非理想三相电网的特征信号提取

Characteristic Signal Extraction of Non-Ideal Three-Phase Grid

当三相电网电压发生畸变或不平衡时,并网系统存在诸多非理想特征信号,例如谐波和负序分量等。针对此类问题,文中提出了一种基于ISDFT的谐波与负序分量提取算法。该算法通过对SDFT传递函数进行重新设计,在保留良好的信号过滤特性同时提高了系统的响应速率,且具有较强的灵活性。实验结果表明,ISDFT能够快速、准确地提取特征谐波及负序分量,且在负载发生突变时具有良好的动态性能。此外,以提取三相电网电压的5次、7次谐波为例,DFT、SDFT、ISDFT提取谐波的效果一致,但ISDFT的响应速率比SDFT快44.56%,比DFT快65.32%。

When the three-phase grid voltage is distorted or unbalanced,there are many non-ideal characteristic signals in the grid-connected system,such as harmonics and negative sequence components.In view of such problems,this study proposes a harmonic and negative sequence component extraction algorithm based on ISDFT.This algorithm redesigns the transfer function of the SDFT,which retains good signal filtering characteristics while improving the response rate of the system,and has strong flexibility.Experimental results show that ISDFT can quickly and accurately extract characteristic harmonics and negative sequence components,and ISDFT has good dynamic stability when the load changes suddenly.In addition,in terms of the extraction results of the 5th and 7th harmonics,DFT,SDFT,and ISDFT have the same effect of extracting harmonics,but the response rate of ISDFT is 44.56%faster than SDFT and 65.32%faster than DFT.