弱电网下基于超螺旋滑模的LCL并网逆变器控制研究

Research on LCL Grid-Connected Inverter Control Based on Super-Twisting Sliding Mode Under Weak Power Grid

针对LCL型滤波器的固有谐振、滤波器参数及弱电网下电网阻抗的波动会严重破坏并网系统稳定性的问题,提出了弱电网下基于超螺旋滑模的LCL并网逆变器控制策略。根据并网系统模型构建超螺旋滑模观测器,对滤波电容电压及逆变器侧输出电流进行估计,消除额外传感器需要,降低成本。采用具有非奇异快速终端滑模面控制(NFTSMC)的超螺旋滑模控制器来快速地跟踪参考给定电流及降低并网系统动稳态误差,且提高并网系统对外界干扰和参数不确定性的全局鲁棒性。仿真结果表明,当滤波参数摄动和电网阻抗变化时,系统表现出较强的鲁棒性,且并网电流的THD值保持在0.5%左右。

Aiming at the problem that the inherent resonance of LCL filter,filter parameters and impedance fluctuation in weak power net-work will seriously damage the stability of grid-connected system,a super spiral sliding mode based control strategy for LCL grid-connected inverter under weak power grid is proposed.Firstly,according to the grid-connected system model,the super-twisting sliding mode observer is constructed,and the filter capacitor voltage and the output current on the inverter side are estimated,eliminating the need for additional sensors and reducing costs.Secondly,a super-twisting sliding mode controller with non-singular fast terminal sliding mode control(NFTSMC)is used to quickly track the reference current and reduce the dynamic steady-state error of the grid-connected system,as well as to improve the global robustness of the grid-connected system against external disturbances and parameter uncertainties.Finally,the simulation results show that the system shows strong robustness when the filter parameters are perturbated and the grid impedance changes,and the THD value of the grid-connected current is maintained at about 0.5%.