equipment at hps

7/31/2019 Equipment at HPS

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Electro-mechanical Equipment

in Hydro Power Station


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Main Electro-Mechanical Equipments

Turbine MIV (Spherical Valve)/Butterfly Valve Governing System

Mechanical Auxiliaries like Cooling water system, drainage

dewatering system, Fire fighting system HVAC etc. Generator Electrical Auxiliaries like Bus Duct, LT/HT switchgears, DC

battery system, earthing, cabling, Station/Auxiliary Transformer etc. Generator Transformers

Switchyard and Pot head yard XLPE Cables/Tie line Control and Instrumentation Systems( SCADA)


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Hydraulic Turbines

Hydraulic Turbines

Impulse Turbine Reaction Turbine

Pelton Turbine Francis Turbine

Propeller Turbine

Kaplan Turbine

Bulb Turbine

Deriaz Turbine


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Types of Hydraulic Turbines

Reaction Turbines Derive power from pressure drop across turbine

Totally immersed in water

Angular & linear motion converted to shaft power Propeller, Francis, and Kaplan turbines

Impulse Turbines Convert kinetic energy of water jet hitting buckets

No pressure drop across turbines

Pelton, Turgo, and crossflow turbines


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Pelton Turbine


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PELTON ARRANGEMENT


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Francis Turbine

Runner

Spiral CasingSectional View


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Kaplan Turbine


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Deriaz Turbine


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Spiral case and wicket gates/Nozzles- to direct and control the

water entering the turbine runner. The spiral case is a steel-linedconduit connected to the penstock or intake conduit, and itdistributes flow uniformly into the turbine. Wicket gates areadjustable vanes that surround the turbine runner entrances andthey control the area available for water to enter the turbine.


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SELECTION CRITERIA FOR TYPE OF HYDROTURBINE

Depends mainly on:

Head availableSpecific Speed

Impulse Turbine :- Pelton Wheel turbine for Head>300m

Reaction Turbine:- Francis Turbine for Head 30m to 400mKaplan Turbine for Head 10m to 60m

Bulb/Tubular Turbine Head 3 to 30m

In the overlapping zone of head more detailed analysis is required fromtechno-economic considerations.


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Overlapping Regionbetween Francis

and Pelton Turbine

TapovanVishnugad,Head-494,

Francis Sp.Speed-78

LoharinagPala. Head-438, FrancisSp. Speed-

85.3

LoharinagPala. Head-438, PeltonSp. Speed-

56

TapovanVishnugad,Head-494,Pelton Sp.Speed-54.6

Figure 1: Selection of

turbines; Head vs

Specific Speed (Ns)

(Source:IS:12837:1989)


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Turbines of NTPC Projects

PROJECT TYPE OF TURBINE

Koldam(4X200 MW) Francis

Loharinag Pala(4X150 MW) Pelton

Tapovan Vishnugad(4X130 MW) Pelton

Lata-Tapovan(3X57 MW) Francis

Rammam Pelton


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Main Inlet Valve

Main inlet valves at the inlet of the turbine areinstalled to isolate the flow in case ofmaintenance and emergency .

Spherical ValveGenerally used as Main Inlet Valve for high headinstallation in case of the Pelton type of turbine (In LNP&TVN)

Butterfly valveGenerally used as Main Inlet Valve for medium headinstallation in case of the Francis type of turbine (InKoldam) and as Penstock valve (e.g. LNP& TVN)


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Cross-section of Power house -LNP


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L-section of Power house -LNP


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MIV floor drawing -LNP


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Governing System

It regulates the speed and the output of the Turbine-Generatorunits by controlling the position of the wicket gates (in Francis)and Nozzles (in Pelton) to adjust the water flow through theturbine.

The hydraulic turbine governor is equipment to control the guidevanes/ nozzles by detecting the turbine speed and the opening ofthe guide vane/nozzles in order to keep the turbine speed stableor to regulate its output.

Accordingly the controllability of the power station and the quality

of the electric power depends upon the performance of thegovernor.

It operates the Deflector (in Pelton) in case of sudden loadrejection to divert the water jet.


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Contd

Main components of the Governor systemOil Pressure UnitPressure accumulatorElectro-Hydro actuatorPressurizing system

Air Pressure (40-70Kg/cm2) Nitrogen pressure (100 Kg/cm2 and above)

High pressure systems are compact as compared to the Lowpressure system.

Due to space constraints in case of underground Power house,generally high pressure system is used .KoldamAir pressure systemLNP&TVN- Nitrogen/Air High Pressure System


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Schematic diagram of Governor


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DEFLECTOR SERVOMOTOR


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LINKAGE ARRANGEMENT OF

DEFLECTOR SERVOMOTOR


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NOZZLE SERVOMOTOR


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OIL PRESSURE UNIT


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Mechanical Auxiliaries

Cranes

Cooling Water System & General water system

Fire Fighting system

Air conditioning and Ventilation System Drainage and dewatering system


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Cranes

Cranes used in the hydro-power house Power house crane

Transformer house crane (in case of underground PH)

Butterfly valve house crane

Capacity of the PH crane is decided by heaviest

equipment (Generally Generator Rotor) to be lifted bythe crane.

