Comparison of PI and PR Controllers with Adaptive Notch Filter for LCL Filtered Grid-Tie Converters under Weak Grid

Renewable energy sources such as solar and wind require power converters and harmonic filters for interconnection with the grid. Central to the operation of such systems is the controller, which ensures that the maximum possible power is transferred from the source to the grid. Of these controllers, the proportional-integral (PI) controller is the most commonly used, owing to its ease of implementation. This report therefore aims at comparing the operation of the PI controller with its stationary reference frame equivalent known as the proportional-resonant (PR) controller. Both controllers are implemented in the voltage oriented control scheme for a three phase converter connected to a weak grid through an LCL filter. The characteristics of the controllers are analysed and compared in both the time and frequency domains. Simulation results validate the performance of each controller.