Method for evaluating main transformer capacity expansion scheme in 500-kilovolt transformer substation power supply area

The invention discloses a method for evaluating a main transformer capacity expansion scheme in a 500-kilovolt transformer substation power supply area. The method comprises the following steps: acquiring power grid data and an expansion scheme; calculating a load rate safety margin in an existing state and performing judgment; calculating the short-circuit current safety margin, the minimum value of the line limit transmission capacity safety margin and the standard deviation of the off-grid load; and constructing an evaluation objective function and evaluating the to-be-evaluated main transformer capacity expansion scheme. According to the method for evaluating the main transformer capacity expansion scheme in the 500-kilovolt transformer substation power supply area provided by the invention, the main transformer capacity expansion scheme is comprehensively evaluated from four aspects of transformer load rate safety margin, bus short-circuit current safety margin, line limit transmission capacity safety ma