Design of a cost effective micro hydro power generation system using the discharge water of the central steam power plant

Abstract

Electric energy plays an important role in accelerating economic growth of a country. Sustainable human development, which means economic growth through equitable distribution of benefits, can only be ensured through the fulfillment of the energy needs of the nation. Reliable electricity supplies have a great positive impact on our gross domestic product (GDP). Bangladesh is one of the developing and most densely populated countries in the world besides it has very limited indigenous natural energy resources like natural gas, coal and oil. So the present electric energy crisis has made the necessity to the exploitation of non conventional and renewable energy sources. This research work presents the prospects of micro hydro potential in Bangladesh by using discharge cooling water of Central Stream Power Plant (CSPP) as an alternative source for Micro Hydro Electric Power Generation System (MHPS). In this research suitable type of turbine and generator set has been proposed for various CSPP according to their site condition. Moreover a cost effective MHPS has been designed, fabricated and implemented according to the measured discharge and net head available in Chittagong Thermal Power Plant (CTPP). Here a Cross-Flow Hydro Turbine (CFHT) is used as prime mover and induction motor available in local market used as Self-Excited Induction Generator (SEIG). The parameters of the CFHT are calculated by soft program where some optimum design parameters were used that amplify the efficiency of CFHT. This soft program also helps, to calculate and identify the best design parameters for the site under consideration. In an electric power system, consumers require uninterrupted power at rated frequency and voltage. To maintain these parameters within the prescribed limits, suitable control strategy has been developed for the system. Voltage is maintained by the control of excitation of the generator and frequency is maintained by eliminating the mismatch between generation and load demand. In this research work this task has been suitably done by a microcontroller based Electronic Load Controller (ELC). Here the ELC is used to control the excitation of induction generator (IG) as well as to maintain balanced load on IG terminal. To improve the dynamic performance of the system, battery energy storing facility and a ballast load bank is also included in the designed ELC. Preliminary test of the design system has been performed in the fluid mechanic laboratory, BUET to predict performance of the system. In the preliminary test the MHPS generated 384 watt electric power and the overall efficiency of the system was found 43 percent. This project is technologically and economically sustainable because of that it is developed by indigenous technology and the materials used in this project are available in the local market.