NHPC - FaridabadNHPC - Faridabad

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Training ReportTraining ReportOn On

Study of Hydro Power Plants and Detailed Study of Hydro Power Plants and Detailed Design of Large HydroDesign of Large Hydro

GeneratorsGenerators

ContentsContents Overview of NHPCOverview of NHPC Design E & M DivisionDesign E & M Division Hydro Power PlantsHydro Power Plants Hydro TurbinesHydro Turbines Power HousePower House Hydro GeneratorsHydro Generators Design StudyDesign Study About the SoftwareAbout the Software

About NHPCAbout NHPC NHPC (National Hydro Power Corporation)NHPC (National Hydro Power Corporation) AA Govt. of India Enterprise Govt. of India Enterprise Established in 1975Established in 1975 Started with an authorized capital of Rs. 2000 Started with an authorized capital of Rs. 2000

million, today has an asset value of Rs. 200000 million, today has an asset value of Rs. 200000 millionmillion

One of the largest organization for Hydro-Power One of the largest organization for Hydro-Power development in Indiadevelopment in India

Has constructed 13 hydro-power projects in Has constructed 13 hydro-power projects in India and abroadIndia and abroad

Total Installed Capacity of 3694.35 MWTotal Installed Capacity of 3694.35 MW

Projects completedProjects completed Baira Siul (MP)Baira Siul (MP)

Salal (J&K)Salal (J&K)

Chamera (Himachal Pradesh)Chamera (Himachal Pradesh)

Dhauliganga (Uttaranchal )Dhauliganga (Uttaranchal )

Indira Sagar (MP)Indira Sagar (MP)

3 X 603 X 60

3 X 1153 X 115

3 X 1803 X 180

4 X 704 X 70

8 X 1258 X 125

Projects under ConstructionProjects under Construction Teesta– V (Sikkim)Teesta– V (Sikkim)

Parbati–II (Himachal Pradesh)Parbati–II (Himachal Pradesh) Subansiri (Arunachal Pradesh)Subansiri (Arunachal Pradesh)

Chamera-III (Himachal Pradesh)Chamera-III (Himachal Pradesh)

510 MW510 MW

800 MW800 MW

2000 MW2000 MW

231 MW231 MW

DESIGN ( E & M) DIVISIONDESIGN ( E & M) DIVISION

One of many divisions of NHPC One of many divisions of NHPC Deals with the design Electrical & Deals with the design Electrical &

Mechanical components of power plantMechanical components of power plant

Functions of Design E&MFunctions of Design E&M

Planning and preparation of Electrical and Planning and preparation of Electrical and Mechanical design for DPR Mechanical design for DPR

Power Potential Studies & Power System Power Potential Studies & Power System Studies Studies

Preparation of Technical specification of Preparation of Technical specification of E & M equipments E & M equipments Standardization of Technical specificationStandardization of Technical specification Assistance in evaluation of all tenders Assistance in evaluation of all tenders

Hydro Power PlantsHydro Power Plants Reservoir : Holds the water from the riverReservoir : Holds the water from the river Dam : Civil construction Dam : Civil construction Penstock : Large pipes through which water Penstock : Large pipes through which water

flows from the reservoir to the turbineflows from the reservoir to the turbine Turbine :Turned by the force of water on their Turbine :Turned by the force of water on their

bladesblades Power Plant : Power generation and Power Plant : Power generation and

transmissiontransmission Generator : Converts mechanical energy of Generator : Converts mechanical energy of

turbine into electrical energy turbine into electrical energy Control Gates : Control the flow of waterControl Gates : Control the flow of water

Types of Hydro Power PlantsTypes of Hydro Power Plants

Storage PlantsStorage Plants Pumped Storage PlantsPumped Storage Plants Run-of-River Plants Run-of-River Plants

Storage PlantsStorage Plants Impound and store water in a reservoir formed Impound and store water in a reservoir formed

behind a dam. behind a dam. During peak demands, enough water can be During peak demands, enough water can be

released to meet the additional demand.released to meet the additional demand. Water flow rate may change greatlyWater flow rate may change greatly May involve dramatic environmental May involve dramatic environmental

consequences including soil erosion, degrading consequences including soil erosion, degrading shorelines, crop damage, disrupting fisheries shorelines, crop damage, disrupting fisheries and other wildlife, and even flooding and other wildlife, and even flooding

Pumped Storage Plants Pumped Storage Plants

Reuse water after it is initially used to Reuse water after it is initially used to generate electricity. generate electricity.

