Research Output

Operational optimisation of water distribution networks.

  Water distribution networks are a fundamental part of any modern city and their daily operations constitute a significant expenditure in terms of energy and maintenance costs.
Careful scheduling of pump operations may lead to significant energy savings and prevent wear and tear. By means of computer simulation, an optimal schedule of pumps can
be found by an optimisation algorithm. The subject of this thesis is the study of pump scheduling as an optimisation problem.

New representations of pump schedules are investigated for restricting the number of potential schedules. Recombination and mutation operators are proposed, in order to use
the new representations in evolutionary algorithms. These new representations are empirically compared to traditional representations using different network instances, one of
them being a large and complex network from UK. By means of the new representations, the evolutionary algorithm developed during this thesis finds new best-known solutions
for both networks.

Pump scheduling as the multi-objective problem of minimising energy and maintenance costs in terms of Pareto optimality is also investigated in this thesis. Two alternative
surrogate measures of maintenance cost are considered: the minimisation of the number of pump switches and the maximisation of the shortest idle time. A single run of
the multi-objective evolutionary algorithm obtains pump schedules with lower electrical cost and lower number of pump switches than those found in the literature. Alternatively,
schedules with very long idle times may be found with slightly higher electrical cost.

Finally, ant colony optimisation is also adapted to the pump scheduling problem. Both Ant System and Max-Min Ant System are tested. Max-Min Ant System, in particular,
outperforms all other algorithms in the large real-world network instance and obtains competitive results in the smallest test network. Computation time is further reduced by
parallel simulation of pump schedules.

  • Type:

    Thesis

  • Date:

    31 October 2009

  • Publication Status:

    Unpublished

Citation

Lopez-Ibanez, M. Operational optimisation of water distribution networks. (Thesis). Edinburgh Napier University. Retrieved from http://researchrepository.napier.ac.uk/id/eprint/3044

Keywords

Computer simulation; Water distribution networks; Optimisation algorithms; Evolutionary algorithms; Max-min ant colony simulations; Parallel simulations; Applications; Pump scheduling; Switch reduction; Maximising idling times; Cost reduction

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