La distribution reste le segment du secteur de l’électricité le moins étudié. Mais les débats s’animent autour d’elle depuis deux ou trois ans quant aux changements structurels possibles du fait notamment de l’émergence amorcée ou annoncée des smart technologies: ils pourraient en effet remettre en cause dans les prochaines années les modèles d’affaires actuels des GRD et leur mode de régulation. Mais de nombreuses incertitudes pèsent sur leurs choix d’investissements. La thèse vise à anticiper les évolutions des modèles d’affaires des GRD en Europe à l’horizon 2030 en tenant compte des paramètres technologiques, macroéconomiques et géographiques. Elle propose une vision théorique et analytique originale, en introduisant tout d’abord la notion de « technologies à potentiel naturel » pour étudier le développement optimal de différentes technologies par contexte géographique et par scénario de référence. A partir de ces résultats, elle définit alors différentes évolutions possibles des activités de la distribution. Le croisement de ces futurs avec les différentes stratégies d’investissement envisageables pour les GRD permet de définir les futurs modèles d’affaires des GRD européens en fonction des combinaisons de smart technologies déployées et des contextes géographiques contrastés. Dans sa dernière partie, la thèse s’intéresse tout particulièrement aux changements prévisibles dans la relation GRD / régulateur sectoriel via une formalisation par la théorie des jeux. Enfin, en s’appuyant notamment sur les études théoriques de Brian Arthur, la thèse identifie les différents effets lock-in qui pourraient entraver l’émergence des smart technologies et les solutions possibles / Distribution activities have been the least studied domain of the electricity sector; over the last few years though, strong debates emerged with regards to the future. Indeed, this activity might soon undergo some deep structural changes, particularly as smart technologies are deployed: theses technologies could strongly impact the current business cases of the DSOs, along with the regulation now in effect, at a time when numerous uncertainties weigh on the distributors choices of investments. This thesis investigates the distributors’ business models evolutions in Europe for the next 20 years, based on technological, macroeconomic and geographical parameters. It proposes an original approach, both theoretical and analytical, to better understand the future world of DSOs. At first, it introduces the notion of “technologies with natural potential” in order to study the optimal development of the different technologies, by geographical context and macroeconomic scenarios. From these results, it then defines various possible evolutions of the distribution activities. Crossing these futures with the various possible investment strategies for the DSOs makes it possible to define the future business models of the European DSOs, according to various combinations of smart technologies displayed and contrasted geographical contexts. In its last part, the thesis studies the predictable changes in the relation DSO / regulator, using a formalization based on the Games Theory; this work is complemented by identifying the different lock-in effects (using the approach described in Brian Arthur’s studies) that could hinder the emergence of smart technologies, and the possible solutions

<p>U disertaciji je predložen algoritam za proračun kratkih spojeva zasnovan na korelisanim intervalima. U savremenim distributivnim mrežama postoje različiti tipovi generatora koji proizvode električnu energiju iz energije obnovljivih izvora. Za takve generatore, kao i za potrošače, karakteristično je to što je njihova proizvodnja i potrošnja neizvesna. Predloženi algoritam u disertaciji uvažava te neizvesnosti, kao i korelacije između navedenih elemenata. Neizvesnosti su modelovane intervalima i direktno su uvažene u predloženom algoritmu za proračun kratkih spojeva. Algoritam je prvenstveno razvijen za proračun kratkih spojeva savremenih distributivnih mreža sa velikim brojem distribuiranih generatora i potrošača. NJime je moguće proračunavati režime sa kratkim spojevima distributivnih mreža velikih dimenzija, što je numerički verifikovano u disertaciji. Predloženim algoritmom se dobija režim distributivne mreže sa kratkim spojem koji je realističniji od režima dobijenih algoritmima sa determinističkim pristupom. Proračuni kao što su: koordinacija, podešenje i provera osetljivosti relejne zaštite, provera kapaciteta prekidača i osigurača, lokacija kvara itd. mogu na osnovu realističnijeg režima, dobijenog predloženim algoritmom, da daju kvalitetnije rezultate, što je numerički potvrđeno na primeru koordinacije prekostrujne zaštite</p> / <p>In this dissertation an algorithm for correlated intervals-based short-circuit calculation is<br />proposed. In modern distribution networks there are various types of generators that produce<br />electric energy from renewable energy resources. For these generators, as well as loads, uncertain<br />production and consumption is characteristic. The proposed algorithm in the dissertation deals<br />with above-mentioned uncertainties, as well as correlations among them. The uncertainties are<br />modeled with intervals and directly taken into account in the proposed algorithm for short-circuit<br />calculation. The algorithm is primarily developed for short-circuit calculation in modern<br />distribution networks with a great number of distributed generators and consumers. The proposed<br />algorithm enables calculation of short circuits states of large-scale distribution networks, which is<br />numerically verified in the dissertation. The proposed algorithm provides short circuit state of<br />distribution network which is more realistic than the one obtained with algorithms with<br />deterministic approach. Calculations such as: coordination, settings and sensitivity check of relay<br />protection, breaker and fuse capacity check, fault location, etc. can give better results, on the basis<br />of the more realistic state obtained by the proposed algorithm for short circuit calculation, which<br />is numerically confirmed by the example of coordination of overcurrent protection.</p>

