Abstract: Aiming at the problems of increased volatility and reduced accuracy of calculation results under wide operating conditions in both existing time and frequency domain identification methods, a quadratic iterative parameter identification method based on the construction of increasing rank condition is proposed to improve the parameter identification ability under wide operating conditions and variable power grid conditions. Firstly, in view of the problem of insufficient adaptability of the existing time-domain methods to the change of power grid operation conditions, the interaction characteristics of the grid-forming energy storage converter and the power grid are mathematically abstracted, and a closed-loop identification model is constructed for single-machine and two-machine/multiple-machine forms. Secondly, to address the problem that the existing frequency domain methods tend to fall into local optimization during iterative computation, a quadratic iterative solving method based on increasing the rank of state equations is proposed, which improves the global optimization performance by applying the increasing-rank condition, and improves the consistency of the identification results under a wide range of operating conditions. Finally, the effectiveness of the closed-loop identification model is verified by simulation. Resultsshow that the proposed method can obtain more accurate identification results under variable operating conditions and power grid scenarios.

Key words: closed-loop system model, parameter identification, abstract power grid model, quadratic optimization, single/multi-unit system