Interconnection and damping assignment control of a three-phase front end converter

•A nonlinear controller for a front-end grid-connected converter is designed.•All the generated power is injected to the grid and the reactive power is controlled.•A direct control of the DC-Link voltage dynamics is performed.•An integral action is added in order to eliminate steady state error.•Validation is performed through simulations using a realistic converter model. A new nonlinear control strategy for a three-phase front end converter used to connect renewable energy sources to the grid is proposed in this paper. The controller is designed in order to inject all the generated power into the grid, while the reactive power can be controlled to meet the power system requirements. The system is represented through its port controlled Hamiltonian model, and the controller is designed by interconnection and damping assignment. This design method allows an intuitive way to remove the undesired couplings between system dynamics while assigning the damping required to achieve the expected convergence rate. The proposed controller allows a direct control of the DC link voltage by proper selection of the controller parameters. Moreover, an integral action is added to the proposed controller in order to eliminate the steady-state error in the system variables. The proposal is validated through simulation tests performed using a realistic converter model.