Online Flowrate Monitoring Experiences at Hydro-Québec · Online Flowrate Monitoring Experiences...
Transcript of Online Flowrate Monitoring Experiences at Hydro-Québec · Online Flowrate Monitoring Experiences...
Jonathan Nicolle & Gilles ProulxJune 2012
Online Flowrate Monitoring Experiences at Hydro-Québec
9th conference of the International Group on Hydraulic Efficiency MeasurementsTrondheim, Norway
2 Groupe − Technologie, Hydro-Québec
Summary
> Intro > Results with a 200 MW Francis> Results with a 110 MW Propeller> Details of the experimental setup> Conclusions
Intro – 200 MW Francis – 110 MW Propeller – Exp. setupIntro – 200 MW Francis – 110 MW Propeller – Exp. setup
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Intro
> Hydro-Québec • the largest hydro-utility in the world• Government owned• Operates 350 hydro turbines in 60 plants• Located in Québec, Canada• mostly Francis turbines, high flowrate + medium head
> Dedicated division for flow and efficiency measurement (ESP)
> Research center (Ireq)• Electricity production, transport and distribution• CFD expertise
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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Intro
> Research project: dream of online monitoring system• No such thing as too much flow measurements• Information is the key• Accurate, affordable, usable for various types of unit
> Allow for better business decisions at various levels• Daily production decision (which unit, which plant should I use ?)• How do I operate when the head changes ?• Reservoir management, river spate, how do I avoid spillway?• When should I clean the trash rack ?• What kind of losses are introduced by that manifold/ collector?• Is a cavitation repair justified based on efficiency losses ?• Does aeration, adjacent groups, tail water level, etc, have an
impact … ???
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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Intro
> For existing powerhouse flow monitoring, index seems like the best (only) choice
> Q? Why is it so difficult to use index testing with low head plants ?
> 2 problems from CFD investigation• Signal amplitude problem:
sensitivity to adjacent group operation
• Flow homology problem: the flow distribution change with the opening of the guide vane (streamlines are not the same so should not use an index)
> WK coefficients are not constants
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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Intro
> Our solution: angular index• First presented at 8th
IGHEM conference in India • Pressure behind the guide
vane• Measure of the guide vane
angle• Experimental calibration
from a curve
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
5.0*)( PopeningKQ
one Q is predicted for a given angle
and P combination
R2 = 0.9999
R2 = 1
0
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300
25 30 35 40 45 50 55
Opening angle
Coe
ffic
ient
WK p1-p3WK p2-p3Psup - p1Pinf - p1Psup - pinf
best
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Results for a 200 MW Francis
> Long penstock> 8 paths acoustic time travel (ATT) flowmeter as a
reference> Index
• Upstream: probes at the spiral casing inlet• Downstream: 4 probes behind the guide vane
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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Results for a 200 MW Francis
> Calibration curve smooth• Kop = Qref/P0.5
• 2nd order polynomial fit was enough
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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0 1 2 3 4 5 6 7 8 9 10
Days
Nor
mal
ised
flow
rate
Angular IndexSonic
Results for a 200 MW Francis
> 10 days of monitoring> Good news: 2 independant signals almost identical
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8
Days
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ised
flow
rate
Angular IndexSonic
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Results for a 200 MW Francis
> A surprise• After some time, a constant offset (∼ 1.2%) was detected
between the relative and the reference method• Automatic correction of the ATT method• Angular index unaffected and lower dispersion
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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22 23 24 25 26 27 28 29 30
Opening [deg]
Nor
mal
ised
flow
rate
Sonic series 1Sonic series 2
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Opening [deg]
Nor
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flow
rate
angular index
Flow ± 0.5 m3/s
RMS∼ 0.2 %
Flow ± 1 m3/s
RMS∼ 0.5 %
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Results for a 110 MW propeller
> 4 pressure probes located between the guide vane and the runner. External WK for high pressure.
