An $H_\infty$-Optimization Reinforced Adaptive VSG Control to Improve the Overall Stability of a PV-Dominated Power System

The extensive integration of inertia-less renewable energy sources, such as solar photovoltaic (PV) systems, has introduced several stability challenges. The virtual synchronous generator (VSG) has emerged as a promising solution for addressing low-inertia issues. However, the integration of numerous VSG-controlled PV plants into the power system may introduce additional oscillations due to the dynamic interaction between VSG and PV inverter controls. In this paper, a large number of utility-scale VSG-controlled PV units are deployed to analyze their effect on the small-signal oscillations. Subsequently, an$H_\infty$-based VSG parameters optimization is proposed to enhance the small-signal stability. A systematic modal analysis procedure is also established to define the highest and lowest levels for adaptive variation of VSG parameters to further improve the large-signal stability. These optimized and adaptive features are combined in the form of$H_\infty$-optimization reinforced adaptive (HORA) VSG control to improve the overall stability of the PV-dominated grid. The performance of the proposed HORA VGS control is compared with non-adaptive and conventional adaptive VSG control techniques. The studies are conducted on the IEEE 68-bus, 16-machine power system by means of both frequency and time domain analyses through various case studies on the MATLAB/Simulink platform.