Sampling frequency determination method for calculating harmonic amplitude on basis of filtering and sampling

The invention discloses a sampling frequency determination method for calculating a harmonic amplitude on the basis of filtering and sampling. Sampled electrical signals comprise a direct current component, a fundamental component and second and larger harmonic components. The method comprises steps as follows: step 101, determining the maximum frequency omega m of calculated harmonic in A/D (analog to digital) input signals; step 102, obtaining a theoretical accurate cut-off frequency omega d used for designing a filter according to the maximum frequency omega m of the calculated harmonic and frequency margin omega delta, wherein omega d is equal to the sum of omega m and omega delta; step 103, determining an actual accurate cut-off frequency omega' d of the filter according to the theoretical accurate cut-off frequency omega d, wherein omega' d is larger than or equal to omega d; step 104, determining a sampling frequency omega s, wherein omega s is equal to the sum of omega' d and omega m; and step 105, sa