基于阻抗模型的集中式光伏电站谐波放大机理研究

Research on Harmonic Amplification Mechanism of Centralized Photovoltaic Power Plant Based on Impedance Model

针对现有多逆变器并网系统研究缺乏对集中式大型光伏发电系统建模的问题,利用诺顿、戴维南等效定理对集中式光伏并网系统的发电单元、各级升压变压器、传输线路以及电网进行等值建模,建立并网发电系统的阻抗模型,并在此基础上推导谐波与系统各阻抗间的关系。利用频域分析研究谐波在传输过程中的放大机理,仿真结果给出了谐波电流放大倍数受阻抗模型的等效电源系数与等效耦合导纳的影响关系,为后续研究谐波抑制策略提供理论基础。

Aiming at the lack of modeling of large-scale centralized photovoltaic power generation systems in the study of the existing multi-inverter grid-connected systems,the Norton and Thevenin equivalent methods are used for equivalent modeling of power generation units,boost transformers,transmission lines and power grid for centralized photovoltaic grid-connected systems,and the impedance model of grid-connected power system is established.On this basis,the relationship between harmonics and system impedances is derived,and the frequency domain analysis is used to study the amplification mechanism of harmonics in the transmission process.The influence of equivalent power coefficient and equivalent coupling admittance of the impedance model on harmonic current amplification factor is given by the simulation results,which provides a theoretical basis for the subsequent research on harmonic suppression strategies.