Selective Harmonic Elimination Technique Research Articles

Selective Harmonic Elimination Technique Improvement for Cascaded H-Bridge Multilevel Converters Under DC Sources Uncertainty

The performance of multilevel converters (MLCs) is at the risk of uncertainty of DC sources. This issue has a more negative effect on three-phase cascaded H-bridge MLCs (CHB-MLCs) due to more isolated DC sources. DC voltage variation can take place in all phases, but in this paper, the effect of DC voltage variation of one phase on line voltages is considered. This problem can lead to unbalanced line voltages and a lack of third harmonic elimination in a spontaneous way. Therefore, these problems cause to modify the formulation of quarter-wave symmetrical selective harmonic elimination (SHE) for three-phase CHB-MLCs so that the line voltages become resistant to DC voltage variations as well as mitigating third harmonic. To keep line voltages amplitude fixed under variation of DC voltages, it is necessary to take advantage of non-identical modulation indices to exploit the maximum capacity of DC voltages. Furthermore, regarding unequal DC voltages that can appear in numerous states in a phase, a new method based on the average of DC voltages (ADCV) per phase is employed in the formulation of SHE to reduce these states. Finally, both simulation and experimental results are presented to validate the performance of the proposed method.

Selective harmonic elimination in PUC‐5 multilevel inverter using hybrid IGWO‐DE algorithm

AbstractThe use of a multilevel inverter has received significant attention in recent years due to its numerous advantages. Because of the widespread use of multilevel inverters in industries and applications that require a wide range of voltages, achieving high‐quality voltage has presented a number of challenges. Many studies have been carried out to address the problem of unwanted harmonics in multilevel inverters. The inverter switching can be done at a low frequency using the Selective Harmonic Elimination (SHE) technique, and the unwanted harmonics can be significantly reduced; however, the issue with SHE is solving the transcendental equations and determining the optimum switching angle. To address this problem, a new and improved hybrid algorithm is proposed that combines two evolutionary algorithms, gray wolf optimization (GWO) with an improved and new convergence factor and Differential evolution (DE) with a dynamic scaling factor using a crossover operator. In this paper, the optimum switching angles for a packed U cell 5‐level inverter are estimated using the proposed algorithm for distinct modulation index values, and simulation results are compared with different algorithms. The simulation result of the proposed algorithm, IGWO‐DE is confirmed through experiment.

Hardware Implementation of a Single Phase 11-Level Novel SC-MLI with Reduced Component Count and Boosting Capability

Conversion of DC power into AC power at medium and high level utilize Multilevel-inverter (MLI) because of many advantages of MLI over conventional inverters. The MLI converter topologies have gained a huge attraction towards various applications like photovoltaic and even electric vehicles (EVs). This article represents a new switched capacitor topology (SC-MLI). The proposed SC-MLI contains ten power electronic switches and has a boosting capability with the help of one capacitor. It also uses two input DC sources and has a voltage gain of 1.4. Also, the capacitor is self-balancing and switches have less stress as compared to other configurations. Selective Harmonic Elimination (SHE) technique is employed for the generation of eleven levels. A comparison is also made with the recently developed MLI topologies based on different parameters. Finally, a hardware prototype is developed to check the feasibility of the proposed MLI in the laboratory and satisfactory results have been presented.

Harmonic elimination of a fifteen‐level inverter with reduced number of switches using genetic algorithm

AbstractMultilevel inverters play a crucial role in high‐power renewable energy applications and medium voltage drives. However, existing solutions such as capacitor‐clamped and diode‐clamped multilevel inverters are not suitable for these applications due to their dependence on isolated DC sources, complex control techniques, and potential reliability issues. Here, a novel fifteen‐level inverter topology is proposed which addresses these limitations. The proposed multilevel inverters utilize a topology with reduced number of switches, which can effectively accommodate isolated DC sources. It consists of eight switches for level generation and four switches for polarity generation (H‐bridge). One of the key advantages of this topology is that it significantly reduces the Total Harmonic Distortion (THD) in accordance with the IEEE 519 standards. Genetic algorithm‐based selective harmonic elimination technique was employed for THD minimization. A detailed switching loss calculation and harmonic analysis were performed to support the effectiveness of the proposed topology and the control used. The implementation of the proposed topology is simple and straightforward. Furthermore, to validate the results, insulated gate bipolar transistor based hardware model was developed. The optimized firing pulses were generated using the dSPACE 1104 controller. The results were compared with the existing recent literature and was found to address the limitations of existing topology.

