  Robust solving of critical large power flow cases (with 50k or greater buses)
forms the backbone of planning and operation of any large connected power grid.
At present, reliable convergence with applications of existing power flow tools
to large power systems is contingent upon a good initial guess for the system
state. To enable robust convergence for large scale systems starting with an
arbitrary initial guess, we extend our equivalent circuit formulation for power
flow analysis to include a novel continuation method based on transmission line
(Tx) stepping. While various continuation methods have been proposed for use
with the traditional PQV power flow formulation, these methods have either
failed to completely solve the problem or have resulted in convergence to a low
voltage solution. The proposed Tx Stepping method in this paper demonstrates
robust convergence to the high voltage solution from an arbitrary initial
guess. Example systems, including 75k+ bus test cases representing different
loading and operating conditions for Eastern Interconnection of the U.S. power
grid, are solved from arbitrary initial guesses.Interconnection of the U.S.
power grid, are solved from arbitrary initial guesses.
