OPTIMIZATION IN SMALL HYDRO POWER PLANTS

Abstract

The hydro power is renewable source of energy and widely used in the world. Mainly the small hydro is renewable, non-polluting and environmentally benign source of energy. There is not a standard definition of small hydro, its upper limit varies from 5 MW to 50 MW, in India upper limit is 25 MW. The small hydro power plants are generally run-of-river type. The important issues in planning SHPPs in mountainous region are selection of major components like diversion structure, water conveyance system, type of generating equipment etc. Proper selection of the major components of SHPPs reduces the operation & maintenance cost as well as minimizes the energy losses at the time of operation. A water conductor of a small hydropower plant is a major component of civil works involving large chunk of land, cost and time—span for installation. Due to its length it is also important in respect of stability and geophysical conditions of site, felling of trees, safety of houses, fields, orchards and roads, maintenance and repair cost, ecological and environmental considerations. Therefore it is important that a most economical, sound and optimally suitable system should be adopted for the water conductor system. A comparative study is carried out in the five operational small hydropower plants of the Uttaranchal State of India for the selection of best water conductor system in the long run. It is found that the tunnel is best option than the open channel comparing the construction cost and energy loss amount. Similarly, other most important issue in planning SHPPs is to determine the optimal installation capacity and optimal energy value. Stream discharge, head, power transmission system, cost of civil works & electro-mechanical equipment and load & demand characteristics are the main input to calculate the optimal economic and reliable installed capacity of SHPPs. The power is directly proportional to head and discharge, for the particular site the head of run-of-river SHPP can be considered almost constant and discharge is varying in whole year, thus the stream discharge plays important role to finalize the installed capacity for economic energy generation. For the determination of installed capacity of the project, the different 36 capacities are calculated on the basis of available 10 daily average discharges of the selected year and on the basis of minimum unit generation cost for first year of operation, the optimal economic installed capacity can be fixed. The unit generation cost can be calculated from the annual cost and annual XII energy generation. Annual cost of project is interest on loan, operation & maintenance cost, depreciation, return on equity, taxes etc and annual energy can be estimated for any restricted power from the available discharge in a year. In this study annual cost for first year of operation is converted into the percentage of project cost and project cost is computed from the developed relationship of cost, head and capacity of different projects.