Upp í vindinn - 01.05.1998, Page 27

New Approach in Engineering: Global Optimisation of Design Aiming for Maximum Profit of Investment
assumptions, such as unit-prices and
market characteristics are entered by
the use. When the input phase is fin-
ished, the model is ready for calcula-
tion. The user can get one detailed
solution by using the default variables,
see how varying one variable affects the
result, or perform a global optimisa-
tion. The program returns a detailed
solution which includes specific data,
cost summary and bill of quantities.
Besides performing direct optimisa-
tion the application can, for example,
be used for sensitivity and what-if
analysis, i.e. check how adjustment of
one or more input parameters (includ-
ing adding or removing structures)
affects the optimal design and as a
training tool to get a feeling for the
importance of different structures and
parameters.
Experience of Hydra
In the early stages of the development
of Hydra, the program was usecl to
optimise a calibration example where
the real optimum could be calculated
mathematically. The algorithm suc-
ceeded in reaching this true global
optimum.
In cooperation with the Landsvirkjun
and their engineering consultants, the
model was used to perform a case study
on the Fljótsdalur Hydroelectric
Project. The resulting design variables
of the GA optimisation where then
compared with the project planning
report, from April 1991. Two runs
where made, firstly, a Plant Stage run,
and secondly, an Allocation Stage run.
This was done in order to find out, by
comparing the results, if the Allocation
Stage coulcl be simulated with the
model. The case study led to a
improved design, with similar energy
and load capacity compared to the pro-
ject planning report, but approximate-
ly 6% better economical result, due to
different dimensions of dam and con-
duits in the plant stage, and 3% in the
allocation stage (Elíasson & Ludvigsson
1996).
In 1997 the Hydra was used in a fea-
sibility study of hydropower in the
Skagafjörður region and in 1998 it is
on schedule to use it in a feasibility
study of possible plants in the region
north-east of Vatnajökull.
Final words
The purpose of the development of the
program ‘Hydra’ was to create a tool
for design of hydropower plants. The
positive experience of this development
has raised the questions if it is not pos-
sible to use the same method in other
fields of engineering. The same
approach could be used as well in
design of other types of projects such as
sewage systems, transmission lines,
road construction etc. Also it could be
implemented as a tool in project man-
agement, optimising resources (man-
power, equipment etc.) against con-
struction time. The main conclusion is:
- Promising beginning,
long way to go - □
References
Eliasson, J. & G. Ludvigsson 1996. Optimal
Design of Hydropower Plants. Univ. Iceland,
Engineering Research Institute, Water
Resource Department. (Research Report).
Elíasson, J. 1994. Hönnun vatnsorkuvera me_
heildarkostna_arbestun. Upp í vindinn.
Fljótsdalur Engineering Joint Venture. 1991.
Pljótsdalur Hydroelectric Project - Project Planning
Report. Landsvirkjun.
Goldberg, D. E. 1989. Genetic Algorithms in
Search Optimization & Machine Learning.
Addison-Wesley.
Masters, T. 1993. Practical Neural Network
Recipes in C+ + . Academic Press.
Mosonyi, E. 1991. High-Head Power Plants
Vólume Two/A & Two/B. Akadémiai Kiadó,
Budapest.
Pirlot, M. 1994. General local search heuris-
tics in Combinatorial Optimization: a tutorial.
Belgian Journal of Operations Research, Statistics
and Computer Science 32(1-2).
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