Abstract: Decaying DC component and time variation of frequency and magnitude of fundamental component,which reduce the accuracy of phasor estimation of discrete Fourier transform （DFT）,tend to exist in fault current when a fault occurs under dynamic conditions. A new dynamic signal model extended from a static signal model was introduced to express time variation and decaying DC component. Then two filters,one for fundamental phasor and another for DC component,were employed to estimate them. Finally,the accurate phasor estimation was attained by revising the phasor estimation of DFT. Ideal signals and PSCAD/EMTDC generated signals were adopted to verify the performance of proposed algorithm. The simulations show that the proposed algorithm can eliminate the impacts of time variation and decaying DC component and improve estimation accuracy compared to traditional algorithms though some additional computation is needed.