Abstract This thesis deals with the pump schedule optimisation of regional water distribution systems. The aims and the possible applications of the presented methods differ from each other; all of them are intended to solve a particular but realistic problem. The developed techniques use the capacity of the water reservoirs in order to find the optimal pump-schedule of the system. The optimisation task is always deterministic and discrete in time; the stochastic behaviour of the water consumptions is approximated by expected values. A so-called neutral genetic algorithm equipped with new constraint handling is presented first. The method is able to solve the scheduling problems of real-size and complex networks, e.g. the network of Budapest with coupled hydraulic simulations where both variable and fixed speed pumps are in the network. The results are compared to other ones obtained by widely used genetic algorithms and state-of-the-art general purpose optimisation solvers. A dynamic programming based method was also carried out which provides the global optimum of the so-called ’combinatorial’ pump scheduling problems. This modelling type is very common in the industry, which can be used if the operation points of the pumps take discrete values. The basic idea of the method is exploiting the ’permutational invariance’ of the model which results in a perfect discretisation of the state space without any loss of information. An approximate dynamic programming technique is also presented which solves the same type of problems as the formerly mentioned genetic algorithm does. The technique splits the water network model into smaller units, namely into the so-called well fields and the main distribution system. The state space of the main distribution system was further decreased while the quality of the results does not decay. A part of the test examples is the same as in the case of the former presented genetic algorithm; thus, the two methods can be compared. Finally, a small water network fed by a single variable speed pump was investigated. The presented methods are based on the minimisation of the specific energy consumption. The gained results are compared to ones obtained using a high-resolution discrete dynamic program. Novel optimisation techniques for water distribution network pump scheduling were developed in this work. A particular focus was put on the dynamics between pumping, water reservoirs, and water use. The work shows the applicability of the approach via numerous realistic simulation case studies. / Tiivistelmä Työ käsittelee alueellisten vedenjakelujärjestelmien pumppauksen aikataulutuksen optimointia. Esitettyjen menetelmien tavoitteet ja mahdolliset sovellukset poikkeavat toisistaan. Kaikki on kuitenkin tarkoitettu tiettyjen todellisten ongelmien ratkaisemiseen. Kehitetyt tekniikat käyttävät vesivarastojen kapasiteettia optimaalisen pumppausohjelman löytämiseksi. Jokainen optimointitehtävä on aikadiskreetti ja deterministinen, vedenkulutuksen stokastista käyttäytymistä on approksimoitu odotusarvoilla. Ensimmäiseksi työssä esitetään ns. neutraaleja geneettisiä algoritmeja varustettuna rajoitusten käsittelyllä. Menetelmällä voidaan ratkaista skedulointiohjelmia reaalimittakaavaisille ja monimutkaisille verkostoille (esim. Budapestin verkosto varustettuna hydraulisilla simuloinneilla, sekä muuttuvanopeuksisilla että vakionopeuksisilla verkoston pumpuilla). Tuloksia verrataan toisiin yleisesti käytössä olevilla geneettisillä algoritmeilla saatuihin, sekä johtavilla yleiskäyttöisillä optimointitekniikoilla saatuihin tuloksiin. Työssä käytettiin myös dynaamiseen ohjelmointiin pohjaavaa menetelmää, jolla saadaan globaali optimi ns. "kombinatoorisille" pumppauksen aikataulutusongelmille. Tällainen mallinnustapa on hyvin yleistä teollisuudessa. Sitä voidaan käyttää, jos pumppujen toimintapisteet saavat diskreettejä arvoja. Menetelmän perusajatuksena on "permutationaalisen invarianssin" hyväksikäyttäminen, josta seuraa tila-avaruuden virheetön diskretointi ilman informaation häviämistä. Työssä esitellään myös approksimoidun dynaamisen ohjelmoinnin tekniikka, jonka avulla voidaan ratkaista samantyyppisiä ongelmia kuin yllämainituilla geneettisillä algoritmeilla. Tämä tekniikka jakaa vesijohtoverkoston