基于DFT的电力系统相量及功率测量新算法

随着全球定位系统(GPS)的全面民用化以及通信技术的发展，电力系统实时相量测量技术日益受到关注。传统的基于离散傅里叶变换(DFT)的频率跟踪算法对相角误差的考虑不全面，从而其频率、相角、幅值等计算结果也不够准确。文中对 DFT 在非同步采样情况下的误差产生机理进行了全面分析，给出了非同步采样情况下 DFT 相角计算结果的精确误差表达式，基于该相角误差公式，提出了一种新的基于 DFT 的电力系统相量测量算法。与传统算法相比，该算法具有精确度高、可以自适应地抑制谐波干扰、计算量不大等优点，并用算例验证了这些优点。此外，还给出了实用的利用传统 DFT 方法计算功率的误差估计公式。

A DFT-based Method for Phasor and Power Measurement in Power Systems

With the development of GPS-based communication technology,the technique of synchronous phasor measurement inpower systems is arousing increasingly great concern.In the conventional phasor measuring method based on DFT(discreteFourier transform),no overall consideration is given to the phase angle error.Thus,the frequency calculation and phasorestimation results are not sufficiently accurate.A comprehensive analysis of the DFT error mechanism is made and a simple butexact expression of phase angle error and practical formulas for calculating the true phase angle and amplitude are presented.Inaddition,a new frequency tracking method is developed,which is capable of recursive calculation.With notable accuracyimprovement,the calculating burden with the new method is slightly heavier than that with the traditional DFT method.Anadaptive method of suppressing the effect of harmonics is presented,which adds very little calculating burden and hassatisfactory performance.An error estimating expression is also given to estimate power measuring errors of the conventionalDFT phasor measuring method.Some examples are given to demonstrate the feasibility,accuracy and simplicity of the methodproposed.