Two-degree-of-freedom ℋ∞ control design for harmonic current control of shunt active filters

This paper presents a precise harmonic current control for shunt active filters (SAF) based on the robust control design. To ensure robust stability causing by system uncertainties and tracking performance, the robust control employing a two-degree-of-freedom ℋ_∞ control method is designed to accurately track harmonics generated by nonlinear loads in power system. The controller is synthesized by using mixed sensitivity loop shaping. The principle of the proposed control method and the design procedure are described. Robustness to parameter uncertainties can be achieved. The excellent control performance has been carried out by simulations.