Harmonic Distortion Reduction of Transformer-Less Grid-Connected Converters by Ellipsoidal-Based Robust Control

A photovoltaic generator connected to a large network and supplying nonlinear load (source of harmonics) injects distorted current into the grid. This manuscript presents an invariant-ellipsoid set design robust controlled active power filter inject grid with minimum total harmonic distortion (THD). The is considered external disturbance minimize its effect on injected current. Moreover, modeled as fixed voltage source in series Thevenin impedance whose value changes within interval. Using technique, problem cast disturbance-rejection tracking control. volume ellipsoid minimized, which results minimizing system performance keeping trajectories close possible origin. matrix inequalities that are linearized by fixing scalar. resulting convex optimization solved iteratively linear (LMIs). simulation experimental findings show proposed successful reducing THD when uncertain variable loads applied (balanced unbalanced cases).