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经典的离散傅里叶变换(DFT)算法在静态条件下具有较好的相量估计性能,但在动态条件下其估计精度往往达不到实际应用要求。文中分析了DFT算法在动态条件下产生估计误差的原因,在此基础上利用一阶泰勒模型对DFT算法进行修正,设计了满足动态要求的同步相量估计新算法。该算法利用一阶泰勒展开式对动态电力信号进行建模,然后引入相邻数据窗之间的相量变化率来表征相量一阶导数,通过相量一阶导数修正DFT算法的估计结果;最后将得到的中心时刻相量估计值相移到报告时刻,从而实现准确的相量估计。仿真分析及对实际采样数据的分析表明,该算法在频率偏移、低频振荡等动态情况下均优于DFT算法,具有一定的应用潜力。
The classical Discrete Fourier Transform (DFT) algorithm has better performance of phasor estimation under static conditions, but its estimation accuracy often fails to meet practical application requirements under dynamic conditions. In this paper, the reason why DFT algorithm produces the estimation error under dynamic conditions is analyzed. Based on this, the first-order Taylor model is used to correct the DFT algorithm and a new algorithm of the synchronized phasor estimation is designed to meet the dynamic requirements. The first-order Taylor expansion is used to model the dynamic power signal. Then, the first-order derivative of the phasor is introduced by introducing the rate of change of the phasor between the adjacent data windows. The first-order derivative of the phasor is used to correct the estimation result of the DFT algorithm. Finally, the obtained center moment phasor estimates are shifted to the reporting moment to achieve accurate phasor estimation. The simulation analysis and the analysis of the actual sampling data show that the proposed algorithm is superior to the DFT algorithm under the dynamic conditions of frequency offset and low frequency oscillation, which has some potential applications.