AC grid modeling in power electronics-based power systems for eigenvalue stability studies

Increased application of power electronics devices in modern power systems, initiated by increased renewable energy integration, has changed the modeling paradigm of AC grids. Synchronous generator interactions in traditional power systems appear at subsynchronous frequencies, thus enabling the employment of phasor-based or RMS modeling simplification in the analysis of power systems. However, interactions between power electronics devices and the adjacent AC grid can appear at much higher frequencies, thus necessitating the use of high-bandwidth EMT AC line models. First, the chapter provides a systematic review of the most common simplifications in AC line modeling and the associated AC line models. Afterward, different state-space compatible AC line models (the pi-model, the cascaded model, and the frequency-dependent model) are compared in the frequency domain for typical overhead line parameters and a simple power system. Subsequently, challenges in modeling large interconnected power systems with power electronics devices are presented. Finally, a mathematical formulation of the hybrid grid model—consisting of the RMS and EMT sections—is introduced.