59 results found
Ulusoy A, Stoianov I, Chazerain A, 2018, Hydraulically informed graph theoretic measure of link criticality for the resilience analysis of water supply networks, Applied Network Science, Vol: 3, ISSN: 2364-8228
Water Distribution Networks (WDN) are complex and highly interconnected systems. To maintain operation under failure conditions, WDNs should have built-in resilience based on topological and energy redundancy. There are various methods for analysing the resilience of WDNs based on either hydraulic models or surrogate network measures; however, not a single universally accepted method exists. Hydraulic modeling of disruptive operational scenarios suffer from combinatorial restrictions and uncertainties. Methods that rely on surrogate network measures do not take into account the complex interactions between topological and energy redundancy. To bridge this gap, the presented work introduces a hydraulically informed surrogate measure of pipe criticality for the resilience analysis of WDNs, called Water Flow Edge Betweenness Centrality (WFEBC). The WFEBC combines the random walk betweenness centrality with hydraulic (energy) loss principles in pipes. The proposed network resilience estimation method is applied to a case study network and an operational network. Furthermore, a network decomposition approach is proposed to complement the network estimation method and facilitate its scalability to large operational networks. The described resilience analysis method is benchmarked against a hydraulic model-based analysis of WDN reserve capacity. WFEBC is also applied to assess the improvement in resilience allowed by the implementation of a dynamically adaptive topology in an operational network. The benefits and limitations of the proposed method are discussed.
Pecci F, Abraham E, Stoianov I, Model reduction and outer approximation for optimising the placement of control valves in complex water networks, Journal of Water Resources Planning and Management, ISSN: 0733-9496
The optimal placement and operation of pressure control valves in water distribution networks is a challenging engineering problem. When formulated in a mathematical optimisation frame work, this problem results in a nonconvex mixed integer nonlinear program (MINLP), which has combinatorial computational complexity. As a result, the considered MINLP becomes particularly difficult to solve for large-scale looped operational networks. We extend and combine network model reduction techniques with the proposed optimisation framework in order to lower the computational burden and enable the optimal placement and operation of control valves in these complex water distribution networks. An outer approximation algorithm is used to solve the considered MINLPs on reduced hydraulic models. We demonstrate that the restriction of the considered optimisation problem on a reduced hydraulic model is not equivalent to solving the original larger MINLP, and its solution is therefore sub-optimal. Consequently, we investigate the trade-off between reducing computational complexity and the potential sub-optimality of the solutions that can be controlled with a parameter of the model reduction routine. The efficacy of the proposed method is evaluated using two large scale water distribution network models.
Armand H, Stoianov I, Graham N, 2018, Impact of network sectorisation on water quality management, Journal of Hydroinformatics, Vol: 20, Pages: 424-439, ISSN: 1464-7141
Pecci F, Abraham E, Stoianov I, 2018, Global optimality bounds for the placement of control valves in water supply networks, Optimization and Engineering, ISSN: 1389-4420
© 2018, The Author(s). This manuscript investigates the problem of optimal placement of control valves in water supply networks, where the objective is to minimize average zone pressure. The problem formulation results in a nonconvex mixed integer nonlinear program (MINLP). Due to its complex mathematical structure, previous literature has solved this nonconvex MINLP using heuristics or local optimization methods, which do not provide guarantees on the global optimality of the computed valve configurations. In our approach, we implement a branch and bound method to obtain certified bounds on the optimality gap of the solutions. The algorithm relies on the solution of mixed integer linear programs, whose formulations include linear relaxations of the nonconvex hydraulic constraints. We investigate the implementation and performance of different linear relaxation schemes. In addition, a tailored domain reduction procedure is implemented to tighten the relaxations. The developed methods are evaluated using two benchmark water supply networks and an operational water supply network from the UK. The proposed approaches are shown to outperform state-of-the-art global optimization solvers for the considered benchmark water supply networks. The branch and bound algorithm converges to good quality feasible solutions in most instances, with bounds on the optimality gap that are comparable to the level of parameter uncertainty usually experienced in water supply network models.
