基于改进虚拟磁链的dq谐波检测方法

Harmonic detection method for dq based on the improved virtual flux

为了提升传统dq谐波检测法对网侧电压畸变的应对能力,提出一种基于复合二阶广义积分器的虚拟磁链定向的谐波检测方法。该方法采用虚拟磁链作为同步参考坐标系锁相环的改进环节,利用复合二阶广义积分器替代常规低通滤波器,消除了传统dq谐波检测方法由于三相电网电压不对称和畸变等恶劣工况造成的检测误差,并能准确锁定电网相位角和频率。仿真和实验结果表明,电网不平衡和谐波畸变对改进后的谐波检测方法影响较小,所得基波正序电流基本不存在畸变,且能够准确跟踪频率的变化,证实了所提出的基于复合二阶广义积分虚拟磁链定向的谐波检测方法的有效性。

In order to improve the ability of traditional dq harmonic detection method to respond to grid-side voltage distortion,a virtual flux-oriented harmonic detection method based on composite second-order generalized integrator is proposed in this paper.The method adopts the virtual flux as an improvement of the synchronous reference frame phase-locked loop,and replaces the conventional low-pass filter with the composite second-order generalized integrator,which eliminates the detection error of the traditional dq harmonic detection method that due to the harsh conditions of voltage asymmetry and distortion of the three-phase power grid,and the grid phase angle and frequency can be accurately locked.The simulation and experiment results show that the improved harmonic detection method is not affected by the imbalance and distortion of the power grid,the fundamental wave positive sequence current has no distortion,and it can accurately track changes of frequency,which proves the effectiveness of the virtual flux directional harmonic detection method based on composite second order generalized integrator proposed in this paper.