Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-03-24T19:57:30Z No. of bitstreams: 2 Dissertação - Igor Lopes Mota - 2015.pdf: 2620143 bytes, checksum: c895dad8e571f14172d9b7e9506f3d94 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-03-28T11:35:07Z (GMT) No. of bitstreams: 2 Dissertação - Igor Lopes Mota - 2015.pdf: 2620143 bytes, checksum: c895dad8e571f14172d9b7e9506f3d94 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-03-28T11:35:07Z (GMT). No. of bitstreams: 2 Dissertação - Igor Lopes Mota - 2015.pdf: 2620143 bytes, checksum: c895dad8e571f14172d9b7e9506f3d94 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-09-18 / In this dissertation, we present a detailed study of techniques for islanding detection of distribution systems in the presence of distributed generators in various forms of access and connection. The aim is to set up protection system solutions capable of ensuring the detection of the islanding based on local passive techniques, which have lower costs with respect to remote techniques, for example, the transfer trip. The objective of this work is to achieve through the association of several islanding detection techniques in order to achieve adequate reliability of distributed synchronous generators protection system. Among the existing techniques, the protection functions studied were the overfrequency and underfrequency (ANSI 81 o/u), rate of change of frequency (ROCOF or ANSI 81 df/dt), vector jump (ANSI 78) and directional reactive power (ANSI 32Q). It was found that the 32Q function for loads with inductive power factor less than one complements the functions based on frequency precisely in the range where these are insensitive to islanding, wherein the threshold for operation of this relay depends on the equivalent load power consumed locally. For cases of islanding caused the intentional opening of the distribution feeder, the islanding detection for loads with a inductive power factor can be guaranteed with the use of passive local techniques without the need to burden the installation of synchronous generators protection systems distributed. Although in practice it is very unlikely a distribution circuit has a unity power factor, the association of these protective functions arises as a good solution for the detection of islanding of distributed synchronous generators. / Nesta dissertação de mestrado apresenta-se um estudo das principais técnicas de detecção de ilhamento de geradores distribuídos considerando dados reais de 3 acessantes com diferentes capacidades de geração e diferentes tensões de conexão com o sistema interligado. Visa definir soluções de composição de sistemas de proteção capazes de garantir a detecção do ilhamento baseados em técnicas locais passivas, que apresentam custos mais reduzidos com relação às técnicas remotas, como por exemplo, a teleproteção. O objetivo deste trabalho é alcançar, por meio de associação de várias técnicas de detecção de ilhamento, um grau de confiabilidade adequado do sistema de proteção de geradores síncronos distribuídos. Dentre as técnicas existentes, foram estudadas as funções de proteção de sub e sobrefrequência (ANSI 81 o/u), taxa de variação de frequência (ROCOF ou ANSI 81 df/dt), salto de vetor (ANSI 78) e direcional de potência reativa (ANSI 32Q). Constatouse que a função 32Q, para cargas com fator de potência indutivo e menor que um, complementa as funções baseadas em frequência justamente na faixa onde estas são insensíveis a ilhamentos, sendo que o limite para a operação deste relé depende da potência equivalente da carga consumida localmente. Para os casos de ilhamento provocado pela abertura intencional do alimentador de distribuição, a detecção de ilhamento para cargas com fator de potência indutivo poderá ser garantida com a utilização das técnicas locais passivas sem a necessidade de se onerar a instalação dos sistemas de proteção de geradores síncronos distribuídos. Apesar de que na prática é muito improvável um circuito de distribuição possuir um fator de potência unitário, a associação das referidas funções de proteção surge como uma boa solução para a detecção de ilhamentos de geradores síncronos distribuídos.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-19T18:21:33Z No. of bitstreams: 1 jorgejaviergimenezledesma.pdf: 1333717 bytes, checksum: c7a67b49a38e446b2cbd5a0b04c85f70 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-20T12:30:20Z (GMT) No. of bitstreams: 1 jorgejaviergimenezledesma.pdf: 1333717 bytes, checksum: c7a67b49a38e446b2cbd5a0b04c85f70 (MD5) / Made available in DSpace on 2017-04-20T12:30:20Z (GMT). No. of bitstreams: 1 jorgejaviergimenezledesma.pdf: 1333717 bytes, checksum: c7a67b49a38e446b2cbd5a0b04c85f70 (MD5) Previous issue date: 2012-04-12 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho propõe o desenvolvimento de modelos e métodos numéricos para a análise da seletividade e coordenação da proteção de sobrecorrente em sistemas de distribuição. A