Optimal analytic LCL filter design for grid-connected voltage-source converter

Grid connected converters produce current harmonics, which need to be mitigated towards the grid. Passive output filters are the standard solution. Considering the growing count of low-power energy sources, the cost of output filters as well as the energy losses in them must be taken into account during the design phase. Existing design methods for these output filters are tedious in use; optimality of the filter design is not guaranteed, adapting the methods for other objectives is difficult. In this paper, an analytic design method for converter output filters is proposed, functional for filters of any order, and demonstrated for filters of 3^rd order. It is optimized for minimal total material and energy loss cost over the lifetime. Based on the converter, grid, expected lifetime and use, cost of energy and material, and grid harmonic standards, this method calculates the optimal filter components; it outperforms other methods in optimal cost and energy efficiency. This method is readily usable, fully analytic and adaptable to other conditions, prerequisites or optimality objectives.