Previous efforts to apply risk analysis for water distribution systems (WDS) have not typically included explicit hydraulic simulations in their methodologies. A risk classification scheme is here employed for identifying vulnerable WDS components subject to an intentional water contamination event. A Monte Carlo simulation is conducted including uncertain stochastic diurnal demand patterns, seasonal demand, initial storage tank levels, time of day of contamination initiation, duration of contamination event, and contaminant quantity. An investigation is conducted on exposure sensitivities to the stochastic inputs and on mitigation measures for contaminant exposure reduction. Mitigation measures include topological modifications to the existing pipe network, valve installation, and an emergency purging system. Findings show that reasonable uncertainties in model inputs produce high variability in exposure levels. It is also shown that exposure level distributions experience noticeable sensitivities to population clusters within the contaminant spread area. The significant uncertainty in exposure patterns leads to greater resources needed for more effective mitigation.

Threat management of water distribution systems is essential for protecting consumers. In a contamination event, different strategies may be implemented to protect public health, including flushing the system through opening hydrants or isolating the contaminant by manipulating valves. To select the most effective options for responding to a contamination threat, the location and loading profile of the source of the contaminant should be considered. These characteristics can be identified by utilizing water quality data from sensors that have been strategically placed in a water distribution system. A simulation-optimization approach is described here to solve the inverse problem of source characterization, by coupling an evolutionary computation-based search with a water distribution system model. The solution of this problem may reveal, however, that a set of non-unique sources exists, where sources with significantly different locations and loading patterns produce similar concentration profiles at sensors. The problem of non-uniqueness should be addressed to prevent the misidentification of a contaminant source and improve response planning. This paper aims to address the problem of non-uniqueness through the use of Niched Co-Evolution Strategies (NCES). NCES is an evolutionary algorithm designed to identify a specified number of alternative solutions that are maximally different in their decision vectors, which are source characteristics for the water distribution problem. NCES is applied to determine the extent of non-uniqueness in source characterization for a virtual city, Mesopolis, with a population of approximately 150,000 residents. Results indicate that NCES successfully identifies non-uniqueness in source characterization and provides alternative sources of contamination. The solutions found by NCES assist in making decisions about response actions. Once alternative sources are identified, each source can be modeled to determine where the vulnerable areas of the system are, indicating the areas where response actions should be implemented.

The purpose of this research is to compare the performance for the water quality of two traditional water treatment plants (WTP) and three advanced water treatment plants (AWTP), and to investigate the treated drinking water in distribution systems in Kaohsiung area for promoting the consumers¡¦ self-confidence. Samples of the treated water from five major water supplies¡¦ WTP(noted numbers: WF1, WF2, WF3, WF4 and WF5) and the tap water at user¡¦s end were selected in planning of this work. It was the traditional WTP stage with treated drinking water and distribution systems in Kaohsiung area During 91 year to 92 year, so we conducted WF1 and WF2 of 8 times sampling and WF3, WF4 and WF5 for 2 times sampling at this stage. In and after 93 year, we conducted WF1, WF2, WF3, WF4 and WF5 of 8 times sampling from 93 year to 94year for the advanced WTP stage. The major tests related with the parameters of influencing operation condition included pH, odor (abbreviated as TON), total trihalomethane (abbreviated as THMs), haloacetic acids (abbreviated as HAAs), nitrogen (abbreviated as, NH3-N, hardness, total dissolved solid (abbreviated as TDS), alkalinity, total organic carbon (abbreviated as TOC), calcium ion, flavor profile analysis (abbreviated as FPA), and suspension observation in boiling with treated waters from two WTP , three AWTP and the tap water at user¡¦s end in a distribution system. It point out the better quality of treated water used the advanced water treatment plants than that of traditional water treatment plant. The items with improvement of water quality, including THMs, HAAs, hardness, TON, 2-MIB, TOC, alkinality and Ca ions concentration, is presented. Their efficiency for improvement are respectively 47%, 29%, 43%, 11%, 29%, 15%, 14% and 34%. The insignificant efficiency were concentrated at TDS, NH3-N, pH and FPA. Water quality of six items are fitted for the drinking water standard at present in Taiwan (such as: odor<3 TON; THMs<0.1 mg/L; NH3-N<0.1 mg/L; TDS< 600 mg/L; Hardness <400 mg as CaCO3/L; 6.0<pH <8.5). The HAAs is fit for water quality USEPA first stage water standard (HAAs<80 £gg/L). In the suspension observation in boiling experimentation, we cooperate with the experiment of suspension observation in boiling to do contrast with TDS and hardness experiment, which can find out, the treated water after the advanced procedure, the time with boiling increases, the condition of its suspended substance has great reduction. It show treated drinking water after the advanced WTP can huge improve the traditional WTP¡¦s white suspended substance or white material precipitate questions in the boiling. In the contour map for water quality , we found that Gushan District, Lingya District, Qianzhen District, Xiaogang District, Fongshan City and Daliao Shiang etc had higher concentration profile in the four season (included spring, summer, fall and winter ) and during two seasons (included raining and drying) in the water supplies systems. We hope the contour map can offer a clear information of conveyer system administrator of drinking water and let administrator know where areas have high concentration produced in water quality management planning, in order to having priority or effective solutions (included washing the pipeline, changing the pipeline, changing the water flow, etc.).

