Turbine Engineering for Hydropower Plants

Transcription

1 Turbine Engineering for Hydropower Plants Prof. François Avellan Itaipu Power Plant

2 Basic Concepts Scope Turbine Specific Energy Specific Speed Specifications Pelton Turbines Francis Turbines Outlook Unit 4 Turbine Engineering for Hydropower Plants 2

3 Hydroelectric Power Plant: Storage or Run-of-River Power Station Turbine Engineering for Hydropower Plants 3

4 Hydropower: Turbine Driving an Electrical (Synchronous) Generator Machine Power Output P = ω T ( W) Available Hydraulic Power P ( W ) h = ρq E J s kg m 3 m s Turbine Efficiency 3 J kg T T P= η P h ; η 100 % Driving Power Defined as Positive : P 0 gh Q I I I E gh gh P h dω J = T+ Tel ( Nm ) dt T ω gh QI I = ρq E I I ( 1 J kg ) ( ) = ρq gh gh I I I Basic Concepts 4

5 Rotating train dynamics Rotating train angular momentum equation Synchronous conditions : Power failure : runaway speed Synchronous speed relation : f grid z p n : Grid frequency : Number of poles : Rotating frequency T = T el dω Tél. = 0 = T > 0 dt = 2 fgrid n Hz z p ( ) dω J = T + T dt el ( Nm ) f grid = 2 16 Hz; 50 Hz; 60 Hz 3 Basic Concepts 5 5

6 Discharge - Head Chart of Hydropower Plant Capacity Ph = ρq gh Basic Concepts 6

7 Definition of State Variables Mean Flow Local Specific Energy Discharge: Extensive Variable Q 2 p C ht = + g Z + + Cste J kg ρ 2 C 1 C nda A Pressure ( 3 m s 1 ) Mean Flow Specific Energy: Intensive Variable: 2 P h p C C n gh = + gz + da 0 J kg ρq ρ 2 Q A ( -1 ) Gravity Potential Kinetic n 1 A 1 Σ ( -1 ) V A 2 n 2 On Σ C n= 0 V = A1 Σ A2 Basic Concepts 7

8 gh Q 1 1 Hydraulic System: Specific Energy and Discharge Budgets A gh 1 2 A2 Q Specific Energy Budget Steady Flow? Straight Stream Lines, free of Secondary Flow Flow Budget Discharge Discharge Velocity ( ) gh1 gh2 gh r i = + Q = Q 1 2 A C = A C Basic Concepts 8

9 Runner/Impeller Specific Energy Transfer 1 Q t ω Brillant Extension Project, British Columbia, Canada, Kaplan Turbine CAD Model, PF2 EPFL Test Rig 1 Traversing Discharge Q t ( m 3 s -1 ) Transferred Specific Energy Power Transfer P ρqe Drive: Turbines ( -1 ) gh1 gh1 = Et ± Erb J kg ( ) = W t t t P > 0 Brake: Pumps, Propellers P < 0 Turbine Specific Energy 9

10 gh 2 p C = + gz + ρ 2 Specific Energy Transfer ( -1 J kg ) Reaction 2 2 p 1 p1 C1 C1 Et = + + ± ρ ρ gz gz E 2 2 Water Wheel Displacement Impulse [ ] 1 1 rb Loss ( -1 J kg ) Turbine Specific Energy 10

11 Power Plant Conditions Dimensional Analysis Discharge [ Q] = LT 3 1 ( m 3 s -1 ) Specific Energy 2 2 ML T E gh I ghi = L T = J kg M Unit Characteristic Angular Speed [ ] ( ) 1-1 ω = T s Turbine/Pump Dimension D = L m [ ] ( ) ( ) / Specific Speed 1111

12 Dimensional Analysis Dimensionless Angular Speed Condition Yields Linear System Dimension of Time 1 α 2β = 0 Dimension of Length 3α + 2β = α = ; β = 2 4 Solution α β [ ν] ω = Q E = M T L T L = T L T L T α α 2β 2β Specific Speed ω ν = π Q E (Contd) / 1212

13 Discharge Coefficient ϕ = Cm U Energy Coefficient 2E ψ = U 2 Specific Speed Unit Specific Speed Rotating Speed Dimensional Analysis 2 ϕ ν = = k N ψ ( 1 min ) Discharge Factor Speed factor U k n Specific Speed Cm Q k k Cm U Cm = 2 E U = 2 E 1 (Contd) 2 Q = N = ν S.I. H 3 4 ( ) 1313

14 Selecting Hydraulic Turbines Head Highest eff. 96% 97% Head = H ( m) 3 1 ( ) 1 ( min ) Discharge = Q m s Speed = N 2 f n = z p grid ( Hz) Specific Speed Specific Speed 14

15 Hydro Turbines International Market Breakdown by Types of Turbines GW Installed Capacity in 2012 Modernization Market GW to be built before 2050 Greenfields Project Bulb 2% Kaplan 17% Pump- Turbine 12% Pelton 8% Francis 61% Turbine Specifications 15

