A NEW DECOMPOSITION METHOD FOR OPTIMAL OPERATION OF TRANSMISSION GENERATION AND SUBTRANSMISSION/DISTRIBUTION SYSTEMS/

The level of automation in electric power systems and, particularly, i n subtransmission/distribution (SD) systems is becoming higher and hig her. The continuous surprising increase of the number of control actio ns should be properly taken into account in optimal power flow (OPF) p rograms. This is important, in order to avoid deficiencies and inaccur acies which can degrade the usefulness of the OPF application. In the first part of the paper a generalized formulation of the OPF problem i s provided which takes into account the entire set of controls and inv olves specific goals for the SD systems. This leads to the definition of a non-linear multiobjective optimization problem which can be solve d off-line only with a very heavy computational burden. To overcome th is difficulty, the second part of the paper deals with the development of an optimization procedure which exploits the naturally decomposabl e structure of the power system model. Namely, on the basis of a Decom position-Coordination technique, the proposed method turns the global optimization problem to the solution of several decoupled subproblems. The validity of the suggested procedure and the accuracy of the resul ts are illustrated by a numerical example.