Quick Calculation of Filtering Parameters for LCL Grid-connected Inverters
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.
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