In this work, the primal-dual interior point method is studied and developed to solve the predispatch DC (direct current) problem that minimizes losses in the transmission and costs in the generation of a hydroelectric power system, formulated as a network flow model. The matrix obtained by the application of the interior point method is reduced of such form that the final linear system can be implemented of efficient form. Moreover, a modification of this method is made on the basis of a heuristic that determines a new perturbing parameter. This modified method (VPMPD) showed to be efficient in the practical and achieved convergence in fewer iterations when compared with an existing implementation of the network flow model, that does not take in consideration such perturbing parameter.75533538