414 / 2022-03-15 20:31:49

Simulation of gas migration in the ascending flanged base of oil immersed transformer

fault gas,Dissolved gas analysis,transformer

Purpose/Aim

The large oil gap and poor oil circulation in the ascending flanged base of large transformers may lead to delay in the transport of fault characteristic gases, making it difficult to detect a potential fault in time by the on-line or off-line dissolved gas analysis technology, which seriously endangers the safe operation of the transformer.

Experimental/Modeling methods

A simulation model of the L-shaped ascending flanged base of the forced oil circulation transformer is established in ANSYS Fluent. Hydrogen was chosen as the representative species due to its highest diffusion coefficient among the fault gases. Using the finite element method, and considering the convection and diffusion processes, numerical simulations of the velocity distribution and hydrogen transport in the ascending flanged base were carried out.

Results/discussion

Results showed that the slow oil flow in the ascending flanged base impedes the transport of the fault gases, i.e. the H₂ content at the port is more than two orders of magnitude smaller (~6 μL/L, lower than the alarming concentration) than that near the equalizing ball of high voltage bushing (~1000 μL/L, which may lead to the failure in fault detection.

Conclusions

The slow oil flow in the ascending flanged base makes the characteristic gas difficult to diffuse. Through Ansys modeling and simulation, the flow rate distribution and the dissolved gas transport process are analyzed in the ascending flanged base, which provides a reference for oil circulation structure optimization and online monitoring.