An efficient tap control applied to the maximum loadability of electric power systems

This paper presents an effective methodology to deal with load tap change transformers (LTC) in the maximum load-ability problem. The computational of a critical loading in a pre-specified direction can be established as an optimization problem, in which the objective function is the load factor α that parameterizes the real and reactive power demands. The maximization process is subject to equality (real and reactive power mismatches) and inequality (operation and/or equipment limits) constraints. With respect to the operation limits, the minimum and maximum values of both bus voltage magnitudes and taps of the LTC transformers are considered. The optimization problem is solved through interior point algorithms and a heuristic is included in the iterative process to avoid a great number of iterations. Numerical results are presented for IEEE test-systems and for a bulk realistic power system.