IMPROVEMENT OF THE APPARENT IMPEDANCE ANGLE SEPARATION CRITERION
Gao Peng, Wang Jianquan, Zhou Wenping(Zhejiang University, Hangzhou 310027, China)(Guodian Nanjing Automation Co Ltd, Nanjing 210003, China)
Based on the study on the characteristics of the changes of tie-line power flow and apparent impedance angle of out-of-step equivalent two-machine power system, this paper has found that the apparent impedance angle separation criterion cannot get the actual number of swings. That is because system loses its synchronism quickly due to severe accident and becomes asynchronous in excess electromagnetic transient state. A method of calculating the number of swing is proposed by setting a proper threshold to compute the number of the active power zero-crossing. Simulation studies are given in the paper and the field experiences have proved that the method can detect the correct number of short period swings.
【CateGory Index】： TM712