doi.org/10.4028/www.scientific.net/amm.573.59.

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Nowadays the number of non linear loads in power systems is increasing dramatically. These non linear loads inject harmonic currents and voltage which makes the supply currents non-sinusoidal. These harmonics are eliminated via an active power filter. The reference currents are generated by shunt active filter which is provided to compensate harmonic currents demanded by the load. Different current control strategies are implemented to improve the performance of shunt active power filter. These techniques are useful in making the supply currents sinusoidal. The performance of the current control techniques are different from each other. The %THD can be reduced with the aid of shunt active power filter. In this paper, different current control schemes are analyzed and their outputs are compared to determine the effectiveness. The most effective current controller generates less %THD. The power quality of the system is improved with the reduction of %THD. The different current controllers which are compared in this paper are GA controller and PI-VPI controller.Under analysis, the PI-VPI controller is found to be effective.
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NGUYỄN, Nhờ Văn, and HONG-PHONG NGUYEN LE. "A study on performances of carrier-based pulse-width modulation techniques for three-phase three-level t-type neutral-point-clamped inverter under switch-open-circuit fault on two neutral-point-connected legs." Science & Technology Development Journal - Engineering and Technology 3, no. 3 (December 18, 2020): first. http://dx.doi.org/10.32508/stdjet.v3i3.659.

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Multilevel voltage source inverters (VSIs) have been used for several decades thanks to their advantages compared with traditional two level VSI. Among various types of multilevel configuration, the T-type neutral-point-clamped VSI (3L TNPC VSI or 333-type VSI) has gained the attention in recent years. Due to the unique structure, the 333-type VSI has critical issues in reliability in operation such as switch-open-circuit (SOC) and switch-short-circuit (SSC), which lead to several unrequired issues, for instance, reduction of system performance, distorted and unbalanced output voltages and currents, or triggering the protection circuits. In some applications, the amplitude reduction and harmonics distortion of output voltages in SOC faults are not acceptable. Therefore, it is necessary to develop a pulse-width modulation (PWM) algorithm for 333-type VSI working under SOC fault which guarantees the desired output fundamental component voltage. The simultaneous SOC fault on two neutral-point-connected legs in the 333-type VSI may cause a large reduction in the output voltage. Under this circumstance, the 333-type VSI becomes an asymmetrical one called 322-type VSI. Certain studies regarding to the operation of 333-type VSI under SOC faults have been carried out. However, these studies require more semiconductor devices in order to create a redundant switching circuit. This leads to higher system cost with reduced inverter effieciency due to the additional loss. In this study, two carrier-based pulse-width modulation (CBPWM) techniques, i.e. 322-sinusoidal PWM (322-SPWM) and 322-medium offset CBPWM (322-MOCBPWM) are proposed for 322-type VSI. The proposed techniques are firstly simulated in MATLAB/Simulink and then implemented on a hardware setup. Performances of the proposed techniques are evaluated in terms of total harmonic distortion (THD) and weighted-THD (WTHD) of output voltages. Simulation results show that considering the worst output voltage under SOC fault, vBC, the proposed 322-SPWM technique could improve the THD by 40% and the WTHD by 94% compared with the uncompensated case with m=0.8. The corresponding results of 322-MOCBPWM technique are 42% and 96%, respectively. Characteristics of THD and WTHD values are also presented for demonstration the effectiveness of the proposed algorithm.
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Kumar, Dilip. "Voltage THD Reduction for Cascaded H-bridge Multi-level Converter using Sliding Mode Control." International Journal for Research in Applied Science and Engineering Technology 7, no. 11 (November 30, 2019): 463–67. http://dx.doi.org/10.22214/ijraset.2019.11075.

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40

Kumar, N. Siva, and A. Sumathi. "Reduction of THD in Seven Level H-Bridge Inverter with Reduced Number of Switches." Asian Journal of Research in Social Sciences and Humanities 6, no. 8 (2016): 2106. http://dx.doi.org/10.5958/2249-7315.2016.00734.6.

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41

Sivakumar, Natesan, and S. Sumathi. "Reduction of THD in Thirteen-Level Hybrid PV Inverter with Less Number of Switches." Circuits and Systems 07, no. 10 (2016): 3403–14. http://dx.doi.org/10.4236/cs.2016.710290.