Afin de maintenir une bonne qualité de l’électricité, les gestionnaires de réseaux doivent maintenir les niveaux de tension harmonique en-dessous de certaines limites spécifiées dans les normes. Les niveaux de tension harmonique résultent des équipements non-linéaires présents dans les installations, qui injectent des courants harmoniques sur le réseau.Dans ce but, une solution consiste à appliquer des limites d’émission à ces installations. Les gestionnaires de réseaux ont besoin pour cela d’un indicateur fiable pour évaluer le niveau d’émission harmonique d’une installation.Dans ce cadre, nous nous sommes tout d’abord intéressés aux différentes méthodes existantes, que nous avons appliqué sur des cas de réseaux simplifiés afin de les évaluer sur plusieurs critères. Nous avons ainsi identifié dans un premier temps les définitions qui répondent le mieux à notre besoin ainsi que leurs limites restectives. Dans un deuxième temps, nous avons amélioré une des définitions retenues en proposant une nouvelle solution : la définition “quatre quadrants”.Cette nouvelle définition permet d’évaluer le courant harmonique émis par une installation sur le réseau en se basant sur les mesures de la tension et du courant au point de livraison de l’installation. Son principal intérêt par rapport aux méthodes existantes est de mieux identifier les installations moyennement perturbatrices sur le réseau. Ce point a été validé en simulation sur un réseau dérivé du benchmark CIGRE. / In order to maintain good power quality, Distribution Systems Operators (DSOs) must keep harmonic voltage levels under limits specified in standards. These harmonic voltages result from non-linear equipment connected in installations, which inject harmonic currents into networks.A possible solution to solve this problem consists to implement emission limits per installation. In order to apply these limits, DSOs need to have an accurate and reliable indicator to assess the harmonic emission of an installation.In this context, we studied different methods from the literature. We implemented each of them on several simplified distribution networks in order to evaluate them on several criteria. First, we identified the most interesting definitions from the literature, and emphasized their respective theorical limits. Then, we improved one of these definitions by proposing a new solution: the “four-quadrants” definition.This new definition is able to assess the harmonic current injected by an installation into the network by using current and voltage measurements at the point of common coupling of this installation. Its main advantage in comparison to other methods is a better detection of “medium” disturbing installations over the network. This advantage has been confirmed by implementing the proposed solution in simulation on a distribution network derived from the CIGRE benchmark.

Distribution load flow and state estimation are two important functions in distribution energy management systems (DEMS) and advanced distribution automation (ADA) systems. Distribution load flow analysis is a tool which helps to analyze the status of a power distribution system under steady-state operating conditions. In this research, an effective and comprehensive load flow algorithm is developed to extensively incorporate the distribution system components. Distribution system state estimation is a mathematical procedure which aims to estimate the operating states of a power distribution system by utilizing the information collected from available measurement devices in real-time. An efficient and computationally effective state estimation algorithm adapting the weighted-least-squares (WLS) method has been developed in this research. Both the developed algorithms are tested on different I testeeders and the results obtained are justified.

