H-6. Analysis of Existing Facilities. In order to fully develop an evaluation report, an analysis of
the existing components that will be affected by the proposed work is to be performed. Even if
the proposed work does not include an uprating of project capacity, a review of the existing
facilities is necessary. The required power train analysis is commonly referred to as "water to
wire." The economics of an uprating can be adversely affected by the necessity of replacing a
main power transformer or a turbine shaft and bearings because of inadequate component
capacities.
A partial list of items to be analyzed:
penstock water hammer
excitation equipment capacities
stator winding capabilities
equipment cooling requirements
power transformer rating
unit and switchyard switchgear
H-7. Economic Analysis. The economic analysis for hydropower major rehabilitation evaluation
is based on losses or gains in capacity and energy and avoided repair and O&M expenses. By not
doing the proposed rehabilitation, there will be a cost associated with the reduced reliability of the
power unit. Benefits can be lost by not restoring lost efficiency or taking advantage of additional
capacity and/or efficiency. A regional power benefits model must be used to reflect the value of
energy and capacity for the project being evaluated.
a. Realistic increases in capacity and efficiency must be presented. The results of the
power train analysis will show if there are additional modifications (and costs) associated with the
proposed project. For turbine replacements a sensitivity analysis is needed to show the affects of
a range of efficiencies, instead of assuming the highest possible value. Not all turbine
replacements are going to achieve 95% efficiency.
b. At this point in the development of the hydropower evaluation guidance, not all types
of equipment have well defined risk assessment methodologies. This, coupled with the issue of
separable elements of a power plant, leaves many major auxiliary components without fully
developed procedures. Efforts should be made to quantify NED benefits associated with the
replacement of a voltage regulator, hydraulic governor, alarm system and the like. Also, give
other justification if these benefits can not be economically quantified or justified.
H-2
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