The distribution system containing numerous protective facilities and switch equipment ranges over a wide boundary . The most urgent problem the dispatcher has to tackle right after the breakdown of distribution system in how to resume as soon as possible power supply for the none-faulted out-of-service area. Therefore, distribution system service restoration is an important and practical subject. During the process of maintaining and operation ,the distribution district collected a lot of data. These data includes substation-related automatic operating data , switch section of doing a feeder , load data of high and low tension customers, and historical distribution system planning information concerning load transfer while operation, etc. The useful resource could help the dispatcher to get the best load transfer on distribution system service restoration. Datum-oriented researcher refers to the exploration of the concealing regulations and knowledge and the techniques regarding comprehensible model. This thesis manages to collect the maintaining and operation data of the distribution district ; it makes use of the information exploration techniques and ID3 decision tree and fuzzy theory to get the load transfer rule and knowledge , and to establish the load transfer model. After the fault occurred, it would help the dispatcher to get the best tactics for the load transfer on distribution system service restoration under the constraint condition. This thesis chooses the underground distribution system in sijhih of the Keeling District Offices of Taiwan Power Company as a sample. That underground distribution system comprising 8 distribution feeder ,73 distribution spaces,16 high tension customers, 28 feeder section, 4 feeder-tie-switch and 19 lateral-tie-switch will be simulated on computers to verify the proposed method for the distribution system service restoration.

The Power System Automation Lab at Texas A&M University developed a fault location scheme that can be used for radial distribution systems. When a fault occurs, the scheme executes three stages. In the first stage, all data measurements and system information is gathered and processed into suitable formats. In the second stage, three fault location methods are used to assign possibility values to each line section of a feeder. In the last stage, a fuzzy resolver is used to aggregate the outputs of the three fault location methods and assign a final possibility value to each line section of a feeder. By aggregating the outputs of the three fault location methods, the fuzzy resolver aims to obtain a smaller subset of line sections as potential faulted sections than the individual fault location methods. Fuzzy aggregation operators are used to implement fuzzy resolvers. This dissertation reports on a methodology that was developed utilizing fuzzy aggregation operators in the fuzzy resolver. Three fuzzy aggregation operators, the min, OWA, and uninorm, and two objective functions were used to design the fuzzy resolver. The methodologies to design fuzzy resolvers with respect to a single objective function and with respect to two objective functions were presented. A detailed illustration of the design process was presented. Performance studies of designed fuzzy resolvers were also performed. In order to design and validate the fuzzy resolver methodology, data were needed. Due to the lack of real field data, simulating a distribution feeder was a feasible alternative to generate data. The IEEE 34 node test feeder was modeled. Time current characteristics (TCC) based protective devices were added to this feeder. Faults were simulated on this feeder to generate data. Based on the performance studies of designed fuzzy resolvers, the fuzzy resolver designed using the uninorm operator without weights is the first choice. For this fuzzy resolver, no optimal weights are needed. In addition, fuzzy resolvers using the min operator and OWA operator can be used to design fuzzy resolvers. For these two operators, the methodology for designing fuzzy resolvers with respect to two objective functions was the appropriate choice.

