Transcript
NHPC - Faridabad
ATraining Report
OnStudy of Hydro Power Plants and Detailed
Design of Large Hydro Generators
Contents
Overview of NHPC Design E & M Division Hydro Power Plants Hydro Turbines Power House Hydro Generators Design Study
About the Software
About NHPC NHPC (National Hydro Power Corporation) A Govt. of India Enterprise
Established in 1975 Started with an authorized capital of Rs. 2000
million, today has an asset value of Rs. 200000million
One of the largest organization for Hydro-Powerdevelopment in India
Has constructed 13 hydro-power projects inIndia and abroad
Total Installed Capacity of 3694.35 MW
Projects completed Baira Siul (MP)
Salal (J&K)
Chamera (Himachal Pradesh)
Dhauliganga (Uttaranchal )
Indira Sagar (MP)
3 X 60
3 X 115
3 X 180
4 X 70
8 X 125
Projects under Construction
Teesta– V (Sikkim) 510 MW
Parbati–II (Himachal Pradesh) 800 MW
Subansiri (Arunachal Pradesh)2000 MW
Chamera-III (Himachal Pradesh)231 MW
DESIGN ( E & M) DIVISION
One of many divisions of NHPC
Deals with the design Electrical &Mechanical components of power plant
Functions of Design E&M
Planning and preparation of Electrical andMechanical design for DPR
Power Potential Studies & Power SystemStudies
Preparation of Technical specification of
E & M equipments
Standardization of Technical specification
Assistance in evaluation of all tenders
Hydro Power Plants Reservoir : Holds the water from the river
Dam : Civil construction
Penstock : Large pipes through which waterFlows from the reservoir to the turbine
Turbine :Turned by the force of water on theirblades
Power Plant : Power generation andtransmission
Generator : Converts mechanical energy ofturbine into electrical energy
Control Gates : Control the flow of water
Types of Hydro Power Plants
Storage Plants
Pumped Storage Plants
Run-of-River Plants
Storage Plants
Impound and store water in a reservoir formedbehind a dam.
During peak demands, enough water can bereleased to meet the additional demand.
Water flow rate may change greatly
May involve dramatic environmentalconsequences including soil erosion, degradingshorelines, crop damage, disrupting fisheriesand other wildlife, and even flooding
Pumped Storage Plants
Reuse water after it is initially used togenerate electricity.
Water is pumped back to the reservoirduring peak-off hours
During peak hours this water is used againfor generating electricity
Run-of-River Plants
Amount of water running through theturbine varies with the flow rate of water inthe river
Amount of electricity generated changeswith seasons and weather conditions
Since these plants do not block water in areservoir, their environmental impact isminimal
Hydro Turbines
Hydro turbines can be classified on thebasis of force exerted by water on theturbine A) Reaction Turbines
Francis Kaplan Propeller Bulb
B) Impulse Turbines Pelton
Hydro Turbines
Type of turbine to be used in a plant isdecided on the basis of available head
Head Range 2m to 70 m Kaplan 30m to 450 m Francis above 300 m Pelton
Also a turbine is characterized by itsspecific speed.
Power House
POWER HOUSE BUILDING CONSISTS OFTHREE MAIN AREAS NAMELY
1. Machine Hall/Unit Bay
2. Erection/Service Bay
3. Control Room/Auxiliary Bay
HEAD CALCULATION
• Avg. Gross Head = MDDL + 2/3(FRL - MDDL) -TWL(4 Units Running)= 203 + 2/3(208 - 203) -184.24
= 22.09 m. • Rated/Net Head = Avg. Gross Head - Head Loss
= 22.09 - 0.75= 21.34 m.
• Max. Gross Head = FRL - min TWL= 208.00 - 181.78= 26.22 m
• Max. Net Head = Max. Gross Head-Head Loss= 26.22-0.75= 25.47 m
• Min. Gross Head = MDDL - TWL(4 Units Running)= 203.00 - 184.24= 18.76m
• Min. Net Head = Min. Gross Head - Head Loss=18.76 - 0.75=18.01 m.