> Semi-spiral casing> Again smooth calibration curve based on previous
current meters measurements
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
30 32 34 36 38 40 42 44 46 4825
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Angle [deg]
K c
oeffi
cien
t
Propeller index quadratic
P
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Results for a 110 MW propeller
> Able to follow head change• Index results taken close to the expected head• Measurements are from a similar group (normalized)
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
Flow ± 1 m3/s
RMS ∼ 0.2-0.3 %
0.9
0.95
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750 770 790 810 830 850 870 890
Opening [mm]
Qno
rm
angular index 25.5 m Current meters 25.5angular index 27.5 m Current meters 27.5mAngular index 30 m Current meters 30 m
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Results for a 110 MW propeller
> Online monitoring: a real story• Comparison between « optimal »
(manual adjustments) and 2 standard automatic procedures
• Interface showing last 3 hours
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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Experimental setup
> Pressure probes• Must be able able to take the full head
when the guide vanes are closed• Averaged with a manifold• 4 probes are enough for Francis, ok for
propeller• Two words:
Automatic Bleed….
> Guide vane• Angular encoder is preferred to
servomotor strokes
> Signal acquisition• Filter when the guide vanes move
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
before after
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Conclusion
> Until now, not much attention has been given to online monitoring
• Pursue different goals than absolute measurements (complementary)• More interesting & difficult for low head plants• Demonstrated angular index usefulness for 2 very different turbines
(random error 0.2-0.3 %)• Captured phenomena that would be difficult to observe otherwise
– ATT flowmeter recalibration– Automatic PFR procedures impact on efficiency
What’s next…> Building a new experimental set
• More industrial• Fully numerical signal• Bleed valves controller
> Starting to integrate flow data to the various HQ systems
Intro – 200 MW Francis – 110 MW Propeller – Exp. setup
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If you think angular index is a good system,
try it or contact us !!!
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Good questions you might ask …
Why use an angular encoder instead of servomotor stroke?What happened with the ATT flowmeter on the Francis?What about CFD and experimental comparisons?Is the calibration transposable from one group to another? What if the turbine is replaced?What are the pitfalls for angular index?
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Why prefer angular encoder
> Servomotor strokes would work in theory… > …but as a CFD guy, I’ve been struggling with
servomotors stokes for my whole life• Old powerhouse, modifications, extensions, not always on
plan• In-house system not enough accurate• Pre-loading different for each unit• Zero definition not always the same• Servomotor is of value to the operator
> Angular encoder is fresh start• Accurate & return a value that has a meaning in terms of
fluid flow• Angular position is of value to the fluid flow analyst
RETURN
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ATT reference flowmeter
> Not exactly sure…• Acquired the data and analysed them
afterward> Seems like there was a problem with
one of the path and the system recalibrated itself…
> Dont know if the flow value was good before or after the event
> Important point is the random error or RMS value of both methods
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CFD vs experiment
> PropellerMean error 1.1%
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Opening Angle
K c
oeffi
cien
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CFD exp
> FrancisMean error 0.9%
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Opening Angle
K C
oeff
icie
nt
CFD
exp
> Not exactly there but not far either…
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Calibration generality
> Question still open for debate > Is the calibration applicable to a similar unit?
• K would probably be very close but may be not identical
> Is a new calibration curve necessary when the turbine change?
• Limited results from a kaplan turbine seem to suggest so…
• Variation in the meridionnal flow distribution affects the index
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Pitfalls> Be as accurate as you can for the guide vane
opening, it is quite sensible> Calibration might not be valid for the whole
operating range > If you use a low number (< 4) of downstream
probes, you might have unwanted sensitivity> Bleed valves are essentials to survive de-watering
of the unit and long term operation> It not just a change in technology, it requires a
change in mentality, so plan data integration ahead. Flow values are of no use if they do not make their way through the compagny operating systems. Beware of admistrative inertia…
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