16 Matching Turbine Specific Speed to Site Conditions Site Potential Specific Energy Site Specific Energy Data Science: Flow Duration Statistics Average Discharge 1'000 m 3 /s ( Z ) g Z B B ( ) ( -1 ) B r gh = 1 gh1 g Z ZB gh J kg ( 3-1 ) Q Instal. m s Diverted Flow Total Flow % 100 Percentage of time discharge was exceeded Turbine Specifications 16

17 Matching Turbine Specific Speed to Site Conditions Targeted Unit Specific Speed Rated Head Specification of Unit Number Specification of rotating frequency Runaway Speed Limitation E = gh Q nq = N z units H z units Limitation of Apparent Power per Poles 1 instal 3 4 Air cooling < 28 MVA < Water cooling < 35 MVA N p fgrid 60 s = z Turbine Specifications 17

18 500 MVA Generators min -1 1'269 MW Bieudron Power Plant 3 Pelton Turbines 14 poles, 35.7 MVA/pole* Water Cooled 423 MW Pelton* Turbines, 5 injectors 1'883 mwc Head* 25 m 3 /s Discharge D1 = m ~28 t Runner Mass Pelton Turbines 18

19 Impinging Jet on Pelton Buckets FVPM Flow Numerical Simulations Christian VESSAZ, EPFL Doctoral Thesis N 6470, 2014 Pelton Turbines 19

20 Silt Erosion Needle Bucket Needle Severe Erosion Erosion Ripples on Buckets ~2'500 Total Hours of Operation Pelton Turbines Silt Erosion of Turbine Components: 4 x 100 MW Pelton, 900 m Head 20

21 SPHEROS Finite Volume Particle Method Solver Multi Scale Silt Laden Flow Erosion Simulation Copper sample Ø 3 mm slurry jet, 10 m/s LEGUIZAMON Sebastián, EPFL Doctoral Student, CTI Project GPU-SPHEROS Pelton Turbines 21

22 Hydropower Plant Giga Hydropower Plants are Francis Powered Country Capacity (MW) Energy (TWh) Capacity Factor EPFL Model Testing Three Gorges China 22' Storage Itaipú Brazil-Paraguay 14' Storage Xiluodu China 13' Storage Type Belo Monte Brazil 11'233 - Run-of-River Guri (Raúl Leoni) Venezuela 8' Storage Tucurui Brazil 8' Storage Grand Coulee USA 6' Storage Longtan China 6' Storage Xiangjiaba China 6'400 NA NA Storage Krasnoyarsk Russia 6' Storage Robert Bourassa (LG2) Canada 5' Storage Churchill Falls Canada 5' Storage Tucurui Dam, Eletro Norte Francis Turbines 22

23 Xiangjiaba Power Station (Jinsha River, Yunnan) 8 Francis Turbines 825 MW Max. Power 10.5 m Diameter kg What level of p fluctuations to be expected for a 800 MW turbine? 23

24 n ED HYPERBOLE Turbine Case Study Hill Chart and Operating Range Q ED Deep Part Load Part Load Full Load Francis Turbines 24

25 Unsteady Flow in Francis Draft Tube Alligné et al., Journal of Hydraulic Research, Vol. 51, 6, Müller et al., Experiments in Fluids n 54 : 1514, Simon Pasche PhD Work, SNF GRANT N _ Francis Turbines 25

26 Machine Setting Level IEC Definitions IEC Standard, "Hydraulic Turbines, Storage Pumps and Pump-Turbines-Model Acceptance Tests". International Electrotechnical Commission; Geneva, Nov Specific Energy E gh gh > 0 J kg Net Positive Suction Specific Energy pv NPSE ghi gz ρ Setting Level hs = Zref ZB I I ( 1 ) ref ( 1 J kg ) Turbine Specifications 26

27 HYPERBOLE ERC/FP7-ENERGY Grant N HYdropower plants PERformance and flexible Operation"towards Lean integration of new renewable Energies Dynamic Assessment of Francis Turbines & Pump-Turbines 42 Months, EUR 6.3 Mio EUR 4.3 Mio Supported by European Commission 1 st Sept th Feb Consortium coordinated by EPFL 27

28 HYdropower plants PERformance and flexible Operation towards Lean integration of new renewable Energies Headwater reservoir Surge Tank Hydraulic Eng. Tailwater reservoir Mechanical Eng. Electrical Eng. System Approach HYPERBOLE ERC/FP7-ENERGY Grant

29 System Approach Methodology Francis Turbines 29

30 HYPERBOLE Inter blades vortices Deep part load operating conditions Q << QBEP Francis Turbines page 30

31 Deep part load Inter blades vortices HYPERBOLE Visualization Hollow guide vanes with window Boroscope with swiveling prism High Speed Camera High intensity Xenon flash Compact power LED DPL2: n ED = Francis Turbines 31

32 HYPERBOLE Flow Numerical Simulations Deep part load Inter blades vortices Void Fraction 10% Isosurface Francis Turbines 32

33 Hydroelectric Plants Generate 17% of the World Electricity Luciano dos Santos, "Digital Disruption of Hydroelectricity", HYPERBOLE Conference, Porto, February 2-3,

34 THANK YOU FOR YOUR ATTENTION 34