Scott transformers have widely used to convert three phases into two phases and compensate the unbalance . Theoretically, the loads of the two secondary phases are same, no unbalance appears in the PCC(point of common coupling). But Due to the uncertainty of traction load, the unbalance are generally presented at the PCC. In this paper The amount of the voltage unbalance is expressed in the ratio of the negative sequence voltages to the positive sequence voltage. We tried to compensate the unbalance using SVC(Static Var Compensator)in an unbalance traction loads state by modeling. The SVC are installed and controlled to provide different amounts of reactive power compensation.