HYDRO POWER PLANT BASIC TERMS, TYPES and

COMPONENTS

By

Prasad VejendlaFaculty in Mechanical Engineering

KHIT, Guntur

03.09.2012

TYPES OF POWER HOUSE

• Surface.

• Semi Under Ground

• Under Ground.

• All components of the Hydro power projects are on the natural/excavated ground surface. Surface power house has the advantage of pre- determined topography ,design and is easy to construct. However, these have the disadvantage of limitation of head available as per the topography.

• In such projects the water inlet to the machines could be from a penstock or from a tunnel terminating into a penstock. The water outlet goes into a tail race.

• If the power house is located just adjacent to the Dam then it is sometimes called a Dam-toe power house.

SURFACE POWER HOUSE

Surface Power House

GENERATORTURBINE

EOT CRANE

Surface power house

Semi Underground powerhouse

Some components of the power house are underground, while others are on surface. The advantages of both surface & underground are clubbed together in a semi-underground powerhouse, provided topography & geology so permit.

UNDER GROUND POWER HOUSE

• Depending on the topography, a power house may have to be located inside a mountain. Such a power house is called an under ground power house.

• In such power houses the complete power house equipment are located inside Cavern. In such power houses various tunnels such as Head race tunnel for the water inflow to the turbine, Tail race tunnel for water out flow of the turbine and various access tunnel have to be provided inside the hill/mountain.

• Such power houses take greater amount of time and capital cost to construct.

Contd---• This is very advantages as it overcomes the

limitations of head available as per topography and provide compact and economical layout.

• This requires less land and consequently reduce rehabilitation and resettlement problems(R&R). However, this has the disadvantages of geological uncertainties resulting into indeterminate design and construction problems leading to time and cost over runs

Under ground power house with tunnels

Salient Features of Uri Project(underground power house)

Under ground power house of – 4 X 120MW.HRT - 10.6 km X 9.5m dia. Horse shoe Concrete

lined

TRT - 2.2 km X 9.5m dia Horse shoe Concrete lined

Surge Shaft - 22m circular X 90m depthAdits- 4Nos Total1.7km X 6m modified shoeAdits- 6-TRT .471km X 6.5 X 7m modified shoeMain Access -- .630km tunnelTotal Tunneling- 19.34kmMachine Hall- 127mLx22mBx28mH

All the equipment are placed inside a Cavern

Underground Chamera HEP

CH PH

CH PH

TYPE OF HYDRO POWER PROJECT

• Multi-purpose Project

• Purely Hydro-electric Project

• Run of river project

• Storage Project

• Pump Storage project

Multi-purpose ProjectPower generation may be one of the benefits along with Flood Control, Irrigation, Navigation, Drinking Water Supply etc.

Purely Hydro-electric ProjectProject is conceived exclusively for power generation.

Run of River Project• As the name implies, the project is planned as run of

the river.• Water is diverted from the river, routed through the

water conductor system and finally water after generation of power is thrown back to the river at a lower level on down stream.

• It takes advantage of the drop in elevation that occurs over a distance in the river and does not involve water storage.

• Power generation fluctuates with the river flow and the firm power is considerably low, as it depends on the minimum mean discharge.

• Canal power projects are also run-of-river projects.

Storage Project

• Storage projects provide storage or pondage and thereby, evens out stream flow fluctuations and enhances the water head.

• It increases firm power and total power generation by regulating the flow.

• Providing storage is complicated and costly as it involves construction of dam.

Pump Storage project• Pump storage projects involve reversible

turbines, which can generate power from water of upper reservoir during peak hours and pump back water from lower reservoir to the upper reservoir during off peak hours.

• These projects are advantageous in power system of mix type, which have thermal and nuclear power houses in addition to hydro power projects.

• Pump storage project utilizes the off peak surplus power of the grid in lifting the water from lower reservoir to higher reservoir and generates power during peak hours thus flattening the load curve.

HYDRO DEVELOPMENT- IMPORTANT TERMS

• FRL (FULL RESERVOIR LEVEL)FRL is the Upper level of the reservoir (selected based on techno-economic& submergence considerations)

• MDDL (MINIMUM DRAWDOWN LEVEL)Lowest level up to which the reservoir level could be drawn down to withdraw waters for energy generation (selected from considerations of silt & turbine operational limits)

• GROSS STORAGETotal storage capacity of the reservoir

Hydro Development- IMPORTANT TERMS- Cont

• DEAD STORAGEReservoir storage which cannot be used for generation and is left for silt deposition( below MDDL)

• LIVE STORAGE The storage in the reservoir which is available for power

generation (between FRL & MDDL)

• FIRM POWERContinuous power output in the entire period of hydrological data at 90% dependability

• FIRM ENERGYEnergy generated corresponding to firm power

Hydro Development- IMPORTANT

TERMS- Cont

• Peak Energy Electric energy supplied during periods of relatively high system demands.

