Optimal Design and Scheduling of Irrigation Pumps by Using General Algebraic Modelling Systems (Gams) A Case Study of Fentale-Qawa Pump Station
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Date
2015-03
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Addis Ababa University
Abstract
Traditionally, design engineers tend to be conservative in calculating pump station
decision variables by focusing on peak demands that occur about1% of the time. On
the other hand, optimal design and operation of pumping stations are mathematically
large-scale non-linear problems. Consequently, there is a possibility of using an
optimum operation schedule on a set of non-optimum pump combinations that are
selected narrowly based on peak discharge of system demand. Thus, optimization
model is developed in this thesis work to tackle optimization problems in pump
stations.
Optimal design and operation of irrigation pump station system is carried out with a
help of a computer model developed in a General Algebraic Modeling Systems
(GAMS). The model makes use of the latest advances in optimization techniques that
utilize in-built solvers in GAMS to solve optimization problems with lots of decision
variables and constraints. It is based upon one major objective function to find
optimized solutions of equations. Automatically generated model outputs include
selected pump type, capacity, number of pumps and optimum schedule of pump
operation for problems involving design phase. For existing pump stations, it simply
generates a preliminary optimum operation schedule.
The developed optimization model was tested on previously optimized problem by
different researchers and then implemented on a case study, Fentale-Qawa Pump
Station, to optimize the annualized investment cost of the pumping station and its
annual operating cost. GAMS results were presented and compared with five other
well-known optimization techniques. The results were unique and stood second to
Lagrange multipliers (LM) method in minimizing Annual Total Cost (ATC) of the
sample problem.
Implementation of the model would have saved 35% of Initial Investment Cost in
pumps had it been used during design phase. The savings occurred in the annual
operation cost is 11% compared to the optimized operation cost of the existing pump
station. It is clear that the developed optimization model provides the designer and the
operator with optimized combination of design variables and operation parameters.
(Key words: GAMS, Optimum design variables, Optimum operation schedule, Pump)
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Keywords
GAMS, Optimum design variables, Optimum operation schedule, Pump