On-load tap-changers (OLTC) are devices in the power grid that keeps the voltage level constant for consumers, regardless of the power demand. Hitachi ABB Power Grids, producer of the OLTC family named VUC, guarantees 30 years of lifetime. Such a pledge requires high standard devices. This thesis has analyzed data from routine tests of switching times in the diverter switch of OLTC’s, performed before devices were put in service. The correlation of part switching times for all units leaving the factory during the past year was evaluated by calculating Pearson’s correlation coefficient. A linear trend was fitted to the data, realizing that the prediction errors, as well as the part switching times, were Gaussian distributed. The time while the resistor vacuum interrupter was open could be predicted within the interval of approximately 2ms with 2 standard deviations accuracy. To classify time series from the routine test as expected or unexpected, a model-based algorithm was implemented. The average switching time for all consecutive switches was used to define expected series. A moving average was implemented to neglect outliers and remove oscillating patterns. The majority of all data was classified as expected time series. The ones who did not, still preserved a good correlation between the part switching times. Examining the relationship between part switching times could be a valuable perspective in further classification of expected time series. The possibility of incorporating measurement of part switching times on OLTC’s in normal operation, to use the knowledge gained by this thesis, was investigated. Position sensors were mounted to measure the position of the lifting yokes, opening and closing the vacuum interrupters. The time while the vacuum interrupter contacts were open could be estimated with better accuracy than the position sensor provided. Unfortunately, those sensors cannot be utilized in normal operation. If other possibilities could be found, perhaps a laser position sensor, the implemented algorithm would be valuable.

This dissertation focuses on daily volt/var control in distribution networks with feeder capacitors, substation capacitors and transformers equipped with on-load tap changers. A hybrid approach is proposed to solve the daily volt/var control problem. To reduce the computational requirements of the problem, this approach combines two methods, namely heuristic and optimal scheduling for the substation and feeder sub-problems respectively. The feeder capacitor dispatch schedule is determined based on a heuristic reactive power setpoint method. At this stage the objective is to minimize the reactive power flow through the substation bus in every time-interval. And as such, mathematical modeling of the distribution network components is adapted to suit time-varying conditions. Furthermore, an optimization model to determine a proper dispatch schedule of the substation devices is formulated. The objective of this model is to minimize the daily total energy loss and voltage deviations. Additionally, the reference voltage of the substation secondary bus and the transformer tap position limits are modified to adapt to given load profiles. The optimization model is solved with a discrete particle swarm optimization algorithm, which incorporates Newton’s method to determine the power-flow solution. The proposed method is applied to a time-varying distribution system and evaluated under different operational scenarios. It is also compared to on-line volt/var control with various settings. Simulation results show that the proposed approach minimizes both the voltage deviations and the total energy loss, while on-line control prioritizes one objective over the other depending on the specified settings. / Dissertation (MEng)--University of Pretoria, 2015. / Electrical, Electronic and Computer Engineering / Unrestricted

Στην παρούσα διπλωματική εργασία γίνεται αναλυτική περιγραφή της λειτουργίας της διάταξης του Μεταγωγέα Τάσης Υπό Φορτίο ενός μετασχηματιστή υψηλής τάσης 150 kV/ 21 kV. Επίσης, περιγράφονται και αναλύονται σφάλματα που εμφανίζονται σε μετασχηματιστές με Μεταγωγέα Τάσης Υπό Φορτίο με χρήση εμπειρικών δεδομένων από την εταιρεία Δ.Ε.Η. Α.Ε. και τη θεωρητική ανάλυση και εξήγησή τους μέσα από βιβλιογραφική μελέτη . Συγκεκριμένα, περιγράφονται τα αίτια που δημιουργούν αυτά τα σφάλματα, τα συμπτώματα που εμφανίζονται στο μετασχηματιστή και το μεταγωγέα τάσης , οι επιπτώσεις των σφαλμάτων αυτών στο μετασχηματιστή και τη διάταξη του μεταγωγέα τάσης . Επιπλέον, γίνεται αναφορά στα συστήματα προστασίας που διαθέτει ο μετασχηματιστής και ο μεταγωγέας τάσης προκειμένου να προστατευθεί από τις επιπτώσεις αυτών των σφαλμάτων. Στη συνέχεια, μελετάται συγκεκριμένο σφάλμα, που παρουσιάστηκε στο Μ/Σ 150 kV/21 kV Νο1 του Υ/Σ 150 kV/21 kV των Ελληνικών Ναυπηγείων Σκαραμαγκά, και καταγράφεται η αντιμετώπισή του βήμα προς βήμα σε συνεργασία με την εταιρεία ΠΑΡΑΛΟΣ ΤΕΧΝΙΚΗ Α.