scholarly journals Development of a Modularity Index for Reliability Assessment of Isolation Valve Systems

10.29007/m56l ◽  
2018 ◽  
Author(s):  
Orazio Giustolisi
Keyword(s):  
Failure Probability ◽  
Water Distribution ◽  
Reliability Assessment ◽  
Water Distribution Network ◽  
Operating Conditions ◽  
System Component ◽  
Hydraulic Systems ◽  
Mechanical Reliability ◽  
Abnormal Operating Conditions ◽  
Modularity Index

Mechanical reliability refers to the assessment of the capacity of the water distribution network (WDN) to provide a correct service to the different type of costumers under abnormal operating conditions due to a failure of a system component. It depends on the effectiveness of the isolation valve system (IVS) and on the failure probability of components. Starting from the calculation of the actual customer demands during abnormal operating conditions of the hydraulic systems due to valve shutdowns and the failure probability of the separated segments, the work develops a metric for WDN reliability assessment. The finding is that the topologic part of WDN reliability assessment, relating to the IVS, is based on the risk of disconnection. Starting from it, the works develops a special modularity index for IVS reliability assessment.

Uncertainty quantification of pressure-driven analysis for water distribution network modeling

2015 ◽  
Vol 16 (3) ◽  
pp. 599-610 ◽  
Author(s):  
Ho Min Lee ◽  
Do Guen Yoo ◽  
Doosun Kang ◽  
Hwandon Jun ◽  
Joong Hoon Kim
Keyword(s):  
Negative Pressure ◽  
Water Distribution ◽  
Real Life ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Operating Conditions ◽  
Service Reliability ◽  
High Degree ◽  
Pressure Driven Analysis ◽  
Pressure Driven

The hydraulic analysis of water distribution networks (WDNs) is divided into two approaches: namely, a demand-driven analysis (DDA) and a pressure-driven analysis (PDA). In the DDA, the basic assumption is that the nodal demand is fully supplied irrespective of the nodal pressure, which is mainly suitable for normal operating conditions. However, in abnormal conditions, such as pipe failures or unexpected increase in demand, the DDA approach may cause unrealistic results, such as negative pressure. To address the shortcomings of DDA, PDA has been considered in a number of studies. For PDA, however, the head-outflow relation (HOR) should be given, which is known to contain a high degree of uncertainty. Here, the DDA-based simulator, EPANET2 was modified to develop a PDA model simulating pressure deficient conditions and a Monte Carlo simulation (MCS) was performed to consider the quantitative uncertainty in HOR. The developed PDA model was applied to two networks (a well-known benchmark system and a real-life WDN) and the results showed that the proposed model is superior to other reported models when dealing with negative pressure under abnormal conditions. In addition, the MCS-based sensitivity analysis presents the ranges of pressure and available discharge, quantifying service reliability of water networks.

scholarly journals Pressure-driven modelling of water distribution systems

2003 ◽  
Vol 3 (1-2) ◽  
pp. 255-261 ◽  
Author(s):  
T. Tanyimboh ◽  
B. Tahar ◽  
A. Templeman
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Line Search ◽  
Water Distribution Systems ◽  
Operating Conditions ◽  
Governing Equations ◽  
Novel Method ◽  
Newton Raphson ◽  
Abnormal Operating Conditions ◽  
Demand Driven Analysis

This paper presents a novel method to model water distribution systems (WDS) with insufficient pressure. Methods for the prediction of the performance of a WDS with pressure deficiencies are reviewed. The influence of imposed relationships between nodal heads and outflows is assessed and numerical results are given. A Newton-Raphson technique plus line search is employed for solving the governing equations. It is demonstrated that the approach offers superior results for the hydraulic performance of networks under abnormal operating conditions compared to demand-driven analysis-based models.

scholarly journals Water distribution network optimization using maximum entropy under multiple loading patterns

2013 ◽  
Vol 13 (5) ◽  
pp. 1265-1271 ◽  
Author(s):  
Anna M. Czajkowska ◽  
Tiku T. Tanyimboh
Keyword(s):  
Design Optimization ◽  
Maximum Entropy ◽  
Water Distribution ◽  
Optimization Procedure ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Operating Conditions ◽  
Statistical Entropy ◽  
Computationally Efficient ◽  
Nsga Ii

This paper proposes a maximum entropy-based multi-objective genetic algorithm approach for the design optimization of water distribution networks (WDNs). The novelty is that in contrast to previous research involving statistical entropy the algorithm can handle multiple operating conditions. We used NSGA II and EPANET 2 and wrote a subroutine that calculates the entropy value for any given WDN configuration. The proposed algorithm is demonstrated by designing a six-loop network that is well known from previous entropy studies. We used statistical entropy to include reliability in the design optimization procedure in a computationally efficient way.

scholarly journals Functional Feasibility in Optimal Evaluation of Water Distribution Network Performances

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3404
Author(s):  
Flavia Fuso ◽  
Maria C. Cunha ◽  
Gianfranco Becciu
Keyword(s):  
Water Distribution ◽  
Network Performance ◽  
Traditional Approach ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Point Of View ◽  
Operating Conditions ◽  
Worst Case ◽  
The Real ◽  
Operation Conditions

The traditional approach for the optimization of water distribution networks (WDNs) does not always lead to consistent solutions from an operational point of view. The latest optimization algorithms identify solutions that are “the best solutions” in mathematical terms but that can be less than robust against changes in operating conditions, resulting in the worst case in hydraulically infeasible configurations. Thus, this paper aims to provide a methodology that can synthesize the network performance capabilities under the change in operating conditions with two convergent strategies. The first consists of the implementation of new performance indices (PIs), the demand deficit and the pressure range, and the evaluation of their ability to criticality highlight in operating conditions. The second is the introduction of a new approach to weight the infeasible solutions in the final result, which are those inconsistent with the real hydraulic network performances. The analysis shows that the use of these new indices makes it easier to understand the behavior of the network and to identify any weaknesses. This is true if these indices consider the hydraulically inconsistent solutions that may arise from the simulations of different operation conditions; otherwise, results that poorly represent the real behavior of the network would be obtained.

scholarly journals Probability of network disconnection of water distribution system for maintenance prioritization

2018 ◽  
Vol 67 (3) ◽  
pp. 252-269 ◽  
Author(s):  
Hieu Chi Phan ◽  
Ashutosh Sutra Dhar ◽  
Premkumar Thodi ◽  
Rehan Sadiq
Keyword(s):  
Failure Probability ◽  
System Reliability ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Distribution Network ◽  
Algebraic Connectivity ◽  
Network Failure ◽  
Pipe Segment

AbstractUnexpected pipe breaks in municipal water distribution systems may cause isolation of parts of the network or reduction of redundancy, leading to reduced system reliability. While a network with less redundancy implies less tolerance to further breaks, the isolation of nodes explicitly indicates unavailability of the system to service the nodes. This paper presents a method of measuring these topological changes using algebraic connectivity (AC). AC is a parameter that can be used to assess robustness and redundancy of a network. The changes in AC associated with pipe breaks are compared with the AC of intact networks to assess whether the removal of the pipe causes reduction of redundancy or isolation in the network. An AC of 1.5625 × 10−5 is calculated for an intake of a medium-sized water distribution network (WDN). The fluctuation in AC is used to assess the criticality of each pipe segment to the overall structure of the network. This study also evaluates the failure probability of the WDN, assuming that the network failure probability is equivalent to the probability of isolation of parts of the system due to pipe breaks. The breaks leading to the failure are identified using the method of the minimum cut-sets.

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