基于多重二阶广义积分的电网谐波分量检测

Harmonic detection of power grid based on multiple second order generalized integrators

当电网出现三相电压不平衡或含有低次谐波等状况时,为保证功率变流器输出与电网同步,采用了一种频率自适应同步检测方法。该方法是基于多重二阶广义积分器基础上的解耦网络,通过锁频环来进行频率调节,同时利用交叉对消网络来进行对各阶谐波分量的解耦,并通过等效滤波器来实现基波和各次谐波分量的分离。该方法可以检测出功率信号在基波频率下的正负序分量,且适用于低次谐波连续分量的检测。理论分析和Matlab仿真表明,采用的频率自适应同步检测方法可以在电网故障条件下有效地获得谐波正负序分量的相位和幅值,并且具有良好的静态和动态性能。

To ensure the synchronism between the grid-connected power converter and grid, in case of three-phase power grid voltage becoming imbalance or containing low-order harmonics, a frequency-adaptive synchronization detection method was presented. This method is based on a deeoupled network consisting of multiple second order generalized integrators （MSOGI） which are frequency-adaptive by using a frequency-locked loop （FLL）. Mean- time, the cross-feedback network is applied to decouple the multiple harmonics and the equivalent filtering is used to individually detect the fundamental or each harmonic component in real time. The positive- and negative-se- quence components of the power signal at the fundamental frequency can be detected, and other sequence compo- nents at multiple frequencies can also be detected. The simulated results show that the MSOGI-FLL is a very suit- able solution to detect fundamental-frequency positive and negative sequence components of unbalanced and distort- ed grid voltages, and exhibits a better static and dynamic performance.