• Off-peak EnergyElectric energy supplied during periods of relatively low system demands.

• Load Factor

Ratio of the average load over a designated period to the peak-load occurring in that period

• DIURNAL STORAGEStorage required to meet daily variations in load demand. It depends upon the minimum flows and peak discharges.

Hydro Development- IMPORTANT TERMS Cont

• CRITICAL PERIOD

Most critical period with respect to system load requirements, begins when reservoir begins delivering water for generation from full i.e the available storage is fully drafted at one point during the period; and the critical period ends when the storage has completely refilled.

• CRITICAL DRAW DOWN PERIOD That portion of the critical period in which reservoir live storage is completely drafted while meeting firm energy requirements

IMPORTANT TERMS HEAD – Cont.

• Design HeadThe head at which the turbine will operate to give the best overall efficiency under various operating conditions.

• Gross Head The difference of elevations between water surfaces of the forebay/ dam and tailrace under specified conditions.•

• Net Head The gross head chargeable to the turbine less all hydraulic losses in water conductor system.

Major components of Hydro Power Stations

• Dam/Barrage

• Water Conductor System

• Power House

Dam/Barrage

• Located on rivers, where rock is available at larger depth.

• The dam/ Barrage is used for delivering/diverting the water to the water conductor system.

• The barrage is used to regulate the water for power generation.

DAM KURICHU

BARRAGE AT URI

Water Conductor System• Water conductor system consists of

head race tunnel of suitable size.

• Water conductor system may consist of tunnel, channel, cut and cover as per the topography involved.

• At end of tunnel there is surge shaft.

• The water conductor system conveys water to penstock.

Components of Water Conductor System

• Water intake structure

• Head Race Tunnel

• Surge shaft ,Pressure shaft ,gates, gates and hoisting mechanism

• Penstock Protection Valve

• Penstock

• Main inlet Valve

• Tail Race Tunnel

Water Intake Structure• It consists of gated structure at the

dam/Barrage to control the flow of water and provided with gates along with hoisting arrangement.

• Normally these gates remain open and allows water to flow to the tunnel /channel as the case may be until and unless water conductor system is taken under shut down for repair and maintenance.

Surge Shaft• Surge shaft is located at the end of

tunnel . • It is a well type structure of suitable

height and diameter to absorb the upcoming and lowering surges in case of tripping and starting of the machine in the power house.

• The surge shaft is provided with gates to stop flow of water to the penstock if repairs are to be carried out in the penstock or inlet valves.

Penstock Protection Valve

The Penstock protection valves are provided after the surge shaft to facilitate maintenance of the penstocks. The valves are of butterfly type. The BF valve are operated hydraulically with provision of pressure accumulators in case of power failure.

Pressure Shaft

• When the water conduits in the Surge shaft and Main Inlet valve are not exposed to the atmosphere and buried in the ground/concrete due to its high pressure, these are called Pressure shaft.

Penstock• Penstocks are the water conductor conduit of

suitable size connecting the surge shaft to main inlet valve

• It allows water to the turbine through main inlet valve.

• At the end of the penstock a drainage valve is provided which drains water from penstock to the draft tube.

• In case of long penstock and high head, butterfly valve is provided just before the penstock.

• It takes off from the surge shaft in addition to spherical valve at the end of the penstock acting as the main inlet valve.

Main Inlet Valve• Main inlet valve works as the gate

valve/isolating valve in the water conductor system.

• It is located before turbine and allows water flow from penstock to turbine.

• MIV acts as closing valve and cuts the flow of water during an emergency trip.

• They are of following type.• Butterfly valve (upto 200 m head)• Spherical valve (more than200m head)

BUTTERFLY VALVE

BUTTERFLY VALVE

SPHERICAL VALVE

Components of MIV

• Spherical valve/Butterfly valve• Bypass valve• Oil pumping unit

Spherical valve consist of plate which is in line with the flow of water when in open condition and in totally vertical direction when in closed position.

Bypass valve acts as a means to charge the spherical valve and balance the pressure on either side of valve I,e penstock and turbine

Oil pumping unit is used to pump the oil to operate the valve.

