Feedforward phase compensation method of LCL grid‐connected inverter based on all‐pass filter in weak grid. Issue 19 (18th February 2021)

• Record Type: Journal Article
• Authors: Xue, Tongyu; Sun, Pengju; Xu, Zezhong; Luo, Quanming
• Is Part Of: IET power electronics. Volume 13:Issue 19(2020)
• Page Start: 4407
• Page End: 4416
• Publication Date: 2021-02-18
• Subjects: power grids -- compensation -- distributed power generation -- power filters -- electric current control -- digital control -- invertors -- feedback -- feedforward; weak grid -- inverter‐side current feedback control -- distributed generation systems -- actual operating conditions -- capacitor voltage feedforward -- analogue control -- phase lag -- digital control delay -- reverse resonance peak changes -- grid impedance -- feedforward phase compensation method -- LCL grid‐connected inverter -- all‐pass filter -- reverse resonance peak frequency -- control method; Power electronics -- Periodicals; 621.31705
• DOI: 10.1049/iet-pel.2020.0897
• Languages: English
• ISSNs: 1755-4535

Abstract

Abstract : Inverter‐side current feedback control (ICFC) has been extensively adopted in distributed generation systems because of its simple implementation and better consistency with actual operating conditions. At the same time, when there are a large number of background harmonics in the grid, capacitor voltage feedforward (CVF) is usually added to the system for its suppression. This method could make the system keep the first‐order characteristics under the analogue control. However, under digital control, due to the digital control delay, a reverse resonance peak will be generated in the loop gain, which makes the system unstable in the weak grid. In order to solve the aforementioned problems, this study proposes a feedforward phase compensation method of LCL grid‐connected inverter based on the all‐pass filter (AF). By introducing AF into the CVF channel, the phase lag in the range of reverse resonance peak frequency is compensated, so as to enhance the robustness of the system in the weak grid. At the same time, this study gives the detailed design process of the proposed method. Experimental results on a 3‐kW prototype are provided, and the effectiveness of the proposed control method is verified..