In order to solve the dimension disaster of simulation equation caused by high order generator utility model and the trapezoidal method for power system transient simulation and the problem of iterative solution for equations between generators and network

a discrete time-domain d-q axis and x-y axis of Thevenin＇s dynamic equivalent model is established using trapezoidal integration method on the bases of the Thevenin equivalent princi- ple. A more accurate generator model for simulation should be chosen to avoid affecting the simulation equation di- mension. The model

over a period of time

is equivalent to the generator model instead of an integration step

thereby reducing the computation of modifying model. The value of power angle depends on the corresponding variables＇ values in the past time

which consequently solves the problems caused by the use of iterative solution of trapezoidal method for solving machine network equations. The simulation results show that

the model has a high simulation precision and stability.