Design of Switched Capacitor Multilevel Inverter with Selective Harmonic Elimination

In this paper, Selective Harmonic Elimination (SHE) technique is applied to control multilevel inverters that can be used to eliminate the low order dominant harmonics. This is considered a low frequency technique, in which the switching angles are predetermined based on solving a system of transcendental equations. Newton Raphson is one among the heuristic techniques utilised for selective harmonic elimination. The proposed SHE strategy is simulated along with Sinusoidal Pulse Width Modulation (SPWM) technique and the harmonic distortions are measured and compared for both techniques in MATLAB/Simulink software.

Optimizing performance of a reduced switch multi‐level inverter with moth‐flame algorithm and SHE‐PWM

AbstractMulti‐level inverters are widely used in high‐voltage and high‐power applications due to the increasing demand for renewable energy. This study proposes a novel single‐phase reduced switch multi‐level inverter topology that generates 11 levels of output voltage steps, operates in asymmetric mode, and uses fewer power electronic switches with efficient switching control. To optimize the inverter's performance, Moth Flame Optimization (MFO), Particle Swarm Optimization (PSO), and Whale Optimization Technique (WOA) are utilized to apply the selective harmonic elimination technique. The proposed circuit is implemented in PSIM software using optimized switching angles, and the fitness functions and switching angles for the three optimizers are evaluated and reported. The inverter's performance at optimal modulation points for the three optimizers is computed and analyzed, with the Total Harmonic Distortion (THD) measured at 0.82 modulation point before and after filtering. Results show that MFO outperforms PSO and WOA with the lowest THD values of 0.85% and 0.78%, respectively; therefore, complying with the IEEE 519 standard. The experimental validation of MFO's superiority is performed using the Typhoon HIL‐402 hardware device. This study provides a promising solution for the design and optimization of multi‐level inverters, paving the way for more efficient and reliable renewable energy systems.

Red deer algorithm-based selective harmonic elimination technique for multilevel inverters

This paper proposed a red deer algorithm (RDA)-based selective harmonic elimination (SHE) method for multilevel inverters (MLIs). To eliminate the desired harmonic orders, the optimum switching angles of the MLI have been calculated using the proposed RDA. The calculated switching angles have been applied to the 3-phase cascaded H-bridged 11-level inverter. In addition, the performance of the proposed RDA method was compared with the results of methods such as the Newton-Raphson (NR) method, LSHADE/EpSin technique (LSHADE), whale optimization algorithm (WOA), and particle swarm optimization (PSO) used for the SHE problem in the literature. The results obtained prove that the proposed RDA optimization solves the SHE problems more effectively than other methods. It has also been observed that RDA produces good solutions in different modulation indexes.

Broyden's method assisted differential evolution (BMADE) based selective harmonic elimination in a cascaded H‐bridge multilevel inverter

AbstractThis paper implements Broyden's Method Assisted Differential Evolution (BMADE) algorithm for eliminating third and fifth harmonics in the output voltage of 7‐level cascaded H‐Bridge multilevel inverter (CHB‐MLI) using selective harmonic elimination technique. Calculations of switching angles are done for various modulation index values (M). Initial guess for Broyden's method is calculated by Differential Evolution (DE). Exact value of switching angles is then calculated by Broyden's method using initial guess obtained from DE. Code of BMADE algorithm for obtaining the required switching angles is written in MATLAB. Results obtained with BMADE algorithm are compared with various other techniques that is, Genetic Algorithm (GA), DE, and Whale Optimization Algorithm (WOA). BMADE is able to successfully eliminate third and fifth order harmonics in the output voltage. Along with removing the desired harmonics, BMADE also provides lower THD than GA, DE, and WOA for certain range of M. The results also showed that BMADE is faster than GA, DE, and WOA as the execution time of BMADE is lesser than GA, DE, and WOA. Moreover, laboratory experiments are used to test the simulation's findings. The experimental results support the simulation results.

