This study focuses on the design, construction and operation of a distributed generation system based on micro-hydro technology. The project is sited in the Totara Valley, a small rural community approximately 70km from the Massey University, Turitea campus, Palmerston North. The Massey University Centre for Energy Research (MUCER) has a long history of renewable energy research within the Totara Valley community. This project complements these existing schemes and provides a foundation for future research into distributed generation technologies. The project encompasses the following objectives: - to gain practical experience in the design, engineering and implementation of a distributed generation system in rural New Zealand; - to evaluate contemporary micro-hydro technology and compare the performance of this equipment in a theoretical and practical context; - to identify barriers that hinder the widespread adoption of micro-hydro systems in rural New Zealand; - to develop a spreadsheet based life cycle costing tool. The results from this study demonstrate that economic considerations are the fundamental aspect to be considered when assessing the long-term viability of these projects. The viability of micro-hydro projects are primarily determined by four factors: - the volume and head (height) of water available above the turbine site; - the length and therefore the cost of the pipeline required for transporting water to the turbine; - the legal and administrative costs involved in obtaining a resource consent to maintain access to the water resources; - the prices received and paid for electricity. Considerable charges were payable to the local authority to secure and maintain the right to harness the water resources at this site. This cost contributed considerable risk to the project and creates a significant barrier to establishing similar systems at other sites. The reduction of resource consent charges to levels that fairly reflect the negligible environmental impacts of these projects would encourage the adoption of this technology and deliver benefits to rural New Zealand communities.

Thesis (Ph.D.) -- Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Η παρούσα διπλωματική έχει ως αντικείμενο την μελέτη και μοντελοποίηση ενός συστήματος μικροστροβίλου και ανεμογεννήτριας ως συστατικά στοιχεία ενός συστήματος κατανεμημένης παραγωγής. Παρουσιάζεται αναλυτικά η έννοια της κατανεμημένης παραγωγής καθώς επίσης και οι τεχνολογίες που χρησιμοποιούνται σε αυτή, ενώ ένα κεφάλαιο είναι αποκλειστικά αφιερωμένο στην τεχνολογία των μικροστρόβιλων. Στο τελευταίο κεφάλαιο γίνεται μια μελέτη της δυναμικής συμπεριφοράς ενός συστήματος μικροστροβίλου σε μεταβλητές συνθήκες φόρτισης καθώς επίσης και της απόκρισης του στην περίπτωση προσθήκης ενός επιπλέον φορτίου, την κάλυψη του οποίου αναλαμβάνει ως εφεδρικό μέσω μία ανεμογεννήτρια σταθερών στροφών. / The current diploma thesis deals with the development of a distributed generation system with a micro-turbine and a wind-turbine as its basic components. What is more, it is given the meaning of the “distributed generation”, we analyze the basic characteristics of it and we present the most important technologies that complete the distributed generation. Furthermore we refer to the micro-turbine technology and its characteristics in the third chapter of this essay. In the last chapter we analyze the dynamic response of a micro-turbine based system in variable load conditions and the response of the system when an additional load, which is powered by a fixed speed wind-turbine, is added in the micro grid.

