An adaptive DFT algorithm for measuring power system synchrophasors based on rectangular coordinate

When the power system frequency shift occurs, using the discrete Fourier transform (DFT) in synchronized phasor measurement will be error due to asynchronous sampling. The error is composed of fixed error and dynamic error. To cut down the dynamic error as much as possible, an adaptive DFT algorithm based on rectangular coordinate was presented. By tracking the frequency of power grid, this algorithm determines the length of the sampling window, which was used to DFT. Based on this, Synthesizing the new phasor by utilizing three sampling window which were away from 1/4 sampling window length to each other, and then compensating the fixed offset. The simulation results show that the proposed algorithm increases the accuracy significantly, and satisfies the requirements of real time applications for smart grid.