Application of Gravitation Search Algorithm in Harmonic Reduction of Cascade Multilevel Inverter’s Output Voltage

The Selective Harmonic Elimination (SHE) is one of the methods, which is applied to eliminate harmonics and so, reduce Total Harmonic Distortion (THD) in Output Voltage of Multilevel Inverters. To apply SHE for cascade multilevel inverters, the switching angles of all stages of cascade multilevel inverters have to be computed by solving a set of nonlinear transcendental equations. For this purpose, optimization algorithms are used to solving these equations. In this paper, one of the most novel optimization algorithms which is called Gravitation Search Algorithm (GSA) is used to solve these nonlinear transcendental equations. To show the superiority of the proposed algorithm to other traditional algorithms, this algorithm is applied for different levels of cascade multilevel inverter and its results are compared with Particle Swarm Optimization (PSO). This comparison shows that, in higher levels of cascade multilevel inverter, GSA has more reduction in selected harmonics than PSO, and so, leads to reach better results in amplitude of selected harmonics and THD

Keywords:

Gravitation Search Algorithm , Multilevel inverter , Cascade multilevel inverters , Particle Swarm Optimization , Selective Harmonic Elimination , Total Harmonic Distortion