mallin pienempiin yksiköihin: lähdekenttiin ja pääjakeluverkostoon. Pääjakeluverkoston tila-avaruutta voitiin edelleen pienentää ilman, että tulosten laatu heikkeni. Osa käsitellyistä esimerkkitapauksista on samoja kuin edellämainittujen geneettisten algoritmien osalla, joten tuloksia voidaan verrata. Lopuksi tutkittiin pienen muuttuvanopeuksisella pumpulla syötetyn vesijohtoverkoston toimintaa. Esitetyt menetelmät perustuvat ominaisenergiankulutuksen minimointiin. Saatuja tuloksia verrataan korkearesoluutioisella diskreetillä dynaamisella ohjelmoinnilla saatuihin tuloksiin. Työssä kehitettiin uusia optimointitekniikoita vedenjakelujärjestelmien pumppauksen aikataulutuksen optimintiin. Erityisesti työssä keskityttiin pumppauksen, vesitornien ja kuluttajien käyttäytymisen väliseen dynamiikkaan. Työssä osoitettiin tekniikoiden toimivuus realististen esimerkkisimulointien avulla. / Kivonat Jelen doktori disszertáció regionális ivóvízellátó-hálózatok üzemvitel-optimalizációjával foglalkozik. A bemutatott módszerek alkalmazhatósági köre rendszerint eltér egymástól, mindegyik egy-egy speciális, de a való életben is előforduló problémára kíván megoldást nyújtani. A kidolgozott módszerek a medencék tárolókapacitását kihasználva, az optimális szivattyú-menetrendet keresve kívánják megtalálni az adott vízműhálózat üzemviteloptimumát. Az optimalizáció egy időben diszkrét, ugyanakkor determinisztikus feladat megoldását igényli, a vízfogyasztások sztochasztikus viselkedését a várható értékekkel közelítettem. Elsőként egy új mellékfeltétel-kezeléssel ellátott, ún. neutrális genetikus algoritmus bemutatása a cél. A kidolgozott módszer alkalmas nagy, valós méretű (pl. Budapest) és bonyolultságú (kapcsolt hidraulikai szimulációk, frekvenciaváltós és direkt szivattyúk a hálózatban) ivóvízhálózatok napi üzemvitel optimalizálására. Az eredményeket más genetikus algoritmusokkal és a világ élvonalába tartozó, de általános célú optimalizációs módszerekkel hasonlítottam össze. Kidolgozásra került egy dinamikus programozás alapú, a valós, globális optimumot adó módszer is. Az algoritmus a gyakorlatban elterjedt, ún. "kombinációs" hálózatként modellezhető vízműhálózat típusokra alkalmazható, ahol a szivattyúk munkapontjai diszkrét értékek. A megoldás alapját az ún. "permutációs invariancia" jelensége adja, mely lehetővé teszi az állapottér információveszteség nélküli, tökéletes diszkretizációját. Egy, a korábban bemutatott genetikus algoritmuséhoz hasonló problémakört megoldó, de közelítő dinamikus programozás alapú módszer is bemutatásra kerül. Az algoritmus a hálózat kisebb részegységekre (víztermelő területekre és fő elosztó hálózatra) való felbontásával és a fő elosztó hálózat állapotterének önkényes, de a megoldás jóságán jelentősen nem rontó csökkentésével éri el a program futtatásához szükséges számítási igény csökkentését. A tesztfeladatok egy része megegyezik a genetikus algoritmus tesztfeladataival, így azok közvetlenül összehasonlíthatóak. Végül bemutatásra kerül egy kisméretű, mindössze egy darab változtatható fordulat- számú szivattyúval táplált rendszer energetikai vizsgálata. Az itt bemutatott módszerek mind a fajlagos energiafelhasználás minimalizálásán alapulnak. Az eredményeket egy nagyfelbontású dinamikus programozás alapú módszerhez hasonlítottam.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2015-12-16T11:21:48Z No. of bitstreams: 1 igordelgadodemelo.pdf: 4931795 bytes, checksum: cf03c45f0f2492c6cf9186af1b3866a2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2015-12-16T11:57:23Z (GMT) No. of bitstreams: 1 igordelgadodemelo.pdf: 4931795 bytes, checksum: cf03c45f0f2492c6cf9186af1b3866a2 (MD5) / Made available in DSpace on 2015-12-16T11:57:23Z (GMT). No. of bitstreams: 1 igordelgadodemelo.pdf: 4931795 bytes, checksum: cf03c45f0f2492c6cf9186af1b3866a2 (MD5) Previous issue date: 2015-09-18 / Este trabalho objetiva apresentar uma metodologia capaz de estimar os componentes harmônicos em sistemas de distribuição com topologia radial utilizando PMUs (Phasor Measurement Units). Os estados a serem estimados serão as correntes passantes em todas as linhas do sistema em coordenadas retangulares. Uma vez que essas correntes são obtidas, torna-se possível o cálculo de outras grandezas elétricas através das equações