The distribution system is the primary cause of taste and odor complaints in drinking water. This research examined the ability of small diameter pipes used in home plumbing to affect drinking water quality. The properties of the materials were investigated in the absence of disinfectant and the presence of either chlorine or chloramines. A panel was trained in flavor profile analysis (FPA) according to Standard Methods 2170B and used to assess the sensory properties of all samples. Chemical analyses were performed to determine disinfectants, total organic carbon (TOC), pH and specific organic contaminants. The first part of this study investigated PEX pipes manufactured by the silane (PEX-b) and peroxide (PEX-a) cross-linking technology, using the utility quick test (UQT) method. Silane PEX-b had a greater effect on water quality properties such as odor, TOC and residual disinfectant demand than peroxide-linked PEX-a. Chemical analysis revealed that PEX pipes can contribute fuel oxygenates such as ETBE (PEX-b) and possibly MTBE (PEX-a) to drinking water. PEX pipes did not contribute any significant trihalomethanes to drinking water. This study showed that the type of PEX used in homes will determine the extent to which drinking water quality is affected. The second part of this study used simulated plumbing rigs to investigate seven different materials under low flow and stagnant conditions; chlorinated polyvinyl chloride, cross-linked polyethylene, polyethylene, epoxy-lined copper, copper, stainless steel, galvanized iron and glass (control). Results showed that these plumbing materials have the potential to affect water quality characteristics such as TOC concentrations, residual disinfectant and odor when newly installed in homes. A high TOC concentration was consistent with the presence of a distinct odor or a high FPA intensity rating. Galvanized iron produced the worst odors that were consistently described as "motor oil". Polyethylene generated more intense plumbing associated odors than PEX or cPVC plastic material. cPVC and copper generated the least odors. Both copper pipe and epoxy-lined copper consumed residual chlorine and chloramines. / Master of Science

Power distribution systems continue to evolve to accommodate the advancements in the field of microgrids and renewable energy resources. The future grids will be highly connected and will require increased reliability of the network. To this effect, low-voltage distribution systems with meshed or networked topology can be utilized. Currently, the use of low-voltage heavily-meshed distribution systems is restricted to urban areas with high load density that require increased reliability of power. A reason for this is the high cost of construction of such systems and complex topology which creates additional challenges. The direction of power flow in such systems is not unidirectional, which makes the power flow analysis difficult. Complicated network analysis techniques are required to determine the fault currents and protection settings in the network. Due to the aforementioned reasons, there is limited work analyzing the effectiveness of existing power flow algorithms to solve complex meshed systems. In this thesis, the robustness of two power flow algorithms is compared using an index called static stability breakdown margin parameter of circuit elements. For this study, a low-voltage heavily-meshed distribution test system is also proposed. Additionally, a study is conducted to show how reliable the meshed test system is against any fault in the system. The steady-state voltage stability of the test system is observed during the event of a fault. The stability margin parameter is then used to determine the vulnerable components in the system which need to be strengthened to increase the stability and voltage profile of the system. / Master of Science / Distribution systems carry electricity from the transmission system and deliver it to the customers. Distribution systems mainly operate using two topologies for their feeders: Radial and Meshed. The majority of customers are served using radial distribution systems, as in the radial feeders power flows in one direction (i.e. from substation to the end-user). They are simple in design and operation and are constructed at a moderate cost. However, if there is a fault along the main feeder, there will be an interruption of power to the end-use customer. On the other hand, meshed distribution systems involve multiple paths of power flow between all the points in the network. If a fault occurs along the feeder, the power flow is rerouted to the other available paths. Thus, Heavily Due to their complex topology, meshed systems are expensive to construct and deploy. The power flow analysis of these systems poses many challenges. Because of these reasons, their use is mainly restricted to urban areas with high load density which require very high reliability. The future grid is becoming increasingly complex and evolving to a meshed distribution topology has its own advantages. However, as presently the use of meshed systems is sparse, the work done on evaluating the stability of these systems is minimal. As a result of which, this thesis focuses on determining the optimal power flow solvers for these complex systems, analyzing their stability under abnormal operating conditions, and suggesting methods to reinforce the vulnerabilities in the system.