Στην παρούσα διπλωματική εργασία εξετάζεται το ζήτημα της προστασίας σε Συστήματα Διανομής Ηλεκτρικής Ενέργειας με παρουσία Κατανεμημένης Παραγωγής. Η παραδοσιακή ακτινική μορφή των Συστημάτων Διανομής μεταβάλλεται με την παρουσία μονάδων Κατανεμημένης Παραγωγής, καθώς αυτές αποτελούν ενεργά στοιχεία και συμβάλλουν στο ρεύμα βραχυκύκλωσης. Συνεπώς ανακύπτει ένα σύνολο προβλημάτων στην λειτουργία του Συστήματος Προστασίας, όπως αύξηση του επιπέδου σφάλματος και διαταραχή στην επιλογική συνεργασία των διατάξεων προστασίας. Συχνά, τα προβλήματα που επιφέρει η παρουσία μονάδων Κατανεμημένης Παραγωγής στο Σύστημα Προστασίας του δικτύου διανομής, θέτουν το όριο στην εγκατάσταση περαιτέρω μονάδων. Αρχικά, παρουσιάζονται γενικές έννοιες, που έχουν σχέση με την προστασία σε δίκτυα διανομής , και παρατίθενται γενικά στοιχεία για την Κατανεμημένη Παραγωγή. Στην συνέχεια, παρέχεται η μεθοδολογία υπολογισμού των ρευμάτων βραχυκύκλωσης και τα μοντέλα των στοιχείων σε περίπτωση σφάλματος. Με τα ανωτέρω, επεξηγούνται οι αλλαγές στο ισοδύναμο κύκλωμα σε περίπτωση σφάλματος του Συστήματος Διανομής με την παρουσία Κατανεμημένης Παραγωγής και αναφέρεται το ζήτημα της αύξησης του επιπέδου σφάλματος. Επιπλέον, παρουσιάζονται τα επιμέρους ζητήματα που έχουν σχέση με τις επιπτώσεις της παρουσίας Κατανεμημένης Παραγωγής στο Σύστημα Προστασίας του Συστήματος Διανομής, όπως το ζήτημα της διαταραχής στην επιλογική συνεργασία ηλεκτρονόμων, ασφαλειών και διακοπτών αυτόματης επαναφοράς, το ζήτημα της μείωσης της επέκτασης των ηλεκτρονόμων απόστασης κ.α. Ακολούθως, επεξηγείται η Προστασία Διασύνδεσης και οι μέθοδοι και πρακτικές που χρησιμοποιούνται ώστε να προσαρμόζεται μία μονάδα Κατανεμημένης Παραγωγής στην παραδοσιακή λειτουργία του Συστήματος Προστασίας του Συστήματος Διανομής. Ιδιαίτερα αναλύεται το φαινόμενο της λειτουργίας νησίδος ενώ επεξηγείται και ο ρόλος του μετασχηματιστή διασύνδεσης στην λειτουργία του Συστήματος Προστασίας του δικτύου. Με βάση την ανάλυση και τη θεωρητική εξέταση εννοιών, μεθόδων και επιμέρους ζητημάτων (Μέρος Α), στο Β Μέρος της παρούσας εργασίας, παρουσιάζονται χαρακτηριστικά παραδείγματα εγκατάστασης Κατανεμημένης Παραγωγής σε εναέρια ακτινικά δίκτυα Μέσης Τάσης του ελληνικού Συστήματος Ηλεκτρικής Ενέργειας, στα οποία διερευνώνται οι επιπτώσεις στην λειτουργία του Συστήματος Προστασίας. Μέσω της μελέτης περιπτώσεων καταδεικνύεται ο ρόλος των χαρακτηριστικών των μονάδων Κατανεμημένης Παραγωγής και της θέσης εγκατάστασης τους στην εμφάνιση πιθανών προβλημάτων. Η διαταραχή στην επιλογική συνεργασία διακόπτη αυτόματης επαναφοράς και ασφαλειών, η εσφαλμένη λειτουργία του διακόπτη αυτόματης επαναφοράς λόγω ρευμάτων βραχυκύκλωσης και η αύξηση του επιπέδου σφάλματος, προκύπτουν ως τα σημαντικότερα προβλήματα. Τέλος, εξάγονται γενικά συμπεράσματα και προτείνονται λύσεις. / -

