电网电压不平衡时基于二阶广义积分器SOGI的2倍频电网同步锁相方法

为了实现逆变器在电网电压不平衡时的控制并网，提高锁相环节的速度和精度，本文基于二阶广义积分器(second order generalized integrator, SOGI)，提出一种新型的2倍频锁相方法，该方法对不平衡电网电压产生的2倍频交流量进行锁相，从而快速准确地实现与电网同步。介绍了2倍频正负序交流量提取方法，2倍频锁相工作原理及电网同步锁相过程。优化了SOGI正交发生器(SOGI-quadrature signal generator，SOGI-QSG)，消除了输入电压直流偏置对其输出产生的影响。在电网电压不平衡条件下对所提方法进行了仿真与实验，验证了该锁相方法的有效性。与传统基波锁相方法相比，所提方法提高了对电网电压正序分量检测的快速性和准确性。

Double Fundamental Frequency PLL with Second Order Generalized Integrator Under Unbalanced Grid Voltages

In order to detect the positive-sequence component at fundamental frequency of the grid voltage fast, this paper proposes a new phase-locked loop method, called double fundamental frequency phase-locked loop (DFF-PLL). The operation principle is analyzed, the process of DFF-PLL and the detection of grid voltage positive-sequence component are shown. The paper improves the second order generalized integrator quadrature-signals generation (SOGI-QSG), so that the DC bias voltage can be removed and guarantee the orthogonality of SOGI-QSG. The performance of DFF-PLL is verified by using simulation and experimental results. Compared with DSOGI-PLL, this method increases the detection speed and accuracy under unbalanced grid voltage conditions.