Cellular networks in Africa have grown exponentially over the past 10 years and their data centres (DCs) on average consume 3 MW of electrical power. They require a reliable electrical power supply and can have a downtime loss of over a million dollars per hour. Power quality, reliability and availability have emerged as key issues for the successful operation of a data centre. Investigations are carried out into emerging technologies and their application in data centre power distribution systems for cellular networks in Africa. Best practices are applied to develop a power distribution system (PDS) with the objective of achieving optimal reliability and availability. Analytical techniques are applied to determine and compare the reliability and availability of various power systems. Minimal cut set simulations identify system weak points and confirm component selection. Components’ inherent characteristics (CIC) and system connectivity topology (SCT) are key factors in the improvement of data centre availability. The analysis practices can be used by engineers and managers as a basis for informed decision making in determining power system reliability and the availability of an existing or a new data centre design. Weak points in the PDS of a data centre causing downtime are identified through analysis, and accurate solutions can be determined to prevent or minimise downtime. System connectivity topology (SCT) techniques were identified that could increase the reliability and availability of data centres for cellular networks in Africa. These techniques include multiple incomers from the utility company, redundancy levels of critical equipment and parallel distribution paths. Two case studies were carried out on data centres for a cellular network, one in Nigeria and one in Cameroon. The reliability and availability of both data centres was improved, with substantial reduction in downtime per year. The outcome of the case studies shows the importance of designing and implementing the power distribution system with sufficient levels of redundancy for critical equipment, and parallel distribution paths. / MSc (Engineering Sciences in Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

Cellular networks in Africa have grown exponentially over the past 10 years and their data centres (DCs) on average consume 3 MW of electrical power. They require a reliable electrical power supply and can have a downtime loss of over a million dollars per hour. Power quality, reliability and availability have emerged as key issues for the successful operation of a data centre. Investigations are carried out into emerging technologies and their application in data centre power distribution systems for cellular networks in Africa. Best practices are applied to develop a power distribution system (PDS) with the objective of achieving optimal reliability and availability. Analytical techniques are applied to determine and compare the reliability and availability of various power systems. Minimal cut set simulations identify system weak points and confirm component selection. Components’ inherent characteristics (CIC) and system connectivity topology (SCT) are key factors in the improvement of data centre availability. The analysis practices can be used by engineers and managers as a basis for informed decision making in determining power system reliability and the availability of an existing or a new data centre design. Weak points in the PDS of a data centre causing downtime are identified through analysis, and accurate solutions can be determined to prevent or minimise downtime. System connectivity topology (SCT) techniques were identified that could increase the reliability and availability of data centres for cellular networks in Africa. These techniques include multiple incomers from the utility company, redundancy levels of critical equipment and parallel distribution paths. Two case studies were carried out on data centres for a cellular network, one in Nigeria and one in Cameroon. The reliability and availability of both data centres was improved, with substantial reduction in downtime per year. The outcome of the case studies shows the importance of designing and implementing the power distribution system with sufficient levels of redundancy for critical equipment, and parallel distribution paths. / MSc (Engineering Sciences in Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

The presented thesis investigates the identification of burst locations in water distribution systems (WDS) by analysis of field and simulation experimental data. This required the development of a new hybrid method of burst detection and sizing, and also a burst location identification algorithm. Generally, existing practice relies on a combination of some simple procedure and experience of the involved staff and cannot be easily automated. The practical methods are based on direct manifestation of burst on the surface or on systematically surveying suspected areas e.g. by using listening sticks, such methods are very time consuming. The proposed burst location algorithm is based on comparing data by means of statistical analysis of field data with results of water network simulation. An extended network hydraulic simulator is used to model pressure dependent leakage terms. The presence of a burst changes the flow pattern and also pressure at network nodes which may be used to estimate the burst size and its location. The influence of such random factors as demand flows and background leakage on the process of burst detection is also considered. The field data is from a generalised fixed area and variable area (FAVOR) test where inlet pressure is being stepped up and down and the following variables are measured: inlet flow, inlet pressure (head) and pressure at a number of selected sensitive nodes. The method has three stages and uses two different models, one is inlet flow model (IFM) to represent the total inlet flow and another is the extended hydraulic model to simulate different burst locations. Initially the presence of a potential burst is investigated. If this is confirmed precise values of the demand, background leakage flow and burst flow in IFM are subsequently estimated. They are used to identify the burst site at the third stage of the method. The method can be easily adapted for practical use. It requires data from experiments carried out at night between 1am and 5am and involves placing typically about 20 temporary loggers to collect the measurements during this period. It also requires the availability of a hydraulic model which normally is in the possession of a water company. The program has been implemented in the Matlab package and is easy to use. The current methodology is tuned to identify a single burst but can be generalised to identify locations of multiple bursts.

