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为了应对电网发生电压跌落、频率突变、谐波污染等电网畸变条件，该文为并网逆变器提供了一种新的基于快速正负序分离算法的自适应锁频环同步技术。基于自适应陷波器的锁频环本质上是一个2阶陷波器，加上非线性微分方程后可以实现基波频率跟踪，实现电网信号的同步，前提条件是电网无扰动和谐波。电网发生畸变时，为了抑制扰动和谐波，提出了一种快速正负序分离算法，结合自适应陷波器，改进后的自适应锁频环同步技术利用简单的矩阵运算，可以在5个采样周期内实现正、负序分量及各次谐波的快速分离。与1/4周期延时的传统锁相环相比，该方法无需压控振荡器，无需比例积分参数调试，简化了系统的结构，实现了频率的自动跟踪，消除了系统检测误差，提高了系统的动态性能。文中对所提锁频方案进行了详细的理论分析，最后仿真和实验结果验证了所提方法的可行性及良好的暂态特性。“,”This paper investigates and presents a new adaptive frequency locked loop synchronization scheme based on fast positive-negative sequences decomposition for grid-connected power converters under distorted grid conditions, such as voltage dip, frequency change and harmonic distortion and so on. The frequency locked loop (FLL) based on adaptive notch filter (ANF) is a second-order notch filter that is further furnished with a nonlinear differential equation to track the fundamental frequency of the grid signal without disturbances or harmonics. For noise reduction purpose under distorted grid conditions, a fast positive-negative sequences decomposition (FPNSD) algorithm is proposed;collaborating with ANF, the modified ANF-based synchronization technique can extract the positive-negative sequences and low order harmonics exactly in 5 sampling periods by matrix operation. Unlike the traditional algorithm based on phase-locked loop (PLL) with a quarter-period delay, the performance of the proposed algorithm does not need voltage-controlled oscillator or proportional-integral (PI) controller; this makes its structure much simpler for implementation, and the proposed method with high dynamic performance can completely eliminate the detection errors and track the grid fundamental frequency. The paper presents detailed description and derivation of the proposed FLL method; simulations and experiments are presented to verify and validate the excellent transient performance.