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42

Kiadehi, Abbas Dehghani, Khalil El Khamlichi Drissi, and Christophe Pasquier. "Voltage THD Reduction for Dual-Inverter Fed Open-End Load With Isolated DC Sources." IEEE Transactions on Industrial Electronics 64, no. 3 (March 2017): 2102–11. http://dx.doi.org/10.1109/tie.2016.2620420.

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43

Attaianese, C., V. Nardi, and G. Tomasso. "Space Vector Modulation Algorithm for Power Losses and THD Reduction in VSI Based Drives." Electric Power Components and Systems 35, no. 11 (August 28, 2007): 1271–83. http://dx.doi.org/10.1080/15325000701351724.

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44

Nazir, Refdinal, Syafii Syafii, Andi Pawawoi, Fadjril Akbar, and Axel Doriza. "Differences in the impact of harmonic distortion due to the installation of electronic load controller in self-excited induction generator and synchronous generator." International Journal of Power Electronics and Drive Systems (IJPEDS) 10, no. 1 (March 1, 2019): 104. http://dx.doi.org/10.11591/ijpeds.v10.i1.pp104-116.

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In general, the application of Self-Excited Induction Generator (SEIG) or Synchronous Generator (SG) on the Stand-Alone Micro Hydel Power Plant (MHPP) is equipped with Electronic Load Controller (ELC) to control generator output during variations in consumer load. One type of ELC that is cheap and rigid developed today is the ELC, which is constructed by the uncontrolled bridge rectifier with DC Chopper. Based on the operational concept, basically this type of ELC can be implemented on both SEIG and SG, but both of these generators will have a different harmonic distortion effect on the output and its load. This paper examines the differences in the effects of harmonic distortions due to ELC installation on SEIG and SG. The initial stage of this study was to design the ELC developed. Then, the harmonic distortion response due to the installation of ELC on SEIG and SG is tested, which includes harmonic distortion in: stator current, PCC voltage, and consumer load current. THD<sub>I </sub>(Current Total Harmonic Distortion) stator current at SEIG with ELC has shown an average value smaller than the THD stator current in SG with ELC. Likewise, the THD<sub>V</sub> (Voltage Total Harmonic Distortion) value of PCC voltage and THDI value of the current consumer load on SEIG equipped with ELC has been shown to be smaller than the THD<sub>V</sub> value of PCC voltage and THD<sub>I</sub> value of the current consumer load on SG equipped with ELC. The effects of harmonic distortions due to the installation of ELCs that developed in this study on SEIG is still within the permitted limits, while on the SG, the harmonic distortion reduction is needed at the generator output.
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45

Munir, Hafiz Mudassir, Rami Ghannam, Hong Li, Talha Younas, Noorbakhsh Amiri Golilarz, Mannan Hassan, and Abubakar Siddique. "Control of Distributed Generators and Direct Harmonic Voltage Controlled Active Power Filters for Accurate Current Sharing and Power Quality Improvement in Islanded Microgrids." Inventions 4, no. 2 (May 15, 2019): 27. http://dx.doi.org/10.3390/inventions4020027.

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Harmonics are regarded as one of the main challenges in a microgrid. This issue may even get worse when different distributed generators (DGs) work together to solve the load sharing problems due to mismatched feeder impedances and diversified DG ratings. Even though load sharing can be achieved, the microgrid suffers from voltage unbalance and total harmonic distortion (THD) issues at the output of DG terminals as well as at the point of common coupling (PCC). Thus, in this paper, the power quality improving method is discussed, with a target of load sharing under the hierarchical control of different DG units and an active power filter (APF) in microgrids. To achieve this objective, we propose integrating a direct harmonic voltage controlled APF with DGs to improve their harmonic compensation performance. This proposed control scheme has many advantages over conventional control using a shunt resistive active power filter (R-APF) with voltage controlled DGs. First, based on the existing THD level of the PCC voltage, the proposed scheme provides improved voltage compensation and reduction in THD in the islanded microgrid. Secondly, equal load sharing can be achieved simultaneously. Thus, the proposed scheme provides better performance and a seamless interface as the proposed study mainly contains both the voltage controlled DGs and the local based voltage detection APF.
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46

Nigam, Rashmi S., R. U. Khan, Reshu Singh, and Joginder Singh. "Bioefficacy of rhizospheric fungal isolates against wilt and root-rot pathogens of Pea." International Journal of Agricultural Invention 5, no. 01 (November 27, 2019): 133–37. http://dx.doi.org/10.46492/ijai/2020.5.1.20.