Water is pumped back to the reservoir Water is pumped back to the reservoir during peak-off hoursduring peak-off hours

During peak hours this water is used again During peak hours this water is used again for generating electricityfor generating electricity

Run-of-River PlantsRun-of-River Plants

Amount of water running through the Amount of water running through the turbine varies with the flow rate of water in turbine varies with the flow rate of water in the riverthe river

Amount of electricity generated changes Amount of electricity generated changes with seasons and weather conditionswith seasons and weather conditions

Since these plants do not block water in a Since these plants do not block water in a reservoir, their environmental impact is reservoir, their environmental impact is minimalminimal

Hydro TurbinesHydro Turbines Hydro turbines can be classified on the Hydro turbines can be classified on the

basis of force exerted by water on the basis of force exerted by water on the turbineturbine

A) Reaction TurbinesA) Reaction Turbines Francis Francis KaplanKaplan PropellerPropeller BulbBulb

B) Impulse TurbinesB) Impulse Turbines PeltonPelton

Hydro TurbinesHydro TurbinesType of turbine to be used in a plant isType of turbine to be used in a plant isdecided on the basis of available headdecided on the basis of available head

Head RangeHead Range   2m   2m   to      70  m                    to      70  m                    Kaplan Kaplan 30m 30m to    450  m                    to    450  m                    Francis Francis above 300 m                     above 300 m                     PeltonPelton

Also a turbine is characterized by its Also a turbine is characterized by its specific speedspecific speed..

Power HousePower House

POWER HOUSE BUILDING CONSISTS OF THREE MAIN AREAS NAMELY

1. Machine Hall/Unit Bay1. Machine Hall/Unit Bay 2. Erection/Service Bay2. Erection/Service Bay 3. Control Room/Auxiliary Bay3. Control Room/Auxiliary Bay

HEAD CALCULATIONHEAD CALCULATION

• • Avg. Gross HeadAvg. Gross Head = MDDL + 2/3(FRL - MDDL) -TWL(4 Units Running) = MDDL + 2/3(FRL - MDDL) -TWL(4 Units Running)= 203 + 2/3(208 - 203) -184.24= 203 + 2/3(208 - 203) -184.24

= 22.09 m.= 22.09 m. • • Rated/Net HeadRated/Net Head = Avg. Gross Head - Head Loss= Avg. Gross Head - Head Loss = 22.09 - 0.75= 22.09 - 0.75 = 21.34 m.= 21.34 m. • • Max. Gross HeadMax. Gross Head = FRL - min TWL= FRL - min TWL = 208.00 - 181.78= 208.00 - 181.78 = 26.22 m= 26.22 m • • Max. Net HeadMax. Net Head = Max. Gross Head-Head Loss= Max. Gross Head-Head Loss = 26.22-0.75= 26.22-0.75 = 25.47 m= 25.47 m • • Min. Gross HeadMin. Gross Head = MDDL - TWL(4 Units Running)= MDDL - TWL(4 Units Running) = 203.00 - 184.24= 203.00 - 184.24 = 18.76m= 18.76m • • Min. Net HeadMin. Net Head = Min. Gross Head - Head Loss= Min. Gross Head - Head Loss =18.76 - 0.75=18.76 - 0.75 =18.01 m.=18.01 m. # calculations has been done for PARBATI H.E. PROJECT, STAGE-II# calculations has been done for PARBATI H.E. PROJECT, STAGE-II

Selection of Machine SpeedSelection of Machine Speed

Economically should have highest Economically should have highest practicable speedpracticable speed

Deciding parameters :Deciding parameters :• Variation of headVariation of head• Silt contentSilt content• CavitationCavitation• VibrationsVibrations• Drop in peak efficiency Drop in peak efficiency

HYDRO GENERATORSHYDRO GENERATORS

Hydro Generators are low speed salient pole type Hydro Generators are low speed salient pole type machines. machines.

