The initial water storage period of a pumped-storage power station usually exceeds one year,hence engineering design should account for storage spanning two years and calculate the design runoff for two consecutive years.In the current standard the moving average frequency analysis method is adopted.Although this method ensures the length of the sample series,yet there is strong autocorrelation between the selected samples,which makes it difficult to meet the assumption of sample independence in frequency analysis calculations.In the paper a joint distribution model for the runoff over two consecutive years is established based on Copula function theory to find the solution of the model using a double numerical integration method to obtain the frequency curve.Compared to the traditional method,this method avoids the aforementioned issues while maintaining the sample length and considering the correlation between data series,which is more theoretically appropriate.The case study indicates that there are differences in the design values obtained by different methods in the low-probability segment when calculating the design runoff for two consecutive years.However,for higher probability design results,such as 50%and 75%,the differences are not significant.
moving average frequency analysisCopula functionspumped-storage power stationsinitial storage
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