中文摘要：

电网不对称故障时，光伏发电系统中的负序分量和谐波分量会影响并网逆变器中的锁相环及控制算法。文章提出一种具有自适应滤波的双二阶广义积分锁频环技术，用于电网电压和并网电流正负序分量的提取以及电网电压同步信号的检测，并将该技术引入到正负序双电流环控制策略，通过优化不平衡控制策略中锁相环的方法，提升光伏并网逆变器整个控制系统应对电网不对称故障的能力。通过Matlab／Simulink软件平台搭建基于DSOGI—FLL锁频环的光伏并网发电系统模型并进行了仿真研究，结果表明，文章控制策略在电网不对称故障时有助于消除有功功率的2倍频波动以及抑制并网电流中的谐波分量。

英文摘要：

Negative sequence and harmonic components of PV power generation system had an important influence on phase locked-loop and control algorithm of grid-connected inverter under grid asymmetrical fault. Based on the above problems, in order to extract positive-negative sequence components of grid voltage and grid-connected current and detect the synchronization signal of grid voltage, this paper proposed a double second-order generalized integrator frequency-locked loop （DSOGI-FLL） technology with adaptive filtering. And the technology was introduced into the positive- negative sequence dual current control strategy. The method of optimizing phase-locked loop in unbalanced control strategy improved the whole control system＇s ability of PV grid-connected inverter to cope with gird asymmetric fault. The grid-connected PV power generation system based on DSOGI- FLL was simulated by using Matlab/Simulink software. The results showed thatThis method contributes to eliminate the 2 harmonic wave of active power and restrain the harmonic component of grid- connected current under grid asymmetrical fault.