Selective harmonic elimination in hybrid cascaded multilevel inverter using modified whale optimization

Abstract

Summary This article presents a modified whale optimization (MWO) for harmonic mitigation in a three‐phase 11‐level hybrid cascaded multilevel inverter (HC‐MLI). The proposed MWO has improved rate of convergence as compared with conventional whale optimization (WO). This is achieved by improving the exploration‐exploitation feature of the conventional WO. Selective harmonic elimination–pulse width modulation technique is applied through MWO for generating the optimal switching angles of the HC‐MLI so as to eliminate the lower‐order harmonics such as 5th, 7th, 11th, and 13th from the output voltage. In the proposed MWO optimized HC‐MLI, capacitor voltage balance is made possible even at higher modulation indices using the available redundant switching states of HC‐MLI. The proposed work is useful where the HC‐MLI has to work at the low switching frequency and the conversion efficiency is of prime importance such as medium‐ and high‐power motor drives, static synchronous compensators, and active power filters. The performance of the proposed work is validated through simulation and experimentation on a 1.5‐kW prototype. The results obtained show that the MWO algorithm is more efficient and accurate than other reported algorithms such as genetic algorithm, particle swarm optimization, and WO in terms of performance, harmonic mitigation, and rate of convergence.

Selective Harmonic Elimination of a Multilevel Voltage Source Inverter Using Whale Optimization Algorithm

“…However, the obtained results are not compared with the results from using another optimization method. A modified WOA is presented for harmonic elimination of a 11-level threephase VSI [17]. The results showed a superior performance compared to the simple WOA results.…”

“…The frequency of each cell is equal to the fundamental frequency (fs). By these definitions, the output phase voltage of the 7-level CHB inverter (Vo) can be expressed using Fourier Transform as follows [17]:…”

“…where E is the DC bus voltage of each cell, and αk is the switching angle of k th cell. The modulation index is defined to be a representative value of the fundamental harmonic V1 [17]:…”

“…Finally, by weighting each harmonic by inverse of its order, elimination of loworder harmonics gets higher importance. The more detailed mathematical model for harmonic elimination using WOA is presented in previous published research works [15][16][17][18].…”

“…One of the best methods for solving optimization problems is whale optimization algorithm (WOA) which is proposed by several researchers [15][16][17][18]. Whale optimization algorithm is inspired by the bubble-net hunting strategy of the humpback whale.…”