Tools and algorithms are proposed that are useful for planning, designing, and operating a distribution network with a significant penetration of distributed generation (DG). In Task 1, a PV system simulation program is developed, which incorporates the most rigorous models for the calculation of insolation, module temperature, and DC and AC power output of a PV system. The effect of random inverter failures is incorporated in the model of a PV system, and a novel performance-derating coefficient is introduced. Furthermore, a novel inverter control algorithm is presented for systems with multiple inverters. The algorithm is designed to increase overall DC/AC conversion efficiency by selectively shutting down some of the inverters during periods of low insolation, thus forcing the remaining inverters to operate at higher efficiency. In Task 2, a procedure is developed to incorporate the uncertainties imposed by stochastic, renewable DG into the conventional tools for analysis of distribution systems. A clustering algorithm is proposed to reduce large input data sets that result from the interaction of stochastic processes that drive DG output with field measurements of feeder load profiles. In addition, a procedure is proposed to determine the boundary points of the original data set, which yield feeder extreme operating conditions. Finally, a Monte Carlo analysis using a reduced data set is presented, to determine the effects of deploying a large number of renewable DG systems on a distribution feeder. In Task 3, the reliability model of an asymmetric, three--phase, non-radial distribution feeder equipped with capacity-constrained DGs is developed and used to quantify the potential reliability improvements due to the intentional islanded operation of parts of the feeder. A procedure for finding optimal positions for DG and protection devices is presented using a custom-tailored adaptive genetic algorithm.

Στην παρούσα διπλωματική εργασία θα ασχοληθούμε με την αξιολόγηση της προστασίας σε κατανεμημένη παραγωγή. Γενικά η κατανεμημένη παραγωγή, καλύπτει ένα μεγάλο εύρος νέων και παραδοσιακών τεχνολογιών με μικρές μονάδες εγκατεστημένες κοντά στην κατανάλωση και πιστεύεται ότι θα συμβάλει στην κάλυψη ενός μεγάλου μέρους της ενεργειακής ζήτησης στα επόμενα χρόνια με τη δυναμική της είσοδο στην απελευθερωμένη αγορά ενέργειας. Αρχικά γίνεται μια ανασκόπηση της υφιστάμενης παγκόσμιας ενεργειακής κατάστασης. Αναλύονται οι κυριότερες τεχνολογίες παραγωγής ηλεκτρικής ενέργειας και τα καύσιμα που χρησιμοποιούνται, τα οποία κατά συντριπτική πλειοψηφία βασίζονται στους ορυκτούς πόρους. Αποτυπώνεται αφενός, η συνολική συνεισφορά αυτών στην ενεργειακή ζήτηση, αφετέρου τα παγκόσμια αποθέματα αυτών. Στη συνέχεια παρουσιάζεται η υφιστάμενη κατάσταση στον ηλεκτρικό τομέα, οι αλλαγές που συνεπάγονται με τη απελευθέρωση της αγοράς ενέργειας, καθώς και το γενικό πλαίσιο και οι ρυθμίσεις που διέπουν τον τομέα της ενέργειας με βάση τα νέα δεδομένα. Γίνεται εισαγωγή και ορισμός της κατανεμημένης παραγωγής και αναλύονται τα βασικά χαρακτηριστικά που συνθέτουν την έννοια αυτής καθώς επίσης γίνεται μια παρουσίαση των κυριότερων τεχνολογιών που ολοκληρώνουν τη κατανεμημένη παραγωγή. Στη συνέχεια ασχολούμαστε με το φαινόμενο της νησιδοποίησης. Η αύξηση της παραγωγής ισχύος από διανεμημένους παραγωγούς καθιστά την εμφάνιση του φαινομένου όλο και συχνότερη. Η ανίχνευση και διακοπή του φαινομένου είναι καθοριστικής σημασίας για την ορθή λειτουργία του Δικτύου και την ασφάλεια του προσωπικού που εργάζεται σε αυτό. Εδώ περιγράφουμε μερικές από τις πιο βασικές εφαρμοζόμενες μεθόδους ανίχνευσης και διακοπής του. Ύστερα παρουσιάζουμε τα βασικά χαρακτηριστικά των μέσων προστασίας έναντι υπερεντάσεων. Προχωράμε σε μελέτη των διατάξεων προστασίας ενός παραδείγματος μιας εγκατάστασης φωτοβολταϊκών με σκοπό τη διασφάλιση της σε περίπτωση εμφάνισης σφαλμάτων. Τέλος αναφερόμαστε σε κάποιες νέες προσεγγίσεις και μελλοντικές τάσεις και προοπτικές για τον καθορισμό των τρόπων ενσωμάτωσης ομαλών τεχνολογιών ΚΠ και τη ρύθμιση θεμάτων σχετικά με τη διασύνδεση και τη λειτουργία τους. / In this work we will do a research about the appraisal of the distributed generation .All in all the distributed generation encloses a great range of new and traditional technologies. Some of them are installed close to the consumption and it is believed that the distributed generation will contribute to cover a great part of the energy demand in the next years. In the beginning we refer to the global energy situation. We analyze the most important technologies of distributed generation and the fuels that are used which are based on the mineral resources. These fuels contribute in the energy demand and we also refer to the global store of fuel. We present the situation of the electric section today, the changes and the regulations that happen in this section day by day. 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 problem of islanding. Because of the fact that the power production is increasing lately, the problem is appeared more and more often. We must look for this phenomenon and stop it immediately in order the network work correctly and the persons who work in this part of network be safe. We describe some of the most important methods of “tracking” the islanding and stopping it. Afterwards we present the basic characteristics of the protection arrangement that we must use in case of errors and short circuits. We continue presenting an instance for a photovoltaic system installation and what sort of protection must be used in order this system to work with safe when errors happen. In the end we refer to what must be done in the future so that the technologies of distributed generation be used more and more often and much more efficiently.

