The invention relates to a 
flicker value calculation method based on improved FFT and an 
inverter. In order to solve the technical problems, the 
flicker value calculation method based on the improved FFT and the 
inverter are provided, and high-precision 
flicker value calculation is achieved. According to the technical scheme, the method includes the steps that (1), all phases of 
voltage signals are sampled to obtain a 
voltage sampled sequence; (2), a 
voltage root-mean-square value is calculated according to sampling length per semi-circle wave, so that a voltage root-mean-square value sequence is obtained; (3), the average value of the voltage root-mean-square value sequence is calculated, and the average value is subtracted from each voltage root-mean-square value, so that a new voltage root-mean-square value sequence is obtained; the new voltage root-mean-square value sequence is windowed, FFT is performed, and amplitude frequency is corrected through double spectrum line interpolation operation; (5), 
curve fitting is performed on 
voltage fluctuation and fluctuation frequency 
discrete points; (6), please see the formula in the specification, a transient flicker value P is calculated; (7), the steps from one to six are repeated, all transient flicker values P within ten minutes are calculated, and according to the formula in the specification, a short-time flicker value Pst is calculated. The flicker value calculation method and 
inverter are used for the field of 
electric power technologies.