Switched-Capacitor-Based Multi-Source Multilevel Inverter With Reduced Part Count

This paper proposes a switched-capacitor (SC) based multi-source multilevel inverter (MSMLI) for high-frequency AC power distribution systems. The proposed topology is a potential alternative in applications involving asymmetric dc voltage sources (in the case of renewable source-based AC microgrids). Using the available dc sources as an aggregated input eliminates the need for paralleling of inverters. In addition, the proposed topology offers a common ground among the multiple input sources and, thus, has a more straight forward design and avoids stacking voltage sources. By employing nine switches, two diodes, and two SCs, an 11-level voltage waveform is synthesized. The SC voltages are self-balanced owing to their series-parallel charging technique. A simple selective harmonic elimination technique is used to obtain the desired output voltage level and simultaneously eliminate the lower-order harmonics. A detailed comparison of the proposed MSMLI is carried out, and the test results obtained from a laboratory prototype are presented to validate the feasibility and highlight the benefits of the proposed topology.

Investigation and validation of PV fed reduced switch asymmetric multilevel inverter using optimization based selective harmonic elimination technique

Pulse width modulation for Selective Harmonics Elimination (SHE) is mostly employed in the reduction of lower order harmonics. The PV system in this research provides input voltage to the reduced switch 31-level inverter, which is based on the Artificial Bee Colony algorithm. With a high gain DC-DC single-ended primary-inductor converter (SEPIC), the PV panel output voltage is kept constant. The Grey wolf optimization algorithm (GWO) approach is used to get the most power out PV scheme. Multi Carrier modulation, a high-frequency modulation technology, is also used in this novel design of the inverter to reduce upper order harmonics. The suggested Artificial Bee Colony (ABC) algorithm, harmonics is compared to a SHE technique based on a genetic algorithm. The hardware findings were confirmed using DSPIC30F2010 controller simulation, and the recommended system was validated using Matlab simulation.

OPTIMIZATION OF SWITCHING ANGLES FOR SELECTIVE HARMONIC ELIMINATION IN CASCADED H-BRIDGE MULTILEVEL INVERTERS EMPLOYING ARTIFICIAL INTELLIGENCE TECHNIQUES – A MINI REVIEW

Considering present shortage of fossil fuels and discharges of ozone harming substances, power developed from Renewable Energy Sources (RES) is identified as the excellent choice for producing the electricity. The characteristic of an inverter is to transform the dc power into ac power to fulfill out the requirements of load. Despite its advantage, the presence of harmonics in the output voltage reduces both the efficiency and the performance of the inverter. Several researches have been carried out since last three decades for eliminating the harmonics. Based upon several researches, it reveals that the Selective Harmonic Elimination Pulse-width Elimination technique (SHEPWM) has proven to be the best in eliminating lower order harmonics. But when calculus based methods are used for solving the non-linear transcendental equations, this technique has shown some complications. Artificial Intelligence (AI) techniques appear to be better in solving the above said equations. This review paper provides the performance of some AI techniques used for eliminating the harmonics in inverters. Based upon the information collected from various literatures and its results, conclusion has been made.

Selective Harmonics Elimination Technique for Artificial Bee Colony Implementation

In this research, an Artificial Bee Colony (ABC) algorithm based Selective Harmonics Elimination (SHE) technique is used as a pulse generator in a reduced switch fifteen level inverter that receives input from a PV system. Pulse width modulation based on Selective Harmonics Elimination is mostly used to suppress lower-order harmonics. A high gain DC-DC-SEPIC converter keeps the photovoltaic (PV) panel’s output voltage constant. The Grey Wolf Optimization (GWO) filter removes far more Photovoltaic panel energy from the sunlight frame. To eliminate voltage harmonics, this unique inverter architecture employs a multi-carrier duty cycle, a high-frequency modulation approach. The proposed ABC harmonics elimination approach is compared to SHE strategies based on Particle Swarm Optimization (PSO) and Flower Pollination Algorithm (FPA). The suggested system’s performance is simulated and measured using the MATLAB simulation tool. The proposed ABC approach has a THD level of 4.86%, which is better than the PSO and FPA methods.

