Modelling and robust control of digitally controlled large‐scale PV plants. Issue 7 (1st May 2020)

• Record Type: Journal Article
• Authors: Xie, Bao; Mao, Mingxuan; Guo, Ke; Zhou, Lin; Liu, Tiantian; Zhang, Qianjin; Wan, Yihao
• Is Part Of: IET power electronics. Volume 13:Issue 7(2020)
• Page Start: 1291
• Page End: 1301
• Publication Date: 2020-05-01
• Subjects: digital control -- closed loop systems -- control system synthesis -- power grids -- invertors -- robust control -- Gaussian distribution -- photovoltaic power systems -- power system stability -- power generation control -- H∞ control; grid impedance -- robust controller -- robust control -- large‐scale photovoltaic plants -- digital control delay -- grid‐connected inverters -- equivalent impedance model -- desired tracking error performance -- mixed‐sensitivity optimisation control design -- traditional dual current loop control strategy -- system stability‐robustness -- digitally controlled large‐scale PV plants -- LCL filter -- Gaussian distributions -- system stability; Power electronics -- Periodicals; 621.31705
• DOI: 10.1049/iet-pel.2019.0888
• Languages: English
• ISSNs: 1755-4535

Abstract

Abstract : Large‐scale photovoltaic (PV) plants may be destabilised by the large grid impedance introduced by transformers and long transmission lines. When considering the digital control delay of grid‐connected inverters, the problem will become more serious. In this study, the equivalent impedance model of digitally controlled large‐scale PV plants is established, considering that the values of the parameters of the LCL filter follow Gaussian distributions. Then, the system stability can be analysed conveniently, and the stability analysis shows that the digital control delay will make the system robust to large grid impedance worse. To enhance the stability‐robustness of the system, an H ∞ robust controller is proposed in this study. By properly selecting the weighting functions, the desired tracking error performance and robustness are achieved on the basis of the mixed‐sensitivity optimisation control design. Compared with the traditional dual current loop control strategy, the H ∞ robust controller improves significantly the system stability‐robustness against large grid impedance. Finally, simulation and experimental tests are carried out in this study, and the results demonstrate the effectiveness of the proposed H ∞ robust controller.