How does the volume of water going through a hydroelectric dam affect electricity production? Could the flux of the generators not be modulated to different amounts of electricity with the same flow of water? If so, what would the minimum flow be?
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The Efficiency of a turbine is expressed in a Hill Chart -
The efficiency can be improved at off-design points by using variable geometry guide vanes in the induction section, as described in the paper below. This is the best we can do at the moment in terms of variable flow and variable head and variable demand.
https://iopscience.iop.org/article/10.1088/1755-1315/1079/1/012083/pdf
Phil Sweet
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Hydraulic power is the product of a flow variable (mass per second) times the effort variable (pressure head). To increase the output power of a hydro plant, the flow is increased by opening up the inlet valve to the turbine so the flow rate goes up.
Knowing the characteristic curves (the Hill Chart) for the turbine, the operating point of the hydro plant can be chosen so as to coincide with the maximum efficiency point of the turbine(s).
To cover as broad a range of power outputs as possible, while still maximizing efficiency, it is common to build a hydro plant with a number of separate turbogenerator units in place. Then in times of peak demand the power output of the plant is increased by bringing additional turbo units on-line, where all of them are operating at their peak efficiency point.
niels nielsen
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