The goal of this study was to determine the economic feasibility of battery energy storage system (BESS). Three major economic benefits derived from BESS using were studied: 1. Energy Purchase Shifting, 2. Distribution Feeder Deferral, 3. Outage Avoidance. The economic analysis was based on theoretical modeling of the BESS and distribution system. Three simulation models were developed to quantify the effects of different parameters, such as: BESS round-trip efficiency, life span, rated power, rated discharge time, marginal cost of electric energy, 24 h feeder load profile, annual load variation, feeder load growth rate and feeder length. An optimal battery charging/discharging method was presented to determine the differential cost of energy (DCE). The annual maximum DCE was calculated using stochastic probability analysis on seasonal load variation. The net present value was evaluated as the present value difference between two investments: first, the distribution feeder upgrade without BESS deferral, and second, with BESS deferral. Furthermore, the BESS’s contributions under different outage strategies were compared. It was determined that feeder length is the most significant parameter. The economics of the studied system becomes favorable when the feeder length exceeds a critical value.

Orientador: José Roberto Sanches Mantovani / Banca: Fabio Bertequini Leão / Banca: Luis Gustavo Wesz da Silva / Resumo: Neste trabalho propõe-se um algoritmo baseado na meta-heurística busca dispersa para o problema de reconfiguração de redes de distribuição de energia elétrica radiais, considerando como sistema de codificação uma estrutura denominada representação nó profundidade (RNP). O problema é modelado como não linear inteiro misto e considera como objetivo principal minimizar as perdas de potência ativa nos alimentadores do sistema de distribuição. Utiliza-se neste trabalho o modelo de cargas com potência constante, como também o modelo exponencial de cargas. O algoritmo proposto é implementado em linguagem de programação C++ e testado em quatro sistemas conhecidos na literatura, 14, 84, 136 e 202 barras. A partir dos resultados obtidos, verifica-se o bom desempenho do algoritmo, pois é capaz de gerar soluções de boa qualidade atendendo a todas as restrições físicas e operacionais do problema. / Abstract: This work proposes a scatter search algorithm to solve the electric power distribution system reconfiguration problem, considering the encoding system node depth representation. The problem is a mixed-integer nonlinear programming and the objective is to minimize the real power losses in the distribution system. It is used in the work load model with constant power, but also exponential model load. The proposed algorithm is implemented in C + +. The validity of the methodology is verified through four commonly case studies such as 14, 84, 136 and 202 bus system. Results show the effectiveness and good performance of the proposed algorithm, where it obtains the good quality solution satisfying the operational and physics constraints of problem. / Mestre

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.

Distribution system design and planning is facing a major change in paradigm because of deregulation of the power industry and with rapid penetration of distributed generation (DG) sources. Distribution system design and planning are key features for determining the best expansion strategies to provide reliable and economic services to the customer. In classical planning, the load growth is typically met by adding a new substation or upgrading the existing substation capacity along with their feeders. Today, rapid advances in DG technology and their numerous benefits have made them an attractive option to the distribution companies, power system planners and operators, energy policy makers and regulators, as well as developers. This thesis first presents a comprehensive planning framework for the distribution system from the distribution company perspective. It incorporates DG units as an option for local distribution companies (LDCs) and determines the sizing, placement and upgrade plans for feeders and substations. Thereafter, a new heuristic approach to multi-year distribution system planning is proposed which is based on a back-propagation algorithm starting from the terminal year and arriving at the first year. It is based on cost-benefit analysis, which incorporates various energy supply options for LDCs such as DG, substations and feeders and determines the size, placement and upgrade plan. The proposed heuristic approach combines a bi-level procedure in which Level-1 selects the optimal size and location of distribution system component upgrades and Level-2 determines the optimal period of commissioning for the selected upgrades in Level-1. The proposed heuristic is applied to a 32-bus radial distribution system. The first level of the distribution system planning framework is formulated as a mixed integer linear programming (MILP) problem while the second level is a linear programming (LP) model. The results demonstrate that the proposed approach can achieve better performance than a full optimization for the same distribution system.

