ANN-based Transient Synchronization Stability Monitoring Method for Grid-Following Converters

Loss of synchronization (LOS) of grid-following converters (GFC) under grid faults can lead to severe impacts on the operation of the rest of power systems. To cope with this issue, either the development of stabilization controls or the proper activation of relay protections is often considered. To better implement those methods, the capability of online monitoring the transient synchronization stability (TSS) of GFC is crucial. To this end, this article proposes an artificial neural network (ANN) based TSS monitoring method, which can be used for online TSS assessment thus laying the basis for control and protection actions. First, TSS model of the phase-locked loop (PLL) synchronized converter considering LVRT control is derived and the correlation between CCT and grid parameters is analyzed. Then the ANN-based critical clearing time (CCT) estimation is obtained by model-based training, resulting in the ANN based online TSS monitoring method of GFC. Finally, effectiveness of the method is verified by simulations in Matlab/Simulink.