INVESTIGATION ON OPERATION AND MAINTENANCE CHALLENGES OF HYDRO TURBINES

Abstract

Hydropower is one of the oldest methods of electricity generation. Hydroelectric power plants convert the potential energy of water into electricity. It is one of the cleanest, reliable, efficient and economical sources of renewable energy. In hydropower, two parameters of running water i.e., quantity of water known as discharge (Q) and drop or fall which is called head (H), are utilized for conversion of water power into mechanical energy through turbines and then into electrical energy by generators. One of the most critical parts of the hydropower plant is hydro turbine. It converts the kinetic and pressure energy of water available at its inlet to mechanical energy which rotates the rotor of the generator to generate electricity. Hydro turbines have been developed from water wheels through last few centuries of research and development at various places around the world. Early researchers found that key to increasing the turbine efficiency is shock-free entry of water and minimum exit velocity. Over the past years, various scientists, researches and engineers have studied to improve efficiency and mitigate or minimize the problems that occur during design, installation, operation and maintenance phases. However, the problems associated with the hydro turbines still exist and there is scope to bring further improvement in the technology. In this dissertation work, different types of turbines and their associated challenges in operation and maintenance are studied based on available literature. Many of the problems associated with the hydro turbines are common throughout the world but detailed investigation of actual problems can be found by being site specific. Therefore, this study is based on operation and maintenance challenges faced by 1020 MW Tala Hydropower Plant in Bhutan over years of operation and maintenance. Tala Hydropower is the biggest operating power plant in Bhutan and has immense importance to the energy security and economy of the country. Since its commissioning time, the plant has faced several teething issues. Some of the critical failure incidents of turbine system are investigated and attempt has been made to identify the root cause of the problem, remedial measures taken and the future directions. Estimation of yearly erosion rate and revenue loss due to reduction in turbine efficiency and repair works have been studied. Limiting value of Suspended Sediment Concentration (SCC) above which the power plants need to be taken shutdown has also been estimated for the power plant in this study.