Research on distribution terminal voltage frequency tracking method based on DFT phase difference method

To improve the accuracy of power grid voltage and frequency monitoring by distribution terminals (FTUs) and reduce the impact of power grid frequency deviation on real-time monitoring of distribution terminals, a new voltage and frequency tracking method based on DFT phase difference method is derived by improving the traditional phase difference frequency monitoring method. A phase difference frequency estimation method is designed under the combined influence of multiple harmonics and noise interference, which is based on the mutual promotion of real-time frequency estimation and real-time frequency tracking. Frequency estimation completes sequence sampling, phase difference calculation, and frequency calculation. Frequency tracking improves the next sampling interval based on the previous frequency, thereby reducing the error value. Through simulation and physical experiments, it was found that the algorithm can synchronously analyze the harmonics of 10kV lines. The frequency estimation, frequency tracking, and harmonic analysis algorithms can quickly improve the accuracy of distribution terminal frequency estimation and harmonic analysis, and can complete real-time and high-precision harmonic analysis with small computational complexity.