Abstract: As a significant carrier on the construction of modern power system，the physical analysis of extra high voltage（EHV）transmission line is important on the operations and the faults of transmission lines. Therefore，EHV transmission line is crucial to studies on relay protection，the safety and the stability of the parallel operation of power system. Through seeking for the variation of physical parameters amid the state change of power system stimulated by physical components，the static simulation system provides a scientific basis for studies on the characteristics of line faults and the stability of power system. On the basis of the combination of computer simulation technology and basic physical components，the system can truly reflect the various operations of the transmission lines. Especially，the system can simulate any possible fault of the transmission lines and guarantee the action situations during the course of fault simulation， providing an experimental test before the commissioning of newly developed protection.

Key words: static simulation, transmission line, relay protection, power system stability