Transient Stability Analysis and Fault Clearing Angle Estimation of VSG Based on Domain of Attraction Estimated by Trajectory Reversing Method

TL;DR

This paper develops a method to analyze the transient stability of virtual synchronous generators (VSGs) using the trajectory reversing method to estimate the domain of attraction, providing more accurate fault clearing angles for converter-based power systems.

Contribution

It introduces a large signal model of VSG, applies the trajectory reversing method to estimate the domain of attraction, and compares the critical clearing angle with traditional methods for improved accuracy.

Findings

The estimated domain of attraction predicts loss of synchronization accurately.

The critical clearing angle derived from DOA is more precise than conventional methods.

Time-domain simulations confirm the effectiveness of the proposed stability analysis.

Abstract

The virtual synchronous generator (VSG), with the analogous nonlinear power-angle relationship to the synchronous generator (SG), has attracted much attention as a promising solution for converter-based power systems. In this paper, a large signal model of the grid-connected VSG is first established. The trajectory reversing method (TRM) is then introduced to estimate the domain of attraction (DOA) of VSG. Subsequently, the transient instability mechanism is revealed in detail based on the estimated DOA boundary. The impacts of system parameters on the DOA range are further investigated. It is found that loss of synchronization (LOS) occurs if the system trajectory lies outside the post-fault DOA range. In scenarios where no equilibrium points exist after a grid fault, system stability can be reestablished only when the fault clearing angle (FCA) does not exceed the critical clearing angle (CCA). Finally, the CCA derived from the DOA and that from the conventional equal area criteria (EAC) are compared. The results show that CCA obtained by our solution has a higher accuracy. Time-domain simulations are performed to verify the effectiveness of the proposed transient stability analysis method of grid-connected VSG.