基于泰勒展开模型的同步相量估计新算法

Research on Synchrophasor Estimation Algorithm Based on Taylor Expansion

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。

Discrete Fourier transform （DFT） is widely used in power system to estimate phasor because of its good performance under steady state. However it often fails to meet the estimation accuracy requirement for applications in a realistic dynamic power system, With research on DFT and IEEE C37. 118, a novel algorithm based on the first order Taylor series expansion is proposed to reduce the estimation error. Firstly, a dynamic power system signal is expressed using Taylor series expansion. Secondly, the phasor＇s first order derivative calculated by its changing rate between two continuous sampling windows is used to revise the results of DFT, Finally the revised results will be shifted according to the interval between the reported time and the window center time to get the accurate pbasor estimation results at the reported time. Simulation results and the analysis on practical data show that the new algorithm has better performance than traditional DFT under various conditions, e.g. frequency deviation and low frequency oscillation.