primeira etapa consiste na adaptação de um programa existente para cálculo de defeitos em coordenadas de fase, incorporando dois algoritmos para cálculo de defeitos. As metodologias de cálculo de defeito foram desenvolvidas utilizando as equações de injeção de correntes em coordenadas retangulares. Em seguida, foi desenvolvida e implementada uma formulação trifásica para análise da coordenação e seletividade dos dispositivos de proteção, com capacidade de detectar falhas e indicar limites de coordenação e seletividade dos dispositivos de proteção em sistemas de distribuição. Também foram desenvolvidos modelos matemáticos dos principais equipamentos de proteção e das funções de proteção encontrados em sistemas de distribuição. Foram modelados: fusíveis, disjuntores, relés, religadores, transformadores de corrente e de potencial, bem como as funções de proteção 50 e 51 com base nas normas ANSI e IEC. A metodologia proposta foi desenvolvida no ambiente MatLab® e com o intuito de avaliar sua eficiência foram analisados diversos sistemas testes. Os resultados obtidos dos estudos de cada sistema são apresentados sob forma de coordenogramas, tabelas dos tempos de atuação e gráficos comparativos de tempos. De forma complementar são apresentadas as principais filosofias e critérios utilizados na seleção e coordenação dos dispositivos de proteção. / This work proposes the development of models and numerical methods for the analysis of selectivity and coordination of overcurrent protection in distribution systems. The first step is to adapt an existing program for calculation of faults in phase coordinates, incorporating new algorithms for exact and approximate calculations of fault conditions. The methodologies for fault calculations were developed using the current injections equations in rectangular coordinates. It was then developed and implemented a three-phase formulation for analysis of coordination and selectivity of protection devices, capable of detecting faults and indicating limits of coordination and selectivity in distribution systems. The mathematical models of the main protective equipment and protective functions found in distribution systems were also developed. Fuses, circuit breakers, relays, reclosers, current and potential transformers as well as the protection relay functions 50 and 51 based on the ANSI and IEC standards were modeled. The proposed methodology was developed in MatLab ® and its efficiency was validated using several test systems. The results of studies of each system are presented in the form of Time Currents Curves, tables of operation times and graphs of comparative performance times. As a complement the main philosophies and criteria used in selection and coordination of protective devices are presented.

This study deals with the perspective of vulnerability of the Swedish electricity distribution system to climate and weather related risks. How and to what extent the electricity sector is adapting to the risk and what possibilities are formed in this respect are investigated. This is a quantitative and qualitative analysis where statistical data has been used to apprehend the extent of disturbances of the electricity distribution system and their causes. Interviews have been used in order to investigate different views among actors working within the electricity distribution system sector. The result shows that the dominating cause of disturbances in the electrical network in Sweden is the weather, giving most hours of breaks. The countryside has more often disturbances than urban areas. It also emerges that it is the lines overhead that are most affected by disturbances. The system is flexible. If one line is disturbed the electricity can be distributed using another line (redundancy). It seems like there is a diversion between the respondents on how and if a future climate change really is a risk for the electricity distribution system. It is clear that the vulnerability has increased in the society during the past 10-20 years, and so has the societal costs of the disturbances because of the increasing dependence on electricity. Reducing the consequences of a weather related impact on the electrical system will make society more resilient and less vulnerable. The respondents in this study are somewhat adapting to the weather related risks that they have identified with technical solutions. It is important to learn more about how the electrical system properties influence the sensitivity in society. There is a need to investigate the dependency of electricity in society. It is also important that all the actors have the same interpretation of the difference between a recurrent event and a nature disaster. More work should be done to clarify where the responsibility for adapting the electrical sector to the possible climate change lies. This complex responsibility issue with all affected actors influences the sensitivity of society and the electrical system.

