Research On The Measurement Method Of Lumped Equivalent Source Based On GIS Switching Transient Field

Gas-Insulated substation is the most concentrated place of high voltage intelligent equipment, is also the most prominent situations of electromagnetic compatibility. Intelligent component failures caused by EMI is the main reason on the reliable operation. Switching transient field is the most common and most serious disturbance source, and its coupling with the secondary cables is a major way electromagnetic disturbance to intelligent component ports. The paper mainly studied the suppression measures of the secondary cables terminal disturbance voltage, carried out the following works:Firstly, based on transmission line theory the lumped equivalent source is presented in this paper. Depending on the nature that the lumped equivalent source is independent of the terminal load, the lumped source is the same for the different terminal load under the identical incident field. The terminal responses of different terminal conditions can be researched using the obtained equivalent sources. The validity and accuracy of this method was verified by experiments. The method combined with the experimental measurement and theoretical calculation, through experimental measurements obtained lumped equivalent source, then it can be used to research the efficiency of different suppression measures systematically.Secondly, in order to better study the suppression measures of the secondary cables terminal disturbance voltage and obtain the necessary lumped equivalent source, the experiments of transient electromagnetic process caused by disconnector operation. The experiment was carried out in the 252kV GIS experimental platform. Measured VFTO and TEV of different positions, obtained the characteristics of the transient disturbance source; Measured the secondary cable terminal disturbance voltage under the situation of simulate the actual substation intelligent components, studied the influence of shielding and grounding of the cable shield on disturbance voltage.Lastly, Using the lumped equivalent sources obtained in 252kV experimental platform efficiency of different suppression measures was analyzed. Suppression measures include shunting capacitance at cables terminal and shorting inactive conductors to the cable shield. Analysis results show that after shorting inactive conductors to the cable shield, the voltage decreases more than 13%; after shunting 1nF capacitance, the voltage decreases by 60%.