Influence Of Non-uniform Temperature On Transient Electric Field For ±500kV Converter Transformer Under Non-sinusoidal Steady AC-DC Compound And Polarity Reversal Voltage

The safety of converter transformer takes an important part in HVDC system,and it's necessary to analyze electric field coupled temperature field,including hybrid electric field and PR electric field which are both calculated in this paper.The domestic and foreign experts have done a lot of researches about temperature field and electric field in converter transformer recently,however,the calculation of the multi-physics coupling filed is vacant.In this paper,a one-way coupling method is adopted.The ±500kV converter transformer with the heat losses of iron core and windings is calculated by Fluent,a kind of CFD software,and the velocity and temperature field can both be got.The results can be verified by empirical formulas and thermal-electrical analogy theory.Meanwhile the factors(e.g.the velocity of inlet,the guided partition numbers and ring numbers)which could affect the heat disputation are discussed.Then,the fast mapping method is utilized to transmit data to the model in electric field.In calculating hybrid electric field,the frequency domain finite element method with scalar potential is used to get the electric fields at both conditions with temperature fields or not.Besides,the lumped-parameter model from thermal-electrical analogy theory is established to calculate the temperature time constant which compared with the time of PR process in PR electric field.Finally,the results with temperature or not which include different of time of PR process could guide to design the transformer insulation.