IEEE Power & Energy Magazine - September/October 2020 - 41

Operational data, such as maximum power output and turbine
efficiency, provided a baseline to evaluate possible capacity or
performance increases and the associated costs and benefits.
carried out according to the checklist in Table 2. From the
electrical perspective, several physical tests were performed
on the generators in addition to a visual inspection (Figure 5).
The procedure of the test performed was based on the standard stated in Table 3.
The third site visit was planned to perform turbine efficiency testing on one unit in each powerhouse and conduct
online vibration measurements (Figure 6). Additional time
was required to organize for the shipment of the measuring equipment from overseas, including customs clearance.
In addition, load rejection tests were performed as part of a
transient hydraulic study on Acaray II.
Data were collected to help develop a baseline scenario
representative of the existing conditions. A condition assessment of the equipment was useful in establishing a long-term
investment plan with optimal equipment-replacement timing
based on the risk of failure and replacement costs, as calculated during simulations by the asset management model.
Operational data, such as maximum power output and turbine efficiency, provided a baseline to evaluate possible
capacity or performance increases and the associated costs
and benefits.
Performance Testing

One unit at each station was tested using the dye dilution
methodology, as described in IEC Standard 60041 (Field
Acceptance Tests to Determine the Hydraulic Performance
of Hydraulic Turbines, Storage Pumps, and Pump Tur-

bines). Three operating points on each unit were selected
for dye dilution measurements to determine the absolute
flow and efficiency. The data were supplemented by index
test points taken across the range of operation and calibrated against the absolute flow measurements. The test
results produced unit efficiency curves that were used as
a baseline to evaluate the upgrade potential of a refurbishment project.
Three teams were on site during the testing procedure.
The first team was located at the intake, injecting dye into the
water passage at a constant flow rate using a peristaltic pump,
laboratory scale, and a data acquisition system to precisely
calculate the flow rate. Headwater level measurements were
also recorded at the intake during the testing (Figure 7).
The second team was located on the turbine floor level
of the facility, operating the data acquisition system and
retrieving water samples through the fluorometer once the
dye concentration had stabilized during an absolute flow test
point. The data acquisition system was used to measure the
following signals (Figure 8):
✔ turbine inlet pressure
✔ tailwater level
✔ wicket gate position
✔ dye concentration
✔ Winter-Kennedy differential pressure.
The third team was located in the control room. Load
changes were made on site by an ANDE operator, and the
operating point was held constant with stabilized flow, power,

figure 4. The Acaray dam and intake structure for Acaray I and II.
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IEEE Power & Energy Magazine - September/October 2020

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