Η παρούσα διδακτορική εργασία αφορά στο σχεδιασμό και εφαρμογή ελέγχου σε κατανεμημένη παραγωγή ηλεκτρικής ενέργειας ώστε να είναι δυνατή η ένταξή της σε μικροδίκτυα στο δίκτυο χαμηλής τάσης. O σχεδιασμός του ελέγχου αποσκοπεί: 1) Στην δυνατότητα σύνδεσης-αποσύνδεσης (Plug and play) της κατανεμημένης παραγωγής στο μικροδίκτυο χωρίς καμμία ιδιαίτερη παρέμβαση από κεντρικό έλεγχο. 2) Η κατανεμημένη παραγωγή, που περιλαμβάνει συστοιχία κυττάρων καυσίμου και ανεμογεννήτρια, πρέπει να παρέχει στήριξη ενεργού και άεργου ισχύος στο μικροδίκτυο διανομής όταν συμβαίνουν διαταραχές φορτίου. 3) Να τροφοδοτεί όλο το φορτίο σε κατάσταση νησιδοποίησης, στην οποία θα μπορεί να μεταβαίνει είτε λόγω σφάλματος στην μέση τάση είτε γιατί το μικροδίκτυο είναι επιθυμητό να λειτουργεί εσκεμμένα στην προαναφερθείσα κατάσταση. 4) Η μετάβαση από τη διασυνδεδεμένη κατάσταση του μικροδικτύου στη νησιδοποίηση και αντίστροφα να γίνεται με τον ομαλότερο δυνατό τρόπο. Λόγω της έντονης μη γραμμικότητας των υπό μελέτη συστημάτων, στο σχεδιασμό των συστημάτων ελέγχου εφαρμόζεται ασαφής λογική. Τα αποτελέσματα της έρευνας αφορούν τόσο τον θεωρητικό σχεδιασμό των παραπάνω συστημάτων με την βοήθεια προγράμματος εξομοίωσης (Matlab/Simulink) όσο και την πειραματική επιβεβαίωση των συμπερασμάτων στο εργαστήριο. Αρχικά, εξομοιώνεται μια συστοιχία κυττάρων καυσίμου συνδυασμένη με μια μπαταρία (υβριδικό σύστημα) και ενσωματώνεται σε ένα ασθενές δίκτυο διανομής. Ο έλεγχος δοκιμάζεται για τοπικές μεταβολές φορτίου και για μετάβαση από την διασυνδεδεμένη σε νησιδοποιημένη κατάσταση προκειμένου να διαπιστωθούν τα επιθυμητά χαρακτηριστικά του ελέγχου που αναφέρθηκαν. Επιπλέον, γίνεται μια διερεύνηση για το εύρος της αποτελεσματικότητας του ελέγχου για διαφορετικού τύπου γραμμών διανομής. Η συμπεριφορά του ελέγχου κρίνεται ικανοποιητική σε όλες τις περιπτώσεις. Στην συνέχεια, το ίδιο υβριδικό σύστημα (μεγαλύτερης όμως ισχύος) και μια ανεμογεννήτρια με γεννήτρια διπλής τροφοδότησης ενσωματώνονται σε ένα μικροδίκτυο που συνδέεται σε ασθενές δίκτυο διανομής στο πρόγραμμα εξομοίωσης. Ο έλεγχος του υβριδικού συστήματος δεν αλλάζει λόγω της ευελιξίας της ασαφούς λογικής. Ο έλεγχος των μικροπηγών δοκιμάζεται για τοπικές μεταβολές φορτίου και για μετάβαση από την διασυνδεδεμένη σε νησιδοποιημένη κατάσταση και αντιστρόφως για μετάβαση από νησιδοποιημένη σε διασυνδεδεμένη κατάσταση. Επιπλέον, γίνεται μια διερεύνηση της δυναμικής απόκρισης του μικροδικτύου κατά την ύπαρξη μπαταρίας και κατά την απομάκρυνσή της από το μικροδίκτυο. Η συμπεριφορά του ελέγχου κρίνεται ικανοποιητική σε όλες τις περιπτώσεις. Για την πειραματική επιβεβαίωση, αξιοποιείται ένα σύστημα συστοιχίας κυττάρων καυσίμου (Ballard& Nexa System) συνδυασμένο με μια μπαταρία στο χώρο του εργαστηρίου. Εφαρμόζεται η τεχνολογία ψηφιακού ελέγχου σήματος μέσω ενός ψηφιακού επεξεργαστή σήματος (DSP). Έτσι, δίνεται η δυνατότητα σε τμήματα του ελέγχου που έχουν ήδη σχεδιαστεί να μεταφέρονται μέσω ειδικού λογισμικού στον επεξεργαστή και να ενσωματώνονται στην κατανεμημένη παραγωγή με ελάχιστο κόστος. Το πραγματικό σύστημα που δημιουργείται δοκιμάζεται για τοπικές μεταβολές φορτίου. Η συμπεριφορά του ελέγχου κρίνεται ικανοποιητική σε όλες τις περιπτώσεις. Μέσω εκτενών αποτελεσμάτων εξομοίωσης αλλά και πειραματικών, αποδεικνύεται πως ο προτεινόμενος έλεγχος συγκεντρώνει τα επιθυμητά χαρακτηριστικά που αναφέρθηκαν. Αποδεικνύεται, μάλιστα, ιδιαίτερα ευέλικτος και πρακτικός όχι μόνο σε θεωρητικές εφαρμογές αλλά και σε πραγματικά δεδομένα. Το τελευταίο είναι ιδιαίτερα σημαντικό αφού δίνει την δυνατότητα στον μηχανικό με ελάχιστο κόστος και με εύκολο χειρισμό λόγω της ασαφούς λογικής και του ψηφιακού επεξεργαστή να ελέγχει οποιαδήποτε κατανεμημένη παραγωγή (easy engineering) με ελάχιστες διορθωτικές κινήσεις. / Σhe present Ph.d thesis regards to the design and application of the control of the distributed generation (or microsource) so that distributed generation integrates into microgrids at the low voltage side. The design of the control has to achieve the following: 1) Meet the «plug and play» operation mode that implies that a microsource can be added to the microgrid without reengineering the central control and protection of units that are already part of the system. 