Voltage Stability Dynamic Security Region Partitioning Method Considering Boundary Crises for Direct- Drive Wind Power System

The sudden change of the region of attraction (ROA) under parameter variation can be ascribed to global bifurcations. When global bifurcations involve chaotic attractors, their inherent randomness and suddenness may cause catastrophic threat to large-disturbance voltage stability. In the subcritical Hopf bifurcations, the unstable limit cycles surrounding stable equilibrium points will bring instability risks to the post-fault system through boundary crises. To this end, this paper proposes the partitioning method of the voltage stability dynamic security region considering boundary crises (BC-VSDSR). In theoretical analysis, the occurrence mechanism of boundary crises is studied based on manifold analysis. Then, the numerical analysis method of boundary crises is studied based on the homoclinic Melnikov method. In simulation analysis, the effects of various bifurcations due to parameter variations on the large-disturbance voltage stability of a direct-drive wind power grid-connected system are researched. Meanwhile, combined with state space analysis, the impact of boundary crisis on the ROA is studied. Finally, the BC-VSDSR in the space of power injections is divided. The division of BC-VSDSR helps guide the parameter adjustment to ensure the voltage stability in actual operation.