一种降低电网谐波影响的单相自适应锁频方案

Single-phase Adaptive FLL Scheme for Reducing the Influence of Power Grid Harmonics

随着分布式发电的发展,在单相光伏场景中性能可靠的电网同步技术是实现逆变器高效并网的重要前提。提出了一种有效的单相自适应锁频算法,该算法主要由1个级联的二阶广义积分正交信号发生器SOGIQSG(second-order generalized integrator-quadrature signal generator)和1个简单可靠的频率自适应控制器组成。理论分析表明,级联SOGI-QSG结构具有良好的滤波性能,可以改善谐波含量高的电压信号。在电网遭受频率波动时,所提出的频率自适应控制器可以快速跟踪电网频率的瞬时变化。仿真和实验验证了所提方案的可行性和有效性。

Along with the development of distributed generations, a reliable grid synchronization technology in the single-phase photovoltaic （PV） scenario is an important precondition for inverters to be effectively connected to power grid.In this paper, an effective single-phase adaptive frequency-locked loop （FLL） algorithm is proposed, which consists of a cascaded second-order generalized integrator-quadrature signal generator （SOGI-QSG） and a simple and reliable frequency adaptive controller. Theoretical analysis reveals that the cascaded SOGI-QSG has a good filtering performance, so it can improve the voltage signal containing more harmonic distortions; moreover, the proposed frequency adaptive controller can fast track the transient change of grid frequency when the grid suffers from frequency fluctuations. Simulation and experimental results verified the feasibility and effectiveness of the proposed scheme.