Rotor is characterized by large diameter and short axial Rotor is characterized by large diameter and short axial length. length.

Capacity of such generator varies from 500 KW to 700 Capacity of such generator varies from 500 KW to 700 MW. MW.

Power factor are usually 0.90 to 0.95 lagging. Power factor are usually 0.90 to 0.95 lagging. Available head is a limitation in the choice of speed of Available head is a limitation in the choice of speed of

hydro generator.hydro generator. Standard generation voltage in our country is 3.3KV, Standard generation voltage in our country is 3.3KV,

6.6KV, 11 KV ,13.8 KV, & 16KV at 50 Hz. 6.6KV, 11 KV ,13.8 KV, & 16KV at 50 Hz. Short Circuit Ratio varies from 1 to 1.4.Short Circuit Ratio varies from 1 to 1.4.

A typical Hydro GeneratorA typical Hydro Generator

CLASSIFICATION

Classification of Hydro Generators can be Classification of Hydro Generators can be done with respect to the position of rotordone with respect to the position of rotor

(i) Horizontal(i) Horizontal(ii) Vertical (two types)(ii) Vertical (two types) a) Suspension Typea) Suspension Type b) Umbrella Type b) Umbrella Type

Suspended Type Vertical Generator

Umbrella Type Vertical GeneratorUmbrella Type Vertical Generator

COMPONENTS OF GENERATORCOMPONENTS OF GENERATOR

1.1. STATORSTATOR

Stator Sole PlatesStator Sole Plates Stator FrameStator Frame Stator Magnetic CoreStator Magnetic Core Stator WindingsStator Windings

2.2. ROTORROTOR

Rotor Shaft Rotor Spider Rotor Rim Rotor Poles Ring Collectors

Rotor Spider Rotor Rim

3. BRACKETS

Upper Bracket Lower Bracket

4. GENERATOR AUXILIARIES

Excitation System Air Cooling System Braking And Jacking System Bearings Fire Protection Heaters

Design StudyDesign Study Output equation can be derived by the basic emf equation of a Output equation can be derived by the basic emf equation of a

hydro generator.hydro generator. This has been taken from Electric Machine Design ,AK Sawhney.This has been taken from Electric Machine Design ,AK Sawhney.

Output Equation: Q = COutput Equation: Q = C00 * D * D22 * L * N * L * Nss

Where, output coefficient, CWhere, output coefficient, C00 = 11 * B = 11 * Bavav * ac * K * ac * Kww * 10 * 10-3-3

Q = kVA rating of machine Q = kVA rating of machine BBavav = specific magnetic loading = specific magnetic loading ac = specific electrical loadingac = specific electrical loading KKww = winding factor = winding factor

Source: Source: (derived from output equation of AC machines) (Pg-(derived from output equation of AC machines) (Pg-456,Electric Machine Design, AK Sawhney)456,Electric Machine Design, AK Sawhney)

Design StudyDesign Study Calculation of Output CoefficientCalculation of Output Coefficient Is calculated from a graph obtained by analyzing the Is calculated from a graph obtained by analyzing the

published data of 40 generators in manufacture in USA, published data of 40 generators in manufacture in USA, Canada, UK, Japan a Europe.Canada, UK, Japan a Europe.

Calculation of Number of PolesCalculation of Number of Poles using P=120f/N using P=120f/N Frequency f is 50 Hz as per Indian StandardsFrequency f is 50 Hz as per Indian Standards

Air Gap DiameterAir Gap Diameter Di= (60 * Vr) / (pi * N)Di= (60 * Vr) / (pi * N) Vr is the Maximum peripheral velocity obtained from a Vr is the Maximum peripheral velocity obtained from a

graph between Vr and Number of polesgraph between Vr and Number of poles

Design StudyDesign Study Calculation of Stator core lengthCalculation of Stator core length Stator core length is the gross length of the stator and Stator core length is the gross length of the stator and

can be calculated by using the formula for output can be calculated by using the formula for output coefficientcoefficient

L L tt= W/ (C= W/ (C00* D* Dii 22 * N) * N) Where,Where, W = Rated KVA of machineW = Rated KVA of machine CC00 = Output coefficient obtained from curve = Output coefficient obtained from curve N = Rated RPM of the machine N = Rated RPM of the machine

Source : Source : (Fig 1-1, Page 4, Large AC Machines by J.H. Walker.)(Fig 1-1, Page 4, Large AC Machines by J.H. Walker.)

