基于DFT的电力系统频率及谐波精确算法

频率是电力系统运行特性评估中最重要的参数之一。传统频率测量算法存在不同程度的误差,而它所带来的频谱泄露则影响谐波测量的精度。提出基于离散傅里叶变换（DFT）的改进测频算法,该算法利用相隔半个周波的3组信号数据求取2个修正系数,分别对相邻两个周波的相角进行修正,再通过其相角差求得实际频率。在此基础上,通过实时修正采样频率实现同步采样,从而精确进行谐波分析。4种不同情况的仿真实验结果表明算法具有较好的频率跟踪效果和谐波测量精度。

An accurate DFT based power system frequency and harmonics measurement algorithm

Frequency is one of the most important parameters in power system operating characteristics assessment.The low precision of traditional frequency measurement method results in frequency leaking which influence harmonic measurement accuracy.An improved frequency measuring algorithm based on DFT(Discrete Fourier Transform) is proposed.Three sets of signal data which are separated by half cycle are used to calculate two modification coefficients,which modify phase angle of two adjacent cycles.The frequency is then measured by the phase angle change.Synchronous sampling is achieved by correcting the sampling frequency in real time in order to analyze harmonic accurately.Four different simulation results show that proposed method has better frequency tracking result and harmonic measurement accuracy.