适用于并网系统的长距离传输电缆建模研究

Research on modeling of long distance transmission cables for grid-connected systems

在包含长距离传输电缆的分布式发电单元并网系统中,由于传输电缆模型是一个非线性模型,如Bode图、Nyquist图等适用于线性模型的分析方法不能直接应用在此类系统的分析中。为了方便对此类系统的分析,需要对传输电缆模型进行线性化。本文在分析了传输电缆实际阻抗模型特征的基础上提出了通过Taylor近似对传输电缆阻抗模型进行线性化的方法。通过对不同长度的传输电缆进行拟合阶数分析得出短传输线使用低阶拟合模型,长传输线使用高阶拟合模型的结论。实验和仿真验证了理论的正确性。

In the grid-connected system with long distance transmission cable distributed power generation unit,since the transmission cable model is a nonlinear model,analysis methods which are suitable for linear models,Bode diagrams and Nyquist diagrams and so on,cannot be directly applied to the analysis of such systems.To facilitate the analysis of such systems,the transmission cable model needs to be linearized.In this paper,the Taylor approximation method is proposed based on the analysis of the actual impedance model of transmission cable.Through the analysis of the fitting order of transmission cables of different lengths,it is concluded that the short transmission line uses the low-order fitting model and the long transmission line uses the high-order fitting model.Experiments and simulations verify the correctness of the theory.