Analysis Of Electric Field On Surface Of Valve Hall Fittings In Converter Station

Ultra high voltage direct current(UHVDC)transmission has many advantages in power transmission,such as large transmission capacity,long transmission distance and low loss.The use of UHVDC transmission technology not only saves transmission resources,but also improves the utilization rate of transmission corridors,and meets the strategic requirements of China's sustainable development.The valve hall of the converter station is the core of the UHVDC transmission project.The internal space is limited,and the equipments are closely arranged.This has high requirements for the corona control,design,manufacturing and installation process of the valve hall fittings.At present,China's ultra high voltage(UHV)valve hall fittings have gradually begun to be localized.Considering China's long-term planning and localization requirement for UHVDC transmission and converter stations,accurate surface electric field distribution calculation for UHV valve hall fittings is of great significance to the design and type selection of the fittings.In order to accurately simulate the electric field distribution on the surface of the internal fittings in the valve hall,this thesis takes a valve hall of a ±800kV converter station as the research object,and uses the finite element method as simulation tool.The research work on how to accurately calculate the electric field distribution on the surface of the fittings and provides a reference for the fittings' design and planning.The specific research contents are as follows:(1)This thesis started with the principle of electromagnetic field calculation,and discussed the potential loading method of high-voltage equipment in the valve hall under steady state conditions.Under alter current voltage,the electric field distribution characteristics of the fittings surface was considered,and static field was used to calculate it instead of transient field.The effectiveness of the voltage loading method was proved by a two-dimensional model;(2)The three-dimension finite element model of valve hall was built using Pro/E modeling software.Because complex models have a large number of elements,equipments for non-focus areas were simplified appropriately.At the same time,to improve the efficiency of mesh and calculation,a block subdivision method was used to divide the grid reasonably and the size of the mesh was discussed.(3)This thesis calculated the electric field of the whole model under steady state conditions,and obtained the potential and electric field distribution cloud map of the valve hall fitting surface in a period.Combined with the Peek formula and experimental data,the initial corona field strength of the grading ring,the tubular bus and the ball fittings in the valve hall were checked.The results showthat when the valve hall runs in steady state condition,there is a large margin of the surface field strength of the fittings.By studying the voltage loading method and the mesh method,the electric field distribution on the surface of the valve hall fittings is effectively solved in this thesis.Under the premise of ensuring the calculation accuracy,the calculation efficiency of the electric field solution of the valve hall full model is improved,and the hardware requirements of the electric field calculation are reduced.For the complex model such as valve hall,this thesis provides a systematic analysis method,which has important reference value for realizing the localization and independent design of valve hall fittings in China.Figure [33] table [11] reference [64]...