Ε., στην οποία ανατέθηκε η επίλυση του σφάλματος. Τέλος, μέσα από την προσομοίωση ενός Μ/Σ υψηλής τάσης με μεταγωγέα τάσης υπό φορτίο με χρήση του λογισμικού πακέτου MatLab/SimuLink κατανοούμε σε βάθος τη λειτουργία του μεταγωγέα τάσης υπό φορτίο. Η προσομοίωση περιλαμβάνει την εφαρμογή διαταραχών της τάσης του δικτύου στο Μ/Σ στην περίπτωση ορθής και εσφαλμένης λειτουργίας του οργάνου του ρυθμιστή τάσης, καθώς η εσφαλμένη λειτουργία του ρυθμιστή τάσης ήταν και η αιτία του σφάλματος στο Μ/Σ του Υ/Σ 150 kV/21 kV των Ελληνικών Ναυπηγείων Σκαραμαγκά. / The particular project deals with the detailed description of the layout and the operation of the on load tap changer belonging to a transformer of high tension 150kV/21 kV. Furthermore, it describes and analyzes faults that occurs to transformers with on load tap changer using empirical data from DEI S.A. (Public Power Corporation) as well as theoretical analysis and explanation based on bibliography. In particular, there are described the reasons behind these faults , the symptoms that appear to the transformer and the tap changer and the consequences to the transformer and the layout of the tap changer. Moreover, there is reference to the protection systems that the transformer and the tap changer have in order to be protected from the consequences of the faults. Further on, a particular troubleshooting is studied that occurred at the transformer 150 kV/21 kV no1 of the high voltage substation 150 kV/21 kV at the Hellenic Shipyards of Skaramagas and its handling is reported step by step in association with PARALOS TECHNICAL S.A. , the company which was assigned to solve the troubleshooting. Finally, the operation of the on load tap changer is studied in depth through simulation of a high voltage transformer with on load tap changer using MatLab/SimuLink software package. The simulation includes the application of voltage variations at the transformer, occurred to the high voltage network in the case of orderly or disorderly operation of the voltage regulator, as the faulty operation of the voltage regulator was the reason behind the troubleshooting of the transformer of the substation of 150 kV/ 21 kV at the Hellenic Shipyards of Skaramagas.

Der Ausbau dezentraler Energieanlagen wie fotovoltaischen Anlagen beeinflusst die Netzzustände signifikant. Dabei ist unsicher, wo und in welchem Maße deren Ausbau zukünftig erfolgt. Es ist nun an den Netzbetreibern gleichzeitig die aktuellen Herausforderungen zu meistern und die Netzplanung und -regelung für die Zukunft zu aktualisieren. Eine statistische Methode wird entwickelt, die Verteilnetzplanung unter Einsatz von quasi-stationär modellierten ”Smart Grid”-Lösungen wie Blindleistungsreglern und regelbaren Ortsnetztransformatoren ermöglicht. Durch Stichprobenverfahren werden Unsicherheiten wie Ort, Größe und Leistungsprofile der Energieanlagen in das Netzmodell eingebunden. Diese als probabilistischer Lastfluss bekannte Methode wird durch Gütemaße im Bereich geringer Kombination evaluiert. Beispiele probabilistischer Netzplanung werden an Netztopologien präsentiert. / Development of distributed energy units such as photovoltaic systems affects grid states significantly. It is uncertain, where and to what extent the development of these units is carried out in the future. It is now up to the distribution system operator to cope with todays grid challenges and to update grid planning and control for the future. A statistical method is developed, which incorporates quasi-stationary modeled ”smart grid” solutions such as reactive power controllers and on-load tap-changers. Uncertainties such as location, size and power profiles of energy systems are integrated into the grid model by sampling. This method is known as probabilistic load flow and is evaluated by quality measures at low combinations. Examples on probabilistic grid planning of different grid topologies are presented.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Voltage regulation still is a problem faced by power utilities currently. In addition to the series impedance and the significant load variation of the distribution grids, the main causes of voltage regulation problems, the requirements for the enhancement of power quality by the electricity regulatory agencies, increasing energy consumption, the inclusion of distributed generation and the development of the smart grids tends to increase the complexity of the distribution systems. One of the most used methods for voltage regulation in alternating current systems is the employment of tap changer on transformers, this method allows voltage regulation by varying the transformation ratio, modifying the value of the secondary voltage. The application of these devices is primarily performed by manual commutation