基于alpha-beta平面合成曲线特性的对称三相电路谐波分析

随着非线性负荷的广泛应用,电网中的谐波问题日益严重,实现对谐波的准确测量与分析意义重大。为降低对称三相电路的谐波分析复杂度,提出了基于谐波信号的alpha-beta平面合成曲线周期特性的谐波成分分析方法。该方法首先对单相电量做alpha-beta变换并求取合成曲线的模长及其周期,其次依据合成曲线周期分析电路中可能存在的谐波成分,最后结合谐波信号的总谐波畸变率等信息计算所存在谐波的谐波含有率。分析表明,当合成曲线模长的周期小于四分之一工频周期时,其计算量约为傅里叶分析方法的三分之二。通过对算例的运算验证了所提方法的有效性。

Harmonic Analysis in Symmetrical Three Phase Circuit Based on Synthetic Curve Characteristics on Alpha-Beta Plane

With wide application of nonlinear loads, the problem of harmonics in the grid is increasingly serious. It has great significance in measuring and analysing harmonics accurately. To reduce complexity of harmonic analysis in symmetrical three phase circuit, method of harmonic components analysing based on synthetic curve periodicity characteristics of harmonic signal on alpha-beta plane is proposed. Firstly, alpha-beta transform to single phase electrical parameters is done, at the same time amplitude and periodicity of synthetic curve are calculated. Then, according to periodicity of synthetic curve, harmonic components existing in circuit possibly are analyzed. Ultimately, combining with information such as total harmonic distortion of harmonic signal, harmonic ratio of existing harmonics is calculated. Analysis shows that when periodicity of synthetic curve amplitude is less than a quarter of power frequency periodicity, calculation amount of the method is only about two-thirds of fourier analysing method. Calculation of cases testifies the availability of proposed method.