考虑谐波电流的并网逆变器阻抗模型研究

分布式发电系统挂载了大量的并网逆变器,逆变器侧和电网侧的谐波存在交互作用,会影响系统的稳定性.本文推导了单相双闭环LCL并网逆变器的阻抗模型,分析了考虑非线性因素下的阻抗模型.为提高系统阻抗模型的准确性,在研究系统低频特性的基础上,提出直接将并网逆变器谐波电流引入到并网系统阻抗模型中,建立谐波阻抗模型.利用提出的谐波阻抗模型对多逆变器并网系统进行建模和谐波交互分析.以电路模型为基准,对采用谐波阻抗模型进行谐波分析的结果做了比较.仿真结果验证:谐波阻抗模型具有较高的准确性.

Research on impedance model of grid-connected inverter considering harmonic current

The presence of harmonic interactions between inverter side and grid side,which a number of inverters are coupled to the grid,may affect the stability of distributed generation(DG) system.This paper deduces the impedance model of single-phase grid-connected inverter with LCL filter based on a dual-loop control scheme,and then analyzes the impedance model in the ease of considering the nonlinear factors.Based on analyzing low frequency characteristics of inverters,grid-eonnected inverter harmonic current is directly incorporated into the impedance mod el to make the impedance model more in line with actual circuit model,the harmonic impedance model is set up.Based on the proposed harmonic impedance model,the harmonic interactions of DG system is modeled and analyzed.Using the circuit model as a standard,the results of harmonic analysis using the harmonic impedance model are compared.The simulation results verify the high accuracy of the proposed model.