Research on control strategy combining pole-assignment and pr control in three-phase grid-connected inverter

Grid-connected inverters are widely used in the distribution generation (DG) systems for the conversion of renewable energies. These inverters are usually connected to the utility grid through LCL filter to reduce the current harmonics injected to the grid. A LCL network, which can achieve reduced levels of harmonic distortion at low switching frequencies with less inductance, is a good alternative. In this paper, a three-phase grid-connected inverter with LCL filter is theoretically analyzed, and the corresponding state-space mathematic model is established. Furthermore, a hybrid controller incorporating proportion resonant control and state feedback pole-assignment control is proposed for the inverter. Simulation results of the converter with LCL filter are provided to verify the validity of the proposed controller.