2) The distributed generation that is a fuel cell system and a wind turbine in this case, have to provide active and reactive power support to the low voltage microgrid in cases of local load disturbances. 3) The distributed generation have to supply the whole demanded power in case of islanding mode of operation either because of a fault at the mean voltage side or because of an intentional disconnection e.g. maintenance work. 4) The transitioning from the interconnected mode to the islanded mode of operation and vice-versa has to be smooth. Due to the intense non linearity of the system, the control design is based on fuzzy logic. The results of this research regard not only to the theoretical design of the above systems via the simulation program Matlab/Simulink but also to the experimental affirmation of the results in the laboratory. Firstly, a fuel cell system combined with a battery bank forming a hybrid system is simulated and integrated into a weak distribution grid. The response of the control system is simulated firstly under a severe step load change under grid connected mode and secondly when a transitioning to islanded operation mode is caused by an upstream supply outage. Also, a study is made in order to ascertain the range of the efficiency of the proposed control for different types of distribution lines. The performance of the control revealed good in all cases. Secondly, the same hybrid system (of bigger nominal power though) and a wind turbine with doubly induction generator are integrated into a microgrid which is connected to a weak distribution grid via the simulation program. The control of the hybrid system remains the same due to the flexibility of fuzzy reasoning. The response of the control system is simulated firstly under a severe step load change under grid connected mode and secondly when a transitioning to islanded operation mode happens and vice-versa when a transitioning from islanded to interconnected operation mode occurs. Also, the transient response of the system is investigated in the cases when the battery bank is part of the microgrid and when it is eliminated. The performance of the control revealed good in all cases. The experimental setup includes a fuel cell system (Ballard& Nexa System) combined with a battery bank. In order to transfer parts of the designed control and integrate them into the experimental setup, the technology of the digital signal control via the digital signal processor (DSP) is exploited. The transfer of the control to the DSP is done through a software program at the minimum costs. The response of the real system is evaluated under a step load. The performance of the control revealed good in all cases.Through a large number of simulation and experimental results, the proposed control proves to meet the desirable requirements that already are mentioned. The proposed controller, also, prove to be particular flexible and practical in real systems. The latter remark makes the designed control suitable in real systems where the engineer tunes the local controller of each distributed generation easier due to fuzzy logic (easy engineering). It has to be reminded, also, that through the digital control technology, the integration of the control by the engineer is at minimum costs.