# calculations has been done for PARBATI H.E. PROJECT, STAGE-II
Selection of Machine Speed
Economically should have highestpracticable speed
Deciding parameters :• Variation of head
• Silt content
• Cavitation
• Vibrations
• Drop in peak efficiency
HYDRO GENERATORS
Hydro Generators are low speed salient pole typemachines.
Rotor is characterized by large diameter and short axiallength.
Capacity of such generator varies from 500 KW to 700MW.
Power factor are usually 0.90 to 0.95 lagging. Available head is a limitation in the choice of speed of
hydro generator. Standard generation voltage in our country is 3.3KV,
6.6KV, 11 KV ,13.8 KV, & 16KV at 50 Hz. Short Circuit Ratio varies from 1 to 1.4.
A typical Hydro Generator
CLASSIFICATION
Classification of Hydro Generators can bedone with respect to the position of rotor
(i) Horizontal
(ii) Vertical (two types)
a) Suspension Type
b) Umbrella Type
Suspended Type Vertical Generator
COMPONENTS OF GENERATOR
1. STATOR
Stator Sole Plates
Stator Frame
Stator Magnetic Core
Stator Windings
2. ROTOR
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 Study Output equation can be derived by the basic emf equation of a
hydro generator.This has been taken from Electric Machine Design ,AK Sawhney.
Output Equation: Q = C0 * D2 * L * Ns
Where, output coefficient, C0 = 11 * Bav * ac * Kw * 10-3
Q = kVA rating of machine
Bav = specific magnetic loadingac = specific electrical loading
Kw = winding factor
Source: (derived from output equation of AC machines) (Pg-456,Electric Machine Design, AK Sawhney)
Design Study Calculation of Output Coefficient
Is calculated from a graph obtained by analyzing thepublished data of 40 generators in manufacture in USA,Canada, UK, Japan a Europe.
Calculation of Number of Polesusing P=120f/N
Frequency f is 50 Hz as per Indian Standards
Air Gap DiameterDi= (60 * Vr) / (pi * N)
Vr is the Maximum peripheral velocity obtained from agraph between Vr and Number of poles
Design Study Calculation of Stator core length
Stator core length is the gross length of the stator andcan be calculated by using the formula for outputcoefficient
L t= W/ (C0* Di 2 * N)Where,
W = Rated KVA of machineC0 = Output coefficient obtained from curve
N = Rated RPM of the machine
Source : (Fig 1-1, Page 4, Large AC Machines by J.H. Walker.)
Design Study STATOR DESIGNING
Pole pitch is defined as the peripheral distance between twoconsecutive poles. It may be expressed as number of slots, degrees.(electrical or mechanical)
Calculated as : ψ= pi x Di/PWhere Pi (constant) =22/7Di = Air gap diameter in metersP = No. of poles
Flux per poleFlux per pole (φ) =Mean flux density * Pole pitch (ψ)* Length of core
Mean Flux density is assumed to be 0.6-0.7 Wb/m2
Turns per phase = = (1.1 * Vph)/4.44fφ
Design Study Calculation of number of parallel paths
Total current per slot should not exceed 5000 A.
If I be the rated current per phase and there be p parallel pathsthen current per conductor is I/p , and current per slot is 2*I/p
This should not exceed the limit of 5000 A.5000 > 2 * I / p
The value of p greater than or equal to this value, that satisfies otherdesigning constraints is chosen as the appropriate number ofparallel paths.
After the calculation of turns per phase we can calculate theapproximate no. of stator slots.
Design Study
No. of slots is given by,
Ns = (no. of phases) * T ph * (no. of parallel paths) /(turns per coil)Note: Turns per coil = 1 for bar winding
Number of conductor per slots = 2 ( for bar winding)
Design Study Short Circuit Ratio
Defined as the ratio of field currentrequired to produce rated voltage underopen circuit conditions to the field currentrequired to circulate rated current at shortcircuit. Short circuit ratio is the reciprocal ofsynchronous reactance Xd
For salient pole hydro electric generatorsSCR varies from 1.0 to 1.1.
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