Control of voltage source converters with LCL filter using state-space techniques

The aim of this paper is to propose and compare two multivariable current controllers of voltage source converters (VSCs) connected to the grid through an LCL filter. The first proposal is a linear quadratic (LQ) servocontroller, which uses a full-order estimator to obtain the full state vector. The second proposal is based on the internal model control (IMC). The behavior of both controllers is tested in presence of grid disturbances and mismatches in the model parameters.