Method for calculating steady state power fluctuation amplitude of AC tie line of interconnected systems in two regions

The invention relates a method for calculating a steady state power fluctuation amplitude of an AC (Alternate Current) tie line of interconnected systems in two regions, which comprises the following steps: calculating the probability distribution of the frequency fluctuation amplitude of the system by probability statistics; describing the uncertainty of a contribution factor by a fuzzy number; and then obtaining the average value and the standard deviation of the power fluctuation of the AC tie line by fuzzy sampling and deblurring. The method is beneficial to the operation of the power systems, is also beneficial for an analyst to know the steady state power fluctuation characteristics of the interconnected power systems in the two regions and provides basis for determining the operation limit of the tie line and establishing the measure of inhibiting the power fluctuation of the AC tie line.