The characteristic of EMP electromagnetic power variation influence limit cycle in power systems in a weakly non-linear system

The article researched the parameters fluctuation of load and the angle oscillatory caused by mechanical power fluctuations, built a mathematics model of one machine infinity bus system. Using the direct average method, it also researched power angle characteristic by the amplitude of load variation and the mechanical power fluctuations. The simulation result shows that periodic disturbance about the mechanical power and may existence uniqueness of limit cycle. It may existence more than one limit cycles under periodic disturbance about parameters of electromagnetic power, and the sub-harmonic resonance may be observed. The above phenomena are all related to structure of nonlinear dynamic systems and the system´s running states.