Environmental Engineering Reference
In-Depth Information
Pump Turbine Limits
1600
Turbine rating
Pump rating
1400
1200
1000
800
600
400
200
0
0
100
200
300
400
500
Output (MW)
FIGURE 3.11
Pump turbine limits and ratings (head versus output). (From Iwabuchi, K. et al. 2006. Advanced
Governor Controller for Pumped-Storage Power Plant and Its Simulation Tool. SICE-ICASE
International Joint Conference. Korea.
IEEE Explore,
pp. 6064-6068
.
)
They are capable of handling a wide range of heads—75 to 1300 feet (20 to
400 meters).
Mixedordiagonallowturbines—
These turbines are typically applied
between 35 and 300 feet (10 to 90 meters) This design is smaller and more
agile than the design of a radial flow Francis type. Mixed or diagonal flow
units have faster pump starting times and adapt to variability more easily
than Francis units. Despite their smaller size, these units typically cost more
than Francis types.
Axiallowpumpturbines—
These turbines are applied between 3 and
45 feet (1 to 15 meters) of head. Their low head application is well suited for
tidal operations. Axial flow turbines exhibit reasonable efficiency within the
full spectrum of their operating ranges.
Variable Speed Turbines
PHES facilitates are regularly characterized by high variations in head effi-
ciency and thus losses are incurred during operation. Optimal design points
for the pumping and generating modes differ. To address these challenges,
dual speed units use an arrangement of stator windings to switch between
numbers of poles. The two settings achieve synchronous speeds.
While dual speed units have only begun to address the varied operating
conditions of PHES facilities, a recent development can enable variable speed
units. Karl Scherer describes the opportunities and challenges of variable
speed units for PHES.
17
These units function by using double-fed motor gen-
erators that operate as asynchronous units by feeding low frequency alter-
native current into excitation windings. Variable speed units achieve higher
generation efficiencies over head ranges and allow variable power consump-
tion during pumping operation.
