三相变流器无源阻尼型LCL滤波器的分析与设计

摘要

在三相电压型变流器(VSC)中,LCL型滤波器以其优越的高频衰减特性,得到了广泛应用,尤其是在大功率场合,但其阻抗特性含有谐振峰,同时额外增加的RC支路消耗有功和无功功率,使得参数设计变得复杂.分析得知,无源阻尼型LCL滤波器的外特性仅取决于其总电感量L、阻尼系数ξ和自然频率ωn.在保证外特性相同的前提下,滤波器的参数将有不同的组合,因此需要进行优化设计.首先对滤波器进行深入的理论分析,在此基础上根据需求确定出滤波器的外特性.然后以RC支路的最小有功和无功损耗为目标对滤波器参数进行优化设计,得到无源阻尼型LCL滤波器的参数设计结果.最后,对不同参数的LCL滤波器进行实验,实验结果验证此分析与设计的合理性和有效性.%In three-phase voltage source converters (VSC),the widely used LCL filter can always achieve an excellent attenuation of high frequency harmonics.However,the resonance peak in its impedance characteristic as well as some extra active and reactive power consumptions of the RC branch is inevitably generated,which will definitely increase the complexity of the filter design and VSC control.The output character of a passively damping LCL filter is determined by only three parameters:total inductance L,damping ratio ξand natural frequency ωn.Actually,different combinations of the three parameters can produce the same output character.Thus,an optimization approach is essential to select proper values for each element.In this work,detailed analysis of a passively damping LCL filter is firstly carried out.And then,the optimization process is implemented,taken the lowest active and reactive power consumption of the RC branch as the target.Hereafter,the design principles are derived.Finally,the proposed analysis and design approach are validated by the experiments of different filter parameter combinations.