Resumo
This paper is focused on a comparison between two linear matrix inequality conditions for design of robust state feedback controllers applied for current regulation of gridconnected converters with LCL filters, operating under uncertain grid impedance at the point of common coupling. The first condition is the well known quadratic stability and the second one is the polyquadratic stability, which uses extra matrix variables. It is shown that the condition with slack variables can provide superior performance in terms of ensuring stable and suitable operation for a larger set of uncertainties. https://doi.org/10.53316/sepoc2021.054