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With the rapid developing of the power system, the security of power system is becoming more and more important, as a result, the online stability analysis has become one of the most important means for the system security operation. Contingency screening, as an important part of dynamic security analysis, has been a very valuable subject.The paper studies the contingency screening based on time-domain simulation, by which, the difficult part is that the solution needs fast computation speed and accuracy of both. For this purpose, a fast transient stability time-domain simulation applying Explicit integration algorithm method is proposed, which is based on Second order generator model. Compared with the traditional Euler explicit integration algorithm, the method presented here can reduce the computation time, and with small truncation errors. According to the characteristics of Second order generator model, the method proposed here changes the solving procedure based on Alternating iterative method, and only need to solve the differential-algebraic equations once at each step, by which,the calculation time can be reduced. Then, In order to reduce the simulation steps needed during the transient stability computation, a transient stability criterion based on SIME is researched. The method described here replaces a multi-machine power system by an one-machine system, terminates the simulation by EAC, at the meantime, identify the unstable and stable OMIB trajectories. The simulations based on the real system testify its effectiveness. At last, the paper presents a contingency screening method based on simple generator model to reduce the computation of the network equation solving. First, It combines dynamic load models and the fixed E’generator model, to simulate the transient stability calculation based on accurate generator models and static load models, by adjusting the proportions of the induction motor load and the constant impedance load in dynamic load models, second, based on the fixed E’q generator model, through setting the angle of the angle criteria to conduct fast contingency screening.
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