  The topology transition problem of transmission networks is becoming
increasingly crucial with topological flexibility more widely leveraged to
promote high renewable penetration. This paper proposes a novel methodology to
address this problem. Aiming at achieving a bumpless topology transition
regarding both static and dynamic performance, this methodology utilizes
various eligible control resources in transmission networks to cooperate with
the optimization of line-switching sequence. Mathematically, a composite
formulation is developed to efficiently yield bumpless transition schemes with
AC feasibility and stability both ensured. With linearization of all
non-convexities involved and tractable bumpiness metrics, a convex
mixed-integer program firstly optimizes the line-switching sequence and partial
control resources. Then, two nonlinear programs recover AC feasibility, and
optimize the remaining control resources by minimizing the $\mathcal{H}_2$-norm
of associated linearized systems, respectively. The final transition scheme is
selected by accurate evaluation including stability verification using
time-domain simulations. Finally, numerical studies demonstrate the
effectiveness and superiority of the proposed methodology to achieve bumpless
topology transition.
