Design analysis of 1200 kV UHV transformer using finite element method

Ultra High Voltage (UHV) power transmission system is a key for providing a stable long-term power supply and will be choice of bulk transmission with reduced losses. The success of the UHV AC systems is depending on the primary equipment, especially on transformers. Due to challenges like large capacity, transportation limit, advanced and innovative technology needs to be applied in the designing stage itself. This paper discusses usage of Finite Element Method based simulation for verifying the critical aspects like insulation design, structural design and magnetic leakage/local overheating. Based on the analysis of initial design, various modifications are made to improve safety margins of the critical regions. By incorporating some of the modifications, a 333 MVA, 1150 kV/400 kV/33 kV, Single Phase Auto Transformer with ODAF cooling was manufactured in 2011. The product is tested for the acceptance tests and it is observed that measured values of short circuit impedance, tank deformation are in agreement with the calculated values. The product is commissioned at Power Grid 1200kV Test station, Bina in Madhya Pradesh, India.