TREATING VOLTAGE CONSTRAINTS IN LARGE SCALE OPTIMAL POWER FLOW PROBLEMS BY AUGMENTED LAGRANGIANS.

The authors present an efficient technique for enforcing limits on voltage magnitudes in large-scale optimal power flow (OPF) problems. The OPF solution methodology employs a modified version of the generalized reduced gradient (GRG) technique which permits the incorporation of a standard power flow and improves convergence of the GRG method. A number of voltage constraints cannot be enforced within this GRG framework and are treated by adapting the augmented Lagrangian approach to the OPF problem. This approach is very effective in enforcing all the voltage constraints without inducing numerical ill conditioning. Numerical results for large-scale OPF problems are presented.