Modeling of grid-forming inverters and analysis under different control approaches

The integration of renewable energy sources into the grid has experienced significant growth in recent decades, driven by environmental concerns and advancements in technology. Photovoltaic (PV) and wind-based systems, among others, are key players in this transition, relying on inverters to connect to the grid. These inverters, known as inverter-based resources (IBRs), offer environmental benefits but also present technical challenges such as system inertia, current limitation, and voltage and frequency control. Addressing these challenges is crucial for ensuring the reliability and stability of modern power systems amidst the increasing penetration of renewable energy. Grid forming (GFM) and grid following (GFL) and are two significant control methodologies employed by IBRs to address these challenges. GFM inverters have emerged as pivotal components in modern power systems, facilitating the integration of renewable energy sources and ensuring grid stability. This thesis delves into the modeling and analysis of grid-forming inverters under various control approaches, aiming to enhance understanding and optimize their performance. The literature review provides insights into the principles of grid-forming inverters, highlighting the significance of accurate modeling and control strategies in ensuring system stability and reliability. Different modeling approaches are evaluated, considering factors such as converter topology, control algorithms, and grid dynamics. Control approaches including voltage control, frequency control, and droop control are examined in detail, with emphasis on their impact on stability, transient response, and grid support. Simulation studies are conducted using MATLAB-Simulink to analyze the performance of grid-forming inverters under different control strategies such as linear quadratic regulator (LQR), with key metrics such as stability, frequency regulation, and grid synchronization evaluated. The results offer valuable guidance for optimizing GFM inverter design and deployment in renewable energy systems, paving the way for enhanced grid reliability and renewable energy integration.