有源滤波器 LCL 并联虚拟阻尼控制策略及离散域稳定性分析

摘要

Resonance existing in an active power filter LCL system should be restrained by introducing damping.When the current timer comparison control method is used,the strategy for the filter capacitor with virtual damping in parallel is proved appropriate by contrast and analysis.By detection of harmonic voltage on the filter capacitor,this method is equivalent to a virtual harmonic resistor in parallel with the capacitor under the function of proportional component to enhance the damping effect.The method is easily implemented without differentiation.In addition,a mathematical model is developed and the stability domain of the virtual damping control coefficient is obtained according to the July stability criterion.Firstly,to ensure system”s stability,the sampling frequency must be six times greater than the resonant frequency.Furthermore,the stable region is enlarged with an increase of sampling frequency,and narrowed with an increase of resonant frequency or total grid-side inductance.Simulations and experiments have proved the validity of the proposed virtual damping strategy and the theoretical analysis.%有源滤波器 LCL 滤波系统存在谐振，需要引入阻尼。通过对比分析，发现当有源滤波器采用电流定时比较控制时，滤波电容并联虚拟阻尼策略最为适宜。该策略检测滤波电容的谐波电压，通过比例环节等效于电容并联虚拟谐波电阻，增强系统的阻尼作用，整个策略实现简单且避免了微分运算。通过建立离散域的数学模型，根据朱利稳定性判据求得虚拟阻尼系数的稳定域条件：即采样频率需大于滤波器谐振频率的6倍，以保证系统的稳定性；进而，系统的稳定域随采样频率的提高而增大，随滤波器谐振频率或滤波器网侧总电感值的增大而减小。仿真和实验分析证明了所提出的虚拟阻尼策略及理论分析的正确性。