无直流分量干扰的自适应锁频环同步优化方法

电网同步是提高并网换流器故障穿越能力的关键技术之一。为实现电网不平衡下换流器快速准确的并网跟踪,提出一种改进的一阶广义积分器锁频环(FOGI-FLL)方法。建立并网换流器数学模型,分析了不平衡电网下的正负序分离原理,并给出了正负序基频分量分离简化结构,讨论了简化结构中一阶广义积分器核心模块的实现方法,在一阶广义积分器滤波结构上进行了改进,增加了可以消除直流分量干扰的积分补偿环节。仿真结果表明,本文所提方法在电网电压不平衡环境中可以实现高性能的同步跟踪效果。

Synchronization optimization method of adaptive frequency-locked loop without DC component interference

Grid synchronization is one of the key technologies to improve the fault ride-through capability for grid-connected converter.To achieve fast and accurate phase or frequency tracking under unbalanced grid voltage,a kind of improved first-order generalized integrator based on frequency-locked loop (FOGI-FLL) method is put forward.A mathematical model of grid-connected converter is established.Its separation principle of positive and negative sequences under unbalanced grid is also analyzed.The separation structure of fundamental negative and positive sequence components is simplified.Its core module configuration of FOGI is discussed.Integral compensation function which can eliminate the interference of DC components for FLL tracking is parallelly added to the basic structure of FOGI filter.Finally,the proposed method is verified by contrast simulation under unbalanced grid voltage with DC components.Simulation results present that the proposed method is capable of achieving better performance for synchronization under unbalanced grid voltage.