Selective Harmonic Elimination Strategy Research Articles

RSO based selective harmonic elimination control for nine-level switched capacitor inverter

Abstract Renewable energy utilization has gained much attention in the recent time owing to the sharp increase in the power demand. Out of different renewable sources, photovoltaic (PV) energy utilization in different forms is one of key focus. Power converter such as multilevel inverters (MLIs) are proven as key components for PV systems as well as for other applications such as motor drives, electric vehicles, and charging stations. With the advancement of the design of MLIs, the switched-capacitor (SC) based MLIs have been widely deployed for their boosting capability which is a major requirement for PV systems. In this paper, a reduced switch single input step-up 9-level SC MLI is first proposed. Followed by this, a new Rat Swarm Optimization (RSO) based Selective Harmonic Elimination (SHE) control method is incorporated for switching operation. RSO has the ability to provide the solution with higher competency within less time and a less computationally complex approach. The operation of proposed structure is analyzed and its advantages are justified by comparison with exiting topologies. The effectiveness of RSO based SHE scheme is also verified by comparing it with other nature-inspired algorithms. The effectiveness and workability of the proposed system are examined using simulation and experimental tests.

Notice of Violation of IEEE Publication Principles: A Hybrid ANFIS/ABC-based Online Selective Harmonic Elimination Switching Pattern for Cascaded Multi-level Inverters of Microgrids

Notice of Violation of IEEE Publication Principles A Hybrid ANFIS/ABC-based Online Selective Harmonic Elimination Switching Pattern for Cascaded Multi-level Inverters of Microgrids, by H. R. Baghaee; M. Mirsalim; G. B. Gharehpetian; H. A. Talebi; A. Niknam-Kumle, in the IEEE Transactions on Industrial Electronics After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE’s Publication Principles. This authorship of this paper was revised without providing attribution to, or permission from, the coauthors of an earlier version of the manuscript. Alireza Niknam-Kumle was responsible for removing the original coauthor names and replacing them with new coauthors, and then resubmitting the content in a new manuscript to IEEE Transactions on Industrial Electronics Due to the nature of this violation, reasonable effort should be made to remove all past and future references to this paper. Control of electronically-coupled distributed energy resources and topology/switching strategy of power converters have the essential roles to provide high quality power for microgrids including unbalanced and nonlinear loads. Multi-level inverters (MLIs) are used to act as high quality converters with more conversion efficiency, and less switching-frequency/switching-losses. Nevertheless their nonlinearity, complexity, and solvability features of selective harmonic elimination strategy that has affected its industrial applications, it can provide desirable output waveform by keeping fundamental component in its desired value as well as eliminating/minimizing of low-order harmonics. This paper presents adaptive neuro-fuzzy inference system (ANFIS) as a switching angle estimator for harmonic optimization problem in cascade MLIs, which is trained based on the database including optimal switching angles obtained for inverter with non-equal DC sources by artificial bee colony (ABC) algorithm. The reliable search ability, accuracy and convergence time of ABC have been compared with particle swarm optimization algorithm. Also, performance of ANFIS is compared with artificial neural network based on correlation coefficient and root mean square error. Simulation results, experimental tests and real-time simulations reveals the effectiveness of proposed estimator for online elimination of low-order harmonics of MLIs in microgrids and its superiority over other methods.

A neural network‐based selective harmonic elimination scheme for five‐level inverter

AbstractThis paper presents the implementation of selective harmonic elimination (SHE) in a five‐level inverter structure using artificial neural networks (ANNs). SHE is an effective low‐frequency modulation technique to eliminate selected harmonics and control multilevel converters. The use of ANN‐SHE requires the calculation of the optimum values of switching angles via the solving system of nonlinear equations for the total harmonic distortion (THD) reduction, where the nonlinear equations are founded by the complex Fourier series analysis of the inverter output voltage. The procured switching angle values are directly implemented by a multilayer perceptron (MLP) algorithm without a lookup table. The ANN model is obtained by training the neural network (NN), taking the modulation index (M) as an input and approximating switching angles as an output. A thorough analysis was carried out to show the programming steps of the proposed ANN‐based SHE using Matlab/Simulink environment. A realized inverter prototype steered by the proposed ANN‐based SHE was tested with various modulation indexes on a real‐time mode using a digital signal processor (DSP) C2000 Delfino–TMS320F28379D‐embedded board. A comparison between the simulation results and the experimental data is presented. The obtained results illustrate that the experimental results match the simulation closely, and the ANN model provides a fast and precise estimate of the switching angles for each value of the modulation index.

