Model Identification of Grid-following System for Stability Evaluation with Transient Data

To accurately identify the dynamic behaviors of inverter-based resources in the time domain for stability evaluation. This paper proposes a model identification method only with operation data for the general grid-following system. Firstly, a general grid-following (GFL) system's structure is introduced and clarified into several standard blocks. The doubly-fed induction generator (DFIG) and high-voltage direct current (HVDC) system are further illustrated. Secondly, the core idea of the proposed method is formulated as a regression form, and the transient data combined with the corresponding GFL model blocks constitute several parallel regression problems. Then, the regression problem is solved using a sequentially thresholded least-squares algorithm. Lastly, a typical DFIG integrated with HVDC lines is tested using the proposed method in the time domain to show its effectiveness, and a pole plot evaluates the damping of modes. This study contributes significantly to acquiring a precise online model for real-time damping estimation, participation analysis, and adaptive control.