Modelling Analysis and Characteristics of Multi-Level Inverter for Integrating Solar PV System to Grid

Abstract

This paper investigates the implementation of a cascaded H-bridge multi-level inverter in a single-phase grid-connected solar photovoltaic (PV) system to address harmonic distortion challenges in DC-to-AC power conversion. The primary objective is to enhance power quality and system efficiency by leveraging the inverter's ability to reduce harmonics through power sharing and a lower switching frequency. A Simulink model is developed to evaluate the proposed system's performance, incorporating a unipolar Pulse Width Modulation (PWM) control strategy and an LCL filter for effective harmonic mitigation. The system employs Maximum Power Point Tracking (MPPT) based on the Perturb and Observe (P&O) algorithm, combined with Synchronous Reference Frame Theory-Phase Disposition PWM (SRFT-PDPWM) for optimal control. The proposed inverter ensures precise synchronization between the grid and inverter frequencies, achieving a Total Harmonic Distortion (THD) below 5%. Simulation results demonstrate the system's robust responsiveness to variations in solar irradiance, with increased irradiance leading to further reductions in THD and improved power quality. These findings validate the proposed inverter's capability to deliver high-quality, efficient power under varying environmental conditions, aligning with global objectives for integrating clean and sustainable energy into utility networks.