Design and Control of Three-Phase PV Grid Connected Converter with LCL Filter

Voltage source converters (VSC) are widely used in the distribution generation (DG) systems for the conversion of renewable energies. These converters are usually connected to the utility grid through a simple L 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 converter with LCL filter is theoretically analyzed, and the corresponding state-space mathematic model is established. Furthermore, a hybrid controller incorporating repetitive control and state feedback pole-assignment control is proposed for the converter. Simulation and experimental results of the converter with LCL filter are provided to verify the validity of the proposed controller.