Stability Analysis of grid-connected solar PV systems under asymmetrical faults.

The global shift towards sustainable energy is heavily impacted by the growing integration of solar photovoltaic (PV) systems into modern power grids. However, ensuring the stability of these grid-connected solar PV systems during asymmetrical fault conditions remains a challenge. Voltage and current imbalances can spread across the network, potentially leading to cascading faults and widespread instability. This study examines the stability of grid-connected solar PV systems under asymmetrical fault scenarios, focusing on the use of Phasor Measurement Units (PMUs) to prevent fault propagation and maintain grid reliability. The main strategies include fault ride-through (FRT) capabilities, unbalanced current injection, and dynamic reconfiguration of PV systems to isolate faulty sections and prevent cascading events. Simulation studies assess the effectiveness of these strategies in maintaining system stability under various fault conditions and grid configurations. The study further attempts to reduce unbalanced current injection and fault duration by comparing the effects of FRT with PIDs and Super Twisting-Sliding mode control. These two methods are analyzed to observe their impact during different fault scenarios. The findings of this study highlight the critical importance of understanding the limitations of fault ride-through with or without sliding mode control for early fault detection and dynamic response to prevent cascading failures. Additionally, this study identifies key design considerations for improving the fault tolerance and resilience of PV systems in high-penetration scenarios. By incorporating advanced monitoring and control solutions, this study establishes a robust methodology for ensuring the stability of grid-connected solar PV systems and enabling the reliable operation of future power networks.