News at STRI
June 17, 2010 - STRI - The Ultra HVDC Specialist
Ultra High Voltage Direct Current (UHVDC) with 800 kV is now being implemented in China and India to efficiently transmit large amounts of energy over long distances from remote hydro power plants. STRI has been involved in the testing of this new technology during the past couple of years both for China and India. This includes testing of basically all components such as bushings and converters as well as a long term test of a complete system during different seasons energized at 850 kV for ABB. Now a number of tests have been performed for the transmission line isolation for the first 800kV UHVDC line in India.
One 800 kV UHVDC transmission line can transmit up to 6000 MW. Any fault on this line requiring the shutdown of the system may consequently result in a significant disturbance. The insulator strings used for these transmission lines have to be designed to minimize the risk for flashover due to lightning strokes, switching surges, rain and pollution. STRI has unique resources to perform all of these tests and also to optimize the insulation by special designed software – The Line Performance Estimator. LPE which is combining theory, statistical and real results from our testing.
Insulation can be of glass, porcelain or composite material. STRI has earlier performed tests on 800 kV UHVDC composite and porcelain insulator strings. (See our website January 20, 2009 - STRI performs successful HVDC testing for BHEL and POWERGRID of India.) During spring 2010 we have continued those tests for the first 800 kV UHVDC project in India for BHEL (Porcelain) and SEDIVER (Glass) according to the requirements of Power grid India.
The successful SEDIVER testing of glass insulators were completed in June, 2010 and included all di-electric tests (Lightning, Switching, RIV, Corona, DC withstand wet test) and pollution tests of two different designs, triple string and Y-string as well as different suppliers of hardware. A challenging procedure testing the insulator string and conductor with a length of 20 meters and a Y with about 16 meter width and 12 meter height. More than 5 ton tension was used for the set up. The wet switching surge test was one of the successful tests being performed during artificial rain at 1850 kV. Together with the other successful tests of different designs, this first 800 kV UHVDC transmission line in India now has been exposed to varying stresses and verified for their performance.