The collective electric transport can be considered as one of the best alternatives to reduce the concentration of pollutants in urban centers, because it reduces the number of vehicles in circulation and eliminates most of the problems arising from the use of fossil fuels. Currently, in this alternative, there is a wide range of options available, however, with the advancement occurred in recent years in terms of battery technology, the pure electric bus has stood out due to advantages related to its flexibility, sustainability and adaptability to the existing infrastructure. However, the use of these vehicles requires special recharging stations, which drain a lot of energy of the grid, in a short time, a feature that generates a significant impact on electrical systems. Moreover, the high amount of energy required for the operation of these vehicles precludes the use of technology in certain places, because it requires large investments in infrastructure for power supply, which often do not is available locally in the short term. Based on this, this dissertation presents a study of the impact generated in the electrical distribution system caused by the replacement of a diesel bus fleet by electric buses in a small town in southern Brazil. The study was based on the measurement of energy consumption through data related to the lines and the vehicle driving cycle, applied to an electric bus model, it was developed with Matlab software. Actual data of the lines was used, as distance, speeds, tilt, number of passengers, among others, obtained through a GPS equipment and information provided by the company analyzed. At the end were generated values related to the energy consumption of vehicles in each of the lines, the electricity consumption increase generated by the substitution in question and an estimate of the daily load curves based on the operating hours of the analyzed lines. / O transporte elétrico coletivo atualmente pode ser considerado como uma das melhores alternativas para a redução da concentração de poluentes em centros urbanos, pois reduz o número de veículos em circulação e elimina a maioria dos problemas decorrentes do uso de combustíveis fósseis. Atualmente, neste tipo de alternativa existe uma vasta gama de opções disponíveis, entretanto, com o avanço ocorrido nos últimos anos em termos de tecnologia de baterias, os ônibus elétricos puros vem se destacando devido a vantagens relacionadas a sua flexibilidade, sustentabilidade e adaptabilidade as infraestruturas existentes. Porém a utilização destes veículos requer estações de recarga especiais, as quais causam um impacto significativo nos sistemas elétricos, pois geram um grande acréscimo de demanda de energia, o que em alguns casos pode sobrecarregar os sistemas. Além disso, a elevada quantidade de energia necessária para a operação destes veículos inviabiliza o uso da tecnologia em determinados locais, pois requer um alto investimento em infraestrutura para o fornecimento seguro e confiável de energia. Baseado nisto, esta dissertação apresenta um estudo do impacto gerado no sistema elétrico de distribuição ocasionado pela substituição de uma frota de ônibus a diesel por ônibus elétricos em uma cidade de pequeno porte situada no sul do Brasil. O estudo foi baseado na mensuração do consumo energético através de dados relacionados às linhas e ao ciclo de condução dos veículos, aplicados em um modelo de ônibus elétrico, o qual foi elaborado através do software Matlab®. Foram utilizados dados reais das distâncias nas linhas, velocidades, relevo das vias, número de passageiros, entre outros, obtidos através de um equipamento de GPS e informações fornecidas pela empresa analisada. Ao final foram gerados valores relacionados ao consumo dos veículos em cada uma das linhas, o acréscimo de consumo de energia elétrica gerado pela substituição em questão e uma estimativa das curvas de carga diárias baseadas nos horários de operação das linhas analisadas.

The topic of the thesis is multi objective condition assessment of water supply systems. The state of the art of condition assessment of water supply systems and the state of the art of multi objective optimization methods are presented within the thesis. Based on these recherches, the uniform methodology of condition assessment of water supply systems and its 7 modules was designed. The thesis deals with the selected modules to condition assessment of water pumping stations, water networks and pipe sections. The output of the methodology is the assignment of a category of the technical condition to the rated object. The proposed methodology was tested on real water facilities and proves the ability of a fair presentation of the technical condition of the object.

This thesis is focused on the opportunities of conceptual development of the local distribution system Prototypa, a.s. At first, there is descripted condition of the current substations and internal electricity distribution system. Practical part of the thesis is dedicated to the evaluation of the construction of new transformer station and projection proposals of connection of the high-power charging station and new electric power supply.

