Generalized LCL-Filter Design Algorithm for Grid-Connected Voltage-Source Inverter

LCL-filters are preferred over conventional L-filters for grid-connected voltage-source inverters (VSIs) due to their superior harmonic attenuation and smaller filter size and weight. The LCL-filter design process is complex and takes an iterative approach due to the considerations of resonance damping, reactive power compensation, harmonic attenuation limits, etc. This paper analyses the parameters of LCL-filter design in order to understand its significance in grid-connected applications. Secondly, based on the analysis, relationships between the resonance frequency, attenuation of switching ripple, reactive power production, and the ratio between the grid-side inductor and the inverter-side inductor are used to realize a simple LCL-filter design algorithm. The design considers LCL-filter as a single filtering unit rather than individual filtering contributions from passive components. The design is verified by simulations in MATLAB and validated experimentally via a hardware prototype. Results demonstrate the efficacy of the proposed method in terms of total harmonic distortion, harmonic attenuation, and reactive power compensated.