Effects on oscillation mechanism and design of grid‐voltage feedforward in grid‐tied converter under weak grid. Issue 5 (1st May 2019)

• Record Type: Journal Article
• Authors: Wang, Guoning; Du, Xiong; Shi, Ying; Yang, Yougeng; Sun, Pengju; Li, Guanghui
• Is Part Of: IET power electronics. Volume 12:Issue 5(2019)
• Page Start: 1094
• Page End: 1101
• Publication Date: 2019-05-01
• Subjects: feedforward -- electric current control -- power grids -- power system stability -- voltage control -- phase locked loops -- power convertors -- optimal control -- proportional control; oscillation mechanism -- grid‐tied converter -- weak grid -- system stability margin -- oscillation problem -- renewable power generation system -- low frequency oscillation -- impedance‐based method -- frequency coupling characteristics -- converter equivalent impedance -- optimal proportional voltage feedforward control -- proportional grid‐voltage feedforward control -- voltage feedforward control effect -- phase locked loop -- PLL; Power electronics -- Periodicals; 621.31705
• DOI: 10.1049/iet-pel.2018.5232
• Languages: English
• ISSNs: 1755-4535

Abstract

Abstract : Grid‐voltage feedforward control is widely used in grid‐tied converters. The reported studies show that the grid‐voltage feedforward may reduce the system stability margin, and may lead to oscillation problem in renewable power generation system. This study revisits the effect of voltage feedforward control on system stability and especially focuses on low frequency oscillation with impedance‐based method. The low frequency oscillation usually happens in industry around 100 Hz and shows frequency coupling characteristics. A converter equivalent impedance which includes the effects of voltage feedforward and also covers the frequency coupling introduced by phase locked loop (PLL) is established. Based on the built impedance, the effect on oscillation mechanism with voltage feedforward and PLL is revealed. The results show that the voltage feedforward could increase the system stability margin and may be employed to improve the system stability. Then how to design an optimal proportional voltage feedforward control is demonstrated. Experimental results verify the theoretical analysis and the design of the proportional grid‐voltage feedforward control.