Design and Implementation of Grid Connected Solar Inverter using Adaptive Harmonic Elimination Technique

Our project mainly focuses work a lot being carried out in the field of distributed generation. For the electric grid, so Many distributed generation systems are being made. At this time when the non-renewable sources of energy such as oil, coal, etc are very fast disappearing, a study of distributed generation systems (DGs) and Establishing of such systems using renewable sources of energy becomes very important. we have seen several major problems will happen, when harmonic content of the current is flows into the grid, like this issue several issues are going to meet. When a Distribution Generation source is being linked to the grid. “The current being injected should have harmonic content conforming to standards such as IEEE 512-1992”[1].To limit the harmonic current injected into the grid. The hardware is tailor-made to be used for a solar PV panels based distributed generation system. This project deals mainly with Establishing the hardware for a grid connected inverter. This means that a proper plan of action should be present in the required system, special type of filters are made to abolish higher order harmonics, this is only the reason why filters would be less bulky and cheap. only the higher order harmonics are decreased by specially made filters, Lower order harmonics are attenuated by a technique called “an adaptive harmonic elimination technique (AHE). In our project we need to develop several blocks called the inverter hardware, design and implementation of closed loop control, transformer, the filters along with adaptive selective harmonic elimination scheme

Multiwinding Transformer Fed CHB Inverter With On-Line Switching Angle Calculation Based SHE Technique for Vector Controlled Induction Motor Drive

A multiwinding transformer for ac–dc converter with multilevel inverter fed induction motor drive (IMD) is presented in this article. An 18 pulse ac–dc conversion is used on input side of the IMD, to meet the power quality requirement as per the IEEE-519 standard. At IM side, a ternary configured nine-level cascaded H-bridge (CHB)-inverter is used to enhance the response of the IMD. A simple online calculation of switching angles and its implementation of selective harmonic elimination strategy, are proposed to control a nine-level CHB-inverter. In this article, a nine-level CHB-inverter is operated at fundamental frequency switching for reducing the losses and suppressing the lower order harmonics (fifth, seventh, and eleventh) to a negligible value and to enhance the torque profile of the IMD. The performances of IMD are evaluated in MATLAB-Simulink environment and then simulated results are verified by test results taken from developed prototype in the laboratory to show its effectiveness for medium power applications.

Selective harmonic elimination strategy in the multilevel inverters for grid connected photovoltaic system

In recent years, power electronic converters are widely used in the industrial as well as domestic applications for the control of power flow. The topologies of multilevel inverter have several adv...

Analysis and application of inventive selective harmonic elimination strategy to eliminate high order harmonic from asymmetrical multi-level inverter

The most prominent issue relevant to the initiative multi-level inverters is how to provide a high-step staircase quasi-sinusoidal voltage against low switch numbers. This paper presents an innovative asymmetrical multi-level inverter structured by cascaded sub-multi-level inverter bonded to H-bridge inverter to unravel aforesaid issue. DC power sources of sub-multi-level inverters have been determined based on an especial exponential model to provide zero and positive steps, and so, negative steps can be achieved using H-bridge inverter bonded to cascaded sub-multi-level inverters. From viewpoint of harmonic components of high level output voltage, high order harmonics must be indispensability eliminated. Toward this subject, Rectangular Incision-Selective Harmonic Elimination-Pulse Width Modulation (RI-SHEPWM) along with fractional values of DC sources have been scheduled to be the fundamental approach aimed at elimination of twenty-ninth, thirty-first and thirty-fifth harmonics. In according to the nature of multi-objective state of the problem, executing the multi-objective optimization method isn’t avoidable. Due to high performance of Multi Objective Bees Algorithm (MOBA) to solve the non-linear objectives, the elimination of these harmonics is formulated by pertinent fitness functions utilizing MOBA. Putting it all together, the pertinent deductive analysis as well as both the simulation and experimental outcomes have transparently corroborated the capability of the held forth asymmetrical multi-level inverter. Meanwhile, elimination of all determined high-order harmonics i.e., twenty-ninth, thirty-first and thirty-fifth harmonics utilizing RI-SHEPWM based on MOBA has been approved.