A water distribution system is composed of thousands of pipes of varying materials, sizes, and ages. These pipes experience physical, environmental, and operational factors that cause deterioration and ultimately lead to their failure. Pipe deterioration results in increased break rates, decreased hydraulic capacity, and adverse effects on water quality. Pipe failures result in economic losses to the governing municipality due to loss of service, cost of pipe repair/replacement, damage incurred due to flooding, and disruptions to normal business operations. Inspecting the entire water distribution system for deterioration is difficult and economically unfeasible; therefore, it benefits municipalities to utilize a risk assessment model to identify the most critical components of the system and develop an effective rehabilitation or replacement schedule. This study compared two risk assessment models, a statistically complex model and a simplified model. Based on the physical, environmental, and operational conditions of each pipe, these models estimate the probability of failure, quantify the consequences of a failure, and ultimately determine the risk of failure of a pipe. The models differ in their calculation of the probability of failure. The statistically complex model calculates the probability of failure based on pipe material, diameter, length, internal pressure, land use, and age. The simplified model only accounts for pipe material and age in its calculation of probability of failure. Consequences of a pipe failure include the cost to replace the pipe, service interruption, traffic impact, and customer criticality impact. The risk of failure of a pipe is determined as the combination of the probability of failure and the consequences of a failure. Based on the risk of failure of each pipe within the water distribution system, a ranking system is developed, which identifies the pipes with the most critical risk. Utilization of this ranking system allows municipalities to effectively allocate funds for rehabilitation. This study analyzed the 628-pipe water distribution system in the City of Buellton, California. Four analyses were completed on the system, an original analysis and three sensitivity analyses. The sensitivity analyses displayed the worst-case scenarios for the water distribution system for each assumed variable. The results of the four analyses are provided below. Risk Analysis Simplified Model Complex Model Original Analysis All pipes were low risk All pipes were low risk Sensitivity Analysis: Older Pipe Age Identified 2 medium risk pipes Identified 2 medium risk pipes Sensitivity Analysis: Lower Anticipated Service Life Identified 2 medium risk pipes Identified 9 high risk pipes and 283 medium risk pipes Sensitivity Analysis: Older Pipe Age and Lower Anticipated Service Life Identified 1 high risk pipe and 330 medium risk pipes Identified 111 critical risk pipes, 149 high risk pipes, and 137 medium risk pipes Although the results appeared similar in the original analysis, it was clear that the statistically complex model incorporated additional deterioration factors into its analysis, which increased the probability of failure and ultimately the risk of failure of each pipe. With sufficient data, it is recommended that the complex model be utilized to more accurately account for the factors that cause pipe failures. This study proved that a risk assessment model is effective in identifying critical components and developing a pipe maintenance schedule. Utilization of a risk assessment model will allow municipalities to effectively allocate funds and optimize their water distribution system. Keywords: Water Distribution System/Network, Risk of Failure, Monte Carlo Simulation, Normal Random Variable, Conditional Assessment, Sensitivity Analysis.

[pt] Os modelos e estudos de roteirização presentes na literatura focam, em geral, nos processos ocorridos desde que os veículos saem do centro de distribuição (CD) até ao seu retorno. Esta visão de roteirização da porta para fora do CD acaba por negligenciar uma etapa importante correspondente às operações de movimentação interna do CD, a qual tem influência direta na jornada de trabalho das equipes de entrega e consequentemente na produtividade de cada veículo. A importância da etapa das operações de pátio é bem visível quando analisado o fluxo de valor da cadeia de distribuição. A procura de uma melhor gestão do tempo das operações de pátio abre, assim, uma oportunidade de melhoria da eficiência das operações de distribuição. Esta dissertação foca na inclusão do gerenciamento das operações de pátio junto com a roteirização como forma de aumentar a produtividade da empresa e maximizar a utilização de recursos humanos e materiais. O modelo de gerenciamento desenvolvido utiliza simultaneamente técnicas de otimização e de simulação capazes de planejar e acompanhar as operações de distribuição de uma empresa, respeitando as normas trabalhistas e indicadores de qualidade pré-estabelecidos. O modelo busca melhorar o aproveitamento da jornada de trabalho das equipes de entrega embarcadas em cada veículo, através da minimização dos tempos não produtivos de pátio (recebimento, acerto de contas, conferência de carga, check list de veículo, etc.). A minimização do tempo das operações de pátio aumenta a disponibilidade de tempo de jornada de trabalho da equipe de entrega em rota, possibilitando o aumento do número de pedidos atendidos por cada veículo, sem impactar nas janelas de entrega impostas pelos clientes, estouro na jornada de trabalho e indicadores de qualidade. Para elaboração e aplicação deste trabalho, foram utilizados 3 softwares, um de simulação, outro de roteirização e outro de captação de dados em tempo