Harmonic Coupling Characteristic Analysis of the VSC-HVDC System Based on Harmonic State Space

With the increasing proportion of power generation from renewable energy, the VSC-HVDC technology that transmits photovoltaic power, offshore wind power, etc., into the main power grid has been gradually attracting attention. The harmonic coupling problem existing in the VSC-HVDC systems will have an adverse impact on the stable operation of the power system, and in order to study the problem, this paper establishes a mathematical model of the VSC-HVDC system based on the theory of Harmonic State Space (HSS). For the purpose of reducing the computational complexity and improving the solution efficiency, this paper decomposes the VSC-HVDC system into two sections: rectifier section and inverter section. In addition, the influence of the maximum harmonic number on the fitting effect of the switching function is discussed in this paper, and the harmonic transfer function matrix using to describe the harmonic coupling characteristics of the VSC-HVDC system is derived. A simulation model of the VSC-HVDC system is built in MATLAB/Simulink to verify the validity and accuracy of the HSS model, and finally a framework for analyzing the harmonic coupling characteristics of the VSC-HVDC system is given by synthesizing the results of simulation and programming calculation.