Effects of hydro-abrasive erosion on efficiency reduction of a Pelton turbine in Indian Himalayas

The problem of hydro-abrasive erosion due to sediment is becoming more severe for hydropower plants (HPP) owing to extreme floods caused as a result of climate change, especially in geologically young mountains, like the Andes and the Himalayas. In high-head HPPs, even small sediment particles cause critical hydro-abrasion resulting in loss of efficiency, interruptions in power production and downtime for repair/maintenance. Currently, only limited information is available as there is a lack of practically proven measurement techniques as well as reliable measurement data on suspended sediment properties and turbine erosion with efficiency losses. Hence, simultaneous measurement of suspended sediment properties, hydro-abrasive erosion and reduction in efficiency was carried out to find the optimum strategy for an HPP located in Indian Himalayas. The curved portion of Pelton buckets towards the bucket root was found to be the most severely affected region by hydro-abrasive erosion apart from splitter and cut-out. The operational strategy to operate the units near rated power after the erosion was recommended to yield more efficiency compared to operations at part load conditions. This study is useful for the optimum operation of an HPP with respect to hydro-abrasive erosion.