A Multi-objective Optimization Algorithm for Sensor Placement in Water Distribution Systems

In this study a multi-objective optimization model is developed for water sensor network design in water distribution systems. In this model the three criteria used for evaluating the performance of the water sensor placement designed are directly used as the objectives of the optimization problem. These include minimizing the expected water volume contaminated, minimizing the expected time of detection and maximizing the detection likelihood. Due to the difficulty of determining sensor placement locations within thousands of junction combinations in the system, the sub-domain concept is introduced, which identifies a subset of junctions for candidate sensor locations. The sub-domains are determined using the roulette wheel method based on junction water demand values. The junctions with larger water demand have higher probabilities to be selected to the candidate sensor subset. For solution of the model an improved approach that is based on the non-dominated sorting genetic algorithm (NSGA-II) is used. The approach works over the sub-domain and the final Pareto optimal front is obtained through the sub-domain iteration process. The two water distribution systems provided in BWSN 2006 are chosen as examples to demonstrate the performance of the model and algorithm proposed. The impact of the non-detected scenarios in calculating objectives on the Pareto optimal front is also addressed in this study. The results show that the proposed model and the algorithm are effective in solving this problem.