real. A integração dos três permite captar informações da operação, tratar e simular os modelos e realizar roteirização de veículos, incluindo o tempo de pátio na fórmula de Tempo de ciclo do veículo. O modelo de operação desenvolvido foi aplicado na empresa BETA do segmento varejista de bebidas localizada no Centro-Oeste do Brasil. Os resultados obtidos, quando comparados com a atual operação da empresa, representam uma redução de custo no total de 685.234,00 Reais com a operação de distribuição. Especificamente, a racionalização do tempo de pátio permitiu uma melhoria de 2:15:15 em redução de filas no fluxo do pátio ao analisar o fluxo de saída e retorno. Teve ainda como consequência a melhoria da produtividade dos veículos passando de uma média de entrega de 25 para 31 entregas por dia. / [en] The models and studies of routing in the literature focus, in general, on the processes that have occurred since the vehicles leave the distribution center (CD) until their return. This vision of routing the door to the outside of the CD ends up neglecting an important step corresponding to the operations of internal movement of the CD, which has a direct influence on the workday of the delivery teams and consequently on the delivery productivity of each vehicle. The importance of the stage of yard operations is well visible when analyzing the value chain flow of the distribution chain. The search for better time management of yard operations thus opens up an opportunity to improve the efficiency of distribution operations. This dissertation focuses on the inclusion of yard operations management along with routing as a way to increase company productivity and maximize the use of human and material resources. The management model developed simultaneously uses optimization and simulation techniques capable of planning and monitoring the distribution operations of a company, respecting the labor standards and pre-established quality indicators. The model seeks to improve the utilization of the workday of the delivery teams embarked in each vehicle, by minimizing non-productive yard times (reception, accounting, cargo check, vehicle check list, etc.). By minimizing patio operations time we increase the time available for the delivery team to operate, and consequently increase the number of requests served by each vehicle, without impacting on the delivery windows imposed by the customers, work and quality indicators. During the elaboration of this work 3 softwares were used, one of simulation, another of routing and one of data acquisition in real time. The integration of the three allows you to capture information from the operation, treat and simulate the models and perform vehicle routing, including yard time in the Vehicle Cycle Time formula. The operating model developed was applied in the BETA company of the beverage retail segment located in the Center-West of Brazil. The results obtained, when compared to the current operation of the company, represent a reduction of cost in the total o BRL 685,234.00 with the distribution operation. Specifically, the optimization of patio time allowed for a 2:15:15 improvement in queue reduction in the patio flow when analyzing the outflow and return flow. In addition, the productivity of vehicles increased from an average delivery of 25 to 31 deliveries per day.

The integration of advanced technologies into existing water treatment facilities (WTFs) can improve and enhance water quality; however, these same modifications or improvements may adversely affect finished water provided to the consumer by public water systems (PWSs) that embrace these advanced technologies. Process modification or improvements may unintentionally impact compliance with the provisions of the United States Environmental Protection Agency’s (USEPA’s) Safe Drinking Water Act (SDWA). This is especially true with respect to corrosion control, since minor changes in water quality can affect metal release. Changes in metal release can have a direct impact on a water purveyor’s compliance with the SDWA’s Lead and Copper Rule (LCR). In 2010, the Town of Jupiter (Town) decommissioned its ageing lime softening (LS) plant and integrated a nanofiltration (NF) plant into their WTF. The removal of the LS process subsequently decreased the pH in the existing reverse osmosis (RO) clearwell, leaving only RO permeate and anion exchange (AX) effluent to blend. The Town believed that the RO-AX blend was corrosive in nature and that blending with NF permeate would alleviate their concern. Consequently, a portion of the NF permeate stream was to be split between the existing RO-AX clearwell and a newly constructed NF primary clearwell. The Town requested that the University of Central Florida (UCF) conduct research evaluating how to mitigate negative impacts that may result from changing water quality, should the Town place its AX into ready-reserve. iv The research presented in this document was focused on the evaluation of corrosion control alternatives for the Town, and was segmented into two major components: 1. The first component of the research studied internal corrosion within the existing RO clearwell and appurtenances of the Town’s WTF, should the Town place the AX process on standby. Research related to WTF in-plant corrosion control focused on blending NF and RO permeate, forming a new intermediate blend, and pH-adjusting the resulting mixture to reduce corrosion in the RO clearwell. 