LCL filter optimal parameter selection method for grid-connected inverter

Abstract

The existing filter design methods only consider the filter characteristics. The influence of the change of the ratio of the two inductor parameters on the filter performance is not analyzed, and the limit about the switching frequency of the filter parameter design is also not considered.Therefore, the filter failed to achieve the best performance. In this paper, the mathematical expressions of μ(the ratio of grid side inductance to inverter side inductance) and k(the ratio of switching frequency to resonant frequency) are firstly established. Secondly, the relationship between μ, k parameters and component volume, energy storage and harmonic attenuation is studied. The range of μ、k parameters is determined.Finally, the optimal LCL filter parameters are calculated.Through the simulation, the total harmonic distortion of the single-phase grid-connected inverter is 2.02%, the power factor is 99.82%, and the load can be rapidly responded to the sudden change and the system achieves a new dynamic balance fastly.

Keywords

• grid-connected inverter
• LCL filter
• inductance ratio
• switching frequency
• harmonic