Aiming at problem that traditional full-wave Fourier algorithm can’t filter out decaying DC component generated in electric signal while power system fault occurs

which results in big error of resolving result

cause unpredictable effect

a full-wave Fourier improved algorithm is proposed. Estimate the decay time constant and the starting value of decaying DC component by sampling. Then the sampling values minus the decaying DC component to get the corrected value. At last

full-wave Fourier transform is carried out on the corrected value to obtain the fundamental component. The MATLAB simulation results show that the improved algorithm can effectively reduce the influence of decaying DC component. It can avoid the exponential function and logarithmic function in calculation. The algorithm is so fast

simple and it can increase the sensitivity while ensuring rapidity. It is suitable for microcomputer protection device.