2. The second component was implemented with respect to the Town’s potable water distribution system. The distribution system corrosion control research evaluated various phosphate-based corrosion inhibitors to determine their effectiveness in reducing mild steel, lead and copper release in order to maintain the Town’s continual compliance with the LCR. The primary objective of the in-plant corrosion control research was to determine the appropriate ratio of RO to NF permeate and the pH necessary to reduce corrosion in the RO clearwell. In this research, the Langelier saturation index (LSI) was the corrosion index used to evaluate the stability of RO:NF blends. Results indicated that a pH-adjusted blend consisting of 70% RO and 30% NF permeate at 8.8-8.9 pH units would produce an LSI of +0.1, theoretically protecting the RO clearwell from corrosion. The primary objective of the distribution system corrosion control component of the research was to identify a corrosion control inhibitor that would further reduce lead and v copper metal release observed in the Town’s distribution system to below their respective action limits (ALs) as defined in the LCR. Six alternative inhibitors composed of various orthophosphate and polyphosphate (ortho:poly) ratios were evaluated sequentially using a corrosion control test apparatus. The apparatus was designed to house mild steel, lead and copper coupons used for weight loss analysis, as well as mild steel, lead solder and copper electrodes used for linear polarization analysis. One side of the apparatus, referred to as the “control condition,” was fed potable water that did not contain the corrosion inhibitor, while the other side of the corrosion apparatus, termed the “test condition,” was fed potable water that had been dosed with a corrosion inhibitor. Corrosion rate measurements were taken twice per weekday, and water quality was measured twice per week. Inhibitor evaluations were conducted over a span of 55 to 56 days, varying with each inhibitor. Coupons and electrodes were pre-corroded to simulate existing distribution system conditions. Water flow to the apparatus was controlled with an on/off timer to represent variations in the system and homes. Inhibitor comparisons were made based on their effectiveness at reducing lead and copper release after chemical addition. Based on the results obtained from the assessment of corrosion inhibitors for distribution system corrosion control, it appears that Inhibitors 1 and 3 were more successful in reducing lead corrosion rates, and each of these inhibitors reduced copper corrosion rates. Also, it is recommended that consideration be given to use of a redundant single-loop duplicate test apparatus in lieu of a double rack corrosion control test apparatus in experiments where pre-corrosion phases are vi implemented. This recommendation is offered because statistically, the control versus test double loop may not provide relevance in data analysis. The use of the Wilcoxon signed ranks test comparing the initial pre-corroding phase to the inhibitor effectiveness phase has proven to be a more useful analytical method for corrosion studies.

This dissertation consists of four papers concerning impacts of zinc orthophosphate (ZOP) inhibitor on iron, copper and lead release in a changing water quality environment. The mechanism of zinc orthophosphate corrosion inhibition in drinking water municipal and home distribution systems and the role of zinc were investigated. Fourteen pilot distribution systems (PDSs) which were identical and consisted of increments of PVC, lined cast iron, unlined cast iron and galvanized steel pipes were used in this study. Changing quarterly blends of finished ground, surface and desalinated waters were fed into the pilot distribution systems over a one year period. Zinc orthophosphate inhibitor at three different doses was applied to three PDSs. Water quality and iron, copper and lead scale formation was monitored for the one year study duration. The first article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on surface characteristics of iron corrosion products in a changing water quality environment. Surface compositions of iron surface scales for iron and galvanized steel coupons incubated in different blended waters in the presence of ZOP inhibitor were investigated using X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) / Energy Dispersive X-ray Spectroscopy (EDS). Based on surface characterization, predictive equilibrium models were developed to describe the controlling solid phase and mechanism of ZOP inhibition and the role of zinc for iron release. The second article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total iron release in a changing water quality environment. Development of empirical models as a function of water quality and ZOP inhibitor dose for total iron release and mass balances analysis for total zinc and total phosphorus data provided insight into the mechanism of ZOP corrosion inhibition regarding iron release in drinking water distribution systems. The third article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total copper release in a changing water quality environment. Empirical model development was undertaken for prediction of total copper release as a function of water quality and inhibitor dose. Thermodynamic models for dissolved copper based on surface characterization of scale that were generated on copper coupons exposed to ZOP inhibitor were also developed. Surface composition was determined by X-ray Photoelectron Spectroscopy (XPS). The fourth article describes the effects of zinc orthophosphate (ZOP) corrosion inhibitor on total lead release in a changing water quality environment. Surface characterization of lead scale on coupons exposed to ZOP inhibitor by X-ray Photoelectron Spectroscopy (XPS) was utilized to identify scale composition. Development of thermodynamic model for lead release based on surface analysis results provided insight into the mechanism of ZOP inhibition and the role of zinc.