  Growing penetration of renewable generation in power systems brings more
challenges in transient stability assessment using direct methods. One of the
reasons is the inability to assess the risk of instability brought by tripping
of a large amount of RGs due to violation of their ride through curves. In this
paper, a scalable approach is proposed based on the Lyapunov functions family
to estimate the stability region under ride through constraints. An inner
polytopic approximation to the feasibility region is proposed to convexify the
overall problem. The acquired constrained stability region estimate helps
capture trajectories that trigger undesirable tripping of renewable generation.
A 2-machine system is used to visualize its effectiveness.
