Frequency fast estimating method of power system based on zero-crossing method of DFT output.

Aiming at the low accuracy of discrete fourier transform (DFT) frequency estimation, a new fast detection method was proposed based on DFT output zero-crossing. The DFT output characteristics of the signal were analyzed firstly. The zero-crossing time of the DFT real part (or imaginary) was calculated accurately by using the fourth order Newton interpolation method. The system frequency could be obtained by the time difference between two zero-crossing points. The results of simulation analysis and experimental verification showed that the method had higher frequency estimation accuracy and less harmonic disturbance, and only needed 1.78 cycles to achieve frequency estimation, which was suitable for power system with real time requirement. [ABSTRACT FROM AUTHOR]