Grid Tied Photovoltaic System with Switched Capacitor Multilevel Inverter for Power Quality Enhancement

Abstract

Grid-tied photovoltaic (PV) systems are becoming increasingly important for sustainable energy production. However, conventional inverter designs often face challenges such as high total harmonic distortion (THD), significant switching losses, and increased complexity due to the use of numerous switches. These issues negatively impact power quality, efficiency, and system reliability. To address these problems, advanced multilevel inverters with fewer switches and innovative modulation techniques provide a promising pathway for improving power quality and operational performance. This project introduces a grid-tied PV system utilizing a switched-capacitor multilevel inverter (SCMLI) with a reduced switch count for enhanced power quality. The system incorporates an isolated DC-DC flyback converter to stabilize and boost the DC output voltage for grid connection. A 17-level SCMLI, designed with fewer switches and capacitors, ensures efficient DC-to-AC conversion while minimizing THD in the output waveform. A three-phase H-bridge inverter paired with an LC filter refines the output, producing high-quality AC power that meets grid standards. Advanced pulse-width modulation (PWM) techniques based on DQ theory manage inverter operations and regulate active and reactive power flow. PI controllers are employed to dynamically adjust reference currents, ensuring accurate power tracking and improved grid stability. This configuration enhances power quality, reduces switching losses, and maximizes energy efficiency. By integrating the SCMLI, this grid-tied PV system delivers a cost-effective, energy-efficient, and reliable solution that aligns with modern power quality requirements for renewable energy systems.