Development of an Enhanced Selective Harmonic Elimination for a Single-Phase Multilevel Inverter with Staircase Modulation

A low device switching frequency is recommended for the operation of multilevel inverters (MLIs) to achieve reduced switching losses. Selective harmonic elimination (SHE) and total harmonic distortion (THD) minimization are the two primary switching angle estimation methodologies for low-frequency modulation control. In this regard, a new generalized condition has been developed in this paper for the SHE technique. This original condition will give an output voltage with improved THD in comparison to the conventional SHE technique, while achieving its primary objective of eliminating the specific harmonic content from the output voltage. The proposed condition has been formulated by estimating the error associated with the staircase waveform and the desired sinusoidal output at the fundamental frequency. An infinite harmonic count has been considered for the evaluation of the quality of output, to obtain an accurate THD value without any underestimation. The proposed technique is analyzed, and its critical features are studied in Simulink. The effectiveness of the present work has been also validated by the experimental results.

Grid Connection Circuits for Powerful Regenerative Electric Drives of Rolling Mills: Review

AC regenerative electric drives (AC REDs) are widely used in metallurgical rolling due to their reliability, efficiency, and power sufficient to maintain the process. This paper reviews the latest achievements in building the grid connection circuits for the main AC REDs of rolling mills. The paper discusses multipulse connection circuits formed by various transformer types and algorithms for preprogrammed pulse-width modulation with selective harmonic elimination technique (PPWM with SHE) of three-level active front ends (AFE), provides the theoretical and practical measurement results, and gives recommendations for improving existing systems. For 6-, 12-, and 18-pulse grid connection circuits, switching patterns of AFE semiconductor modules with a smooth downward trend within the modulation index range from 0.7 to 1.15 are provided. A simulation was performed under comparable conditions on simulation models in the Matlab/Simulink to objectively evaluate the performance and opportunities of 6-, 12-, and 18-pulse grid connection circuits, including the three-level AFE and transformer specifications. The waveforms and spectra of the grid currents and transformer secondary winding phase currents are shown; total harmonic distortion (THD) factors have been calculated up to the 60th harmonic for various PPWM with SHE patterns. The results of simulation and experimental measurement on operating equipment have been compared. The paper is expected to provide a broad overview of multipulse connection circuits of the rolling mill’s main AC REDs, in particular, identify the latest solutions capable of significantly improving their electromagnetic compatibility with the grid. The results obtained are of high genericity and can be used by researchers and engineers to provide the electromagnetic compatibility of non-linear consumers in similar circuits, as well as design them.

Reduction in Selected Torque Harmonics in a Three-Level NPC Inverter-Fed Induction Motor Drive

The reduction or elimination of selected torque and current harmonics is widely used in multilevel inverter fed induction motor drives. A wide range of methods are employed to achieve this goal. Those modes of operation allow the avoidance of certain torque and current harmonics that may lead to disturbance and even mechanical and electrical resonance. In this paper, the selective harmonic elimination technique (SHE-PWM) is employed to reduce the chosen torque harmonics in a three-level NPC inverter-fed induction motor drive. The proposed method is compared with the synchronized carrier pulse width modulation technique (SCPWM). For both schemes of control simulation, a model is proposed using Simulink software. Furthermore, laboratory stand experiments are carried out to verify the correctness of torque harmonics formation.

Harmonic Minimization in Grid Coupled Photovoltaic Structures Using Selective Harmonic Elimination Pulse-Width Modulation in Multiple Level Series Linked Nano-Scale Double Gate Hetero-Structure MOSFET Based H Type Bridge Inverters

Semiconductor Chip makers and semiconductor device designers denote that, a reliable device should have a character with high speed and low power loss in its operation, which could be done in a nano-scale regime. A nano-scale double gate hetero-structure MOSFET based multilevel inverter is a power electronic arrangement system that generates multilevel output voltage with lower harmonic distortion and reduced power switching loss. In a grid-connected photovoltaic device, this power electronic inverter is a critical and essential component. Series coupled H-bridge multilayered inverter is a widely satisfactory arrangement for incorporation of renewable power among three multilevel inverter topologies, which might be directly fed by photovoltaic (PV) units, wind turbines, or fuel voltaic cells with enhanced power quality due to accessibility of an individual’s direct current sources. Furthermore, compared to traditional converters, this multilayered configuration will boost output voltage and current accuracy, resulting in lower total harmonic distortion. This concept proposes an innovative series of type H-bridge multilayered inverters arrangement for grid-connected photovoltaic structures. The optimization algorithm, particle swarm was incorporated to estimate the switching angles after the Selective Harmonic Elimination technique was developed to remove 5th, 7th, 11th and finally 13th lower number harmonics. For the first time, a cyclic choice method was used to keep up a constant balance of power among the different sources, in which the sources contribute equally to the output power over the course of operation. A simulation in the MATLAB/SIMULINK foundation was used to validate the integrated definition. The output taken from an experimental arrangement was used to verify the proposed principle of eradicating lower-level harmonics. The harmonic spectrum along with output waveforms for selective harmonic eliminated pulse-width modulation (SHE-PWM) technique was then obtained.

