基于自适应电流预测模型的LCL型三电平逆变器并联零序环流抑制策略

Parallel Zero-sequence Loop Suppression Strategy for LCL Type Three-level Inverters Based on Adaptive Current Prediction Model

提出了一种基于自适应电流预测模型的零序环流抑制策略,该策略适用于共直流母线的并联运行的三电平逆变器。首先构建了零序环流等效模型,分析证明了并联系统的中点电位差和共模电压差为零序环流激励源;随后提出了一种基于预测模型的零共模电压控制方法,兼顾了中点电位平衡的控制效果并改善了并网电流质量,同时对并联系统之间的零序环流进行了有效抑制;其次设计了一种自适应电流预测模型,提高了在参数失配下并网电流的跟踪性能,减少了误差;最后通过MATLAB/Simulink平台搭建仿真模型,验证了所提控制策略的可行性和有效性。

This paper presents a zero-sequence loop suppression strategy based on an adaptive current prediction model,which is suitable for three-level inverters running in parallel on a common DC bus.Firstly,the zero-sequence loop equivalent model is constructed,and the analysis proves that the midpoint potential difference and common-mode voltage difference of the parallel system are zero-sequence loop excitation sources;then,a zero-common-mode voltage control method based on the prediction model is presented,which considers the control effect of the midpoint potential balance and improves the quality of the parallel current,and effectively suppresses the zero-sequence loop between the parallel systems;secondly,an adaptive current prediction model is designed to improve the tracking performance of grid-connected current under parameter mismatch and reduce the error;finally,a simulation model is built on the platform of MATLAB/Simulink to verify the feasibility and validity of the proposed control strategy.