An ℒ∞ Feedback Control Strategy for Grid-Connected Three-Phase Voltage Source Inverters

The renewable energy market is expanding, and this creates a demand for efficient control for energy conversion. Most renewable energy is harnessed as DC and needs to be converted into 3-phase voltage with a voltage source inverter (VSI) to be connected to the grid. PI control is commonly utilized to control the VSI. It provides good steady state performance but suffers from poor disturbance rejection and limited bandwidth. This paper introduces the application of an ${\mathcal{L}_\infty }$ feedback control; an iterative algorithm based on LMIs (Linear Matrix Inequalities). The control objective is to provide the grid voltage and regulate the real and reactive power injected to the grid. The performance of the proposed control scheme is validated analytically and through Matlab/Simulink simulations under nominal conditions, input voltage disturbances and grid impedance uncertainties. The proposed method is compared with existing method (PI controller) showing that the proposed scheme can provide better reference tracking, and improved transient and steady-state performance with low implementation cost.