A PR-RC Controller for LCL-Type SVG to Suppress the Harmonic Distortion

Static var generator (SVG) is mostly utilized under polluted grid conditions with certain power quality problems, of which the grid disturbance will lead to the distortion of grid-side current. Compound repetitive control (RC), as an effective method to suppress periodic distortion of grid-connected converters and improve the dynamic response of conventional RC, has been adopted in existing approaches. However, existing modeling methods based on small gain theorem are too complicated to decouple compound RC. Therefore, the coupling effects among the controllers of compound RC are revealed in this paper. And a universal stability domain for compound RC scheme can be directly obtained. Furthermore, a proportional resonant RC (PR-RC) control strategy is proposed to improve the dynamic response of the SVG under a-b-c coordinate. Experimental results demonstrate the effectiveness and correctness of the theoretical analysis.