TYPES OF POWER HOUSE Surface. Semi Under Ground Under Ground.
SURFACE POWER HOUSE 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.
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
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 depth Adits- 4Nos Total1.7km X 6m modified shoe Adits- 6-TRT.471km X 6.5 X 7m modified shoe Main Access --.630km tunnel Total Tunneling- 19.34km Machine Hall- 127mLx22mBx28mH
All the equipment are placed inside a Cavern Underground Chamera HEP
TYPE OF HYDRO POWER PROJECT Multi-purpose Project Purely Hydro-electric Project Run of river project Storage Project Pump Storage project
Multi-purpose Project Power generation may be one of the benefits along with Flood Control, Irrigation, Navigation, Drinking Water Supply etc. Purely Hydro-electric Project Project 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 STORAGE Total storage capacity of the reservoir
Hydro Development- IMPORTANT TERMS- Cont DEAD STORAGE Reservoir 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 POWER Continuous power output in the entire period of hydrological data at 90% dependability FIRM ENERGY Energy generated corresponding to firm power
Hydro Development- IMPORTANT TERMS- Cont Peak Energy Electric energy supplied during periods of relatively high system demands. Off-peak Energy Electric 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 STORAGE Storage 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 Head The 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.
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)
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
TURBINE Turbine converts potential energy of water to mechanical energy and transmits it to the generator. Turbine converts potential energy of water to mechanical energy and transmits it to the generator. Turbines can be of: Turbines can be of: Kaplan type Kaplan type Francis type Francis type Pelton type Pelton type Bulb type Bulb 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
GENERATOR Hydro generator is coupled to the turbine and converts the mechanical energy transmitted by the turbine to electrical energy Hydro generator is coupled to the turbine and converts the mechanical energy transmitted by the turbine to electrical energy Generators can be of: Generators can be of: Suspended type Suspended type Umbrella type Umbrella type Main Generator components include: Main Generator components include: Stator Stator Rotor Rotor Upper Bracket Upper Bracket Lower Bracket Lower Bracket Thrust Bearing & Guide Bearings Thrust Bearing & Guide Bearings Slip Ring & Brush Assembly Slip Ring & Brush Assembly Air Coolers Air Coolers Brakes & Jacks Brakes & Jacks Stator Heaters Stator Heaters
UMBRELLA TYPE GENERATOR COMBINED LOWER THRUST & GUIDE BEARING
GOVERNOR Used for controlling the guide vanes by detecting turbine speed & its guide vane opening in order to keep turbine speed stable or to regulate its output. Used for controlling the guide vanes by detecting turbine speed & its guide vane opening in order to keep turbine speed stable or to regulate its output. The performance of the governor dominates the controllability of the power plant and quality of electrical power produced. The performance of the governor dominates the controllability of the power plant and quality of electrical power 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
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(SF 6 ) is used in GIS. (yes/no) Rotor is the heaviest part of hydro generating machine.(yes/no)