When the weight of the heaviest equipment is veryhigh then 2 PH cranes are used in the tandem

PH Crane is one of the most important equipmentbecause it plays a major role in the erection of theequipments.


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TF and BF valve House crane

TF hall crane is used for the erection andmaintenance of the GIS equipments.

BF valve house crane is used for the

erection and maintenance of the Butterflyvalve.


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Cooling Water System

Water is used to cool the various equipments like Generator air cooler

Thrust bearing

Guide bearing/Shaft seal

Generator transformer

Due to heavy silt content in river water closed loopcooling system is adopted and circulating water is

cooled in Plate heat exchanger (PHE).

Koldam, LNP &TVN- closed loop cooling system.


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Schematic diagram of CWS-LNP


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COOLING WATER SYSTEM


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COOLING WATER PUMPS


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COOLING WATER FILTERS


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Air conditioning and ventilation

system Air conditioning units (For control room , Shift

engineer room and conference room )

Ventilation Supply and Exhaust air fans Supply and return air ducts

Air Handling Units


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Air conditioning and ventilation system- LNP


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Fire Protection system

Fire alarm and Detection system Bymeans of Smoke detector, heat detector

Protection system

Water based Hydrant system

Medium velocity spray system

High velocity spray system

Inert gas clean agent system

Portable fire extinguisher


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Generator

Convert the mechanical power produced by theturbine into the electrical power.

Major Components- Shaft : coupled with turbine shaft and rotates synchronously.

Rotor :series of large electromagnets that spins inside Stator.

Stator : a tightly-wound coil of copper wire around rotor.

Excitation system: sends an DC current to the rotor.

As the turbine blades turn, so do a series of magnetsinside the generator, Giant magnets (i.e. rotor) rotatepast copper coils (i.e. Stator), producing alternatingcurrent (AC).


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A cross- sectional view of Hydroturbine-Generator Unit


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Generator parameters Output capacity in KVA Rated speed

Rated Voltage Power factor Insulation system Reactive power capability Short Circuit Ratio (SCR) Inertia constant/Fly Wheel Effect Generator efficiency

Bearing arrangement Cooling system Excitation system

Bearing arrangement Umbrella type- Thrust bearing is placed below the rotor, a guide bearing

surrounds it . Mostly used for higher diameter and lower speed.

Semi-Umbrella type - Thrust bearing is placed below the rotor and guidebearing is installed above the rotor.

Suspended type - combined thrust bearing and guide bearing on topbracket above the rotor


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Cooling system of Generator

Air cooling is used for large hydro generators

Cooling of the machine should be as uniformas possible.

Cooling is achieved by forced air cooling bynatural fan action of the rotor or withsupplementary motor operated cooling fans

In our design, cooling is achieved by axial fanfitted on rotor.


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EXCITATION SYSTEM

STATIC EXCITATION SYSTEMStatic, potential source rectifier exciters are generally used for medium to large generators.They are also used for smaller generating sets, partly owing to the free choice of locationand the reduced length of the set and because of the fast-acting response to networktransients. Static potential source rectifier exciters derive the necessary electrical powerdirectly from the terminals of the generator. They consist of a power transformer, thethyristor control element, the electronic regulator and the de-excitation unit.

BRUSHLESS EXCITATION SYSTEMThe essential components of a brushless exciter system are the ac exciter machine withits rectifier bridge and the electronic regulator. Power for the voltage regulator can beprovided by a permanent magnet generator or via a transformer from the generatorterminals. The brushless exciter consists of a salient-pole synchronous generator with athree-phase winding in the rotor and a dc exciter winding in the stator. It is mounted on thegenerator shaft. At the non-driving end of the rotor is the diode carrier ring with six silicondiodes in a bridge connection.


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Transformers

A transformer is an electrical device that takeselectricity of one voltage and changes it into another

voltage.

Type of TF used in hydro power plant Generator Transformer- It takes the low voltage Supply from the

Generator and converts it into High voltage to be transmitted to the Grid.

Unit auxiliary Transformer- It takes the supply from the generatoroutput and converts it to low voltage for the auxiliary consumption of the unit.

Station Transformer - Used to feed the equipments which are common

for the station.


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Electrical Single Line Diagram


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Classification based on Cooling arrangementof TF Air cooled

Water cooled

Koldam LNP

TVN


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Switchyard

It is an interface between generating Unit andGrid.Used to evacuate the generated power to grid.

Elements of Switchyard: Bus bar Insulators

Circuit Breakers (SF6, Vacuum, Air, Gas etc.) Isolators Current Transformer (CT) Capacitive Voltage Transformer (CVT) Surge Arrestor Lightning Protection System Wave Trap


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Types of Switchyard

SURFACE

low cost, Large space requirement, In case of steepslope Stepping of the area Under ground Due to space constrain GIS (Gas insulated

switchyard ), Small area requirement.