Design StudyDesign Study STATOR DESIGNING Pole pitch is defined as the peripheral distance between two Pole pitch is defined as the peripheral distance between two

consecutive poles. It may be expressed as number of slots, degrees consecutive poles. It may be expressed as number of slots, degrees .(electrical or mechanical).(electrical or mechanical)

Calculated as : ψ= pi x Di/P Calculated as : ψ= pi x Di/P Where Pi (constant) =22/7Where Pi (constant) =22/7Di = Di = Air gap diameter in meters Air gap diameter in metersP = P = No. of poles No. of poles

Flux per poleFlux per poleFlux per pole (φ) =Mean flux density * Pole pitch (ψ)* Length of core Flux per pole (φ) =Mean flux density * Pole pitch (ψ)* Length of core

Mean Flux density is assumed to be 0.6-0.7 Wb/mMean Flux density is assumed to be 0.6-0.7 Wb/m22

Turns per phase = = (1.1 * VTurns per phase = = (1.1 * Vphph)/4.44fφ)/4.44fφ

Design StudyDesign Study Calculation of number of parallel pathsCalculation of number of parallel paths Total current per slot should not exceed 5000 A.Total current per slot should not exceed 5000 A.

If I be the rated current per phase and there be p parallel paths If I be the rated current per phase and there be p parallel paths then current per conductor is I/p , and current per slot is 2*I/pthen current per conductor is I/p , and current per slot is 2*I/p

This should not exceed the limit of 5000 A.This should not exceed the limit of 5000 A. 5000 > 2 * I / p5000 > 2 * I / p

The value of p greater than or equal to this value, that satisfies other The value of p greater than or equal to this value, that satisfies other designing constraints is chosen as the appropriate number of designing constraints is chosen as the appropriate number of parallel paths.parallel paths.

After the calculation of turns per phase we can calculate the After the calculation of turns per phase we can calculate the approximate no. of stator slots.approximate no. of stator slots.

Source : (Source : (Current in Slot should lie between 3000 to 5000A as per CEA)Current in Slot should lie between 3000 to 5000A as per CEA)

Design StudyDesign Study No. of slots is given by, No. of slots is given by, Ns = (no. of phases) * T ph * (no. of parallel paths) / Ns = (no. of phases) * T ph * (no. of parallel paths) /

(turns per coil)(turns per coil) Note: Turns per coil = 1 for bar winding Note: Turns per coil = 1 for bar winding Number of conductor per slots = 2 ( for bar winding) Number of conductor per slots = 2 ( for bar winding)

Design StudyDesign Study Short Circuit RatioShort Circuit Ratio Defined as the ratio of field current Defined as the ratio of field current

required to produce rated voltage under required to produce rated voltage under open circuit conditions to the field current open circuit conditions to the field current required to circulate rated current at short required to circulate rated current at short circuit.circuit.

Short circuit ratio is the reciprocal of Short circuit ratio is the reciprocal of synchronous reactance Xd synchronous reactance Xd

For salient pole hydro electric generators For salient pole hydro electric generators SCR varies from 1.0 to 1.1. SCR varies from 1.0 to 1.1.

Design StudyDesign Study Effect of SCR on machine performanceEffect of SCR on machine performance Stability : Low value implies lower stability limit, as the Stability : Low value implies lower stability limit, as the

maximum power output is inversely proportional to Xdmaximum power output is inversely proportional to Xd Parallel Operation : Low SCR leads to high Xd, that is Parallel Operation : Low SCR leads to high Xd, that is

small synchronising power.Machines become more small synchronising power.Machines become more sensitive to voltage and torque disturbances.sensitive to voltage and torque disturbances.

Cost : A high SCR adds to the size of the machine Cost : A high SCR adds to the size of the machine making it costlier.making it costlier.

Present trend is to make a machine with low SCR.Present trend is to make a machine with low SCR. This is due to the recent advancement in fast acting This is due to the recent advancement in fast acting

control and excitation systems.control and excitation systems.