Chlorine is the most widely used disinfectant for drinking water treatment. Chlorine canreact with natural organic matter (NOM) in water sources resulting in the formation of potentially carcinogenic disinfection by-products (DBPs). The most common DBPs measured in chlorinated drinking water distribution systems are trihalomethanes (THMs) and haloacetic acids (HAAs). In 2005, the City of Kamloops, British Columbia upgraded the drinking water treatment system to ultrafiltration membrane treatment. The objective of this study was to determine the extent to which upgrades to a drinking water treatment system, specifically, implementation of an ultrafiltration treatment process, impacted DBP formation within a distribution system. This study used a two-phase research approach. Phase I of the study was a distribution system monitoring program that collected water samples and physical and chemical information using data loggers at five sampling sites within the distribution system. Phase II of the study used bench-scale simulations that modeled DBP formation using a flow-through reactor system, the material-specific simulated distribution system (MS-SDS), constructed of pipe material resurrected from the City of Kamloops distribution system. Phase I results suggested that implementation of the ultrafiltration treatment process and accompanying treatment system upgrade was not effective at reducing the concentration of DBPs delivered to consumers. Concentrations of THMs remained relatively constant at sampling sites, while concentrations of HAAs increased following implementation of the ultrafiltration treatment process. The increase in HAA formation was likely due to an increase in retention time of the water within the distribution system following implementation of the ultrafiltration treatment process, rather than due to the treatment process itself. The results of this study are consistent with previous work on South Thompson River water DBP precursors, which suggested that THM and HAA precursors of this source water are small and hydrophilic, and therefore cannot be removed by ultrafiltration processes. Phase II results showed that the MS-SDS was more representative of distribution system c onditions than traditional glass bottles to estimate DBP formation. It is recommended that the MS-SDS be used in parallel with a simultaneous distribution system monitoring program to estimate distribution system retention times from THM and HAA concentrations.

No description available.

Fault location is very important for distribution systems, and quickly identifying the fault and restoring the system can help reduce the outage time and make the system more reliable. In this thesis, a method for locating faults on distribution systems is introduced to quickly identify the faulted feeder sections by using the overcurrent information from the switches in the system. Fuzzy logic is utilized. The proposed method can quickly and accurately locate faulted sections with different fault locations, fault types and fault resistances. The method is applicable to cases with single-faults or multi-faults, and is applicable to networks with multi-sources. The case study has demonstrated the effectiveness of the proposed method.

Because DGs are introduced into distribution systems, the coordination of fuses and reclosers doesn’t work well. It means the original protection schemes are not available for the distribution systems with DGs. This thesis paper presents the study on the impacts of DGs on the fault current and voltage in the distribution system by the simulation of a model distribution system. After we study the impacts of DG on distribution systems, there is an introduction of current several current protection schemes and fault locations methods. At last, an adaptive protection scheme with a more efficient fault location method for the distribution systems is discussed in this thesis paper.