de fluxo de potência e leis de Kirchhoff. A metodologia considera poucas unidades de medição fasorial (as PMUs) instaladas efetuando a leitura dos sinais de tensões nodais e correntes nas linhas com distorção harmônica. A fim de restaurar a observabilidade do sistema por completo, são considerados dados históricos de demanda de potência ativa/reativa, os quais serão tratados como restrições de desigualdades excursionando entre um valor mínimo e máximo considerados em um problema de otimização não linear que visa diminuir a diferença entre os valores monitorados pelas PMUs e os calculados pela metodologia. As mencionadas restrições permitem ao estimador o acompanhamento das variações sofridas ao longo do tempo na curva de carga para a frequência fundamental e também para as demais frequências. A abordagem proposta neste trabalho considera a modelagem trifásica de equipamentos e linhas de distribuição, portanto, são modelados os efeitos de acoplamento mútuo entre fases e a operação não linear de equipamentos de eletrônica de potência tiristorizados. O método demonstra eficiência não apenas em estimar os componentes harmônicos de um certo espectro considerado no estudo, como também se mostra uma ferramenta prática de detecção e identificação de fontes harmônicas no sistema elétrico de potência, além de explicitar um exemplo prático do uso de PMUs no que tange ao monitoramento de redes de distribuição, carentes de acompanhamento em tempo real. A metodologia ainda se mostra capaz de ser aliada a grandes estudos contextualizados em qualidade de energia, uma vez que permite a estimação de índices de distorção harmônica. / This work aims to present a methodology which is capable of estimating harmonic components for distribution systems with radial topology, using PMUs (Phasor Measurement Units). The estimated states will be all branch currents of the system expressed in rectangular coordinates. Once these currents are obtained, it is possible to calculate other electrical quantities using power flow equations and also Kirchhoff’s law. The methodology considers the installation of a few number of phasor measurement units which will measure voltage and branch currents signals distorted by harmonic sources. In order to make the whole system observable, historical data of active/reactive power demand will be treated as inequality constraints varying between minimum and maximum limits described in a non linear optimization problem, which aims to minimize the difference between the values monitored by PMUs and the ones calculated by the methodology. The already mentioned constraints allows the accompaniment of the variations occured in a typical load curve during a period of time for the fundamental frequency and also for their multiples, allowing the accompaniment of the harmonic load curve, normally unknown. The proposed approach considers a three-phase modelling of equipments and distribution lines, subject to their mutual coupling effects caused by mutual impedances between the lines. It will also be considered electronic-based devices using thyristors located along the distribution feeder, injecting harmonic currents in the system. The method demonstrates efficiency in estimating the harmonic states of the net and also in detecting and identifying harmonic sources in an eletric power system, besides showing a practical use of PMUs for the monitoring of distribution systems, lacking in information and real-time accompaniment. The method also enables the estimation of power quality indicators such as total harmonic distortion.

Thesis, Comparison of selected methods of houses’ evaluation in Znojmo and associated communities, explains some of the currently used valuation methods. It also deals with comparison of prices which were determined by selected valuation methods. Those methods include cost approach, comparative method, the current price and the price of time. It accentuates the consideration of coefficient within connecting into utility networks – especially sewer. Then it focuses on ways of heating. The aim of this thesis is to find out how the aspect of connecting into utility networks is involved in methods of heating. For the evaluation there were selected 10 houses in Znojmo and associated communities.

