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Advanced Hydropower plant engineering SEng70691BAHIR DAR UNIVERSITYInstitute of TechnologyGRADUATE PROGRAM IN

Bahir Dar University , Institute of Technology School of Food Processing and Chemical Engineering Copyright ,TassTad , 2009 2010Hydro-Electric Power Plants4/2/2012

System Studies14/2/2012Introduction

Water flowing from higher level to lower level has kinetic energy which can be converted to mechanical energy and then electrical energy.

The hydro-energy in flowing water is a function of weight of water and the head through which the water falls.Hydro-energy is an easily storable, conventional renewable energy.

The question is how much water can be stored for channelizing through penstocks and hydro turbines, economically and conveniently,

The water stored in the upper reservoir/ lake/ pond constitutes the primary energy. The water flows through the pressure pipe line and through the hydro- turbine and draft tube to the tail race.

The hydro-turbines drive the generators and the water is discharged through tail-race.

The potential energy is stored water in the reservoir at high head is converted into kinetic energy in the flowing water.The flowing water converts the energy into mechanical rotary energy in the hydro turbine.

Hydro-turbine drives the rotor of hydro- electric generator.Bahir Dar University, Faculty of Engineering School of Computing and Electrical Engineering Copyright 2009, TassTad

Hydro-Electric Power Plants4/2/20122Typical Hydro-Electric Power Plants Hydro Electric Schemes have a reservoir or a pool on one side of the darn and turbine generator units on the other side at lower level.

The Head of water results in the flow.

Energy is proportional to total weight of upper level water than can flow through turbine multiplied by the Head of fall.

The head of water and flow rate have decisive influence on the choice of the turbine.

The types of Hydro Plants are: 1. High Head 2. Medium Head 3. Low Head. 4. Underground high head.

Reservoir is created in a valley by building a dam across a river flowing through the valley at reasonably high level.

The power plant is built on the downstream side of the dam. Water from the reservoir may be taken through pressure pipe, tunnel, penstock etc. up to turbine.

The plant rating range covers a few hundred kW to a few thousand MW. Bahir Dar University, Faculty of Engineering School of Computing and Electrical Engineering Copyright 2009, TassTad

Hydro-Electric Power Plants4/2/20123

Bahir Dar University, Faculty of Engineering School of Computing and Electrical Engineering Copyright 2009, TassTad

The figures. below illustrate typical conventional Hydro Reservoir Schemes.Hydro-Electric Power PlantsHigh Head Hydro-Electric Power Plant.High Head Scheme has a large reservoir on higher level and water from high level reservoir flows through pressure pipe to the turbine and is finally discharged into the tail race.

The upper reservoir is usually formed by constructing a dam on a river valley at high level.

The excess water from the reservoir is discharged through the gates in the dam.

The tail race water usually meets the river along the down-stream.4/2/20124Hydro-Electric Power Plants

Medium-Head Hydro Electric Power Plants.Bahir Dar University, Faculty of Engineering School of Computing and Electrical Engineering Copyright 2009, TassTad

Low-head Run-of-River Scheme (Small Hydro).Medium Head Scheme has usually a darn on a river forming the reservoir on the river side and a hydro-electric power plant on the lower level. The tail race water is discharged into the river.Low Head Scheme is usually with a barrage* on a flowing river and turbine-generator units mounted' within the nozzle shaped tubular passage through the barrage.Low Head Schemes are generally Run-of-River schemes with a low high barrage or weir across a river or a canal. The bulb type or tube type turbine-generator is installed axially within the passage of water through the draft tube.* river barrier: an artificial barrier built across a river or canal to provide water or prevent flooding.The low head schemes are generally small hydro schemes rated up to 15 MW.4/2/201254/2/20126Hydro-Electric Power PlantsBahir Dar University, Faculty of Engineering School of Computing and Electrical Engineering Copyright 2009, TassTad

Turbine and Pump at Storage type hydropower plantPumps:n (rpm)lossCentrifugal10-80 HH&SDQH/PiMixed flow70-180 MH&MDAxial flow150-320 LH&LDTurbines:n (rpm)lossPelton10-40 HH&SDP/QHFrancis35-400 MH&MDKaplan300-1000 LH&LD,.-- ; ; . , l

Turbine PumpBahir Dar University, Faculty of Engineering School of Computing and Electrical Engineering Copyright 2009, TassTad

Hydro-Electric Power Plants

Underground Hydro-Electric Power Plant.Underground Hydro Electric Power Plants are built at lower level and inside a cave. The tail race water is discharged through a tunnel into the downstream path of the river.4/2/20127

Example:Tana-Beles Multipurpose Hydro Electric Power Plant The small hydro power plants are considered as nonconventional. Hydro-Electric Projects rated up to and including 15 MW, are called Small Hydro Projects. Projects rated up to and including 1 MW rating are called Mini Hydro Projects.

Projects rated up to 100 kW are called Micro Hydro Projects. The terms are somewhat arbitrary and not exact. Conventional Hydro Projects are generally in the range of 100 MW and above.

The economics of Small/Mini/Micro Hydro Projects is different from that of Conventional Hydro Projects.

The Mini/Micro/Small Hydro Projects are further classified as Low Head/Medium Head/ High head Projects:.

Bahir Dar University, Faculty of Engineering School of Computing and Electrical Engineering Copyright 2009, TassTad

Hydro-Electric Power PlantsLarge> 100 MWLow Head2 to 20 mMedium> 15 MWMedium Head20 to 150 mSmall Hydro 150 mMini Hydro