Orientador: Dionízio Paschoareli Júnior / Resumo: No planejamento da integração de fontes de geração distribuída no sistema de distribuição em baixa tensão é fundamental que haja a investigação dos efeitos provocados nas condições operacionais da rede, tais como níveis de tensão e carregamento de transformadores. Com vista ao potencial aumento da geração fotovoltaica no cenário brasileiro e à iminente migração tecnológica das redes tradicionais para as chamadas redes inteligentes, a resposta da demanda se apresenta como uma das estratégias para possibilitar uma integração eficiente de recursos energéticos distribuídos. Na aplicação de um programa de resposta da demanda, especificamente para o cenário de uma distribuidora, permitiu-se concluir, através da utilização de dados reais, que no processo de planejamento de integração de novas fontes de geração de natureza fotovoltaica, a aplicação de uma estrutura tarifária com custos diferenciados horários baseados no custo marginal de capacidade do sistema, possibilita que sejam observadas melhores condições operacionais da rede. A aplicação da nova estrutura tarifária horária indica uma significativa alteração no perfil de carga esperado dos consumidores de baixa tensão o que refletiu em melhores valores de níveis de tensão e aumento da capacidade livre do transformador em integrar novas fontes distribuídas no sistema. / Abstract: In planning the integration of distributed generation sources in the low voltage distribution system, it is essential to investigate the effects caused by the network operating conditions, such as voltage levels and transformer loading. By the point of view of the potential increase in photovoltaic generation for the Brazilian scenario and the imminent technological migration of traditional networks to the so-called Smart Grids, demand response is one of the strategies to enable the efficient integration of distributed energy resources. By applying a demand response program, specifically for the scenario of a distribution company, it was possible to conclude, by using real data, that in the integration planning process of new photovoltaic based generation sources, the application of a tariff structure with hourly differentiated costs based on the system's marginal cost of capacity, allows better operational conditions of the network to be observed. The application of the new hourly tariff structure indicates a significant change in the expected load profile of the low voltage consumers, which reflected in better values of voltage levels and rising of the free capacity of the transformer to integrate new distributed sources into the system. / Doutor

Orientador: Jose Roberto Sanches Mantovani / Banca: Antonio Padilha Feltrin / Banca: Roberto Cayetano Lotero / Resumo: Neste trabalho propõe-se um algoritmo para a restauração de redes de distribuição de energia elétrica em tempo real baseado na meta-heurística GRASP (Greed Randomized Adaptative Search Procedure) considerando a inserção de geradores distribuídos. O problema é modelado como não linear inteiro misto e considera os dois principais objetivos da restauração de redes de distribuição: minimizar número de consumidores sem fornecimento de energia elétrica e o número de chaveamentos. O algoritmo desenvolvido a partir da metodologia proposta foi implementado em linguagem de programação C++ e testado em um sistema real de distribuição de grande porte. A partir dos resultados obtidos verificou-se o bom desempenho do algoritmo, tanto em termos de robustez quanto em desempenho computacional, ao encontrar um conjunto de soluções factíveis e de boa qualidade, dentro de um tempo computacional considerado adequado para o problema de restauração / Abstract: This work proposes a methodology to distribution power system restoration considering distributed generators installed on the system. The methodology is based on GRASP (Greed Randomized Adaptive Search Procedure) metaheuristic and the restoration problem is established as nonlinear mixed-integer taking account two mainly goals: minimizing both the number of consumers without supply and the number of switching. The algorithm based on proposed methodology is implemented in C++ programming language and tested using a bulk real-life distribution power system. The results show the methodology is able to provide a set of feasible and good quality solutions in a suitable time for the restoration problem / Mestre

