Convergence improving minimization technique for a modified fast decoupled load flow

This paper describes an efficient and reliable algorithm that modifies the Fast Decoupled Load Flow (FDLF) in order to overcome non-convergence troubles in solving strongly stressed power systems. The Hartkopf's algorithm for improving the Newton-Raphson method's convergence features in ill-conditioned cases is taken as a basis. The proposed changes to FDLF consist fundamentally in minimizing the squared power mismatches with a second order interpolation technique. The simple modification makes it possible to establish for sure whether a case of non-convergence is owing to numerical or to physical problems, and lets the operator evaluate the system condition correctly. Several numerical examples show the remarkable behaviour of the algorithm proposed.