Recently multilevel inverters (MLI) have attracted more attention in research and industry, as they are changing into a viable technology for several applications. The concept of MLI was introduced for high power and high/medium voltage applications as they can provide an effective interface with renewable energy sources. Developing of reduced switch MLI topology has been a rapid research topic since the past decade, which has not been reviewed so far. Therefore, this review article focuses on the different reduced switch MLI topologies under three categories such as symmetric, asymmetric and hybrid configurations. The important knowledge on these topologies is carefully tabulated based on the three categories in the comparison tables to understand the essential parameters of the MLI topologies. These configurations are not only generating higher voltage levels to improve the power quality but also to reduce the passive filter requirements. Also, this review includes a detailed perspective of various modulation techniques and control strategies for MLI topologies. In addition to that, the different performance parameters of MLI and its calculation methods are discussed with appropriate mathematical expression. This review will help in the selection of appropriate MLI topology for FACTS, motor drives and renewable applications.

A comprehensive review on reduced switch multilevel inverter topologies, modulation techniques and applications

Observing present scarcity of fossil fuel and emissions of greenhouse gases, electricity generated from Renewable Energy (RE) sources turns out to be the best alternative for generating the power. In RE system, the inverter is normally used to condition the DC power into AC to meet the requirements of load and transmission system. The inverter offers myriad benefits; however, the presence of harmonics (particularly low-order) in the output voltage affects the efficiency and performance of inverter, causes switching losses and decreases the lifetime of the system. In last three decades, significant research has been done to develop the efficient control technique for eliminating the unwanted harmonics. The preliminary review of existing control techniques revealed that the selective harmonic elimination pulse-width modulation (SHEPWM) is more proficient to eliminate the low-order harmonics. However, non-linear transcendental equations used in this technique pose a challenge to solve particularly for calculus-based methods. With the advent of powerful and low-cost computers, bio-inspired intelligent algorithms (BIAs) seem to be a better approach for solving these complex equations. This review paper presents the detailed principle operation of nine well-known BIAs and discusses their application in inverters for harmonic elimination (HE). Moreover, different objective functions are also discussed in this paper which is used by the researchers for HE. Additionally, the performance of five renowned BIAs, namely, Imperialist Competitive Algorithm, Particle Swarm Optimization, Differential Evolution, Bee Algorithm and Genetic Algorithm is critically evaluated. Their performance is analyzed in terms of accuracy, computational complexity, convergence speed, and a number of control parameters. The conclusion has been made on the basis of information extracted from the literature and evaluation results with future recommendations. This single paper covers all the essential information regarding HE in inverters, which will help researchers to design the efficient RE conversion system.

Selective harmonic elimination in inverters using bio-inspired intelligent algorithms for renewable energy conversion applications: A review

Over the last few decades, multilevel inverters (MLIs) are being extensively utilized in many industrial and grid connected applications due to their numerous merits. With the recent development of renewable energy systems (RES), applications of classical MLI topologies are hindered due to their performance issues such as poor power quality, uneconomical structure and low efficiency. These performance issues and limitations in classical MLI topologies have attracted the researchers toward evolving new hybrid MLI topologies. In this article, a comprehensive analysis of these recent hybrid MLI topologies is done on the basis of some qualitative and quantitative performance indices. Special focus has been given to extensively review the influence of MLIs in grid connected renewable energy applications such as photovoltaic (PV) systems, wind energy conversion systems (WECS) and micro-grid. In order to provide the better insight about the working and performance of these MLI topologies, simulation results performed in MATLAB/Simulink environment are also presented.

A comprehensive study of classical and hybrid multilevel inverter topologies for renewable energy applications

An inclusive review on different multi-level inverter topologies, their modulation and control strategies for a grid connected photo-voltaic system

This paper presents an intelligent-based fault-tolerant system for a solar photovoltaic (PV) inverter. Artificial neural network based controller is used to monitor, detect, and diagnose the faults in solar PV panels, battery, semiconductor switches, and inverters. The cascaded multilevel inverter is connected across the combination of solar PV panel and battery for dc–ac conversion. The major advantage of the proposed topology is that it can deliver power from source to the load even under fault and partial shaded conditions. The paper also reviews on various faults in the solar PV energy conversion process and provides suitable solutions for each circumstance. Simulations are undertaken in MATLAB 2016a/Simulink and experimental investigation is carried out for a 3 kWp solar PV system. The results have proven that the system is capable to deliver power in spite of faulty environments. The comparison and discussion of the results were made to show the effectiveness of the proposed system.

An Intelligent-Based Fault-Tolerant System for Solar-Fed Cascaded Multilevel Inverters

In this paper, the power quality improvement techniques with respect to various modulation algorithms for the solar Photovoltaic (PV) inverter are reviewed. In power quality, harmonics are an important concern in all the utility sectors. The factors that contribute the harmonic distortion on distribution systems include increased application of capacitors and non-linear devices. In order to improve the power quality and also to maintain stable power supply performance, an inverter topology with harmonic reduction techniques is required. The design and development of solar Photovoltaic inverter suitable for the Indian sub-continent is proposed and reviewed in terms of survey, simulation and experimental results. The proposed multi-stage inverter provides the advantage of reduced harmonic distortions and suitable for standalone and grid connected systems. The reduction of harmonics is governed by proper switching sequences required for the inverter switches. Modified multicarrier modulation techniques are developed in a single chip controller. A 3 kWp solar PV plant with multistage inverter system is implemented and as per the results, the quality of power is increased and achieved the desired output voltage inspite of variations in the solar PV.

Albert Alexander S

Papers

Development of solar photovoltaic inverter with reduced harmonic distortions suitable for Indian sub-continent