Research On The Eddy Current Field And Related Problems For Ultra-High Voltage GIS Equipments

Along with the rapid development of our country's extra-high voltage power grid, China power grid is develop from extra-high voltage to ultra-high voltage. In the ultra-high voltage power grid, the reliability and security of the GIS equipment is the basic of the power transmission system running. The eddy current loss and the local overheating problem in the GIS equipment is a very important problem. The larger GIS capability is, the greater leakage magnetic is, the greater the eddy loss is, the more distinct calculation of local overheating caused by the eddy loss is. So how to solve this problem has became very vital and practical.The purpose and significance of the current loss and temperature rise field calculation are introduced in the beginning of the thesis, then the development of the eddy loss calculation and the actuality and trend of whole set GIS equipment's field numerical analysis are discussed. By using the theory the finite element method, the large universal finite element software-Ansys is used to analyze and calculate accurately the current loss of the 1100 kV GIS disconnector and bus bar. Firstly, the 3-D finite Element analysis model is established to analyze the power-frequency magnetic field of 1100 kV GIS disconnector and busbar. The distribution of magnetic field intensity, the values of eddy currents and the short circuit force are calculated in the magnetic field. Then the induced current and power loss were calculated for different shell material thickness in multiple-point-earthing system. The effects of shell material and thickness to the loss power were compared in detail.Secondly, on the base of the result of eddy loss calculation in the prime conductor and the shell parts, the magnet-fluent- temperature coupled field in the GIS disconector and busbar is analyzed. This paper considers the joule loss as the load of fluent analysis by using the method of direct coupled field. Then the distribution of temperature rise field and the velocity field of the inner SF₆ gas in the prime conductor and the shell parts can be obtained by solving fluent field and temperature field. The result is similar to the experimental one, so the accuracy of result and the feasibility of Ansys simulation is demonstrated.Finally, based on the example of ultra-high voltage GIS bus bar ,the magnetic field of noncontinuous enclosure type is analyzed and calculated, and the effects of two attended modes to the distribution of magnetic field intensity were compared.