HYDROELECTRIC POWER PLANT PREPARED BY: PROF.DEEPTI G.PATNE
SYLLABUS • Site selection • Hydrology • Estimation electric power to be developed • Classification of Hydropower plants. • Types of Turbines for hydroelectric power plant. • pumped storage plants. • storage reservoir plants.
SITE SELECTION FOR HYDRO ELECTRIC POWER PLANT. • Preliminary investigation: • The purpose of preliminary investigation is to provide sufficient information to find out the practicability of the proposed scheme and choose between alternative schemes. • The preliminary designs and estimations can be prepared and recommendations are made with reasonable confidence.
kW(Power)=(mgH/1000)*ἠh * ἠm * ἠg • Where: • m= Rate of water flow in kg/sec. • H=Height of fall in meters • ἠh =hydraulic efficiency of prime mover • ἠm & ἠg are mechanical and generating efficiencies • kW=(mgH/1000)*ἠoverall
HYDROLOGY • The science which deals with rainfall and run-off is known as hydrology. • Hydrological cycle:
Rainfall and its measurement • Rainfall: it is a natural process of converting atmospheric vapour into water. • Or • Total condensation of moisture from the atmosphere that reaches the earth, including all forms of rains, ice and snow.
One Centimeter Rainfall • When the quantity of water collected on a certain plain area due to rainfall becomes one centimeter in height, one centimeter of rainfall is said to occur.
Intensity of rainfall • I(intensity in cm/hr)=R/T+C • T=duration of rainstorm in hours • R&C= constant
Average or mean depth of rainfall • Arithmetic mean method: • ha =h1 + h…………+hn /n • ∑h/n
Final Investigation • The final investigations include the detailed exploration of the recommended site so as to establish the complete suitability and to enable the final design. • The preliminary and final investigations include: • Hydrological • Topographical • Geological
Once the location of is chosen,the exact position of different components will be fixed after careful consideration of the following factors: • Requirement of head, flow availability and storage capacity. • The character of the foundation ,particularly for dams. • The topography of the surface at proposed location
Arrangement and type of dam,intakes,counduits ,surge tank, power house and many others. • Availability of materials for construction. • Transportation facilities. • The cost of the project and period required for completion.
HYDROLOGICAL INVESTIGATION • It includes following investigation: • Water availability • Water storage • Water head • Ground water data
Water availability • All other designed based on this. • Estimate should be made on average quantity of water throughout the year and also about maximum and minimum quantity of water available during the year. • The details are necessarily to decide the capacity of hydropower plant • It also provide spillway
Water storage • Since there is wide variation in rainfall during the year,therfore it is necessary to store the water for continuous operation of power. • The storage capacity can be calculated with the help of mass amount.
Water head • In order to operate a requisite quantity of power it is necessary that a large quantity of water at sufficient head should be available. • An every increase in head for the given output reduces quantity of water to be stored and therefore the capital cost
Accessibility of site • The site where hydroelectric plant is to be constructed should be easy accessible. • This is important if the electrical power generated is to be utilized at or near the plant side. • The site selected should have transportation facilities of rail and road.
DISTANCE FROM THE LOAD CENTER. • Power plant should be set up near the load center, it reduces the cost of maintainace of transmission lines.
Type of land of site • The land to be selected for the site should be cheap and rockey • The ideal site is one where dam will have largest catchment area to store water at high head and will be economical in construction. • The rock should be strong enough to withstand stresses transmitted from dam structure • Rock should remain stable at all condition.
HYDROLOGY • It is a science which deals with depletion and replenishment of water resources. • It deals with the surface water as well as ground water. • It also concerned of with the transportation of water from one place to another. • It helps to determine the occurrence and availabity of water
HYDROLOGICAL CYCLE • Most of earth water sources, such as river, lake ocean and underground sources get their supply from rain • The evaporation and precipitation continuous forever and process is known as hydrological cycle. • P=R+E • P= PRECIPITATION • R=RUNOFF • E=EVAPORATION
MEASUREMENT OF RUNOFF • Runoff can be measured daily monthly ,seasonally or yearly. • It can be measured by following method. • From rainfall records • Empirical formule • Runoff curves and tables • Discharge observation method.
Rainfall records • Runoff=rainfall*coefficient • Coefficeint of catchment area • Eg: • Garden apartment=0.50 • Commercial and industrial=0.90 • Concrete pavement=0.85
Runoff curves and table • Each region has its own catchment area and rainfall characteristics and for same region the characteristics mostly remain unchanged. • The graph is plotted in which one axis represents rainfall and other runoff • The curve obtained called run-off curve. rainfall runoff
Discharge observation method • By actual measurement of an outlet of a drainage basin runoff over a catchment can be computed. • The complication in this method is that the discharge of the stream outlet comprises surface run off as well as sub surface flow. • To find out subsurface runoff is essential to separate substances from the total flow. • The separation can be in approximate basis but with correct analysis.
HYDROGRAPH • It is defined as graph showing discharge of flowing water with respect to time for specific time. • Hydrograph of steam of river will depend on the characteristics of catchment and precipitation over catchment • It indicate power available from stream at different times of day, week, month and year
The unit hydrograph (discharge Vs time) • The unit hydrograph represents the unit runoff resulted from intense rainfall of unit duration and specific area distribution. • It is possible to predict a runoff hydrograph corresponding to hypothetical storm. • The basic concept of unit hydrograph is that the hydrograph or runoff from two identical storm would be same
How hydroelectric power plant works? • Flowing water is directed at a turbine. • The flowing water causes the turbine rotate, converting the water’s kinetic energy into mechanical energy • The mechanical energy produced by turbine is converted into electric energy using turbine generator. • Inside, the generator the shaft of turbine spins a magnet inside coil. Producing electric current
How much electricity can be generated by hydro power plant • The amount of electricity that can be generated is depends on two factors. • Flow rate: • Quantity of water flowing in a given time. • Flow head: • The height from which water falls • Greater the flow and head more electricity is produced • Flow rate=the quantity of water flowing. • Power production is directly proportional to river flow • The flow rate depends on size of the river and amount of water flowing in it. • Head-height from which water falls. • Power production is directly proportional to head. • When determining head, hydrologist take into account the pressure behind the water. Water behind the dam put pressure on falling water
A standard equation for calculating energy production • Power= head*flow*efficiency • 11.8 • Where • Power=electric power in KW • Head=distance of water falls (feet) • Flow=amount of water flowing (cubic feet per second)or CFS • Efficiency=turbine & generator convert the power falling water into electric power • these can range from 60%(0.60)older poorly maintained from 90% (.90) newer • 11.8=constant in KW
High head hydropower • Up to 25 to 80 meters-low head. • From-30 to 100 meter-medium head. • From 100 meter-high head.
Water stored in reservoir during rainy season when snow melts • Flow control at gate tunnel by butterfly valve • At turbine gate valve • Pelton wheel turbine
medium • 30 to 100 meters • Francis turbines • Forbay work as surge tank