多机并联LCL型APF谐振特性分析及抑制策略研究

Study on Resonance Feature Analysis and Suppression Strategy of Multi-parallel LCL APF System

由于LCL型有源电力滤波器(APF)作为一个三阶系统,不仅能够保证滤除高频开关分量,同时在相同的容量下,可大大降低电感取值,因此在配电网被大量采用。然而,随着LCL型APF大量并网,其自身产生的谐振问题开始凸显。本文针对配电网内并联LCL型APF与电网之间交互影响问题,建立了并联LCL型APF系统等效电路模型,并对多机并联LCL型APF系统进行了并联谐振特性分析,得出了并联谐振的表达式;提出一种基于电容支路电流反馈的有源阻尼策略来替代无源阻尼,对APF并联系统机网谐振进行抑制,进而分析了不同有源阻尼参数对并联谐振抑制效果的影响。最后通过RT-LAB仿真验证了上述理论分析的正确性与抑制策略有效性。

LCL active power filter(APF),as a three order system,is adopted widely in the distribution grid because,it can not only ensure to eliminate high frequency switching components,but also,reduce greatly the value of inductance at the same capacity.However,with the large number of LCL APF parallel access to the distribution network,the problem of its resonance will not be ignored.In view of the interaction problem between the parallel LCL APF and thepower grid in this paper,the equivalent circuit model of the parallel LCL APF system is set up and parallel resonance characteristics analysis of the parallel LCL APF system is performed so to obtain the expression of the parallel resonance.A kind of capacitive damping current feedback active damping strategy instead of the passive damping is proposed to suppress grid resonance in APF parallel system.The effects of different active damping parameters on the suppression of parallel resonance is analyzed further.Finally,the correctness of above theoretical analysis and the effectiveness of the control strategy are verified by the RT-LAB simulation.