In recent years, the power industry has experienced significant changes on the distribution power system primarily due to the implementation of smart-grid technology and the incremental implementation of distributed generation. Distributed Generation (DG) is simply defined as the decentralization of power plants by placing smaller generating units closer to the point of consumption, traditionally ten mega-watts or smaller. While DG is not a new concept, DG is gaining widespread interest primarily for the following reasons: increase in customer demand, advancements in technology, economics, deregulation, environmental and national security concerns. The distribution power system traditionally has been designed for radial power flow, but with the introduction of DG, the power flow becomes bidirectional. As a result, conventional power analysis tools and techniques are not able to properly assess the impact of DG on the electrical system. The presence of DG on the distribution system creates an array of potential problems related to safety, stability, reliability and security of the electrical system. Distributed generation on a power system affects the voltages, power flow, short circuit currents, losses and other power system analysis results. Whether the impact of the DG is positive or negative on the system will depend primarily on the location and size of the DG. The objective of this research is to develop indices and an effective technique to evaluate the impact of distributed generation on a distribution power system and to employ the particle swarm optimization technique to determine the optimal placement and size of the DG unit with an emphasis on improving system reliability while minimizing the following system parameters: power losses, voltage deviation and fault current contributions. This research utilizes the following programs to help solve the optimal DG placement problem: Distribution System Simulator (DSS) and MATLAB. The developed indices and PSO technique successfully solved the optimal DG sizing and placement problem for the I 13-Node, 34-Node and 123-Node Test Cases. The multi-objective index proved to be computational efficient and accurately evaluated the impact of distributed generation on the power system. The results provided valuable information about the system response to single and multiple DG units.