mechanical devices in distribution systems, and by automatic electromechanical on load tap changers in substations. In the case of manual devices, operating costs and the impossibility of automatic voltage regulation are limiting factors, while in the case of electromechanical devices the limitations are mainly related to the costs of employment and maintenance. Currently, the increase of voltage and current operating levels of semiconductor devices has allowed envision the application of semiconductor switches instead of the mechanical switches employed nowadays. However, due to the operating characteristics of these devices, a detailed analysis of the commutation process is necessary, in order to allow the proper design of the devices involved in the commutation and protection process of the electronic tap changer. In this context, this work presents the analysis, design and implementation of an electronic on load tap changer applied to a single-phase distribution transformer, proposed as an alternative to the existing mechanical and electromechanical tap changers. Such a system enables the automatic voltage regulation, avoiding the insulation oil degradation, resulting from the commutation process, and also the elimination of movable parts, the main cause of defects in current automatic commutation devices. In addition to allowing steady state voltage regulation, the system allows the regulation for momentary voltage sags, since they occur in the transformer operating range. The analysis of the commutation process is presented, allowing the design of the electronic switches, as well as the protection system to be employed. Experimental results show the correct voltage regulation for different kinds of load, demonstrating the potential application of electronic on load tap changers in the current distribution systems and in future smart grids. / A regulação dos níveis de tensão é um problema ainda enfrentado pelas companhias concessionárias de energia elétrica atualmente. Além da impedância série e da significativa variação de carga das linhas de distribuição, principais causas dos problemas de regulação, a maior exigência dos agentes reguladores do sistema elétrico para a melhoria da qualidade de energia, o aumento do consumo de energia, a inclusão de geração distribuída e o desenvolvimento das redes inteligentes (smart grids), tendem a aumentar a complexidade dos sistemas de distribuição. Um dos métodos mais empregados na regulação de tensão em sistemas de corrente alternada é a aplicação de comutadores de taps em transformadores. Este método permite a regulação da tensão através da variação da relação de transformação, modificando o valor da tensão secundária. A aplicação desta solução é feita, majoritariamente, através de dispositivos mecânicos de comutação manual nos sistemas de distribuição e de dispositivos automáticos eletromecânicos de comutação sob carga em subestações. No caso dos dispositivos manuais, os custos operacionais e a impossibilidade da regulação automática de tensão são fatores limitantes, enquanto que no caso dos dispositivos eletromecânicos, os limitantes estão relacionados principalmente aos custos de implantação e de manutenção. Atualmente, o aumento dos níveis de tensão e corrente de operação dos dispositivos semicondutores tem permitido vislumbrar a aplicação de chaves semicondutoras em substituição às chaves mecânicas empregadas. Entretanto, devido às características de funcionamento destes dispositivos, uma análise detalhada do processo de comutação do sistema é necessária, de modo a permitir um adequado projeto dos dispositivos envolvidos no processo de comutação e proteção dos comutadores eletrônicos de taps. Neste contexto, o presente trabalho apresenta a análise, projeto e implementação de um comutador eletrônico de taps aplicado a um transformador de distribuição monofásico, proposto como alternativa aos comutadores mecânicos ou eletromecânicos existentes. Tal sistema permite a regulação automática da tensão, eliminando o desgaste do óleo isolante, resultante do processo de comutação sob carga e também a eliminação de partes móveis, principal causa de defeitos nos comutadores automáticos atuais. Além de permitir a regulação da tensão em regime permanente, o sistema possibilita a regulação para afundamentos de tensão momentâneos, desde que estejam na faixa de operação do transformador. A análise do processo de comutação do dispositivo estudado é apresentada, permitindo o projeto das chaves eletrônicas, bem como do sistema de proteção a ser empregado. Resultados experimentais demonstram a correta regulação de tensão do sistema desenvolvido, dentro dos limites de operação do transformador, para diferentes tipos de carga, evidenciando a potencialidade dos comutadores eletrônicos de taps em aplicações nas atuais redes de distribuição e nas futuras redes inteligentes.

