POWER QUALITY IMPROVEMENT IN GRID-TIED SOLAR PHOTOVOLTAIC SYSTEM

Abstract

The integration of grid-tied solar photovoltaic (PV) systems has become a key strategy in transitioning towards a sustainable and renewable energy future. However, the intermittent nature of solar power generation possesses challenges to power quality, affecting the stability and reliability of the electrical grid. This thesis aims to address power quality issues in grid-tied solar PV systems by focusing on the enhancement of multilevel inverter technologies and advanced control methods. The research begins with an extensive literature review, examining the current state of-the-art techniques in power quality improvement for grid-tied solar PV systems. Multilevel inverters are identified as a promising solution to mitigate power quality challenges, and various topologies are explored, including five-level T-Type, three seven-level (PUC, PEC, and K-Type), nine-level CHB, eleven-level PEC, and thirteen-level ladder-type inverters. To achieve accurate grid synchronization and harmonic reduction, advanced modulation techniques such as level shifted multi-carrier, nearest level, and selective harmonic elimination (SHE) are employed. The thesis investigates the performance of each multilevel inverter topology using these modulation techniques under various operating conditions. Simulation models are developed in MATLAB/Simulink to evaluate the steady-state and dynamic performances of the proposed multilevel inverter-based grid-tied solar PV systems. The effectiveness of power quality improvement is analyzed, focusing on parameters like total harmonics distortion (THD), voltage regulation, and current harmonics reduction. The simulation results demonstrate the superiority of the proposed solutions in achieving grid-friendly power injection and reducing voltage fluctuations. v Moreover, a comparative analysis is conducted to highlight the strengths and weaknesses of each multilevel inverter topology and modulation technique concerning power quality enhancement. The findings reveal the most suitable combinations for specific applications and system requirements. To validate the simulation results, real-time testing is performed using the OPAL-RT simulator. The test bench real-time validation experiments validate the simulation outcomes, providing confidence in the real-world applicability of the proposed multilevel inverter solutions. The performance of the grid-tied solar PV systems is assessed in terms of their response to unpredictable variations in irradiance levels and change in temperature. The control mechanisms enable robust operation, ensuring consistent power quality improvement inchallenging environmental conditions. In conclusion, this thesis presents a comprehensive investigation into power quality improvement in grid-tied solar PV systems using multilevel inverters and advanced control techniques. The proposed solutions demonstrate significant enhancements in power quality metrics, making them valuable assets for the reliable integration of solar energy into the electrical grid. The research contributes to the development of more efficient and sustainable renewable energy systems, paving the way for a cleaner and greener energy future.