一种新能源公共连接点系统谐波阻抗计算方法

System harmonic impedance estimation method of new energy access point

针对新型电力系统中谐波责任划分及谐波放大问题研究中的谐波阻抗获取这一关键环节,提出一种改进的基于快速独立分量分析的公共连接点系统谐波阻抗估算方法。通过对公共连接点处电压和电流快速变化分量进行快速独立分量分析,得到四个独立分量及混合矩阵,推导了混合矩阵各元素与谐波阻抗间的线性关系,并基于系统侧和电源侧谐波电流、阻抗的关系及特性,根据独立分量与混合信号间的相关性求取变换矩阵并重新确定独立分量的正确次序和对应的混合矩阵,进而通过该混合矩阵各元素间的关系,推导系统谐波阻抗计算公式。搭建了仿真模型对所提方法进行仿真验证,仿真结果表明,改进的谐波阻抗估算方法可准确估算系统谐波阻抗值,在系统谐波电流幅值小于电源谐波电流幅值且差距较大时,具有较高的估算精度及稳定性。

This paper proposes an improved harmonic impedance estimation method for access point systems based on fast independent component analysis(FastICA),which is a key step in the study of harmonic responsibility division and harmonic amplification in new power systems.By using FastICA for the rapidly changing components of the common connection point,mixing matrices and independent components are obtained,then the linear relationship between the elements of the mixing matrix and the harmonic impedance is derived.Based on the relationship and characteristics of the harmonic current and impedance on the system side and power supply side,then according to the correlation between independent components and mixed signals,a transformation matrix is obtained and the correct order of independent components and the relative mixed matrix are obtained.Finally the calculation formula of harmonic impedance of the system is deduced through the relationship between the elements of the mixed matrix.A simulation model was built to verify the proposed method.The simulation results show that the improved harmonic impedance estimation method can accurately estimate the harmonic impedance of the system.When the amplitude of the system harmonic current is smaller than that of the power supply harmonic current and the gap is large,the proposed method gain higher estimation accuracy and stability.