Este projeto de pesquisa propõe desenvolver um novo modelo e uma nova abordagem para a resolução do problema da otimização Volt/VAr em redes de distribuição de energia elétrica. A otimização Volt/VAr consiste em, basicamente, determinar os ajustes das variáveis de controle tais como bancos de capacitores chaveados, transformadores com comutação de tap sob carga e reguladores de tensão, de modo a satisfazer, simultaneamente, as restrições de carga e de operação para um dado objetivo operacional. Esse problema, matematicamente, foi formulado como um problema de programação não linear, multiperíodo, e com variáveis contínuas e discretas. Algoritmos de programação não linear foram utilizados com o intuito de aproveitar as vantagens das matrizes altamente esparsas montadas ao longo do método de solução. Para utilizar tais algoritmos, as variáveis discretas são tratadas como contínuas por meio da utilização de funções senoidais que penalizam a função objetivo do problema original enquanto estas não convergirem para algum dos pontos pré-definidos no seu domínio. O caráter multiperíodo do problema, contudo, refere-se à consideração de uma restrição que relaciona os ajustes das variáveis de controle para sucessivos intervalos de tempo na medida em que limita o número de operações de chaveamento desses dispositivos para um período de 24-horas. O estudo fundamenta-se, metodologicamente, em métodos do tipo Primal-Dual Barreira-Logarítmica. Para demonstrar a eficiência do modelo proposto e a robustez dessa abordagem, a partir de dados teóricos obtidos de levantamentos bibliográficos, testes foram realizados em sistemas-teste de 10, 69 e 135 barras, e em um sistema de 442 barras do noroeste do Reino Unido. As implementações computacionais foram feitas nos softwares MATLAB, AIMMS e GAMS, utilizando o solver IPOPT como método de solução. Os resultados mostram que a abordagem proposta para a resolução do problema de programação não linear é eficaz para tratar adequadamente todas as variáveis presentes em problemas de otimização Volt/VAr. / This work proposes a new model and a new approach for solving the Volt / VAr optimization problem in distribution systems. The Volt/VAr optimization consists, basically, to determine the settings of the control variables of switched capacitor banks, on-load tap changer transformers and voltage regulators, in order to satisfy both the load and operational constraints, to a given operational objective. The problem is formulated as a nonlinear programming problem, multiperiod, and with continuous and discrete variables. Nonlinear programming algorithms were used in order to take advantage of the highly sparse matrices built along the solution method. The discrete variables are treated as continuous along the solution method by means of the use of sinusoidal functions that penalize the original objective function while the control variables do not converge to any of the predefined discrete points in its domain. The multiperiod, or dynamic, characteristic of the problem, however, refers to the use of a constraint that relates the settings of the control variables for successive time intervals that limits the control devices switching operations number for a period of 24-hours. The study is based, methodologically, on Primal-Dual Logarithmic Barrier method. To demonstrate the effectiveness of the proposed model and the robustness of this approach, the data were obtained from theoretical literature surveys, and tests were performed on test-systems of 10, 69 and 135 buses, and in a 442 buses located in the Northwest of the United Kingdom. The computational implementation was accomplished in the softwares MATLAB, AIMMS and GAMS, using the IPOPT solver as solution method. The results have shown the approach for solving nonlinear programming problems is effective to appropriate cope with all the variables presented in Volt/VAr optimization problems.