A novel optimization harmonic elimination technique for cascaded multilevel inverter

The main goal of utilizing Selective Harmonic Elimination (SHE) techniques in Multilevel Inverters (MLI) is to produce a high-quality output voltage signal with a minimum Total Harmonic Distortion (THD). By calculating N switching angles, SHE technique can eliminate (N-1) low order odd harmonics of the output voltage waveform. To optimized and obtained these switching angles, N of nonlinear equations should be solved using a numerical method. Modulation index (m) and duty cycle play a big role in selective harmonic elimination technique to obtain a minimum harmonic distortion and desired fundamental component voltage. In this paper, a novel Optimization Harmonic Elimination Technique (OHET) based on SHE scheme is proposed to re-mitigate Total Harmonic Distortion. The performance of seven-level H-bridge cascade inverter is evaluated using PSIM and validated experimentally by developing a purposely built microcontroller-based printed circuit board.

Analysis of ANFIS MPPT Controllers for Partially Shaded Stand Alone Photovoltaic System with Multilevel Inverter

<p>This work presents a unique combination of an boost converter run by a set of two photovoltaic panels (PV) with a MPPT, suitable to guarantee MPP even under partial shadowed conditions, managed by an adaptive neuro fuzzy inference system (ANFIS) trained by the training data derived from a Perturb and observation (P&O) conventional algorithm. The single phase cascaded H bridge five-level inverter (CHI) driven by the individual outputs of the boost converter, with selective harmonic elimination scheme to eliminate typically the seventh order harmonics. Simulation was carried out in the MATLAB/SIMULINK environment validated the proposed scheme. It has been thus established; by both simulations the ANFIS model of MPPT scheme outperforms other schemes of conventional control algorithm.</p>

Selective Harmonic Elimination Strategy in the Multilevel Inverters for Grid Connected Photovoltaic System

In recent years, power electronic converters are widely used in the industrial as well as domestic applications for the control of power flow. The topologies of multilevel inverter have several advantages such as high output voltage, lower THD and reduction of voltage ratings of the power semiconductor switching devices. The objective of the work is to design multilevel inverters for PV applications integrated in distribution grids so as to reduce THD and to improve the power quality. The proposed control strategy ensures an implementation of SHE modulation for a 5 to 11 levels. This technique is a method to get rid of harmonics by judicious selection of the firing angles of the inverter and eliminates the need of the expensive low pass filters in the system. This article deals with the reduction of harmonics for multilevel converter sources converter for equal and for unequal DC voltages cases.

Grid Harmonics Compensation Using High-Power PWM Converters Based on Combination Approach

For high-power pulsewidth modulation (PWM) converters, selective harmonic elimination (SHE) modulation scheme is commonly adopted to reduce the low-order harmonics caused by a low switching frequency. However, the SHE scheme itself lacks the capability to actively compensate the grid background harmonics. To enable the active compensation ability of the SHE-modulated PWM converters, a selective harmonic compensation scheme and an SHE phase jittering method have been proposed in the previous works, and their effectiveness to actively attenuate the one grid line current harmonic was verified on a high-power PWM current-source rectifier (CSR) system application. Nevertheless, both the two methods have difficulty in compensating two harmonics simultaneously, which limits their applications with a low resonant frequency of converter system's filter circuit. This paper extends the previous studies to enable the high-power PWM converters to actively compensate two grid background harmonics. The proposed method can not only further reduce the grid line current distortion but also make the application of the active compensation no longer limited by the filter circuit. The experimental results of its application on a high-power PWM CSR system are provided to verify the effectiveness.

