Abstract：By using the simplified two linear lines to represent the curve of transformer core,the mathematical expression of transformer reactive power with geomagnectically induced current (GIC) as the intermediate variable is derived.Through the fitting analysis of the intermediate function,it is proved that when the GIC current is less than a certain value,the relation between the GIC and reactive power is linear,the proportional coefficient between them and the expression of dc upper limit threshold are given.Through the finite element simulation of UHV ac transformer and converter transformer,the correctness of the theoretical conclusion is proved,and a practical expression for GIC-Q calculation of UHV transformer in China is given.The conclusion is further proved to be correct through the experimental study on the ratio model of UHV AC transformer.In view of the difference between the ratio coefficient obtained from the experiment and the coefficient derived from the theory,an explanation is given and the range of the ratio coefficient applicable to the reactive power calculation of the actual UHV transformer is given.
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2020, Vol. 35 