Draft Tube• Draft tube is located between lower ring of

turbine and tail race . It conveys water after discharge from runner to tail race tunnel.

• Draft tube (DT) gates are provided for isolating the Power house and tail pool before taking maintenance of the turbine.

• The DT gates are provided with hoisting mechanism.

• The DT gate may be a single piece or a combination of more than one piece

TURBINETURBINE• Turbine converts potential energy of water to Turbine converts potential energy of water to

mechanical energy and transmits it to the generator.mechanical energy and transmits it to the generator.• Turbines can be of:Turbines can be of:

• Kaplan typeKaplan type• Francis typeFrancis type• Pelton typePelton type• Bulb typeBulb type

• Main components of the turbine include:Main components of the turbine include:• Runner• Labyrinths• Shaft Seal• Guide Bearing• Top Cover• Lower Ring• Guide Vanes

Turbines

• The hydro project are site specific as such the use of standard or off the shelf unit may not be possible. The selection of type of turbine is made on the basis of “Head”. The broad classification is given below.

• Low head(upto60 m)– Kaplan Turbine

• Medium head(30to600m)—Francis Turbine

• High head (more than300m) Pelton

X-SECTION THROUGH KAPLAN TURBINE

PELTON TURBINE

Nore Doppel - NORWAY

KAPLAN

SPIRAL CASING

CUT SECTION SPIRAL CASING

FRANCIS RUNNER

AGUS-PHILIPINES

FRANCIS RUNNER LIFTING

FRANCIS RUNNER BEING HANDLED BY EOT CRANE

GENERATORGENERATOR• Hydro generator is coupled to the turbine and converts the Hydro generator is coupled to the turbine and converts the mechanical energy transmitted by the turbine to electrical energymechanical energy transmitted by the turbine to electrical energy• Generators can be of:Generators can be of:

• Suspended type Suspended type • Umbrella typeUmbrella type

• Main Generator components include:Main Generator components include:• StatorStator• RotorRotor• Upper Bracket Upper Bracket • Lower BracketLower Bracket• Thrust Bearing & Guide BearingsThrust Bearing & Guide Bearings• Slip Ring & Brush AssemblySlip Ring & Brush Assembly• Air CoolersAir Coolers• Brakes & JacksBrakes & Jacks• Stator HeatersStator Heaters

UMBRELLA TYPE GENERATOR

• COMBINED LOWER THRUST & GUIDE BEARING

SUSPENDED TYPE GENERATOR

• UPPER THRUST BEARING -1

• UPPER GUIDE BEARING-1

• LOWER GUIDE BEARING-1

GEN SEC

STATOR SEGMENT

ROTOR

GOVERNORGOVERNOR

• Used for controlling the guide vanes by Used for controlling the guide vanes by detecting turbine speed & its guide vane detecting turbine speed & its guide vane opening in order to keep turbine speed opening in order to keep turbine speed stable or to regulate its output.stable or to regulate its output.

• The performance of the governor The performance of the governor dominates the controllability of the power dominates the controllability of the power plant and quality of electrical power plant and quality of electrical power produced . produced .

GOVERNOR• The hydraulic turbine governor

is equipment for controlling the guide vanes by detecting turbine speed and its guide vane opening in order to keep the turbine speed stable or to regulate it's output

• Governors are provided with the following features;

Quick Response and Stable Control

Guide Vane Opening Detection with High Accuracy

Speed Detection with High Accuracy

High Reliability Easy Maintenance

Thank You

1.What are the component of water conductor system

Ans:Intake structure, Head race tunnel, Surge shaft,Penestock, MIV,Draft tube and Tail RaceTunnel

2.True/falls

MDDL-Minimum draw down level(yes/no)

3.FRL- Full reservoir level (yes/no)

4.RUN OF RIVER have pondage (yes/no)

5. Pumped storage scheme are generally used for peaking power (yes/no)

6.Dewatering system is used to dewater the draft tube and other turbine component

(yes/no)

7. Surge Shaft is used control upsurge/lower

Surge in the hydro power station (yes/no)

8.Under ground power station is installed w

here there is scarcity of land(yes/no)

9.GIS stands for Gas insulated Switchgear

(yes/no)

10.What are advantages of GIS over Conventional switchgear.

• What are the main component on turbine?

• Why single phase transformers are preferred in hydro power plant?

• Sulfer Hexafluoride gas(SF6) is used in GIS.

(yes/no)

• Rotor is the heaviest part of hydro generating machine.(yes/no)