Research On Transformer Models Under Geomagnetically Induced Currents

Transformers are important equipments in power systems,its' operating status influences directly transmission of electric energy and security of power systems.Transformers with neutral grounding will partially be saturated when under Geomagnetically Induced Currents or single ground electrode operation of HVDC.Then vibration of transformers ,Reactive Power and harmonic of systems will increase evidencely.In order to analyze transformers under partial saturation,the paper builds transformer models with J-A Hysteresis loop and single value exciting curve,based on magnetic equivalent circuit in which main and leakage fluxes are considered separately and UMEC magnetic circuit in which main and leakage fluxes are considered together.Structures of iron core and way of windings conection are considered ,and especially auto-transformer models are built in the paper.Based on the models have been built ,great simulations are made about change of harmonic and reactive power ets,and reasonable conclusions are proposed.