Evaluation Method of Main Transformer Capacity Expansion Scheme in Power Supply Area of 500kV Substation

With the development of the national economy, the power system load is increasing, and the capacity of the generator and the main transformer of the substation is also growing. It is necessary to increase the transformer capacity in the substation power supply area to ensure the power supply capacity of the substation. Based on the short-circuit calculation of the 500kV substation and the N-1 failure analysis of the main transformer, the security margin of the 500kV transformer load rate and the security index of short-circuit current of 220kV bus in the 500kV substation are proposed. Then the limit transmission capacity security margin of 220kV transmission lines in the power supply area and the standard deviation of the grid load of the 500kV main transformer after the expansion scheme adopted is calculated. The main transformer reorganization and expansion schemes are assessed comprehensively and objectively from the above four aspects. Finally, the effectiveness and adaptability of the proposed method are verified by a provincial power grid.