Stability Estimation of Nonlinear and Time-Varying Inverter-Dominated Power Systems

As power electronic devices become the backbone of modern energy systems, their complex interactions increasingly shape the stability and dynamics of the grid. Traditional analysis methods can no longer keep pace with the rapid rise of inverter-based technologies. This thesis explores advanced extensions to widely used impedance-based stability analysis, offering new tools to understand and manage the behavior of power-electronic-dominated systems. Combining analytical modeling with innovative experimental techniques, it introduces a method to assess the stability of nonlinear inverters under real, time-varying grid conditions, validated through detailed time-domain simulations. A novel compensation approach for impedance measurements demonstrates significant improvements in accuracy even in grids affected by strong harmonic distortion. Applying these methods to real-world scenarios, the work evaluates the stability of electric-vehicle charging at grid connection points with a high penetration of power electronics and provides a practical framework for estimating how many EVs can be safely integrated.