The penetration of photovoltaic (PV) and electric vehicles (EVs) continues to grow and is predicted to claim a vital share of the future energy mix. It poses new challenges in the built environment, as both PV systems and EVs are widely dispersed in the electricity distribution system. One of the vital tools for analyzing these challenges is load flow analysis, which provides insights on power system performance. Traditionally, for simplicity, load flow analysis utilizes deterministic approaches and neglecting  correlation between units in the system. However, the growth of distributed PV systems and EVs increases the uncertainties and correlations in the power system and, hence, probabilistic methods are more appropriate. This thesis contributes to the knowledge of how uncertainty and correlation models can improve the quality of load flow analysis for electricity distribution systems with large numbers of residential PV systems and EVs. The thesis starts with an introduction to probabilistic load flow analysis of future electricity distribution systems. Uncertainties and correlation models are explained, as well as two energy management system strategies: EV smart charging and PV curtailment. The probabilistic impact of these energy management systems in the electricity distribution system has been assessed through a comparison of allocation methods and correlation analysis of the two technologies. The results indicate that these energy management system schemes improve the electricity distribution system performance. Furthermore, an increase in correlations between nodes is also observed due to these schemes. The results also indicate that the concentrated allocation has more severe impacts, in particular at lower penetration levels. Combined PV-EV hosting capacity assessment shows that a combination of EV smart charging with PV curtailment in all buildings can further improve the voltage profile and increase the hosting capacity.  The smart charging scheme also increased the PV hosting capacity slightly. The slight correlation between PV and EV hosting capacity shows that combined hosting capacity analysis of PV systems and EVs is beneficial and is suggested to be done in one framework. Overall, this thesis concludes that an improvement of uncertainty and correlation modeling is vital in probabilistic load flow analysis of future electricity distribution systems.

The work description is to create a system of measures to prevent the spread and the consequent attenuation of sound in air handling systems serving the cleanrooms. The thesis presents a solution to noise attenuation in the investigated area, and in HVAC duct, which uses a commercially available material in the form of sound insulation hoses. In the systém solution is part of the work focuses on the optimal design of terminal elements to distribute air in a clean room. Processing methods utilize theoretical and experimental approach. The experiment comprises a unique analysis of the sound insulation properties of selected products under specific conditions. The data obtained are analyzed and incorporated into the framework of this work created program module for determining the attenuation and noise propagation in an enclosed space. Math and physical dependence are programmed into their own DLL by programming language DELPHI.

No description available.

[pt] Os novos elementos conectados nos sistemas de distribuição de energia elétrica aumentam a complexidade do planejamento e operação destas redes. Os benefícios da implementação de técnicas clássicas, como Conservation Voltage Reduction (CVR), combinadas com uma operação coordenada dos recursos energéticos distribuídos, podem contribuir para o aumento de eficiência nos sistemas de distribuição de energia elétrica e reduzir o consumo de energia. Na técnica CVR, as tensões são reduzidas objetivando redução de picos de demanda e consumo de energia. Este trabalho propõe um modelo de otimização para o planejamento da operação do dia seguinte nos sistemas de distribuição de energia elétrica, considerando sistemas desequilibrados e com penetração de geração distribuída (GD) fotovoltaica. A técnica CVR será aplicada em uma abordagem determinística, estocástica e robusta, considerando a incerteza nos seus parâmetros e, consequente, na modelagem de carga. O modelo de otimização proposto considera a atuação de elementos de controle tradicionais, como transformador On Load Tap Changers (OLTC) na subestação e bancos de capacitores (BC), além de elementos modernos, como inversores fotovoltaicos inteligentes, para minimização do consumo de energia observado na subestação. O problema, fundamentalmente de programação não-linear inteira mista, é transformado em um problema de programação linear de natureza contínua. Os resultados são avaliados no sistema teste IEEE 123-barras para as diferentes estratégias modeladas. A economia de energia obtida foi significativa nas abordagens propostas, mas o modelo de otimização robusta se mostrou mais adequado para reduzir os riscos de violação de tensão. / [en] The new elements connected in electrical distribution systems increase the complexity of grids planning and operating. The benefits of classical techniques, such as Conservation Voltage Reduction (CVR), combined with a coordinated operation of distributed energy resources, can contribute to increasing efficiency and reducing energy consumption of the distribution systems. In the CVR technique, voltages are reduced in order to reduce peak demand and energy consumption. This paper proposes an optimization model for the day-ahead operation planning of unbalanced distribution systems with photovoltaic distributed generation (DG) penetration. The CVR technique will be applied in deterministic, stochastic and robust approach, considering the uncertainty in its parameters and consequently, in the load modeling. The proposed optimization model considers the operation of traditional control elements, such as On Load Tap Changers (OLTC) at substation and capacitor banks (CB), in addition to modern elements, such as intelligent photovoltaic inverters, to minimize the energy consumption at the substation. The problem, originally of mixed-integer nonlinear programming, is transformed into a continuous linear programming problem. The results are evaluated in the IEEE123-bus test system for the different optimization approaches. The energy savings obtained were significant in all the proposed approaches, but the robust optimization model proved to be more adequate since it reduces the risk of voltage violations.

