Control of AC-DC-AC converter under unbalanced and distorted input conditions

This paper investigates problems of grid voltage distortions and their influence on AC-DC-AC converter. A specific control algorithm is presented, which minimizes influence of voltage dips and higher harmonics on the system. Requirements for control of the Line (Grid) Side Converter (LSC) and Machine (Generator) Side Converter (MSC) are discussed. Effectiveness of proposed control scheme is verified with simulations and experimentally on 3 kW model. Solution is dedicated to variable speed energy systems (VSEGS) connected to high impedance grid, particularly wind farms or ocean wave energy converters such as WaveDragon MW.