Selective harmonic elimination strategy for cascaded H‐bridge five‐level inverter with arbitrary power sharing among the cells

Selective harmonic elimination PWM (SHEPWM) is a well-known fundamental frequency switching method for cascaded multilevel inverters. The main goal in the conventional SHEPWM is to eliminate some lower order harmonics of the output voltage while the fundamental component is satisfied. Thus, this method only regards the inverter output voltage quality, which is not sufficient in many applications. Different cells of the cascaded H-bridge multilevel inverter are supplied by isolated dc sources which may have different amounts of power. To deliver maximum power of these sources to a load or network, power should be properly shared among the cells. This study presents a modified SHEPWM method to control quality of the output voltage of the cascaded H-bridge five-level inverter in wide range of the modulation index while desired power sharing among the cells is also considered as the main priority in the whole range of the modulation index. The method forces new constraint in obtaining optimal switching angles and it may require additional switching. To study the problem, a genetic algorithm optimisation program, based on the modified method, is employed for a three-phase five-level inverter. Simulation and experimental results show the effectiveness of the proposed switching method.

Minimization of Switching Losses in Grid Interfaced PV Inverters using SHE Modulation Strategy

Grid interfacing of multi-megawatt photovoltaic inverters is getting a closer attention in recent past. It is always a hard and challenging task for the engineers as there are certain priorities to be taken while interfacingPV cells to grid without which there will bean unsatisfactory operation of the system will taken. Somehow for high power and medium voltage grid invertersthe priorities like IEEE and IEC standards, satisfaction of grid codes and switching losses are to be strictly considered. Mitigation of switching losses is the active area of research for the PV systems. To meet such requirements weare using the traditional and conventional modulation strategy like SHE (Selective Harmonic Elimination). This paper focus on the reduction of switching losses with the help of new implementation technique for SHE that uses the third harmonics to have the switching angles over 90°, which also increases the modulation index. The Selective harmonic elimination strategy can allow the grid connected inverters to operate using a switching frequency less than 1 KHz while it is still able to provide satisfactory operation like simplicity in operation, independent control of active and reactive powers which is not possible in other cases. To validate potential benefits of SHE, it is compared with THI PWM which is controlled with an operating frequency of 2 KHz.

Selective Harmonic Elimination Method for Cascaded H-Bridge Multilevel Inverter

This paper presents a selective harmonic elimination (SHE) modulation technique for cascaded H-bridge (CHB) multilevel inverter. The main advantage of the proposed SHE concept is its simple implementation to eliminate the specific order harmonics. The procedures used to achieve the appropriate switching angles are presented. The switching angles are offline computed using the Newton-Raphson method. The SHE scheme of the adopted inverter uses the relationship between the angles and a sinusoidal reference waveform through some combinational logic gates. Theoretical results are verified by the experimental work of a single-phase 7-level CHB inverter employing an Altera DE2 field-programmable gate array (FPGA). Results show the inverter producing an optimum stepped output voltage when selected low-order harmonics are eliminated and the voltage total harmonic distortion (THD) is improved.

Improved Selective Harmonics Elimination Scheme With Online Harmonic Compensation for High-Power PWM Converters

To reduce the low-order harmonics produced by the high-power pulsewidth-modulated (PWM) converters, selective harmonic elimination (SHE) scheme is commonly used due to its superior harmonic performance at low switching frequency. However, as an off-line modulation technique, the SHE scheme itself lacks the capability to realize the active compensation of the grid background harmonics. To enable the active compensation ability of the SHE-modulated PWM converters, this paper proposes an active compensation method through the jittering of SHE phase angle. The proposed method can realize the real-time compensation of the preexisting system background harmonics in high-power PWM converters' system. An application example on a high-power PWM current-source rectifier (CSR) system is provided in this paper. Experimental results show that the proposed method can effectively attenuate the line current harmonics caused by the grid background harmonics in the high-power PWM CSR systems.

Virtual Impedance-Based Selective Harmonic Compensation (VI-SHC) PWM for Current Source Rectifiers

To mitigate the line current harmonics of a high-power current source rectifier (CSR) system, the selective harmonic elimination (SHE) scheme is frequently used due to its low switching frequency and superior harmonic performance. However, the SHE scheme only focuses on the harmonics generated by the converter itself. It cannot cope with the line current harmonics caused by the background grid voltage harmonics. In this paper, a selective harmonic compensation scheme using the virtual impedance concept (VI-SHC) is presented. This method compensates for the preexisting grid background harmonics using only the line current measurement, and provides superior line current harmonic performance. The proposed method does not require measuring the grid voltage harmonics (which are typically low), does not rely on an accurate CSR system model, and therefore is very robust for practical implementation. Thi s PWM control scheme has been verified by real-time experiments on a CSR prototype.