Abraham E, Stoianov I, 2017, Constraint-Preconditioned Inexact Newton Method for Hydraulic Simulation of Large-Scale Water Distribution Networks, IEEE Transactions on Control of Network Systems, Vol: 4, Pages: 610-619
Pecci F, Abraham E, Stoianov I, 2017, Quadratic head loss approximations for optimisation problems in water supply networks, JOURNAL OF HYDROINFORMATICS, Vol: 19, Pages: 493-506, ISSN: 1464-7141
Pecci F, Abraham E, Stoianov I, 2017, Penalty and relaxation methods for the optimal placement and operation of control valves in water supply networks, COMPUTATIONAL OPTIMIZATION AND APPLICATIONS, Vol: 67, Pages: 201-223, ISSN: 0926-6003
Menke R, Kadehjian K, Abraham E, et al., Investigating trade-offs between the operating cost and green house gas emissions from water distribution systems, Sustainable Energy Technologies and Assessments, ISSN: 2213-1388
Pecci F, Abraham E, Stoianov I, 2017, Scalable Pareto set generation for multiobjective co-design problems in water distribution networks: a continuous relaxation approach, STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION, Vol: 55, Pages: 857-869, ISSN: 1615-147X
Menke R, Abraham E, Parpas P, et al., 2017, Extending the envelope of demand response provision though variable speed pumps, 18th International Conference on Water Distribution System Analysis (WDSA), Publisher: ELSEVIER SCIENCE BV, Pages: 584-591, ISSN: 1877-7058
Armand H, Stoianov II, Graham NJD, 2017, A holistic assessment of discolouration processes in water distribution networks, URBAN WATER JOURNAL, Vol: 14, Pages: 263-277, ISSN: 1573-062X
Pecci F, Abraham E, Stoianov I, 2017, Outer approximation methods for the solution of co-design optimisation problems in water distribution networks, 20th World Congress of the International-Federation-of-Automatic-Control (IFAC), Publisher: ELSEVIER SCIENCE BV, Pages: 5373-5379, ISSN: 2405-8963
Menke R, Abraham E, Parpas P, et al., 2016, Exploring Optimal Pump Scheduling in Water Distribution Networks with Branch and Bound Methods, WATER RESOURCES MANAGEMENT, Vol: 30, Pages: 5333-5349, ISSN: 0920-4741
Menke R, Abraham E, Parpas P, et al., 2016, Demonstrating demand response from water distribution system through pump scheduling, APPLIED ENERGY, Vol: 170, Pages: 377-387, ISSN: 0306-2619
Abraham E, Stoianov I, 2016, Sparse Null Space Algorithms for Hydraulic Analysis of Large-Scale Water Supply Networks, Journal of Hydraulic Engineering, Vol: 142, Pages: 04015058-04015058, ISSN: 0733-9429
Herrera M, Abraham E, Stoianov I, 2016, A Graph-Theoretic Framework for Assessing the Resilience of Sectorised Water Distribution Networks, Water Resources Management, Vol: 30, Pages: 1685-1699, ISSN: 0920-4741
Abraham E, Stoianov I, An efficient null space inexact Newton method for hydraulic simulation of water distribution networks, ArXiv e-prints
Menke RMM, Abraham EA, Stoianov IS, Modeling variable speed pumps for optimal pumpscheduling, World Environment and Water resource congress
Increasingly more variable speed drive pumps are installed in water distributionsystems worldwide. However, the modeling of variable speed drives in such networksremains difficult, especially in the context of mathematical optimization for pumpscheduling. For the problem of energy usage minimization, formulated as a mixedinteger program, we propose a new simplified convex relaxation of the hydrauliccharacteristics of a variable speed pump. By using different model approximations forthe power curve, as a function of pump speed and volumetric flow rate, we study thetrade-off in the computational complexity and quality of solutions obtained. We usetwo small benchmark networks and real pump data from three different pumps tocalculate operating schedules. We show that these schedules, are computed in a timesuitable for operational usage, enable operation with lower operating cost compared tofixed speed pumps, and their sub-optimality can be computed.
Wright R, Abraham E, Parpas P, et al., 2015, Control of water distribution networks with dynamic DMA topology using strictly feasible sequential convex programming, WATER RESOURCES RESEARCH, Vol: 51, Pages: 9925-9941, ISSN: 0043-1397
Wright R, Parpas P, Stoianov I, 2015, Experimental investigation of resilience and pressure management in water distribution networks, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 643-652, ISSN: 1877-7058
Pecci F, Abraham E, Stoianov I, 2015, Mathematical programming methods for pressure management in water distribution systems, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 937-946, ISSN: 1877-7058
Menke R, Abraham E, Parpas P, et al., 2015, Approximation of system components for pump scheduling optimisation, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 1059-1068, ISSN: 1877-7058
Wright R, Abraham E, Parpas P, et al., 2015, Optimized control of pressure reducing valves in water distribution networks with dynamic topology, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 1003-1011, ISSN: 1877-7058
Armand H, Stoianov I, Graham N, 2015, Investigating the impact of sectorized networks on discoloration, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 407-415, ISSN: 1877-7058
Wright R, Herrera M, Parpas P, et al., 2015, Hydraulic resilience index for the critical link analysis of multi-feed water distribution networks, Computing and Control for the Water Industry (CCWI2015)- Sharing the Best Practice in Water Management, Publisher: ELSEVIER SCIENCE BV, Pages: 1249-1258, ISSN: 1877-7058
Herrera M, Abraham E, Stoianov I, 2015, Graph-theoretic Surrogate Measures for Analysing the Resilience of Water Distribution Networks, Pages: 1241-1248, ISSN: 1877-7058
Abraham E, Stoianov I, 2015, Efficient Preconditioned Iterative Methods for Hydraulic Simulation of Large Scale Water Distribution Networks, Pages: 623-632, ISSN: 1877-7058
Wright R, Stoianov I, Parpas P, et al., 2014, Adaptive water distribution networks with dynamically reconfigurable topology, JOURNAL OF HYDROINFORMATICS, Vol: 16, Pages: 1280-1301, ISSN: 1464-7141
Aisopou A, Stoianov I, Graham N, et al., 2014, Analytical and experimental investigation of chlorine decay in water supply systems under unsteady hydraulic conditions, JOURNAL OF HYDROINFORMATICS, Vol: 16, Pages: 690-709, ISSN: 1464-7141
Wright R, Stoianov I, Parpas P, 2014, Dynamic topology in water distribution networks, 12th International Conference on Computing-and-Control-for-the-Water-Industry (CCWI), Publisher: ELSEVIER SCIENCE BV, Pages: 1735-1744, ISSN: 1877-7058
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