In electric power distribution systems, the major determinant in electricity supply strategy is the quantity of demand. Customers need to be accurately represented using updated nodal load information as a requirement for efficient control and operation of the distribution network. In Distribution Load Estimation (DLE), two major categories of data are utilized: historical data and direct real-time measured data. In this thesis, a comprehensive survey on the state-of-the-art methods for estimating loads in distribution networks is presented. Then, a novel method for representing historical data in the form of Representative Load Curves (RLCs) for use in realtime DLE is also described. Adaptive Neuro-Fuzzy Inference Systems (ANFIS) is used in this regard to determine RLCs. An RLC is a curve that represents the behavior of the load during a specified time span; typically daily, weekly or monthly based on historical data. Although RLCs provide insight about the variation of load, it is not accurate enough for estimating real-time load. This therefore, should be used along with real-time measurements to estimate the load more accurately. It is notable that more accurate RLCs lead to better real-time load estimation in distribution networks. This thesis addresses the need to obtain accurate RLCs to assist in the decision-making process pertaining to Radial Distribution Networks (RDNs).This thesis proposes a method based on Adaptive Neuro-Fuzzy Inference Systems (ANFIS) architecture to estimate the RLCs for Distribution Networks. The performance of the method is demonstrated and simulated, on a test 11kV Radial Distribution Network using the MATLAB software. The Mean Absolute Percent Error (MAPE) criterion is used to justify the accuracy of the RLCs.

No / Due to high penetration of single-phase Photovoltaic (PV) cells into low voltage (LV) distribution networks, several impacts such as voltage unbalance, voltage rise, power losses, reverse power flow arise which leads to operational constraints violation in the network. In this paper, a time series Three Phase Optimal Power Flow (TPOPF) method is proposed to minimize the voltage unbalance in LV distribution networks with high penetration of residential PVs. TPOPF problem is formulated using the current injection method in which the PVs are modelled via a time-varying PV power profile with active and reactive power control. The proposed method is validated on a real LV distribution feeder. The results show that the reactive power management of the PVs helps mitigate the voltage unbalance significantly. Moreover, the voltage unbalance index reduced significantly compared to the case without voltage unbalance minimisation. / Innovate UK GCRF Energy Catalyst Pi-CREST project under Grant number 41358; British Academy GCRF COMPENSE project under Grant GCRFNGR3\1541; Mut’ah University, Jordan

Yes / The low voltage (LV) distribution network is the last stage of the power network, which is connected directly to the end user customers and supplies many dispersed small-scale loads. In order to achieve environmental targets and to address the energy shortage issue, governments worldwide increase the renewable energy sources (RES) into the electricity grid. In addition, different types of low carbon technologies (LCTs) such as electric vehicles (EVs) are becoming widely used. A significant portion of RES and LCTs is penetrated into the LV distribution network, which poses a wide range of challenges. In order to address these challenges, there is a persistent need to develop traditional planning and operation frameworks to cope with these new technologies. In this context, this paper provides a comprehensive review about planning, operation, and management of LV distribution networks. The characteristics, types, and topologies of LV distribution networks plus different aspects of operation and planning are investigated. An insightful investigation of the reasons impacts and mitigation of voltage and current unbalanced in LV networks is provided. Moreover, the main three-phase power flow techniques used to analyze the LV networks are analyzed.