Comparative analysis of distributed MPPT controllers for partially shaded stand alone photovoltaic systems

This paper presents a unique combination of an interleaved soft switched boost converter (ISSBC) run by a set of two photovoltaic panel (PV) with a distributed MPPT, suitable to guarantee MPPT even under partial shadowed conditions, managed by an adaptive neuro fuzzy inference system trained by the training data derived from a particle swarm optimization (PSO–ANFIS) unit. The ISSBC is followed by a, single phase cascaded H bridge five-level inverter (CHI) driven by the individual DC outputs of the ISSBC, with selective harmonic elimination scheme to eliminate typically the seventh order harmonics. A comparison of different intelligent distributed maximum power point tracking (MPPT) algorithms for photovoltaic (PV) system under partial shadow conditions is carried out. The use of the ISSBC guarantees mitigation of ripple and it is meant to handle higher currents with minimal switching losses. Simulation was carried out in the Matlab Simulink environment and an experimental verification with a scaled down model validated the proposed scheme. It has been thus established, by both simulation and experimental verification, that the PSO–ANFIS model of distributed MPPT scheme of control outperforms other schemes of control for MPPT.

Selective Harmonic Elimination for a Single-Phase 13-level TCHB Based Cascaded Multilevel Inverter Using FPGA

This paper presents an implementation of selective harmonic elimination (SHE) modulation for a single-phase 13-level transistor-clamped H-bridge (TCHB) based cascaded multilevel inverter. To determine the optimum switching angle of the SHE equations, the Newton-Raphson method is used in solving the transcendental equation describing the fundamental and harmonic components. The proposed SHE scheme used the relationship between the angles and a sinusoidal reference waveform based on voltage-angle equal criteria. The proposed SHE scheme is evaluated through simulation and experimental results. The digital modulator based-SHE scheme using a field-programmable gate array (FPGA) is described and has been implemented on an Altera DE2 board. The proposed SHE is efficient in eliminating the 3 rd , 5 th , 7 th , 9 th and 11 th order harmonics, which validates the analytical results. From the results, it can be seen that the adopted 13-level inverter produces a higher quality with a better harmonic profile and sinusoidal shape of the stepped output waveform.

Utilizing the Cuckoo Optimization Algorithm for Selective Harmonic Elimination Strategy in the Cascaded Multilevel Inverter

There are several procedures to solve the selective harmonic elimination (SHE) problem. In this paper, the elimination of undesired harmonics in a multilevel inverter with equal DC sources by using cuckoo evolutionary optimization method is presented. SHE is an efficient method for achieving the desired fundamental component and eliminating selection harmonics. The recently developed evolutionary optimization method named cuckoo (COA) is used to solve the nonlinear transcendental equations of SHE problem. To verify the presented method accuracy, simulation and experimental results are provided for a 7-level cascaded multi-level inverter. The feasibility and effectiveness of the proposed algorithm is evaluated with intensive simulation and experimental studies. The obtained results show that the cuckoo algorithm is more e‑cient than Bee algorithm (BA) and Genetic algorithm (GA) in eliminating the selective harmonics which cause the lower total harmonic distortion (THD) in the output voltage.

Application of the Bee Algorithm for Selective Harmonic Elimination Strategy in Multilevel Inverters

This paper presents the Bee optimization method for harmonic elimination in a cascaded multilevel inverter. The main objective in selective harmonic elimination pulsewidth modulation strategy is eliminating low-order harmonics by solving nonlinear equations, while the fundamental component is satisfied. In this paper, the Bee algorithm (BA) is applied to a 7-level inverter for solving the equations. The algorithm is based on the food foraging behavior of a swarm of a honeybees and it performs a neighborhood search combined with a random search. This method has higher precision and probability of convergence than the genetic algorithm (GA). MATLAB software is used for optimization and comparison of GA and BA. Simulation results show superiority of BA over GA in attaining accurate global minima and higher convergence rate. Also, its performance in 10 times run is the same as in 1 time run. Finally, for verifying purposes, an experimental study is performed.