滤除衰减直流分量的动态同步相量测量算法

Dynamic Phasor Estimator With Removing Decaying DC Component

在动态条件下的故障电流不仅往往含有衰减直流分量,而且其基波分量的幅值与频率也可能是随时间而变化的。正是这2个因素影响了由传统傅里叶变换得到的相量测量的精度。拓展了原来的静态信号模型,使其能正确表示信号基波分量的时变性以及衰减直流分量,再利用基波滤波器和直流滤波器来分别对基波分量的时变性以及衰减直流分量进行估计,并对短时傅里叶变换相量测量结果进行修正来提高相量测量精度。分别应用理想信号以及PSCAD/EMTDC仿真信号来检验算法的性能,仿真结果表明,虽然需要增加有限的运算量,但与传统的算法相比,所提出的算法能消除或减弱故障电流的基波分量时变性以及衰减直流分量对同步相量测量的影响,并大大提高故障电流的相量测量精度。

Decaying DC component and time variation of frequency and magnitude of fundamental component, which reduce the accuracy of phasor estimation of discrete Fourier transform （DFT）, tend to exist in fault current when a fault occurs under dynamic conditions. A new dynamic signal model extended from a static signal model was introduced to express time variation and decaying DC component. Then two filters, one for fundamental phasor and another for DC component, were employed to estimate them. Finally, the accurate phasor estimation was attained by revising the phasor estimation of DFT /deal signals and PSCAD/EMTDC generated signals were adopted to verify the performance of proposed algorithm. The simulations show that the proposed algorithm can eliminate the impacts of time variation and decaying DC component and improve estimation accuracy compared to traditional algorithms though some additional computation is needed.