Factor affecting selection of type of AIS and

GIS Space Terrain Cost

Koldam Over ground

LNP - GIS TVN - GIS


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GIS Insulating Medium SF6 Low space requirement due to reduction in clearances Unaffected by climatic conditions such as rains etc. No corona losses SF6 has excellent properties to be used as an insulating medium,

very high dielectric strength, chemically inert, non-inflammable, non

poisonous Costly equipments Online monitoring of pressure of SF6 gas is required Main features: pressure of SF6 gas selected from 5-40 bar

depending upon the requirements Bare conductors run inside metallic enclosures surrounded by

pressurized sf6 gas All CTs, circuit breakers, PTs etc are inside the metal clad

enclosures GIS will be used first time in NTPC in Loharinag pala and Tapovan

Vishnugad HEPP

GAS INSULATED


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SWITCHGEAR


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XLPE Cable

XLPE STANDS FOR Cross linked polyethyleneinsulated power cable (XLPE cable)

XLPE cable is used as interconnecting circuitbetween GIS and transmission lines through

overhead pothead yard.

XLPE cables are generally used because thedistance between GIS and pothead yard is moreand through a Cable ventilation tunnel.

400 KV XLPE cables are used for first time in NTPCin Loharinag Pala and Tapovan Vishnugad HEPP


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XLPE CABLES..


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Electrical Auxiliaries

BUSDUCT

DC supply system

Grounding system

Illumination


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BUS DUCTS AND UCBs


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BUS DUCT

Bus ducts


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Bus ducts


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DC supply system

D.C. Supply distribution systems typicallycontains:-

Batteries

Battery Chargers

Distribution Boards


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D.C. Batteries Batteries are required at most of the hydro-electric stations for control alarm

annunciation, protection, communication, emergency lighting and solenoidoperated valves and field flashing requirements of generating units. Ingeneral, lead acid batteries are widely used. The standard voltage rating forthe batteries used are 110 V or 220 V depending on the DC load of thepower station.

Batteries are generally designed with 10% design margin and 25% of agingfactor. Small and medium hydro plant one battery set (110 V) with twobattery chargers and for large hydro stations, two battery sets (220 V each)and one 48 V battery set with two (2) chargers for each battery are generally

recommended. Minimum load requirement on D.C. system is generator fieldflash load for one unit and emergency lighting.

Battery Chargers The battery charger having rectifiers with thyristors are usually used for

charging the battery system. The charging is generally in float charging i.e.the batteries are kept in float charging condition in the normal operation. In

case of commissioning of the batteries and otherwise the boost charger isused to charge the boost batteries.

G di S


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Grounding System

Separate groundmat, if feasible, be provided for power house, switchyard,remote structures such as control buildings, communication buildings,

spillway gate structures, storage buildings, etc.

Power House Grounding System be designed to provide a maximum 1.0ohm resistance to ground.

If the control, computer and communication rooms are located in electrically

noisy areas (e.g. VFC drives(in case pumped staorage), high voltage GISequipment etc), a "High-frequency signal reference ground grid beneath afalse floor shall be considered, to provide a noise-free, low impedenceground to the equipment.

Switchyard grounding electrode systems should be designed to provide amaximum of 1.0 ohm resistance to ground. The switchyard mat shouldextend 1.5 - 2.0 mts. outside the switchyard fencing.

Touch and Step potentials limit be maintained to an acceptable value.

Ill i i


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Illumination

General indoor and outdoor lighting and receptacle are served by 3-, 4 wire

A.C. system. Transformers and panels are located so as to optimize wiring andto limit voltage drops to acceptable values.

Fluorescent lamps are most used in interior spaces

High-density Discharge (HD)

Sodium vapour lighting fixtures are preferred for outdoor lighting such as

switchyards, spillways and dams, parking areas etc. Automatic switching viaphoto electric cells can be adopted for outdoor lighting to optimize powerconsumption.

Metal-halide fixtures are used for certain indoor areas such as erection bay,generator hall, machine shop, turbine pit and other "high-bay" areas whereproper color redention is needed and long-life is essential.

Emergency lighting is deployed in the event that normal A.C. power distribution

system fails. The emergency requirement are at first met from the dieselgenerator sets and when all alternatives of A.C. supply fail, battery poweredemergency fixtures provide the minimum requirement of lighting. The batteryshould have sufficient capacity to provide 4 hours uninterrupted illuminationindependently.


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C&I COMPONENTS IN A TYPICAL

HYDRO STATION

1. MAIN PLANT CONTROL & INSTRUMENTATION SYSTEM

TURBINE, GENERATOR & AUXILIARIES

COOLING WATER SYSTEM

DRAINAGE & DEWATERING SYSTEM

FLOOD DETECTION SYSTEM

2. SWITCHYARD SCADA AND SUBSTATION AUTOMATION SYSTEM

3. DAM /RESERVOIR INSTRUMENTATION4. SPILLWAY INSTRUMENTATION

C S S C


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CONTROL SYSTEM AUTOMATION HIERARCHY

1. LOCAL

2. UCB

- DRIVE

- SUB GROUP

- GROUP

3. Station

- SUB GROUP

- GROUP

- STATION

4. REMOTE (FUTURE)

- GROUP

- STATION


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THANK YOU

equipment at hps

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