Electric power distribution network is an important part of electrical power systems for delivering electricity to consumers. Electric power utilities worldwide are increasingly adopting the computer aided monitoring, control and management of electric power distribution systems to provide better services to the electrical consumers. Therefore, research and development activities worldwide are being carried out to automate the electric power distribution system. The power distribution system consists of a three-phase source supplying power through single-, two-, or three-phase distribution lines, switches, and transformers to a set of buses with a given load demand. In addition, unlike transmission systems, single-, two-, and three-phase sections exist in the network and single-, two-, and three-phase loads exist in the distribution networks. Further, most distribution systems are overhead systems, which are susceptible to faults caused by a variety of situations such as adverse weather conditions, equipment failure, traffic accidents, etc. When a fault occurs on a distribution line, it is very important for the utility to identify the fault location as quickly as possible for improving the service reliability. Hence, one of the crucial blocks in the operation of distribution system is that of fault detection and it’s location. The achievement of this objective depends on the success of the distribution automation system. The distribution automation system should be implemented quickly and accurately in order to isolate those affected branches from the healthy parts and to take alternative measures to restore normal power supply. Fault location in the distribution system is a difficult task due to its high complexity and difficulty caused by unique characteristics of the distribution system. These unique characteristics are discussed in the present work. In recent years, some techniques have been discussed for the location of faults, particularly in radial distribution systems. These methods use various algorithmic approaches, where the fault location is iteratively calculated by updating the fault current. Heuristic and Expert System approaches for locating fault in distribution system are also proposed which uses more measurements. Measurements are assumed to be available at the sending end of the faulty line segment, which are not true in reality as the measurements are only available at the substation and at limited nodes of the distribution networks through the use of remote terminal units. The emerging techniques of Artificial Intelligence (AI) can be a solution to this problem. Among the various AI based techniques like Expert systems, Fuzzy Set and ANN systems, the ANN approach for fault location is found to be encouraging. In this thesis, an ANN approaches with limited measurements are used to locate fault in long distribution networks with laterals. Initially the distribution system modeling (using actual a-b-c phase representation) for three-, two-, and single-phase laterals, three-, two-, and single- phase loads are described. Also an efficient three-phase load flow and short circuit analysis with loads are described which is used to simulate all types of fault conditions on distribution systems. In this work, function approximation (FA) is the main technique used and the classification techniques take a major supportive role to the FA problem. Fault location in distribution systems is explained as a FA problem, which is difficult to solve due to the various practical constraints particular to distribution systems. Incorporating classification techniques reduce this FA problem to simpler ones. The function that is approximated is the relation between the three-phase voltage and current measurements at the substation and at selected number of buses (inputs), and the line impedance of the fault points from the substation (outputs). This function is approximated by feed forward neural network (FFNN). Similarly for solving the classification problems such as fault type classification and source short circuit level classification, Radial Basis Probabilistic Neural Network (RBPNN) has been employed. The work presented in this thesis is the combinational use of FFNN and RBPNN for estimating the fault location. Levenberg Marquardt learning method, which is robust and fast, is used for training FFNN. A typical unbalanced 11-node test system, an IEEE 34 nodes test system and a practical 69- bus long distribution systems with different configurations are considered for the study. The results show that the proposed approaches of fault location gives accurate results in terms of estimated fault location. Practical situations in distribution systems such as unbalanced loading, three-, two-, and single- phase laterals, limited measurements available, all types of faults, a wide range of varying source short circuit levels, varying loading conditions, long feeders with multiple laterals and different network configurations are considered for the study. The result shows the feasibility of applying the proposed method in practical distribution system fault diagnosis.

Power losses are always a cause of worry for any power grid. In India, the situation is even worse. Though recent reports by Ministry of Power shows that Aggregate Technical and Commercial losses (AT &C losses) have come down from 36.64% in 2002-03 to 27% in 2011-12, yet they are much higher than the losses seen in many of the developed nations. The reduction shown in power loss is because of the Electricity Act, 2003 and the amendments made to it in 2007 which controlled the commercial losses rather than the technical losses. According to Ministry of Power, technical losses (Transmission & Distribution losses or T&D losses) in India are reported to be 23.65% in 2011-12. However, according to the study done by EPRI, for systems deployed in developed countries, these losses are estimated to be in the range of 7-15.5%. T & D losses occur in four system components namely step-up transformers and high voltage transmission (0.5-1%), step down to in intermediate voltage, transmission and step down to sub transmission voltage level (1.5-3%), sub-transmission system and step down to low voltage for distribution (2-4.5%), and distribution lines (3-7%). 1% of power loss is approximately equivalent to annual loss of Rs 600 million for a single state. Hence, in a year, loss in distribution line alone causes approximate loss of Rs 1.8-4.2 billion per state. Understanding and reducing power losses in distribution lines which contribute nearly 50% of the total T&D losses assume significance and has formed the motivation for the work reported in the thesis. In recent years, the trend has been to encourage users to generate solar power predominantly at residential complexes and captive power plants at industrial complexes. It has been suggested in the literature that Distributed Generation (DG) can not only reduce the load demanded from the power grid but also the power loss. In this thesis, it has been shown that by the choice of proper size and location of DG, the power loss can be reduced substantially as compared to unplanned deployment of DGs. The objective of the thesis is to design strategy for location of distributed user generated power to maximize the reduction in power loss. The thesis begins with a study of distributed generation in primary distribution networks and proceeds to problem formulation, with the aim being to develop an algorithm that can find out the optimal locations for DG allocation in a network. A greedy approximation algorithm, named OPLODER (i.e. Optimal Locations for Distributed Energy Resources), is proposed for the same and its performance on a benchmark data set is observed, which is found to be satisfactory. The thesis then moves on to describe the actual data of 101,881 commercial, residential and industrial consumers of Bangalore metropolitan area. A loss model is discussed and is used to calculate the line losses in LV part of the grid and loss is estimated for the said actual data. The detailed analysis of the losses in the distribution network shows that in most cases the losses are correlated with the sanctioned load. However there are also some outliers indicating otherwise. The analysis concludes that the distributed generated sources need to be optimally located in order to benefit fully. Also presented thereafter is a study about the impact of electrical properties and the structure of the network on power loss. In the second part of the thesis, OPLODER was again used to process the BESCOM data of 101,881 consumers by modeling them to be connected in three topologies namely Bus (i.e. linear structure), Star (i.e. directly connected) and Hybrid (i.e. tree structure). In case of Bus topology, when DG capacity available is 5% of the demand in substation, OPLODER reduced the loss from 14.65% to 10.75%, from 11.63% to 7.71% and from 13.33% to 9.24% for IISc, Brindavan, and Gokula substations respectively. Similarly, for the same amount of DG in case of star topology, OPLODER reduced loss from 1.75% to 1.26%, from 3.39% to 2.59% and from 2.96% to 1.99% for IISc, Brindavan, and Gokula substations respectively. Thereafter, the available real world data is re-modeled as a tree-type structure which is closer to the real world distribution network and OPLODER is run on it. The results obtained are similar to those presented above and are highly encouraging. When applied to the three substations viz. IISc, Brindavan and Gokula, the power loss dips from 9.95% to 7.42%, from 6.01% to 4.44% and from 8.07% to 5.95%, in case of DG used is 5% of the demand in substation. For the optimal strategies worked out in the thesis, additional overheads will be present. These overheads are studied and it has been found that the present infrastructure and technologies will be sufficient to handle the smart distribution network and the optimal strategy for distributed sources.

