Sequence Impedance Measurement of Utility-Scale Wind Turbines and Inverters – Reference Frame, Frequency Coupling, and MIMO/SISO Forms

Journal Article · 29 June 2021 · IEEE Transactions on Energy Conversion

DOI: https://doi.org/10.1109/tec.2021.3093516 · OSTI ID:1810538

Shah, Shahil  ^[1]; Koralewicz, Przemyslaw  ^[1]; Gevorgian, Vahan  ^[1]; Wallen, Robert  ^[1]

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1. National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sequence impedance responses with or without considering frequency coupling in both MIMO and SISO forms are increasingly used for the stability analysis of three-phase power electronic systems; however, many aspects of sequence impedance measurement are not fully explored. It is not clear if the sequence impedance has a reference frame similar to the dq impedance. If so, the role of the grid voltage angle estimation in aligning the sequence impedance reference frame has not been discussed. Additionally, existing methods for measuring the sequence impedance with frequency coupling are complicated, are not feasible for large wind turbines and inverters, and provide the sequence impedance responses in only either MIMO or SISO form. This paper presents a sequence impedance measurement method that considers the frequency coupling, performs reference frame alignment, demonstrates the impact of the grid voltage angle estimation, and obtains the sequence impedance response in both MIMO and SISO forms. This paper demonstrates the proposed method and practical problems associated with the sequence impedance measurement of utility-scale wind turbines and inverters on a 1.9-MW Type III wind turbine and a 2.2-MVA inverter using an impedance measurement system built around a 7-MW/13.8-kV grid simulator and a 5-MW dynamometer.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Renewable Energy. Wind Energy Technologies Office
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1810538
• Report Number(s): NREL/JA-5D00-77740; MainId:30655; UUID:f6112bce-7752-445c-856c-81125c4005d2; MainAdminID:25701
• Journal Information: IEEE Transactions on Energy Conversion, Vol. 37, Issue 1; ISSN 0885-8969
• Publisher: IEEECopyright Statement
• Country of Publication: United States
• Language: English