并联有源滤波器输出LCL滤波器研究

基于电流最大允许脉动、逆变器开关频率和阻尼特性要求,提出了应用在三相并联有源电力滤波器中的LCL滤波器的一种新颖的设计方法。LCL滤波器是一种滤除逆变器开关谐波的有效手段,具有比LC滤波器更优异的性能,能够克服由于电网阻抗的不确定性而影响滤波效果的缺点。在详细介绍设计过程的基础上,给出了一个设计实例。为了避免LCL滤波器发生电流谐振,通常需要加入阻尼电阻,则导致损耗增加,降低系统效率。提出一种新的控制策略,引入电容电流反馈的方法,有效地替代了LCL滤波器中电阻的阻尼作用。通过调节反馈系数,不需要改变系统谐振频率,同时增强了阻尼作用,有效地抑制了低次谐波的振荡。仿真和实验结果证明了设计的LCL滤波器和采用的控制策略的优异性能。

Research on LCL filter applied to shunt active power filter

Based on the maximal allowable current ripple,the switching frequency and the damping characteristic,a novel design method of the LCL filter applied to the three-phase shunt APF(Active Power Filter) is proposed.The LCL filter is effective in eliminating switching harmonics of VSI,which has better performance than LC filter and can overcome the influence of the grid parameter uncertainty.With the detail introduction of design process,an example is presented.To avoid the current resonance caused by LCL filter,damping resistance is usually needed,which increases wastage and reduces system efficiency.A novel control strategy is proposed,in which the capacity current feedback is used as damping resistance to strengthen the damp and effectively suppress the resonance of low harmonics by regulating the feedback coefficient with unchanging system resonance frequency.Simulation and experiment validate the design of LCL as well as the control strategy.