Multi-Swing Transient Stability of Synchronous Generators and IBR Combined Generation Systems

TL;DR

This paper reveals that low voltage ride-through and recovery controls in inverter-based resources can cause multi-swing transient instability in synchronous generators, challenging traditional views focused solely on first-swing instability.

Contribution

It introduces a new perspective on transient stability, highlighting the role of inverter-based resources in multi-swing instability through theoretical and simulation analysis.

Findings

Decelerating energy accumulation can lead to multi-swing instability.

Inverter controls influence the energy dynamics during faults.

Simulation confirms the theoretical analysis of multi-swing phenomena.

Abstract

In traditional views, the build-up of accelerating energy during faults can cause the well-known first-swing angle instability in synchronous generators (SGs). Interestingly, this letter presents a new insight that the accumulation of decelerating energy due to the low voltage ride-through (LVRT) and recovery control of grid-following inverter-based resources (GFL-IBRs), might also result in transient angle instability in SGs. The transient energy accumulated during angle-decreasing swing transforms into the acceleration energy of the subsequent swing, hence such phenomena often manifest as multi-swing instability. Both theoretical analysis and simulation support these findings.