Multi-Swing Transient Stability of Synchronous Generators and IBR Combined Generation Systems
A team of 7 researchers identifies a novel instability mechanism where inverter-based renewables can destabilize traditional generators.
A research team from Xi'an Jiaotong University, led by Songhao Yang, has published a groundbreaking paper on arXiv (ID: 2603.25167) that challenges conventional power grid stability theory. The study, 'Multi-Swing Transient Stability of Synchronous Generators and IBR Combined Generation Systems,' reveals a previously unrecognized risk: the very controls designed to help inverter-based renewable resources (IBRs) ride through low-voltage faults can inadvertently destabilize traditional synchronous generators (SGs). This finding upends the traditional view that instability is primarily caused by the build-up of accelerating energy during a fault's first swing.
The team's theoretical analysis and simulations demonstrate a chain-reaction instability. During a grid fault, IBRs (like solar PV or wind farms) execute Low Voltage Ride-Through (LVRT) control to stay connected, which creates decelerating energy in nearby SGs. As the fault clears and voltage recovers, this stored decelerating energy transforms into acceleration energy for the generator's rotor in the subsequent swing cycle. This energy conversion can trigger a dangerous multi-swing instability, where the generator's angle oscillates with increasing magnitude until it falls out of synchronism, potentially leading to cascading blackouts. The paper provides both the mathematical framework for this phenomenon and simulation evidence supporting the new instability model.
- Identifies a novel multi-swing instability mechanism where GFL-IBR controls destabilize SGs, contrary to traditional first-swing instability models.
- Shows decelerating energy from IBR Low Voltage Ride-Through (LVRT) can transform into acceleration energy in subsequent generator swings.
- The findings, supported by theory and simulation (arXiv:2603.25167), are critical for grids with high renewable penetration exceeding 30-40%.
Why It Matters
This discovery is vital for ensuring the reliability of power grids as they transition to high levels of renewable energy, preventing potential cascading failures.