Dynamic Stability Analysis of Multi‐Infeed Wind Power System With Composite Dynamic Short Circuit Ratio

ABSTRACT With multiple wind farms (WF) integrated into a weak receiving‐end AC grid, multi‐infeed wind power system (MIWPS) is facing a critical dynamic stability issue involving wideband oscillatory behaviours. To overcome this challenge, this paper proposes a general dynamic stability analysis method to analyse the stability of the MIWPS. Firstly, a general equivalent decoupling modelling method (GEDMM) is proposed to represent the MIWPS as multiple virtual single‐infeed systems (VSISs). Each VSIS, consisting of a dynamic equivalent circuit, synchronous generator, a single wind farm and other retained components, is modelled as a virtual time‐varying discrete‐time state space model (VTDS 2 M). The unknown parameters of the dynamic equivalent circuit are identified with the proposed hybrid optimization square root cubature Kalman filter (HOSRCKF). Then, taking all VTDS 2 Ms as the model basis, the composite dynamic short circuit ratio (CDSCR) is defined to analyse the system stability. The relationship between the CDSCR and dynamic stability is also established from the perspective of input to state stability (ISS). Finally, to study the connection between the change of the CDSCR and the mechanism of oscillatory instability, the augmented Hilbert‐Huang transform (AHHT) is proposed to identify key oscillatory modal parameters. Moreover, multiple comparative studies are implemented to validate the effectiveness of proposed methods.