Eliminating Synchronization Instability of Grid-Forming Converters by Removing the Periodic Orbit via Homoclinic Bifurcation

Grid forming converters can provide frequency and voltage support to the power systems and are enabling units in modern power systems with high levels of power electronics and renewable energy penetration. However, grid forming converters may experience synchronization instability following large disturbances. During synchronization instability, the system state variable is captured by a periodic orbit. This article presents a novel approach to eliminating the synchronization instability of grid forming converters by removing the periodic orbit responsible for synchronization instability. First, an oscillation index is proposed to estimate the distance to the homoclinic bifurcation, and the periodical orbit sensitivity is derived to assess the sensitivity of the oscillation index to control parameters. Then, the oscillation index and its sensitivity are used to estimate the parameter adjustment required to trigger the homoclinic bifurcation and eliminate synchronization instability. An application framework of the proposed method is also provided. Finally, the proposed method and the application framework are validated through simulations and experimental verifications.