Este projeto de pesquisa propõe desenvolver um novo modelo e uma nova abordagem para a resolução do problema da otimização Volt/VAr em redes de distribuição de energia elétrica. A otimização Volt/VAr consiste em, basicamente, determinar os ajustes das variáveis de controle tais como bancos de capacitores chaveados, transformadores com comutação de tap sob carga e reguladores de tensão, de modo a satisfazer, simultaneamente, as restrições de carga e de operação para um dado objetivo operacional. Esse problema, matematicamente, foi formulado como um problema de programação não linear, multiperíodo, e com variáveis contínuas e discretas. Algoritmos de programação não linear foram utilizados com o intuito de aproveitar as vantagens das matrizes altamente esparsas montadas ao longo do método de solução. Para utilizar tais algoritmos, as variáveis discretas são tratadas como contínuas por meio da utilização de funções senoidais que penalizam a função objetivo do problema original enquanto estas não convergirem para algum dos pontos pré-definidos no seu domínio. O caráter multiperíodo do problema, contudo, refere-se à consideração de uma restrição que relaciona os ajustes das variáveis de controle para sucessivos intervalos de tempo na medida em que limita o número de operações de chaveamento desses dispositivos para um período de 24-horas. O estudo fundamenta-se, metodologicamente, em métodos do tipo Primal-Dual Barreira-Logarítmica. Para demonstrar a eficiência do modelo proposto e a robustez dessa abordagem, a partir de dados teóricos obtidos de levantamentos bibliográficos, testes foram realizados em sistemas-teste de 10, 69 e 135 barras, e em um sistema de 442 barras do noroeste do Reino Unido. As implementações computacionais foram feitas nos softwares MATLAB, AIMMS e GAMS, utilizando o solver IPOPT como método de solução. Os resultados mostram que a abordagem proposta para a resolução do problema de programação não linear é eficaz para tratar adequadamente todas as variáveis presentes em problemas de otimização Volt/VAr. / This work proposes a new model and a new approach for solving the Volt / VAr optimization problem in distribution systems. The Volt/VAr optimization consists, basically, to determine the settings of the control variables of switched capacitor banks, on-load tap changer transformers and voltage regulators, in order to satisfy both the load and operational constraints, to a given operational objective. The problem is formulated as a nonlinear programming problem, multiperiod, and with continuous and discrete variables. Nonlinear programming algorithms were used in order to take advantage of the highly sparse matrices built along the solution method. The discrete variables are treated as continuous along the solution method by means of the use of sinusoidal functions that penalize the original objective function while the control variables do not converge to any of the predefined discrete points in its domain. The multiperiod, or dynamic, characteristic of the problem, however, refers to the use of a constraint that relates the settings of the control variables for successive time intervals that limits the control devices switching operations number for a period of 24-hours. The study is based, methodologically, on Primal-Dual Logarithmic Barrier method. To demonstrate the effectiveness of the proposed model and the robustness of this approach, the data were obtained from theoretical literature surveys, and tests were performed on test-systems of 10, 69 and 135 buses, and in a 442 buses located in the Northwest of the United Kingdom. The computational implementation was accomplished in the softwares MATLAB, AIMMS and GAMS, using the IPOPT solver as solution method. The results have shown the approach for solving nonlinear programming problems is effective to appropriate cope with all the variables presented in Volt/VAr optimization problems.

Voltage imbalance in low voltage (LV) networks is expected to deteriorate as low carbon technologies, e.g. electric vehicles (EVs) and heat pumps (HPs) are increasingly deployed. The new electrical demand attributable to EVs and HPs would increase the voltage magnitude variation, increasing the possibility of voltages moving outside the statutory LV magnitude limits. Moreover, the single-phase nature of EVs and HPs, which will be connected via a single-phase 'line & neutral' cable to a 3-phase four-wire LV mains cable buried beneath the street, further entangles this voltage management problem; the non-balanced voltage variations in the three phases boost the levels of voltage imbalance. Excessive voltage imbalance and magnitude variation need to be mitigated to limit their adverse effects on the electric network and connected plant. The voltage imbalance in LV networks is conventionally reduced by reinforcing the network, generally at a high cost. Some modern methods for voltage imbalance mitigation have been introduced in recent years. The power electronic converter based methods are inadequate due to the generation of harmonics, significant power losses and short lifetime. Besides, automatic supply phase selection and smart EV charging rely on an advanced smart communication system, which currently is not available. This project aims to develop alternative solutions that mitigate the voltage imbalance seen in LV networks. A voltage balancing method based on Scott transformer (ST) is proposed. This method does not generate harmonics and is independent of the smart communication system. Computer simulations demonstrated the proposed method is able to convert a non-balanced 3-phase voltage into a balanced 3-phase voltage at either a point on the LV feeder or a 3-phase load supply point with the predefined voltage magnitude. Besides, a physical voltage balancing system was created based on the proposed method and it was tested in an LV network in the laboratory. The test results show the balancing system is capable of maintaining a low level of voltage imbalance on the LV feeder by rapidly compensating for the voltage rises and sags caused by single-phase load variations. This voltage balancing method is a potential solution for the network utilities to accommodate the significant penetration of low carbon technologies without breaching the network voltage limits. The impact of EVs and HPs on the LV network voltages is investigated based on a Monte Carlo (MC) simulation platform, which comprises a statistical model of EV charging demand, profiles generators of residential and HP electrical demand, and a distribution network model. The MC simulation indicates the impact of EVs and HPs is related to their distribution; when more than 21EVs and 13HPs are non-evenly distributed on a 96-customer LV feeder, the voltage limits are likely to be violated. Moreover, the effectiveness of the ST based voltage balancing method and the demand response based TOU tariff, implemented either alone or together, in mitigating the impact of EVs and HPs is investigated based on the established MC simulation platform. The results indicate the ST based balancing method alone is able to completely mitigate the voltage limit violations regardless of the penetration levels of EVs and HPs. Moreover, using both of the two investigated methods further enhances the balancing effectiveness of the ST based voltage balancing method.

