INDEX TEST ANALYSIS OF GENERATING UNIT PERFORMANCE AT DORENA 1

2nd Index Test at 48 Ft

 

 

ACTUATION TEST EQUIPMENT COMPANY, INC

Winnebago, Illinois

 

March 14, 2016

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

Introduction

Performance analysis of the hydroelectric generating unit at Dorena 1 Dam continued using the new Hybrid Index Testing Method with a second index test at 48 feet Gross Head.

Data recorded by the station data logger is reduced by the Actuation Test Equipment Co, Inc., (ATECo) Index Test Box (ITB) to glean the requisite steady-state data points that are needed for turbine operating efficiency analysis and definition of a new 3-D Cam data surface.

The ITB sorts the data, applies Affinity Law head corrections and computes average values; each with an accompanying Slope and Standard Deviation value which are “figures of merit” for each and every average value.

These average values are then used to produce the index test curves and blade-to-gate cam curve in the code-accepted manner.

When combined with the results of the first index test at 69 Ft., the 48 Ft. results from this test provide a good basis for developing the entire 3-D Cam profile by extrapolating away from these two 3-D cam curves using the head-to-gate-and-blade cam curves from the model-test as a template.

The result of this is a good estimate of the final cam profile that will help identify appropriate gate to blade position pairs for the two remaining index tests.

 

Model Test Data

The model test data provided by the turbine manufacturer provides a first approximation of the optimum efficiency profile for the turbine across the full operating range of head.

Figure 1 Best Efficiency head-lines for 48 and 69 feet Gross Head as interpolated from the model test

The best-cam lines from the two index tests at 69 and 58 feet Gross Head are interpolated from the full model-test data set and then are plotted onto a semi-transparent image of the full model test profile as shown in figure 1.

 

Index Test Data

The method and procedures for collecting, reducing and analysis of the second index test were the same as those for the first test at 69 feet head.

 

Figure 2 Index Test Analysis at 48 Ft (Click image for spreadsheet download).

Next the index-test best-cam lines from the two index tests at 69 and 58 feet Gross Head are added to Figure 1 as shown in Figure 3.

Figure 3 Best Efficiency head-lines for Model Test and first 2 Index Tests.

When the index test data head-lines for 48 and 69 feet Gross Head are added to the model test graph a similar shape-change and position shift are seen for the best-efficiency profiles at these two heads.

 

3-D Cam Surface Analysis

Applying this shape-change and shift to an extrapolation across the entire model test data surface provides a first-guess as to the shape of the entire new 3-D cam surface as shown in Figure 4.

Figure 4 Entire 3-D Cam surface extrapolated from first 2 index tests.

Planning the 3rd Index Test

After the desired Gross Head levels for the next two index tests are determined, the estimated 3-D Cam surface will be very helpful in planning the next two index tests.

Interpolating between these new cam-curve lines to get the best-cam line for the existing head will help the planning for the next index test.

Figure 5 Animated .gif file showing the interpolation of a Best Cam line across the full operating range.

The Index Test Box provides an animated graphical interpolation display to show how the best-cam line shifts with head as shown in Figure 5.

This feature is useful for determining the best blade to gate test point pairs for the next test head.

By stopping the head sweep animation and entering the nest head level in the “Head” indicator box on the graph, the best-cam line for the next head.

To find the best gate and blade position pairs for the next index test, draw horizontal blade angle lines that cross the Best-Cam line for the 3rd head and then select two or more gate positions on either side of the best cam line.

For example, in Figure 6 Gross Head has been set at 85 feet, the Blade-Angle lines are drawn at 1, 10, 20, 40, 60 and 70 percent and then Gate Strokes are placed at every 5-percent.

Figure 6 Proposed Test Points for 85 Feet Gross Head Index Test.

For the 85 Feet Gross Head example in Figure 6 above, the new Gate/Blade pairs are:

Blade

Gate1

Gate2

Gate3

Gate4

Gate5

1

35

40

45

50

55

10

47

50

55

60

65

20

55

60

65

70

75

40

65

70

75

80

85

60

75

80

85

90

95

 

Observations and Conclusion

·        We're halfway there now and the final result is coming into view.

·        Using the best-cam lines from these first 2 index tests, appropriate head-gate pairs for the remaining 2 index tests can easily be determined.

·        Like the first test, the data points from the index-test results fall right on the “smooth curves” in the analysis.

·        Reduced data scatter shows that the ITB provides superior “steady-state” data points to conventional manual field-testing.

 

Sincerely,

Douglas Albright

 

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