<p>  </p> <p>Food systems are facing unprecedented challenges and need reforms to be more efficient and provide safe and nutritious food from farm to fork. In this dissertation, I present new empirical evidence on different strategies to tackle two critical problems of food systems in sub-Saharan Africa (SSA): food contamination and the inefficient delivery and use of subsidized agricultural inputs. The first essay measures demand and network effects for a newly available technology called Aflasafe that delivers credence attributes (i.e., benefits difficult or impossible to observe and measure even after frequent use of the technology). The second essay exploits a policy change in Malawi to estimate the efficiency of public and private channels at distributing inputs to smallholder farmers. I use a panel dataset covering the period from 2010 to 2016 and a difference-in-differences (DID) framework to estimate the impact of the policy change on procurement of subsidized fertilizer, efficiency and service quality, agricultural productivity, and the household’s decision to purchase commercial fertilizer. The third essay identifies a series of constraints faced by smallholder farmers in Senegal and assesses which ones are associated with chemical and microbial contaminants in groundnut (peanut).</p>

[pt] Os incêndios florestais podem ser uma fonte de vulnerabilidade para sistemas de potência. Esses eventos podem afetar especialmente a operação de sistemas de distribuição, interrompendo o fornecimento de energia, aumentando os custos, e diminuindo a confiabilidade. Nesta dissertação, é considerada a relação entre as decisões operativas e a probabilidade de falha nas linhas sob o contexto de queimadas. Este tipo de estudo ainda não foi devidamente avaliado pelo meio acadêmico. Ao não reconhecer este aspecto, o funcionamento dos sistemas de potência pode estar sendo prejudicado. A modelagem adequada dessa dependência poderia reduzir a incidência de queimadas e perda de carga. Considerando este aspecto, um problema de otimização distributivamente robusto de dois estágios com incerteza endógena foi desenvolvido para considerar a operação multiperíodo de sistemas de distribuição. O primeiro estágio determina a topologia da rede e os investimentos nas linhas, e o segundo estágio avalia o custo operacional esperado no pior caso. Nessa estrutura, a incerteza é modelada de forma dependente das decisões do modelo, onde as probabilidades de falha da linha são em função do fluxo de potência das próprias linhas. Um método iterativo é proposto para resolver este modelo e uma análise fora da amostra é desenvolvida para validação através de diferentes estudos. Os resultados mostraram que, ao negligenciar a dependência da incerteza, uma maior perda de carga e um maior custo operacional são esperados. Ao considerar esta nova abordagem, a confiabilidade da rede pode ser melhorada e as consequências dos incêndios podem ser mitigadas com ações mais econômicas. / [en] Wildfires can be a source of vulnerability for power systems operations. These events can especially affect the operation of distribution systems. They can interrupt energy supply, increase costs, and decrease grid resilience. Numerous approaches can be executed to prevent them. In this dissertation, it is considered the relationship between operative actions and the probability of wildfire disruption. This type of study has not been properly evaluated in technical and scientific literature. By not recognizing this aspect, the operation of power systems may be impaired. Properly modeling this dependency could lower wildfire disruption and loss of load. Considering this, a two-stage distributionally robust optimization problem with decision-dependent uncertainty is developed to consider distribution system multiperiod operation. The first stage determines the optimal switching actions and line investments, and the second stage evaluates the worst-case expected operation cost. It is designed a decision-dependent uncertainty framework where the line failure probabilities are a function (dependent) of its power flow levels. An iterative method is proposed to solve this model and an out-of-sample analysis is developed to validate it through different case studies. Results showed that, by neglecting the uncertainty dependency on operative decisions, there could be a higher expected loss of load and a higher operational cost. By considering this new approach when operating power lines, the grid s resilience could be improved and wildfire consequences can be mitigated with less costly actions.