This dissertation investigates in which conditions the optimal configuration of an electric power network is a minimum length spanning tree, and in which conditions it is shortest path tree configuration. For this purpose the dissertation, it applies computational optimization mathematical models of an optimal local access network design problem. The focus of the study is the 13.8 kV spacer cable primary radial networks. Applied models seek for the balance betweenfixedcostsandvariablecosts.Savedvaluesfromanoptimalnetworkcouldbeapplied to increase the range of the network and people reached as well. The bibliographic research is compound by three parts: graph theory, local access network optimization models, and distribution network costs. Research methodology includes the choice of the distribution system, determination of fixed and variable costs, choice and implementation of the local access network optimization models, tests in hypothetical and realistic systems by using the CPLEX solver, analysis of the resulting configuration, and construction of graphics to facilitate the results evaluation. It was found that the relationship between fixed costs and variable costs influences the optimal configuration of the distribution network in such a way that a low value of the quotient between fixed costs and variable costs contributes to a shortest path tree. On the other hand, a high quotient between fixed costs and variable costs contributes to a minimum length spanning tree configuration. However, others parameters must be considered to determine the network configuration such as extension, arches demand and quantity of arches. / O presente trabalho visa investigar sob quais condições a configuração ótima de uma rede de distribuição elétrica é uma árvore geradora mínima (AGM) e sob quais é uma árvore de caminhos mínimos (ACM). Utilizando, para isso, modelos matemáticos computacionais de otimização topológica de redes de utilidade pública. As redes de distribuição estudadas foram do tipo aérea radial primária protegida (ARPP) com nível de tensão em 13,8 kV. Os modelos utilizados prezam pelo equilíbrio entre o custo de investimento inicial (fixo) e os custos decorrentes da transferência de energia elétrica (variável). Os valores economizados através de uma configuração ótima da rede podem ser convertidos em investimentos para aumentar o número de pessoas com acesso aos recursos energéticos com eficiência e qualidade. A revisão bibliográfica foi dividida em três partes: teoria dos grafos, modelos de otimização de redes de acesso local e custos de redes de distribuição. A metodologia utilizada compreendeu as seguintes etapas: escolha do tipo de sistema de distribuição, determinação dos custos fixo e variável, escolha e implementação (GAMS) dos modelos, testes com exemplos de redes usando o solver CPLEX, análise das configurações resultantes e elaboração de gráficos para facilitar a avaliação dos resultados. Os resultados mostraram que a relação entre o custo fixo β e o custo variável γ exerce influência determinante na configuração ótima de uma rede de distribuição ARPP. Um valor baixo de β/γ, favorece a ACM. Já valores elevados de β/γ, conduzem a solução para uma AGM. No entanto, essa relação não é o único fator que determina a configuração da rede, outros parâmetros como extensão, demanda dos nós e quantidade de possíveis arcos influenciam de forma significativa na solução apresentada.