“…Even a small failure at a single transmission line can cause a massive cascade resulting in a large-scale blackout, which has motivated a number of recent studies focusing on the stability of power grids [1,2,3,4,5]. Some studies estimated structural stability arXiv:1807.09420v1 [nlin.CD] 25 Jul 2018 of power grids in response to the amount of transmission load when the electricity flows from power plants to substations [5,6,7,8,9,10,11,12,13], while others focused on the dynamical synchronization stability of power-grid nodes in response to the disturbance in their phase or frequency [14,15,16,17,18,19,20,21]. The synchronization stability refers to the ability to recover synchronization of power-grid nodes after the nodes get perturbed.…”