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


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


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

> 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

> 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


5.0*)( PopeningKQ

one Q is predicted for a given angle

and P combination

R2 = 0.9999

R2 = 1

0

50

100

150

200

250

300

25 30 35 40 45 50 55

Opening angle

Coe

ffic

ient

WK p1-p3WK p2-p3Psup - p1Pinf - p1Psup - pinf

best


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




> Calibration curve smooth• Kop = Qref/P0.5

• 2nd order polynomial fit was enough



90

95

100

105

110

115

120

125

130

0 1 2 3 4 5 6 7 8 9 10

Days

Nor

mal

ised

flow

rate

Angular IndexSonic


> 10 days of monitoring> Good news: 2 independant signals almost identical


90

95

100

105

110

115

120

125

130

7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8

Days

Nor

mal

ised

flow

rate

Angular IndexSonic



> 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


95

100

105

110

115

120

22 23 24 25 26 27 28 29 30

Opening [deg]

Nor

mal

ised

flow

rate

Sonic series 1Sonic series 2

95

100

105

110

115

120

22 23 24 25 26 27 28 29 30

Opening [deg]

Nor

mal

ised

flow

rate

angular index

Flow ± 0.5 m3/s

RMS∼ 0.2 %

Flow ± 1 m3/s

RMS∼ 0.5 %


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


30 32 34 36 38 40 42 44 46 4825

30

35

40

45

50

55

60

65

70

Angle [deg]

K c

oeffi

cien

t

Propeller index quadratic

P



> Able to follow head change• Index results taken close to the expected head• Measurements are from a similar group (normalized)


Flow ± 1 m3/s

RMS ∼ 0.2-0.3 %

0.9

0.95

1

1.05

1.1

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



> Online monitoring: a real story• Comparison between « optimal »

(manual adjustments) and 2 standard automatic procedures

• Interface showing last 3 hours



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


before after


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



If you think angular index is a good system,

try it or contact us !!!


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?


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


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

RETURN


CFD vs experiment

> PropellerMean error 1.1%

20

30

40

50

60

70

80

25 30 35 40 45 50 55

Opening Angle

K c

oeffi

cien

t

CFD exp

> FrancisMean error 0.9%

10

12

14

16

18

20

22

24

26

22 24 26 28 30 32 34 36

Opening Angle

K C

oeff

icie

nt

CFD

exp

> Not exactly there but not far either…

RETURN


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

RETURN


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…

RETURN

Online Flowrate Monitoring Experiences at Hydro-Québec · Online Flowrate Monitoring Experiences...

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