A inserção de fontes de geração distribuída (GD) traz a possibilidade de diversificação da matriz energética e a redução de perdas elétricas no transporte de EE – porque as fontes localizam-se próximas aos clientes finais. Entre elas destacam-se as fontes fotovoltaicas, eólicas, pequenas centrais hidrelétricas (PCH) e termelétricas à biomassa. As duas primeiras, apresentam a peculiaridade de normalmente serem conectadas à rede através de inversores de frequência. As outras duas costumam ser conectadas diretamente ao sistema. Todavia, a GD também propicia consequências ao SEP, muitas vezes indesejadas, como variações nos parâmetros da qualidade da energia elétrica (QEE). O compromisso que se deve manter com a QEE entregue aos consumidores é de vital importância para as empresas transmissoras e distribuidoras de energia elétrica, bem como para os utilitários dessa EE. Além disso, para que haja o correto funcionamento de equipamentos eletrônicos e de diversos processos industriais é necessário que a energia elétrica permaneça em uma faixa de tensão aceitável. Entre os fenômenos de interesse da área de qualidade de energia elétrica, os quais devem ser eliminados ou mitigados para a melhor operabilidade do SIN, pode-se citar: harmônicos, flutuação de tensão, subtensão, sobretensão e afundamentos de tensão. Devido a observabilidade rotineira e aos prejuízos (financeiros e/ou técnicos) associados ao fenômeno, o interesse desse estudo consiste nos afundamentos de tensão. Nesse contexto, apresenta-se uma proposta para análise dos afundamentos de tensão em um ambiente com geração distribuída (fotovoltaica, eólica, PCH e termelétrica à biomassa) através de simulações de curtos-circuitos. Os resultados obtidos através da metodologia proposta mostram que a inserção de GD pode trazer uma variação no número de afundamentos de tensão e melhorar os níveis de tensão nas barras, sobretudo nos locais onde foram inseridas bem como em suas proximidades. Também, há redução no número de afundamentos de maior severidade os quais causam mais prejuízos e preocupação a operabilidade do SEP. / The insertion of distributed generation (DG) sources brings the possibility of diversification of energy sources types and the reduction of electrical losses in the transport of EE - because the sources are located close to end users. Among these sources are photovoltaic, wind, small hydropower and biomass-fired power plants. The first two, are usually connected to the network through frequency inverters. The other two are usually connected directly to the system. However, DG also provides consequences to the electrical power system, often unwanted, such as variations in the parameters of power quality (PQ). The commitment should be retained with the power quality delivered to customers. Moreover, for the correct operation of electronic equipment and various industrial processes it is necessary that the voltage remains within an acceptable range. Among the phenomena of interest to electric power quality, which must be eliminated or mitigated, we can mention: harmonics, voltage fluctuation, undervoltage, overvoltage and voltage sags (dips). Due to losses (financial and/or technical) associated with the phenomenon, the interest of this study consists of the voltage sags. In this context, we present a proposal for analysis of voltage sags in an environment with distributed generation (photovoltaic, wind, thermal and biomass-fired power plants) through simulations of short circuits. The results obtained through the proposed methodology shows that the inclusion of DG can bring a change in the number of voltage sags and improve voltage levels in bars, especially in places where they were inserted and in its vicinity. Also, there is a reduction in the number of severe voltage sags which cause more harm and concern to end-users and utilities.

Asset management and automation are acknowledged by distribution utilities as a useful strategy to improve service quality and reliability. However, the major challenge faced by decision makers in distribution utilities is how to achieve long-term return on the projects while minimising investment and operation costs. Distribution automation (DA) in terms of transformer economic operation (TEO), distribution network reconfiguration (DNR), and sectionalising switch placement (SSP) is recognised as the most effective way for distribution network operators (DNOs) to increase operation efficiency and reliability. Automated tie-switches and sectionalising switches play a fundamental role in distribution networks. A method based on the Monte Carlo simulation is discussed for transformer loss reduction, which comprises of profile generators of residential demand and a distribution network model. The ant colony optimisation (ACO) algorithm is then developed for optimal DNR and TEO to minimise network loss. An ACO algorithm based on a fuzzy multi-objective approach is proposed to solve SSP problem, which considers reliability indices and switch costs. Finally, a multi-objective ant colony optimisation (MOACO) and an artificial immune systems-ant colony optimisation (AIS-ACO) algorithm are developed to solve the reconfiguration problem, which is formulated within a multi-objective framework using the concept of Pareto optimality. The performance of the optimisation techniques has been assessed and illustrated by various case studies on three distribution networks. The obtained optimum network configurations indicate the effectiveness of the proposed methods for optimal DA.