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Pea (Pisum sativum) is an important leguminous crop in many countries including India. Wilt and root rot of pea is an important and widespread disease that often causes significant reduction in the yield and quality of harvested peas throughout the production areas. It is the most important and widespread disease of pea grown in relatively dry and warm area. In-vitro effectiveness of various antagonistic fungal isolates namely T. harzianum (Th1, Th2, Th3, Th4 and Th5) was evaluated against Fusarium oxysporum f. sp. pisi, Rhizoctonia solani and Pythium ultimum by dual culture technique on potato dextrose agar. According to the observation recorded after 5 days, all the rhizospheric fungal isolates evaluated for their antagonistic potential against wilt and root-rot pathogens, exhibited significant effect on radial growth inhibition of pathogens in comparison to control. Among the fungal isolates, Th3 and Th5 of T. harzianum proved to be most effective in reducing the growth of F. oxysporum f. sp. pisi, R. solani and P. ultimum. It was worthy to note that all rhizospheric fungal isolates visualized an increase in their antagonistic potential over the period of time in subsequent hours of inoculation.
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Salgado-Herrera, Nadia Maria, David Campos-Gaona, Olimpo Anaya-Lara, Miguel Robles, Osvaldo Rodríguez-Hernández, and Juan Ramón Rodríguez-Rodríguez. "THD Reduction in Distributed Renewables Energy Access through Wind Energy Conversion System Integration under Wind Speed Conditions in Tamaulipas, Mexico." Energies 12, no. 18 (September 17, 2019): 3550. http://dx.doi.org/10.3390/en12183550.

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In this article, a technique for the reduction of total harmonic distortion (THD) in distributed renewables energy access (DREA) composed of wind turbines is introduced and tested under the wind speed conditions presented in Tamaulipas, Mexico. The analysis and simulation are delimited by a study case based on wind speeds measured and recorded for one year at two highs in the municipality of Soto La Marina, Tamaulipas, Mexico. From this information, the most probable wind speed and the corresponding turbulence intensity is calculated and applied to a wind energy conversion system (WECS). The WECS is composed of an active front-end (AFE) converter topology using four voltage source converters (VSCs) connected in parallel with a different phase shift angle at the digital sinusoidal pulse width modulation (DSPWM) signals of each VSC. The WECS is formed by the connection of five type-4 wind turbines (WTs). The effectiveness and robustness of the DREA integration are reviewed in the light of a complete mathematical model and corroborated by the simulation results in Matlab-Simulink®. The results evidence a reduction of the THD in grid currents up to four times and which enables the delivery of a power capacity of 10 MVA in the Tamaulipas AC distribution grid that complies with grid code of harmonic distortion production.
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48

Prabha, Divya, and Lalit Jain. "Modified Recursive Least Square Algorithm for THD Reduction using Shunt Active Power Filter in Grid." SMART MOVES JOURNAL IJOSCIENCE 5, no. 2 (February 11, 2019): 8. http://dx.doi.org/10.24113/ijoscience.v5i2.183.

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In industrial and utility power system it has been observed that harmonics build a major role in reducing the quality of power. These harmonics are caused because of increasingly utilize of nonlinear loads connected to the power system. In this context, active power filters play a very significant role for improvement in power quality. Moreover, at transmission ground, there is a high requirement to control reactive power and voltage stability. Conventionally, passive and active filters (shunt and series filters) were used for the development of power quality. But, they suffered from the issues like resonance, fixed compensation, and other heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the designed.
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49

Hwang, Yuh-Shyan, Jian-Hong Shen, Jiann-Jong Chen, and Ming-Ren Fan. "A THD-reduction high-efficiency audio amplifier using inverter-based OTAs with filter-output feedback." Microelectronics Journal 45, no. 1 (January 2014): 102–9. http://dx.doi.org/10.1016/j.mejo.2013.10.007.

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50

Durgasukumar, G., and Mukesh Kumar Pathak. "Neuro-fuzzy-based space vector modulation for THD reduction in VSI fed induction motor drive." International Journal of Power Electronics 4, no. 2 (2012): 160. http://dx.doi.org/10.1504/ijpelec.2012.045629.

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