Grid Forming Inverter Small Signal Stability: Examining Role of Line and Voltage Dynamics

This paper presents a small signal stability analysis of a grid-forming inverter when dynamics of transmission lines and nodal voltages are considered or neglected. Electromagnetic transients of lines are usually ignored in traditional power systems small signal stability studies due to separation of time-scales. However, the former assumption may have different implications in the case of inverter dominated power systems, and requires further study. In this paper, we perform an eigenvalue analysis of a virtual synchronous machine connected to an infinite bus under several operating conditions. This allows us to study the effect of line and voltage dynamics approximations on small signal stability. Results show that although the eigenvalues are close for different levels of approximation, the small signal stability regions could significantly differ depending on the approximation used.