Download - Hydro Turbine Jul'11 PVS
56 | Pumps Valves and Systems | July-Aug 2011
Abstract
Hydro-turbines are rotary machines which convert the
mechanical energy o the rotating element into electrical
energy. Te mechanical energy is imparted to the rotating
element by a high speed jet o water stored at a height in a
reservoir which is brought through a pipe; known as a pen-
stock, to the machine. Te rotating element o the machine
is connected through a shat to the generator, which in turn
produces electricity. More the fow through the machine,
more the power generated. A turbine is designed or a spe-
cic output at the rated net head and fow. A turbine must
meet these guarantee conditions in order to deliver the
rated output. Tis paper deals in discussing the actual eld
perormance data o a Francis turbine o 10 MW capacity
tested using thermodynamic method.
Introduction
Te test was conducted on the turbine using thermo-
dynamic method adhering to the code IEC - 60041. Te
test was conducted to guarantee the perormance o the
machine at the then prevailing operating condition. A tur-
bine is controlled automatically or variation in demand
by governor. Governor is a device which controls the
needle valve or guide vane opening to vary the fow rate
through the turbine. A variation in fow rate changes the
power output o the turbine. For example, when the load
on the turbine is reduced due to reduced consumption
on the distribution side, the turbine starts to rotate at a
higher speed, which in turn orces the governor to partial-
ly reduce the fow to match the speed to the rated speed.
Tis reduces the power output rom the machine to match
the demand. Te machine tested was manually control-
led in order to generate the turbine perormance curve.
Te controlling was achieved by changing the Guide Vane
opening positions, which changed the load. Due to site
constraints, the turbine could not be operated at ull load
and hence maximum guide vane opening position o 88%
was used to certiy the guarantee condition.
Guarantee Condition
Te guarantee condition o the turbine is as shown in the
table A. Since, the turbine could only be operated at 88%
Hydro Turbines PerformanceMonitoring - A Case StudyBy Juned Ansari, Secure Meters Limited
Guide vane opening, the guarantee point or the said condi-
tion have been deduced rom the hill chart o the turbine.
able : A
Test Setup
High Pressure Side (Penstock)
wo pressure transducers and two temperature probes were
used on the penstock or HP side energy measurement.
Low Pressure Side (ail Race)
On the tail race side, a 2 x 3 rame was used with 6 tem-
perature probes and one submersible pressure transducer.
Outliers were rejected and only those temperature read-
ings were accepted which were ound consistent in mutual
agreement with the client.
Te arrangement is as shown under:
Power Measurement
Power measurement was done using two wattmeter meth-
od on the generator side. Te generator was producing
power at 11KV and 1000 RPM.
G u i d e V a n e
O p e n i n g ( % )
D e s i g n e d
N e t H e a d ( m )
R u n n e r O u t p u t
A t T u r b i n e
S h a t ( k W )
T u r b i n e
E f c i e n c y ( % )
D i s c h a r g e
( m 3 / s )
100% - Full Load 326.43 10,304.00 92.30 3.49
88.0% 324.84 8,800.82 91.79 3.01
Rated Speed o urbine (RPM) 1000
Temperature Probes
Submersible Transducer
View towards Turbine Side View
Y
58 | Pumps Valves and Systems | July-Aug 2011
Please see the ollowing chart generated rom site testing.
Manuacturer provided generator efciency curve was used to evaluate the generator efciency in order to calculate the
turbine shat output.
Results
Te table 1 below shows the results obtained rom the turbine test using thermodynamic method. Te calculated data
was corrected to the net head; 324.84m, corresponding to the 88% guide vane opening. Simultaneously, the ow was also
measured using an ultrasonic ow meter. Te results o which are shown in able 2.
NetHead(m)
TurbineEfciency
(%)
GeneratorPower (kW)
GeneratorEfciency
(%)
TurbineShatPower(kW)
TurbineDischarge
(m3 /s)
GVOpening
(%)
Corrected to 324.84m
Turbine ShatPower (kW)
TurbineDischarge
(m3 /s)
329.14 87.60 7284.73 97.43 7476.88 2.643 72.20 7625.78 2.660
328.53 88.21 7498.37 97.47 7693.03 2.705 77.30 7824.36 2.720
327.73 88.94 7773.54 97.52 7971.55 2.787 79.90 8077.99 2.799
326.19 90.66 8251.55 97.58 8455.82 2.914 84.00 8508.52 2.920
324.84 91.43 8653.55 97.63 8863.65 3.041 88.00 8863.59 3.041
able 2 USFM Flow data
Te uncertainty in ow measurement (thermodynamic) is
between 1.15 to 1.16% only, which is quite acceptable. Ef-
ciency evaluation using conventional method has a ten-
dency to make an efcient unit appear inefcient and vice
versa.
Te uncertainty in efciency evaluation was ound to be
only 0.45% at 88% guide vane opening condition. Tis is
acceptable. Te turbine satises the guarantee condition.
650075
77
79
81
83
85
87
89
91
93
95
2.05
2.3
2.55
2.8
3.05
3.3
3.55
3.8 DUTY POINT
Turbine No: 1 Tester: AW/MAY/SP Test date: 01-Feb-2011AEMS TEST DATA
7100 7700 8300 8900
TURBINE SHAFT OUTPUT - kW
T U R B I N E E F F I C I E N C Y - %
D I S C H A R G E - m
3 / s
9500 10100 10700 11300
Hydro Power Station At Net Head of 326.43m
able 1 est Results rom Termodynamic est
S r . N o
T h e r m o d y n a m i c
F l o w m
3 / s
U S F M
F l o w
m 3 / s
U n c e r t a i n t y i n F l o w
T h e r m o d y n a m i c
m e t h o d %
U n c e r t a i n t y i n
E f c i e n c y %
P1 2.643 2.320 1.1587 0.4685
P2 2.705 2.390 1.1572 0.4654
P3 2.787 2.460 1.1559 0.4621
P4 2.914 2.600 1.1532 0.4551
P5 3.041 2.730 1.1516 0.4511
July-Aug 2011 | Pumps Valves and Systems | 59
Conclusion
1. he turbine satisies the guarantee condition at 88%
Guide Vane Opening. he turbine is operating at
91.43% eiciency generating 8863 kW.
2. he turbine was ound to be producing slightly more
power (63kW) under present condition than expected
rom the guarantee condition.
3. It is important to keep a watch on the turbine
perormance as silt/scale deposition on the turbine
blades drastically aects the operational efciency.
Tis also unnecessarily aects the lie o bearings,
seals, rotor etc besides requiring more water to
produce same amount o electricity.
4. It is recommended to get the hydro turbines
tested. hey are a green source o energy. esting
reveals any extra generation potential lying with
the turbine by suitable modiication in operating
schedule.
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