Comparative Analysis of Synchronization Stability Domain for Power Systems Integrated with PMSG Based on the Direct Method

The traditional time-domain simulation method evaluates the system stability according to the trajectory during and after the fault. In contrast, the direct method only integrates the trajectory during the fault without considering the dynamics of the trajectory after the fault. The nearest unstable equilibrium point (UEP) method, the controlling unstable equilibrium point (CUEP) method and the potential energy boundary surface (PEBS) method are the classical direct methods. This paper presents the energy function to approximate the boundary of the synchronization stability domain of PMSG in the single PMSG-Infinite bus system, and the three direct methods are analyzed from the perspective of the stability domain. First, a reduced-order nonlinear model describing the dynamic synchronization characteristics of PMSG is established. Based on this model, the transient energy function of PMSG is derived by first integration method. Then, the boundary of the synchronization stability domain is approximated by the nearest UEP method, the CUEP method and the PEBS method. Finally, both simulation and experimental results are presented and thoroughly discussed so that it is possible to establish a fair comparison for the three direct methods.