一种计及频率偏移的谐波与邻近间谐波估计方法

A harmonic and adjacent interharmonics estimation method considering frequency deviation

新能源大规模并网会诱导电力信号中出现关于基波/谐波对称的邻近间谐波对或单个邻近间谐波。对信号中各频率成分进行参数估计时,往往需要获知邻近间谐波的类型以构建准确的计算模型。而当电网频率偏离额定值时,频谱泄漏干扰将使该要求难以实现。为此,文中提出一种在频率偏移时依然有效的邻近间谐波类型判据及基于此判据的谐波与邻近间谐波参数估计方法。首先,通过分析频率偏移与泄漏谱线的映射关系,抑制基波与谐波的频谱泄漏以提取邻近间谐波谱线;然后,通过对比不同类型邻近间谐波的频谱差异,提出利用谱线比值作为邻近间谐波类型判据;最后,基于邻近间谐波类型信息,构建邻近间谐波谱线方程以精准估计谐波及邻近间谐波参数。文中所提方法在频率偏移时仍能准确判断邻近间谐波的类型,并能实现更精准的参数估计。仿真验证了所提方法的准确性。

The adjacent interharmonic pairs or single adjacent interhamonic symmetrical to the fundamental/harmonic component can be caused by the large-scale grid connection of renewable energy.It is usually necessary to confirm the type of adjacent interharmonics to build an accurate calculation model when estimating the frequency components in electric signal.However,the spectrum leakage interferences caused by the grid frequency deviation makes that requirement hard to achieve.Towards the problem,an effective criterion to confirm the type of the adjacent interharmonics and an accurate estimation method of the harmonics and adjacent interharmonics based on the criterion even there is frequency deviation are proposed.Firstly,the spectrum leakage interferences are suppressed to obtain the adjacent interharmonic spectral lines by analysing the relationship of the frequency deviation and spectral lines.Then,the type criterion of the adjacent interharmonics is proposed by comparing the spectrum difference between each type of adjacent interharmonics.Finally,the spectral line equation for each type of adjacent interharmonics are constructed according to the confirmed type to accurately estimate the harmonics and adjacent interharmonics.Even there is frequency deviation,the type of the adjacent interharmnics can be confirmed accurately and a more precise estimation of the harmonics and adjacent interharmonics can be achieved with the proposed method.The accuracy of the proposed method is verified by the simulation.