A comparative study on frequency scanning techniques for stability assessment in power systems incorporating wind parks

• Published in: Electric power systems research 2023-07, Vol.220, p.109311, Article 109311
• Main Authors: Jacobs, Keijo, Seyedi, Younes, Meng, Lei, Karaagac, Ulas, Mahseredjian, Jean
• Format: Article
• Language: English
• Subjects: Controller interactions; Converter; Impedance-based stability analysis; Wind parks
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2023.109311

•The process for extracting impedance models from EMT simulations exhibits differences in terms of computational efficiency and accuracy depending on the chosen reference frame.•αβ-frame scanning and stability analysis is the least attractive among the compared methods.•Impedance-based stability analysis using positive sequence-, αβ-, and dq-frame impedances yields sufficiently accurate stability prediction, with the dq-frame being the most accurate.•For the specific frequency range of 0-120 Hz, the positive sequence and dq-frame scanning procedure exhibit a similar computational efficiency, with the positive sequence scanning being the fastest. In general, for an arbitrary frequency range, positive sequence scanning is the fastest method. Modern power grids incorporating inverter-based resources (IBRs) may be liable to persistent oscillations and instability incidents, which jeopardize the reliable operation of the power system. Due to the high number and the complexity of the involved components, an analytical stability assessment of modern power grids is infeasible. A viable approach is the impedance-based stability analysis (ISBA) using impedances extracted from manufacturer-specific electro-magnetic transient (EMT) models via frequency scanning. This paper reviews the EMT-level positive-sequence, dq-frame and αβ-frame frequency scanning techniques and compares their computational efficiencies. The impact of the model reference frame on IBSA precision is also examined on two test cases: I - a full-size converter (FSC)-based wind park (WP) interacts with transmission grid in the super-synchronous frequency range; II - a doubly-fed induction generator (DFIG)-based WP interacts with transmission grid in the sub-synchronous frequency range. Among the compared techniques, ISBA using dq-frame impedance models features the highest accuracy. However, IBSA using positive-sequence or αβ-frame impedance models is sufficiently accurate. The computational speed of the ps-scan is fastest among the presented techniques. Using αβ-frame models has the slowest computational speed and is, therefore, is not recommended.