Open AccessFrequency‐coupled impedance model based subsynchronous oscillation analysis for direct‐drive wind turbines connected to a weak AC power system
Author(s) -
Liu Wei,
Xie Xiaorong,
Shair Jan,
He Jingbo
Publication year - 2019
Publication title -
the journal of engineering
Language(s) - English
Resource type - Journals
ISSN - 2051-3305
DOI - 10.1049/joe.2018.9297
Subject(s) - electrical impedance , wind power , control theory (sociology) , oscillation (cell signaling) , electric power system , turbine , converters , grid , power (physics) , stability (learning theory) , computer science , maximum power transfer theorem , frequency domain , time domain , transfer function , engineering , physics , electrical engineering , mathematics , aerospace engineering , geometry , control (management) , quantum mechanics , artificial intelligence , machine learning , biology , computer vision , genetics
Recently, the emerging subsynchronous oscillation (SSO) issue caused by interactions between power electronic converters and weak grids has provoked serious stability concerns. Impedance modelling based method has been widely used to analyse the emerging SSO phenomenon. In this paper, a frequency coupled impedance model (FCIM) is proposed to analyse this interaction. The FCIMs at multiple frequencies are measured and then the transfer function model is identified. The modelling method is then applied to type‐4 wind turbine based farms connected to a weak AC grid. The aggregated impedance of the whole system is obtained by combining the FCIMs of all components in the power system. The system stability is then investigated by varying the online number of wind turbines. Time‐domain simulations using PSCAD/EMTDC are carried out to verify the proposed methods of impedance modelling and stability analysis.