Novel harmonic elimination strategy based on Multi-Objective Grey Wolf Optimizer to ameliorate voltage quality of odd-nary multi-level structure

摘要

In this paper, a novel Asymmetrical Multi-Level Inverter (AMLI) is suggested to solve the voltage quality problem. The suggested AMLI has been constructed based on series connection of sub-AMLIs to create a high-step quasi-sinusoidal voltage with considering few semiconductor switches. The ladder capacitors of sub-AMLI have been clamped to the H-bridge structure via several bi-directional switches. Based on an innovative geometric progression for DC power supplies of AMLI, it can operate as so-called odd-nary AMLI. It has effectually created a quasi-sinusoidal with high steps i.e., low Total Harmonic Distortion (THD) with respect to low number of switches. The performance of suggested AMLI has been thoroughly compared with other inventive asymmetrical and symmetrical multilevel inverters. Following that, scission-style harmonic elimination based on Pulse Width Modulation (PWM) is introduced to enhance voltage quality of AMLI. Three prominent criterions related to voltage quality i.e., desired fundamental component, elimination of third harmonic and reduction of THD have been assigned as objective functions of optimization problem. Considering the multi-objective nature of the optimization problem, non-dominated sorting Multi-Objective Grey Wolf Optimizer (MOGWO) has been implemented to solve the optimization problem, and then compared with Non-dominated Sorting Genetic Algorithm II (NSGA-II). To sum up, the relevant analytical studies along with both the simulation and experimental results have transparently validated the performance of suggested AMLI. Also, the voltage quality problem using MOGWO-based scission-style harmonic elimination strategy has been well approved.