The biologically-mediated process of nitrification can occur in chloraminated drinking water distribution systems. In this process, ammonia is oxidized to nitrite by ammonia-oxidizing bacteria (AOB) and archaea (AOA). In complete nitrification, nitrite is further converted to nitrate by nitrite-oxidizers; however, bacterial mediation of this step is less critical as a chemical-oxidation pathway also exists. The initial conversion of ammonia to nitrite is also more critical due to its role in the degradation of the disinfectant residual. Nitrification is affected by factors such as the concentrations of ammonia and total chlorine, the pH of the drinking water, and the temperature. The key consequence of distribution system nitrification is an accelerated decay of the disinfectant residual; it can also lead to increases in nitrite and nitrate, and a potential proliferation of heterotrophic bacteria. The goal of this thesis is to enhance understanding of distribution system nitrification; one aspect to this goal is the evaluation of models for nitrification. The approach followed in this study was to collect water samples from two full-scale distribution systems in Southern Ontario. In the first phase, a sampling campaign was conducted at sites in these systems, with water samples being analyzed for parameters considered relevant to nitrification, such as the concentrations of nitrogen species affected by nitrification, the disinfectant residual, and the levels of ammonia-oxidizing microorganisms. In the second phase, batch tests were conducted with water from these same distribution systems. In the course of the field sampling campaign some indications of nitrification were detected, but there were no severe nitrification episodes as indicated by major losses of the disinfectant or prolonged elevations in nitrite levels. On some occasions at some sites there were small rises in nitrite above baseline levels; moderate declines in total chlorine residual were also seen. Nitrifying microorganisms were present in most samples, as detected by both culture-based and molecular methods (PCR). The latter was able to distinguish AOA from AOB; both were detected in the systems included in this study, with AOB gene counts outnumbering those of AOA at most sites. Using Spearman non-parametric correlations, significant correlations were found between some parameters relevant to nitrification. Notably, AOB were found to be positively correlated with heterotrophic plate counts (HPC), reinforcing the latter's role as a useful indicator of microbial regrowth conditions in a distribution system. Also of interest is the negative correlation between total chlorine residual and levels of microorganisms, reminding drinking water professionals of the value of maintaining a stable disinfectant residual. Batch testing investigations compared total chlorine decay curves between inhibited and uninhibited samples to provide insight into the microbial contribution to disinfectant decay. Four types of decay curves were identified, with qualitative differences in the microbial contribution to the disinfectant residual decay. Liquid chromatography with organic carbon detection (LC-OCD) was applied to investigate changes in the character of the dissolved organic carbon over the course of the batch tests. Based on the results of this study, it is recommended to evaluate the results of nitrification batch tests based on a visual identification of the curve type and calculation of the decay rates and critical threshold residual (CTR), rather than relying on the microbial decay factor alone to express the results. An application of this work was in making comparisons to some models for nitrification proposed in the literature. The ultimate goal of these models is to provide drinking water system operators with a prediction of when nitrification episodes will occur so that action may be taken to avert them. The models considered in this study differ in their degree of complexity and in whether they are based on mechanistic considerations. The differences in the underlying principles and data required for analysis make these models suitable for different applications. The results of this evaluation support the use of the model of Fleming et al. (2005) in full-scale distribution systems and the use of the model by Yang et al. (2008) for research applications, while the other models considered can still offer some useful insights. The results of this research can be applied to monitoring and operational practices in chloraminated distribution systems where nitrification is a potential concern. The correlations between parameters that have significance to distribution system nitrification that were found in this study, along with the modelling and batch testing evaluated in this work, can provide insight into predicting conditions favourable to nitrification and avoiding or averting nitrification episodes.