Crystal Structure Algorithm (CryStAl) Based Selective Harmonic Elimination Modulation in a Cascaded H-Bridge Multilevel Inverter

This paper introduces an effective Selective Harmonic Elimination (SHE) modulation technique in a five, seven, and nine-level cascaded H-bridge (CHB) multilevel inverter (MLI). Minimization of the harmonics and device counts is the basis for the ongoing research in the area of MLI. Reduced harmonics and hence the lower Total Harmonic Distortion (THD), improve the output power quality. SHE is a low-frequency modulation scheme to achieve this goal. SHE techniques are used to eliminate the distinct lower-order harmonics by determining the optimum switching angles. These angles are evaluated by solving the non-linear transcendental equations using any optimization technique. For this purpose, the Crystal Structure Algorithm (CryStAl) has been used in this paper. It is a metaheuristic, nature-inspired, and highly efficient optimization technique. CryStAl is a simple and parameter-free algorithm that doesn’t require the determination of any internal parameter during the optimization process. It is based on the concept of crystal structure formation by joining the basis and lattice point. This natural occurrence can be realized in crystalline minerals in their symmetrically organized components: ions, atoms, and molecules. The concept has been utilized to solve non-linear transcendental equations. SIMULINK/MATLAB environment has been used for the simulation. The simulation result shows that the crystal structure algorithm is very effective and excels the other metaheuristic algorithm. Hardware results validate the performance.

Power Sharing and Control by Droop Controller with Advanced Filter Design: A Case Study in Lock-down Periods

In the lock-down period, the islanding mode of operation with droop controllers has several advantages in the alternating current grid. This study focuses on an improvised droop controller. It consists of an advanced filtering segment embedded with a conventional droop controller, which overcomes the drawback of droop controllers of the non-handling of non-linear loads in an ordinary situation. A selective harmonic elimination technique in grid-connected mode and lock-down mode and an advanced filter embedded with droop control are used so that the proposed controller can also work as an Active Harmonic Filter (AHF). The simulation results in different cases show that the proposed controller can control the active and reactive power in the lock-down period as well as the harmonics in the normal period up to an extent.

Multilevel level Single Phase Inverter Implementation for Reduced Harmonic Contents

Selective harmonic elimination technique SHE is adopted in this work to reduce the harmonic contents in single phase cascaded multilevel inverter. The firing instants for the electronic switches MOSFETs in the inverter are calculated off line for five level to thirteen level inverter. An Arduino microcontroller is programmed to cope with different topologies of the multilevel inverter. The implemented multi-level (MLI) inverter results are compared with Simulink simulation program and are found very close to each other. SHE technique works at system frequency (50Hz or 60Hz) and the switching losses are very small. The sinusoidal pulse width modulation SPWM requires a carrier frequency not less 20 times the system frequency so SHE approach is found to be superior compared with SPWM. Also, SHE technique shows significant reduction in THD as the number of levels increased. Results for the output voltages and currents along with their frequency spectrum are shown and compared with traditional SPWM.

Multilevel level single phase inverter implementation for reduced harmonic contents

<p>Selective harmonic elimination technique SHE is adopted in this work to reduce the harmonic contents in single phase cascaded multilevel inverter. The firing instants for the electronic switches MOSFETs in the inverter are calculated off line for five level to thirteen level inverter. An Arduino microcontroller is programmed to cope with different topologies of the multilevel inverter. The implemented multi-level (MLI) inverter results are compared with Simulink simulation program and are found very close to each other. SHE technique works at system frequency (50 Hz or 60 Hz) and the switching losses are very small. The sinusoidal pulse width modulation SPWM requires a carrier frequency not less 20 times the system frequency so SHE approach is found to be superior compared with SPWM. Also, SHE technique shows significant reduction in THD as the number of levels increased. Results for the output voltages and currents along with their frequency spectrum are shown and compared with traditional SPWM.</p>