665 / 2022-03-31 11:25:42

Analysis of short-circuit fault of 500kV transformer up sear and it structural improvement

Transformer,short-circuit fault,structural improvement,electric field distribution.

Purpose/Aim

Transformer is the core of substation and converter station, which is in the throat of power system. Therefore, in case of sudden failure of transformer, it will inevitably lead to major power failure and huge adverse impact. This paper focuses on an explosion and fire accident in the up seat area of transformer. By analyzing the discharge path and electric field distribution, the cause of the accident is inferred, and strategies are put forward for subsequent structural improvement and optimization and quality control to prevent such accidents from happening again.

Experimental/Modeling methods

In order to deeply analyze the causes of discharge accidents, this paper investigates the discharge traces in the area of transformer rising seat at the scene of the accident. On this basis, the finite element simulation model of transformer raised base area is established, and the influence of different voltage equalizing shielding structure design on the electric field distribution characteristics in this area is simulated and analyzed. According to the simulation analysis results, the main culprit of the explosion accident is further confirmed, and the requirements for the structural design of the up seat area of transformer are put forward.

Results/Conclusions

The main reason of the accident is the significant concentration of electric field caused by the shielding ball which uncoated with insulating paper in the up seat of the transformer. Through structural optimization, the maximum value of electric field on the surface of the shielding ball can be reduced from 4.059kV/mm to 2.429kV/mm, and while the interface between insulating paper and transformer oil is 3.950kV/mm, which is much lower than the original structure.The research results of this paper can provide reference for the design of similar insulation systems.