Research Of Equivalence Of HVDC Corona Loss Of The Conductors Based On Corona Cage And Test Line

In order to meet the increasing power demand of our country,the construction of UHV power grid is an important way to realize the optimal allocation of resources.When the voltage increases,the electric field intensity on the conductor surface increases,and corona generated when the voltage exceeds a certain value.The corona loss is caused by the process of corona discharge,which is unfavorable to the economic transmission of electric energy.The corona loss caused by corona discharge of conductor should be considered in the design of transmission line and controlled within a reasonable range.The corona loss of different types of conductors is usually studied by using UHV corona cage and test line.At present,many theoretical calculation and experimental studies of corona loss of HVDC transmission based on corona cage and test line have been carried out,and many calculation results and test data of corona loss have been obtained.So it is necessary to study the equivalent relationship of corona loss between corona cage and HVDC transmission line.In this thesis,in order to get the equivalent relation of corona loss of corona cage and transmission lines,first,transmission lines and the corona cage are calculated conductor surface nominal electric field intensity respectively,and then calculate the electric field intensity and the ion current density under the two kinds of structure,finally,get the corona loss and compare,get the corona loss equivalent relationship.Based on the mirror image method,a formula for calculating the electric field intensity on the surface of arbitrary split conductors is proposed in this thesis.The formula for calculating the electric field intensity on the surface of arbitrary split conductor and the formula for calculating the nominal electric field intensity on the slope when the single-loop bipolar transmission line passes through the slope topography such as mountains and hills;The formulas for calculating the electric field intensity of the split wire surface in a mono-polar square corona cage and the formulas for calculating the spatial nominal electric field intensity are presented.Based on the formula of the standard electric field intensity and the flux line method,the electric field intensity and ion current density in the space of the bipolar transmission line and the corona cage are calculated.Finally,the corona losses of transmission lines and corona cage conductors are obtained by integrating the ionic current density on the surface of the lines.Considering the influence of pole spacing,conductor height,corona cage edge length and other parameters of the bipolar transmission line,corona losses related only to the nominal electric field intensity of the wire surface are obtained.The corona losses of the transmission line and the corona cage are equivalent,and the equivalent relationship is obtained.The fitting formula of corona loss relation between corona cage and test line is proposed.The results of this thesis are of great significance to the actual corona loss prediction of transmission lines.