Analysis of System Voltage Stability Security Considering the Influence of Subcritical Hopf Bifurcation Limit Cycle

Under the new power system with a large number of new energy sources connected to the grid, the research on system stability faces new problems. The occurrence of global bifurcation phenomena will cause sudden changes in the system's attraction domain, affecting system stability. When the system undergoes subcritical Hopf bifurcation, the unstable limit cycle generated will affect the original stable and unstable manifolds, causing sudden changes in the system's attraction domain. The sudden change in the stability of the limit cycle and the coexistence of different system bifurcation parameters will also affect the attraction domain. This paper proposes a method based on manifold analysis and bifurcation theory to explore the mechanism by which limit cycles affect the attraction domain and their impact on voltage stability under large disturbances. First, the power system equations are analyzed to study the bifurcation phenomena and the impact of limit cycles on stability. In the case analysis, the bifurcation analysis method is used to observe the system's state space diagram to study the influence mechanism of limit cycles under different parameters, and the bifurcation diagram is drawn to study the impact of the limit cycle and its sudden change caused by subcritical Hopf bifurcation on voltage stability, and to determine the voltage stability change range. This method has important guiding significance for understanding the mechanism and impact of subcritical Hopf bifurcation.