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| 摘要: |
| 使用离散傅里叶变换法计算出给定的交流电压的向量,通过计算其向量的实部或虚部值的2个相邻同方向变化的过零点之间的时间,计算其周期和频率,继而推出交流量本身的周期和频率。以正弦曲线为例,从理论上证明了离散傅里叶变换计算输出的向量实部或虚部值是按以时间为自变量的正弦函数形式变化,且其变化频率等于正弦曲线自身变化频率;使用二次插值法计算正弦曲线的过零点时刻,2个相邻的同方向变化的过零点间的时间即是信号变化周期,从而计算其频率,分析了二次插值法用于计算正弦曲线的过零点时刻的理论误差;构造了该测频方案的详细实现方法,并分析了该测频方案的整体测量误差。试验测试结果表明:该算法可以消除谐波、直流分量的影响,计算的频率值离散小、精度高。 |
| 关键词: 频率测量,二次插值法,离散傅里叶变换 |
| DOI： |
| 分类号:TM935.1 |
| 基金项目: |
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| Power frequency measurement algorithm |
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FANG Cun-yang CHEN Yu-lan PAN Han-guang
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| Abstract: |
| The vector of a given AC voltage is calculated by Discrete Fourier Transformation(DFT) and the time interval between two neighboring and iso-directional zero points of its real or imaginary part is obtained,from which the frequency or period of the voltage is deduced.With the sinusoid as an example,it is verified theoretically that,its real or imaginary part calculated by DFT is also a sinusoid with the same frequency as the original sinusoid.Quadratic interpolation technique is used to find two neighboring and iso-directional zero points,from which the frequency of the original sinusoid is deduced.Its theoretical error is analyzed.The measurement algorithm is given and its systematic error is analyzed.Experimental results show that,this algorithm eliminates the influences of harmonic and DC components and has higher accuracy and less dispersivity. |
| Key words: frequency measurement,quadric interpolation technique,discrete Fourier transform |