The concentration of this work is in estimating fault locations in power systems. After describing the basic concepts of fault locating methods, this work describes improving the fault location estimates, applying the fault locating methods, and implementing the methods in a software. Every work described in the Chapter will be evaluated whether by actual field data or simulated data based on field parameters. / text

Voltage control in distribution networks is becoming more challenging due to the growing amount of distributed generation that is being connected to the distribution networks in addition to increasing load. The output of the distributed generation can radically change power flows and voltage profiles in distribution networks, creating conditions that adversely affect the performance of automatic voltage control schemes and in addition cause unacceptable voltage rise. On the other hand, inherent limitations and current operational policies of AVC schemes very often restrict the output of DG or even prevent its connection. This thesis investigates and analyses voltage control in terms of the shift from passive to active distribution networks. The thesis also reviews the performance of AVC schemes under varying load and generation output conditions, investigates effective utilisation of distribution network assets and methods to accommodate active voltage control schemes into existing infrastructure. A range of active voltage control and management schemes based on coordinated voltage control is presented and assessed. These schemes can be used to improve the voltage profile in distribution networks and increase their ability to accommodate distributed generation. The functionality of each scheme is assessed based on a number of factors such as the ability of the scheme to increase network capacity, reliability and accuracy. Simulation software to accurately evaluate the performance of an active voltage control scheme in a particular distribution network scenario is essential before the scheme can be deployed. Formal assessment of advanced AVC models and SuperTAPP n+ functionality is performed using simulation software as developed and presented in this thesis. The accuracy of the software results and performance of the SuperTAPP n+ scheme is validated based on network trials carried out in EDF Energy Networks.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 17, 2007) Includes bibliographical references (p. 77-80).

Thesis (M.S.)--Drexel University, 2007. / Includes abstract. Includes bibliographical references (leaves 81-83).

With an increasing interest for renewable power, photovoltaics (PV) have becomemore and more common in the distribution network. If a customer wants to install aPV system, or another type of distributed generation (DG), the distribution systemoperators (DSO) needs a good way to determine if it the grid can handle it or not. InSweden, a guideline to aid the DSO was published in 2011. However, this guidelineonly considers one connection without considering other DG units. This project isabout developing new guidelines for DG connections in grids with a large number ofDG units. Based on a literature study it has been concluded that one of the mostcritical issue is over-voltage, which is the main focus of this project. Two new methods have been developed; the first proposed method is based onneglecting reactance and losses in the grid, a simple linear relationship between thevoltage level, the resistance in the lines, and the installed power is obtained. Thisrelationship is then used to calculate the voltage level at critical points in the grid. Thesecond method is to find the weakest bus, with a connected DG unit. By assumingthat all power is installed at that point we get a very simple guideline; it is veryconservative but can be used before the first method. A simulation tool has been developed in order to analyze the voltage level in grids forvarious cases with connected DG units. The simulated results have proven that theproposed guidelines are, when considering voltage issues, very reliable and can beuseful. However, further work needs to be done to ensure that other problems donot occur.

This thesis addresses the future of sustainable energy distribution and transportation in the United States. Predictions of future energy and transportation demands promote localized energy as the most likely situation. Existing proposals outlining the benefits of decentralized energy production fail to engage architecture. Cities will require new architectural typologies that can integrate new energy infrastructure in the city. Los Angeles, the archetype of the decentralized American city, is introduced as a case study. The city is examined at multiple scales for the integration of a decentralized electricity network and an efficient transportation infrastructure. Siting the proposed facilities capitalizes on new and existing transportation infrastructures and local energy resources. The new electricity-transportation infrastructure is adapted to a decentralized network functioning on principles of ecosystems and energy economics at an urban scale. Energy storage is paired with multi-modal transportation to develop new architectural and urban typologies. This enables the decentralized urban proposal to function as a network exhibiting mutually beneficial characteristics.

This thesis introduces a power electronic interface for a kinetic hydropower generation platform that enables extraction of electric power from a free-flowing water source such as a river or a stream. The implemented system transfers power from a high-frequency permanent magnet synchronous generator (PMSG) to a 60-Hz load. Special configurations and control techniques were developed to cater for the long distance between the generator and the power interface; and also to address the wide range of the PMSG frequency and voltage variations. The proposed power-electronic interface was constructed and tested in the laboratory as well as in the field. The thesis also introduces two feasible methods for controlling a hydrokinetic plant to supply islanded loads or to deliver the maximum power available from the turbine-generator to the utility network. Application of multiple turbines in a kinetic farm was also investigated, and different approaches to controlling hydrokinetic turbines were developed.