测算电网频率和谐波的新方法

New method for measuring actual frequency and harmonic contents of power systems

提出一种测量电网实际频率的新方法 ,其特点是 :设定一个接近被测频率的假定值 ,按此进行采样 ,所获得数据序列经处理后 ,可较准确地测算出实际频率值。介绍一种电网谐波的近似算法。与离散 Fourier变换 (DFT)不同的是 ,在非同步采样时 ,该算法采用的旋转因子的频率能始终与第 k次谐波的频率一致 ,从而可有效地消除采样不同步引起的误差。这些方法在 PC卡式仪器上实现 ,并利用仿真信号进行了验证。结果表明 ,上述方法可有效地改进电网频率和谐波的测量准确度 。

A novel method for measuring the actual power frequency is described. This method assumes that the approximate frequency of the measured signal is known and the actual frequency can be deduced from sampled data. An algorithm for analyzing the approximate power harmonics is also presented. The algorithm differs from discrete Fourier transform (DFT), in that, when sampling is a synchronous, the frequency of the factor in the algorithm is always coincident with the k th harmonic, so the error caused by asynchronous sampling can be effectively reduced. The algorithm has been tested on a PC card type virtual instrument. The simulated results show that the proposed method and the approximate algorithm can be readily put into practice.