Este trabalho tem como objetivo investigar a máquina de indução funcionando como gerador. Para isso, são pesquisadas as normas e requisitos para operação interligada à rede de distribuição até o presente momento. Os parâmetros elétricos referente ao circuito equivalente monofásico da máquina de indução de 15 kW, pertencente a um grupo gerador a biogás, são levantados, realizando-se uma caracterização e modelamento destes parâmetros. Os resultados teóricos obtidos têm o intuito de predizer o comportamento das grandezas elétricas quando o grupo gerador operar em condições nominais, interligado a rede de distribuição. Também, estes resultados teóricos são comparados com valores medidos em ensaios de campo utilizando um motor CC de 10 kW como máquina primária. / This study aims at investigate the induction machine operating as a generator. For this, we researched the standards and requirements for the operation connected to the distribution grid to the present date. The electrical parameters concerning the equivalent circuit per phase of a 15 kW induction machine are raised, this machine is part of a small biogas plant. An appropriate characterization and modeling of these parameters are realized and the theoretical results obtained are intended to predict the behavior of electrical units when the generator is placed at nominal operation. Also, these theoretical results are compared with experimental measurements using a 10 kW DC motor as primary mover.

Sistemas de Distribuição de Energia Elétrica (SDEE) estão, pelas próprias condições de funcionamento, sujeitos a perdas de energia e quedas nos níveis de tensão. Uma das formas de reduzir as perdas e ao mesmo tempo melhorar o perfil de tensão do SDEE consiste na utilização de bancos de capacitores e reguladores de tensão ao longo dos alimentadores. Para isto a alocação ótima destes equipamentos torna-se de fundamental importância, logo este trabalho tem por objetivo a utilização de um método quadrático de programação por metas multiobjetivo para a ótima alocação desses equipamentos visando a redução de perdas (meta 1) com o menor custo de investimento (meta 2) sujeito a restrições do fluxo de potência, limites técnicos de operação, mudança no controle dos capacitores chaveados e dos taps dos reguladores de tensão. O constante aumento na penetração da geração distribuída traz novos desafios para o controle e a operação dos SDEE. A metodologia proposta considera os efeitos destas fontes de geração e os seus impactos na alocações ótima dos bancos de capacitores e reguladores de tensão. Com o intuito de resolver o problema de otimização em programas comerciais como Gurobi e Cplex uma metodologia linear de cálculo de fluxo de potência é utilizada. Os algoritmos foram desenvolvidos no software Matlab, e posteriormente foi realizada a conversão para linguagem GAMS (Generic Algebraic Modeling System) para utilização dos solvers na plataforma NEOS (Network Enabled Optimization System). / Power distribution systems (DS) are susceptible to energy loss and voltage drops, mainly because of the way that they are operated and built. One way to minimize system loss and improve the voltage profile of DS is with the use of capacitor banks and voltage regulators (VRs) along the distribution feeders. In this scenario, the optimal placement of these devices becomes crucial. In this paper, a quadratic multi objective goal programming method is proposed to obtain the optimal placement of these devices, where the goals are energy loss (goal 1) and the total investment cost (goal 2). The model is subject to system operation constraints, such as power flow demands, limits of voltages and currents, number of stages of switched capacitors and the tap control of VRs. The increase of distributed generation penetration brings new challenges for control and operation of DS. The proposed methodology considers the effects of these power sources and their impact on optimal allocations of capacitors and VRs. With the aim of solving the optimization problem in commercial programs, a linear power flow is used. The algorithms were developed with Matlab software and the conversion was made to a General Algebraic Modeling System (GAMS) language and solved in the NEOS (Network Enabled Optimization System) platform.