(3rd International Conference on Silting Problems in Hydropower Projects, 27-28 February 2008, New Delhi, India, pp. 171-184)
The presence of high silt content in rivers, particularly during peak snow melt and high flows, present an engineering challenge during operation of Hydro Power Plants. This problem is more acute in run-off-the river power plants on Himalayan rivers. Nathpa Jhakri Hydroelectric Power Station (NJHPS)-1500 MW is today the largest Hydro Power Station under operation in the country. It s run-off-the river scheme located in the bouldry reach of Sutluj, a river characterized for carrying hard silt load, large part of which constitute abrasive particles like quartz. As a consequence extensive damage has been experienced particularly to the underwater components of the turbine during the last four year of operation of ths project. Several innovations have been carried out to restrict silt flow to the turbines and also turbines are being refurbished by providing wear resistant coating (HVOF type tungsten carbide). In this paper the provisions for desilting, reservoir flushing and further measures taken for silt control and also the experience gained in refurbishing the turbine with hard coatings for mitigation of damage and operation & maintenance problems due to silt have been addressed. These measures can be useful in planning, design and operation of hydroelectric projects in similar conditions.
