Analysis, control and experimental verification of a single‐phase capacitive‐coupling grid‐connected inverter. Issue 5 (1st May 2015)

• Record Type: Journal Article
• Authors: Dai, Ning‐Yi; Zhang, Wen‐Chen; Wong, Man‐Chung; Guerrero, Josep M.; Lam, Chi‐Seng
• Is Part Of: IET power electronics. Volume 8:Issue 5(2015)
• Page Start: 770
• Page End: 782
• Publication Date: 2015-05-01
• Subjects: power grids -- invertors -- power capacitors -- power inductors -- distributed power generation -- reactive power -- cost reduction -- losses -- electric current control; P‐unit current controller -- proportional‐integral controller -- peak grid voltage -- DC voltage selection method -- energy storage -- DC‐link voltage capacitor -- operational loss reduction -- systems initial cost reduction -- operational voltage -- lagging reactive power -- active power transfer -- AC grid -- low‐voltage DC microgrid -- alternative interface -- IGCI -- inductive‐coupling grid‐connected inverter -- coupling branch -- fundamental‐frequency impedance -- inductor -- power grid -- full‐bridge single‐phase inverter -- CGCI -- single‐phase capacitive‐coupling grid‐connected inverter -- experimental verification -- control verification -- analysis verification; Power electronics -- Periodicals; 621.31705
• DOI: 10.1049/iet-pel.2014.0373
• Languages: English
• ISSNs: 1755-4535

Abstract

Abstract : This study proposes a capacitive‐coupling grid‐connected inverter (CGCI), which consists of a full‐bridge single‐phase inverter coupled to a power grid via one capacitor in series with an inductor. The fundamental‐frequency impedance of the coupling branch is capacitive. In contrast with the conventional inductive‐coupling grid‐connected inverter (IGCI), this structure provides an alternative interface for use between a low‐voltage DC microgrid and an AC grid. A comparison between the CGCI and the IGCI is performed. It is concluded that the CGCI is able to transfer active power and provide lagging reactive power at an operational voltage much lower than that of the IGCI. This reduces the system's initial cost and operational losses, as well as the energy stored in the DC‐link capacitor. The CGCI has been analysed and a DC voltage selection method is proposed. Using this method, the DC‐link voltage of the CGCI remains at approximately of 50% of the peak grid voltage. In addition, a P ‐unit current controller is proposed for use with the CGCI, as a proportional–integral controller is not suitable. Finally, simulation and experiments show the effectiveness of the proposed approach.