Translated Abstract
In order to ensure the reliability of grid performance, the short circuit current which applied on the transformers must increase due to increasing of national power grid capacity, the short circuit capacity of transformer substation bus and single transformer capacity. At present, high impedance transformer was used to resist the attack from grid current for 330kV and below this voltage grid. In other hand, the cost of the transformer will boost due to the increase of the impedance. So, it will be a trend to studying the proper insulation structure of high impedance transformer. In this paper, it is suggested firstly the design scheme of ‘the cost of high voltage winding built-in sort was controllable’ from comparing several types of insulation structures of 330kV high impedance transformers. A new type of 330kV high impedance transformer is designed, whose structure is hgih voltage winding built-in sort according to the basic design principle, calculation and analysis method and the 500kV & 750kV auto-transformer technique is referred.During the design of the high voltage winding built-in sort, ends outlet structure was designed and the key points of electric field was found out according to the electromagnetic field theory and the key points of insulation structure was calculated and analysised using FEM method. The electrical field of the windings and the impulse characteristics of HV winding, MV winding and regulating winding were also calculated and analysised.By calculating and compareing the flux leakage of insulation structure of high voltage winding built-in sort and positive sequence sort, the effect in energy-saving drop row of high voltage winding built-in sort was evaluated, and the economy benefit of two insulation structure was presented. Besides the economic effect on cost saving by using high voltage winding built-in sort insulation structure was calculated. It is verified by trail-manufacturing and experiment that every performance index of high voltage winding built-in sort insulation structure meet the technique requirement. Compared with positive sequence sort insulation structure, high voltage winding built-in sort insulation structure has obviously effect on energy-saving drop raw. It can be as development direction of the 330kV high impedance transformer design. The research result has been used in the production of 200MVA/347kV that exports to ARUKULA substation in Estonia.
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