Electric field calculation and material optimization of 765kV bushing using FEA

Abstract

Transformer bushings are one of the important components in the construction of high voltage power transmission. The structure and materials used in electrical bushings play a vital role in the durability and lifespan of the bushing. Although the cost of transformer bushing is very minimal in the transmission system extensive damages are caused in case of failure. The main reason of failure in the insulation materials are caused due to moisture ingress and formation of voids, cavities. When the appropriate material is used along with an optimized structure, the electric field is distributed evenly which reduces the stress and increases the longevity of the bushing. In this paper, Finite Element Analysis(FEA) is used to calculate The ELECTRIC FIELD DISTRIBUTION and THERMAL(Temperature) Analysis is done for 765kV transformer bushing by using different insulating materials such as Epoxy Resin, Porcelain, Oil Impregnated Paper, Resin Impregnated Paper and Polymer.Henceforth, by using the above insulating materials the total stress level of the bushings corresponding to the net electric field distribution is in turn calculated using ANSYS 13.0Software. The results are compared and analysis is done for the different insulating materials. Based on the electric field distribution over bushing material, it is used to identify optimization of bushing design.

Electrostatic Field Calculation and Structure Optimization of New Shield Ring of 1000 kV Nan-Jing Loop Transmission Line

“…3D Finite element electric field simulation is used to calculate the surface field intensity on the fittings of the transmission line and valve hall, in addition, a visible corona test has been also carried out for true fittings, whose results are consistent with the simulation results [6]. Besides, the 3D finite element method is also utilized for simulating the power-frequency electric fields, which provides necessary reference for optimizing the design scheme, thus making the power-frequency electric fields after scheme optimization meet the design requirements for field intensity [7,8].…”

“…According to the Peek formula, the critical corona inception field intensity of the wire is calculated by Eq. (7).…”

“…On this basis, the structure of TMD shield ring was optimized, and the TMD placement position was changed, with (7…”

Recent Trends in Emerging 765kV/800kV Power Transformers

“…For all 04 bushings above, the measured values are well within the limit of 0.5%, and may be judged as healthy conventionally. But, as per recent trends of tan δ measurement of all EHV bushing must maintain the yardstick limit of 0.5% for entire range of frequency [11] or as per OEM manual. For the cases, where tan δ is within limits at power frequency but exceeding in lower or higher frequency range, then it may be inferred that the same is prone to malfunction and may cause trouble in the long run.…”

“…The reliable design and operation of EHV transformer requires selection of appropriate material/design of the Bushings. The optimization of bushing design of 765kV transformer using different insulating materials such as Epoxy Resin, Porcelain, Oil Impregnated Paper, Resin Impregnated Paper and Polymer are elaborated in [11], and reliability aspects of bushings are discussed in [12] and such the reliability aspects of power transformers based on inservice data/failures statistics are discussed in [13] For implementation of ±800 kV HVDC transmission, an appropriate converter transformer is required. The insulation properties of oil-immersed-paper and transformer oil used with these converter transformers need appropriate design, analysis and testing.…”