LCL并网逆变器滤波参数近似计算方法

Quick Calculation of Filtering Parameters for LCL Grid-connected Inverters

在高频谐波衰减系数相同的条件下,LCL型滤波器的体积和感量要明显小于L型,但是其约束条件有所增加,参数计算也变得更加复杂,不仅要考虑并网电流的质量,还需要关注逆变器侧电感电流纹波和无功功率等限制条件。为简化计算流程,基于有源阻尼提出一种LCL型并网逆变器滤波参数近似计算法。首先,分析拓扑再利用仿真软件分析逆变器输出电压的谐波含量;其次,对滤波器设计相关约束条件的优先级进行重新排序,以谐振比为关键参数推导出计算公式,以谐振频率为关键参数快速计算出总电感值,再综合各个参数的极限值,给出设计流程图,并进行误差分析;最后,通过流程图输出一组参数进行仿真和实验分析,证明所提出的LCL滤波参数计算方法的合理性和有效性。

Under the condition of the same high-frequency harmonic attenuation coefficient,the volume and inductance of the LCL-type filter are significantly smaller than that of the L-type,but its constraints have increased and the parameter calculation has become more complicated,which not only takes into account the quality of the grid-connected currents,but also needs to pay attention to the limitations such as inductor current ripple and reactive power at the inverter side.To simplify the calculation process,an approximate calculation method for the filtering parameters of LCL-type grid-connected inverters is proposed based on active damping.Firstly,the topology is analyzed and then the harmonic content of the inverter output voltage is analyzed using simulation software.Secondly,the priorities of the constraints related to the filter design are reordered,the calculation formula is deduced with the resonance ratio as the key parameter,and the total inductance value is quickly calculated with the resonance frequency as the key parameter,and then the limit value of each parameter is synthesized to give a flow chart of the design,and an error analysis is carried out.Finally,a set of parameters is output from the flowchart for simulation and experimental analysis to prove the rationality and effectiveness of the proposed method for calculating the parameters of LCL filtering.