  This paper proposes a framework for fast short-term scheduling and
steady-state voltage control in distribution systems enabled with both
continuous control devices, e.g., inverter interfaced DGs and discrete control
devices (dcds), e.g., on-load tap changers (oltcs). The voltage-dependent
nature of loads is taken into account to further reduce the operating cost by
managing the voltage levels. The branch and cut method is applied to handle the
integrality constraints associated with the operation of dcds. A globally
convergent trust-region algorithm (tra) is applied to solve the integer relaxed
problems at each node during the branching process. The tra sub-problems are
solved using the interior point method. To reduce the branching burden of the
branch and cut algorithm, before applying tra at each node, a simplified
optimization problem is first solved. Using the convergence status and value of
the objective function of this problem, a faster decision is made on stopping
the regarding branch. Solving the simplified problem obviates the application
of tra at most nodes. It is shown that the method converges to the optimal
solution with a considerable saving in computation time according to the
numerical studies.
