| The paper focuses on analyzing the signal of voltage sags.Firstly,a Kalman filter model for voltage sags is presented to detect the characteristics,and tested using simulated example in MATLAB.The simulation results show that three characteristics of voltage sag,namely,amplitude changing and phase angle jump as well as lasting time, can be extracted using the model.Secondly,we have analyzed the discrete data of voltage sags using symmetrical component method combined with information of amplitude and phase angle,by doing so,a kind of criteria is obtained to discriminate types of voltage sags , and simulation results verified the correctness of the criteria.Finally,a method for calculating sag exposed areas of a sensitive load in a bus in power grid is proposed when short circuit faults happened on the line between two buses named substation.At the same time,sketch map of sag exposed areas is plotted for a phase of the sensitive load. |
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