Niche for Variable Speed Machines: Case Study of Tehri PSP

With the advent of semiconductor technology in power system the variable speed machines have become common practice world over. In the beginning, variable speed drives were mainly cyclo-converters. With the growth in semiconductor technology, IGBT, IGCT etc. based variable speed drives, offering better control & efficiency over wide range of operation of the machine, are available now. Tehri PSP has the credit of employing the first variable speed machine in India. However, some pumped storage plants undergoing retrofitting are also opting for variable speed machines now. In this paper an attempt has been made to analyze the model study data pertaining to the prototype of Tehri PSP machine to illustrate the advantages of variable speed machine over the fixed speed machine.