<ul> <li>Energy Optimization Stategies</li> <li>Hydraulic Models for Water Distribution Systems</li> <li>Heuristic Multi-objective Optimization Algorithms</li> <li>Multi-objective Optimization Problems</li> <li>System Constraints</li> <li>Encoding Techniques</li> <li>Optimal Pumping Operations</li> <li>Sovling Real-World Optimization Problems </li> </ul> / <p>The water supply industry is a very important element of a modern economy; it represents a key element of urban infrastructure and is an integral part of our modern civilization. Billions of dollars per annum are spent internationally in pumping operations in rural water distribution systems to treat and reliably transport water from source to consumers.</p> <p>In this dissertation, a new multi-objective optimization approach referred to as energy optimization strategy is proposed for minimizing electrical energy consumption for pumping, the cost, pumps maintenance cost, and the cost of maximum power peak, while optimizing water quality and operational reliability in rural water distribution systems. Minimizing the energy cost problem considers the electrical energy consumed for regular operation and the cost of maximum power peak. Optimizing operational reliability is based on the ability of the network to provide service in case of abnormal events (e.g., network failure or fire) by considering and managing reservoir levels. Minimizing pumping costs also involves consideration of network and pump maintenance cost that is imputed by the number of pump switches. Water quality optimization is achieved through the consideration of chlorine residual during water transportation.</p> <p>An Adaptive Parallel Clustering-based Multi-objective Particle Swarm Optimization (APC-MOPSO) algorithm that combines the existing and new concept of Pareto-front, operating-mode specification, selecting-best-efficiency-point technique, searching-for-gaps method, and modified K-Means clustering has been proposed. APC-MOPSO is employed to optimize the above-mentioned set of multiple objectives in operating rural water distribution systems.</p> <p>Saskatoon West is, a rural water distribution system, owned and operated by Sask-Water (i.e., is a statutory Crown Corporation providing water, wastewater and related services to municipal, industrial, government, and domestic customers in the province of Saskatchewan). It is used to provide water to the city of Saskatoon and surrounding communities. The system has six main components: (1) the pumping stations, namely Queen Elizabeth and Aurora; (2) The raw water pipeline from QE to Agrium area; (3) the treatment plant located within the Village of Vanscoy; (4) the raw water pipeline serving four major consumers, including PCS Cogen, PCS Cory, Corman Park, and Agrium; (5) the treated water pipeline serving a domestic community of Village of Vanscoy; and (6) the large Agrium community storage reservoir.</p> <p>In this dissertation, the Saskatoon West WDS is chosen to implement the proposed energy optimization strategy. Given the data supplied by Sask-Warer, the scope of this application has resulted in savings of approximately 7 to 14% in energy costs without adversely affecting the infrastructure of the system as well as maintaining the same level of service provided to the Sask-Water’s clients.</p> <p>The implementation of the energy optimization strategy on the Saskatoon West WDS over 168 hour (i.e., one-week optimization period of time) resulted in savings of approximately 10% in electrical energy cost and 4% in the cost of maximum power peak. Moreover, the results showed that the pumping reliability is improved by 3.5% (i.e., improving its efficiency, head pressure, and flow rate). A case study is used to demonstrate the effectiveness of the multi-objective formulations and the solution methodologies, including the formulation of the system-operational optimization problem as five objective functions. Beside the reduction in the energy costs, water quality, network reliability, and pumping characterization are all concurrently enhanced as shown in the collected results. The benefits of using the proposed energy optimization strategy as replacement for many existing optimization methods are also demonstrated.</p> / Doctor of Science (PhD)