Research On Large Scale Transformer Transient Models Under Geomagnetically Induced Current In The Power System

When Geomagnetically Induced Currents and the single polar earthing current of the HVDC project invade the grounded transformer neutrals, the large scale-transformer working at the rated state will partially be saturated, and its magnetic current will be distorted accompanying with various of harmonic,increasing reactive power demand,noise,vibration and some other affiliated phenomenon. In order to precisely analyze the transient behavior of the saturation and various electrical variables, this paper establishes the large scale transformer transient model which is used to study GIC problem through S-function, adopting JA theory and combining equivalent electromagnetic model and UMEC equivalent circuit model of transformers. Simulation of the transformer magnetic inrush current under different closing phase angle, remanent magnetization and the normal current. According to the magnetic storm intensity of 2004, this paper analyzes the distorted magnetic current, reactive power demand, the effect on the differential protection of 750kV transformer in the north-west power grid, finally power system simulation software PSCAD/EMTDC has verified the validity of JA model.