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Sunday, 24 August 2014

1200 kV UHV transmission system: For the second most rapidly growing country

" Recent studies by the US department of energy indicate that China, India and Brazil will be the most rapidly growing countries in terms of electrical demand." 

This is clearly echoed in the report, “Working Group on Power”, Government of India, Ministry of Power, 2012, in which the additional generation capacity to be added in the 12th Five Year Plan is stated as 76000 MW. To meet the long term power transfer requirement and for optimal utilization of Right of Way (ROW), large capacity transmission corridors interconnecting the mega power plants and major load centres have been planned. 


Main transmission level in the next Decade:


In the next decade 1200 kV UHV AC system is expected to emerge as the main transmission level in India along with the 800 kV UHV DC system. The power transfer capacity of 1200 kV UHV AC transmission system is expected to be between 6000 to 8000 MW as against nearly 400 MW for a typical 400 kV line.

In this direction work has already began with the laying of foundation stone of Wardha-Aurangabad 1200 kV transmission line in the year 2011 and it is going to be the first 1200 kV transmission line in India and in the world.

1200 kV test station at Bina:


The only 1200 kV test station at Bina in Madhya Pradesh (India) with two 1200 kV bays, one single circuit (S/C) 1200 kV transmission line of 1.1 km length and 0.8 km of 1200 kV double circuit (D/C) line has already been dedicated to the nation in the year 2012. The system parameters of this 1200 kV UHV system were finalized after an extensive simulation study and giving due weightage to cost and size optimization. 


Testing of In-house manufacturing techniques:


Single phase auto-transformers of 333 MVA, 1200 kV each are installed considering the high voltage level and the difficulties encountered during transportation. With the successful charging of bay –I and the lines, India has achieved world’s highest transmission voltage level. Powergrid Corp. of India Ltd. and the consortium of 34 Indian electrical equipment manufacturers have shown to the world their in-house capabilities in developing the 1200 kV transmission technology


For example, 1200 kV capacitor voltage transformer and optical current transformer were manufactured by Alstom, auto-transformers by BHEL, Crompton Greaves, and Vijay Electricals, 1200 kV circuit breaker and surge arrestors by Siemens, 1200 kV isolators by Hivelm Ind etc. 

Upon charging of bay-II, more extensive field tests with the equipment loaded will be carried out. With this 1200 kV substation this small town of Madhya Pradesh (India) will fare prominently on the global power map as it already has 220 kV, 400 kV and 765 kV substations.

  
This project is a unique example of public-private partnership (PPP) in which all the UHV equipments have been developed indigenously by Indian manufacturers with PowerGrid providing the required basic design and specifications and other resources. This project is a milestone in India’s power transmission sector.

History of UHV transmission system:


Research on UHV transmission system is not new to the world as it started way back in 70’s and 80’s. Experimental UHV lines and substations were built in USA, USSR, Italy, Japan and China to develop the technology. However as the requirement of power transfer was not substantial as seen today in India and China, commercialization of UHV AC system has not taken place at that time. 
" For example, in USSR, a 411 km, 1150 kV Ekibastuz-Kokchotav-Kustanai transmission system was commissioned in 1985. The transmission line was in operation for about two years but after the split of USSR it was operated at 500 kV. "
China’s effort on UHV transmission system is quite advanced. It's preliminary work on UHV AC transmission began in 2004-05. The commercial operation of world’s first 1000 kV UHV AC transmission line at full rated voltage was started in China in the year 2009. The 650 km long Jindongnan-Nanyang-Jingmen line has a transfer capacity of 5000 MW.