Research On Electromagnetic Disturbance Of UHV VFTO For Secondary Equipment

In UHV GIS (gas insulated substation), produced very fast transient over-voltage (VFTO) will affect the normal work of secondary equipment.Supported by China Ministry of Science and Technology under Contract (973Project)(NO.2011CB209405), and VFTO radiation field influencing secondary equipment because of operating disconnect in the GIS is mainly studied.The paper use the finite difference time domain method (FDTD) as the theoretical basis because because it belongs to the transient electromagnetic field.Firstly,the basic principle of electromagnetic shielding,coupling mechanism and coupling path between VFTO radiation field and secondary equipment are analyzed. Secondary,the paper combine with the basic principle of FDTD and uses XFDTD to build rectangular cavity with hole.By changing shape and length-width ratio of the hole,distance between the hole array,and the number of hole array to study hole coupling under VFTO radiation field.Because PCB can affect the time domain and frequency domain properties of coupling field in the cavity,these properties are analyzed by changing the distance between slot and substrates, and size of the substrates.And then VFTO radiation field affecting microstrip line in the secondary equipment is studied by changing the slot’s size and electric polarization direction to analyse microstrip line port harassment voltage level.Because VFTO radiation field can coupling in the secondary equipment through bare part of the cable,the paper studys the influence on the different length of bare part.In order to test and verify the simulation result.the paper places a real second equipment in the1000kV GIS simulation platform.Simulating VFTO radiation field disturb second equipment because of operating disconnect switch.Finally.the paper sums research result on VFTO influencing secondary equipment and and discusses this topic further work.