计及直流偏置和谐波影响的单相电网电压同步频率准确检测

摘要

Frequency detection is one of the most important technologies for the grid-connected inverters of the distributed generation system(DGS).However,DC offset and harmonics in the grid voltage often affect the accuracy of frequency detection.Aiming at this problem,an accurate detection method for frequency synchronization of single-phase grid voltage considering DC offset and harmonic impact is proposed.In the proposed method,the influence of DC offset and harmonic is independently eliminated by using an improved quadrature signal generator (QSG) and an adaptive complex filter.In order to ensure that the proposed method have good dynamic response performance and accurate estimated results even in the frequency-varying situations,a robust frequency adaptive controller realized in αβ axis is suggested.Both the feasibility and validity of the proposed method are verified by simulations and experiments.%对分布式发电系统中的并网逆变器而言,频率检测是一项非常重要的技术.然而电网电压中的直流偏置和谐波会影响频率检测的精度.针对此问题提出了一种计及直流偏置和谐波影响的单相电网电压同步频率准确检测方案.方案中通过改进基于二阶广义积分器的正交信号发生器(SOGI-QSG)和引入自适应复数滤波器来分别消除直流偏置和谐波的影响,为了保证所提方案在电网频率突变情形下仍然具有良好的动态响应性能和准确的检测结果,在αβ坐标系下构建了稳健的频率自适应控制器.通过仿真和实验,对方案的可行性和有效性进行了验证.