Minimizing total harmonic distortion (THD) with less system complexity and computation time is a stringent constraint for many power systems. The multilevel inverter can have low THD when switching angles are selected at the fundamental frequency. For low-order harmonic minimization, selective harmonic elimination (SHE) is the most adopted and proficient technique but it involves the non-linear transcendental equations which are very difficult to solve analytically and numerically. This paper proposes a genetic algorithm (GA)-based optimization technique to minimize the THD of cascaded H-bridge multilevel inverter. The GA is the finest approach for solving such complex equations by obtaining optimized switching angles. The switching angles are calculated by the genetic algorithm by solving the nonlinear transcendental equations. This paper has modeled and simulated a five-level inverter in MATLAB Simulink. The THD comparison is carried out between step modulation method and optimization method. The results reveal that THD has been reduced from 17.88 to 16.74% while third and fifth harmonics have been reduced from 3.24%, 3.7% to 0.84% and 3.3%, respectively. The optimization method along with LC filter significantly improves the power quality providing a complete sinusoidal signal for varying load.

以更少的系统复杂度和计算时间来最小化总谐波失真（THD）是许多电力系统的严格限制。在基频上选择开关角度时，多电平逆变器的THD较低。对于低阶谐波最小化，选择性谐波消除（SHE）是最常用和最熟练的技术，但它涉及非线性先验方程，很难用解析和数值方法求解。本文提出了一种基于遗传算法（GA）的优化技术，以最小化级联H桥多电平逆变器的THD。遗传算法是通过获得最佳开关角来求解此类复杂方程的最佳方法。遗传算法通过求解非线性先验方程来计算开关角。本文在MATLAB Simulink中对五级逆变器进行了建模和仿真。在步进调制方法和优化方法之间进行THD比较。结果表明，总谐波失真从17.88％降低到16.74％，而三次谐波和五次谐波分别从3.24％，3.7％降低到0.84％和3.3％。优化方法与LC滤波器一起可显着改善电能质量，从而为变化的负载提供完整的正弦信号。