This paper proposes a novel approach for siting , sizing , timing and determining the service area of distribution (MV/LV) transformers. Considerable modifications are made to a previous model by changing the objective function and increasing the constraint set to overcome its drawbacks. The objective function includes fixed and variable costs of MV/LV transformers. Electrical constraints such as voltage drop, radiality , transformer loading and power flow are taken into account and a number of constraints to overcome some non-linearities in the objective function are added. The performance of the proposed model is demonstrated by extensive computational experience using the CPLEX11.2 solver.
