一种用于谐波检测的改进虚拟磁链定向方法

An Improved Virtual Flux Linkage Orientation Method for Harmonic Detection

针对传统基于瞬时无功功率理论的ip-iq谐波检测算法对网侧电压畸变应变能力弱的缺点,提出一种基于复合三阶广义积分器的虚拟磁链观测的定向方法,并将其应用于ip-iq谐波检测算法。该方法采用虚拟电网磁链作为锁相环的改进环节,利用复合三阶广义积分器和正负序分量计算模块来实现正序磁链的提取;在准确锁定电网相位角和频率的基础上,消除了传统ip-iq谐波检测算法由于电网电压不对称,波形畸变和直流偏移分量的注入等原因造成的检测误差。仿真和实验表明,改进后的方法基本不受网侧恶劣工况的影响,应用于谐波检测得到的基波电流基本不存在畸变,且能够实时跟踪频率变化,证明了本文提出的基于复合三阶广义积分器的虚拟磁链定向方法的有效性。

In view of the shortcomings of the traditional ip-iqharmonic detection algorithms based on the in stantaneous reactive power theory, a kind of orientation method of virtual flux linkage observation based on composite third order generalized integrator is proposed and is used in ip-iq harmonic detection algorithm. The method uses the virtual grid flux linkage as an improved link of the phase locked loop,uses the compos ite third order generalized integrator and the positive and negative sequence component calculation module to realize the extraction of the positive order flux linkage;on the basis of accurately locking the phase angle and frequency of the grid, eliminates the detection error due to asymmetrical grid voltage,wave distortion and injection of DC offset component which is caused by the traditional ip-iq harmonic detection algorithm. It is shown by the simulation and experiment that the method after modification is basically free from severe condition of grid side, the fundamental current obtained by harmonic detection has basically no distortion, can achieve real time tracking frequency variation,and the effectiveness of virtual flux linkage orientation method based on composite third order generalized integrator proposed in this paper is proved.