Made available in DSpace on 2016-08-17T14:52:58Z (GMT). No. of bitstreams: 1 Raimundo Nonato Rosa Filho.pdf: 1125835 bytes, checksum: 91689e7b58443f6d0eb73d752860ce37 (MD5) Previous issue date: 2005-03-31 / In this work a methodology for reduction of maintenance cost in the on-load tap changers (OLTC) of extra high voltage is proposed. The methodology is based on the use of Artificial Neural Networks (ANN) for the intelligent processing of input signals of the commutator. The neural nets adequately trained allow to create an information system and dedicated diagnosis of the OLTC. This system can interpret and diagnosis the components through the real time input signals in order to delay the power transformer maintenance intervals, foreseeing when the OLTC is going to maintenance have intervention based on its condition. It has been adopted a multiperceptron ANN architecture in which the input vector has 22 components and the output considers only one component with the status of the OLTC condition in function of its operation time. This output information is used to determine the periods of maintenance of the commutators. It is reported an application of the proposed system considering the on load tap changer of an autotransformer bank of 500/230/13.8 kV, 600MVA of Centrais Elétricas do Norte do Brasil S/A (ELETRONORTE). The results indicate the advantages of the maintenance based on the condition using ANN. / Neste trabalho é proposta uma metodologia para redução de custo de manutenção nos comutadores de tap sob carga (OLTC) dos transformadores de potência de extra alta tensão. A metodologia está baseada na utilização de redes neurais artificiais (RNA) para o processamento inteligente dos sinais de entrada dos comutadores. As redes neurais adequadamente treinadas permitem criar um sistema de informação e diagnóstico dedicado a OLTC que podem interpretar e diagnosticar os componentes através das entradas em tempo real de forma a, postergar os intervalos de manutenção, prevendo quando o OLTC deverá sofrer intervenção de manutenção baseada na condição do OLTC. Foi adotada uma arquitetura de RNA de multiperceptron na qual a entrada considera um vetor com 22 entrada e apenas uma saída com o status da condição do OLTC em função do tempo de operação. Essa informação de saída é utilizada para determinar os períodos de manutenção dos comutadores de tap. É realizada uma aplicação do sistema proposto considerando o comutador de tap sob carga de um banco de autotransformador de 500/230/13.8kV, 600MVA da Centrais Elétricas do Norte do Brasil S/A( ELETRONORTE) e os resultados indicam as vantagens da manutenção baseada na condição usando RNA.

Der Ausbau dezentraler Energieanlagen wie fotovoltaischen Anlagen beeinflusst die Netzzustände signifikant. Dabei ist unsicher, wo und in welchem Maße deren Ausbau zukünftig erfolgt. Es ist nun an den Netzbetreibern gleichzeitig die aktuellen Herausforderungen zu meistern und die Netzplanung und -regelung für die Zukunft zu aktualisieren. Eine statistische Methode wird entwickelt, die Verteilnetzplanung unter Einsatz von quasi-stationär modellierten ”Smart Grid”-Lösungen wie Blindleistungsreglern und regelbaren Ortsnetztransformatoren ermöglicht. Durch Stichprobenverfahren werden Unsicherheiten wie Ort, Größe und Leistungsprofile der Energieanlagen in das Netzmodell eingebunden. Diese als probabilistischer Lastfluss bekannte Methode wird durch Gütemaße im Bereich geringer Kombination evaluiert. Beispiele probabilistischer Netzplanung werden an Netztopologien präsentiert.:Abbildungsverzeichnis iv Tabellenverzeichnis viii Abkürzungsverzeichnis viii Formelzeichen x 1. Einleitung 1 1.1. Definition der Herausforderung 1 1.2. Netzplanung 2 1.3. Ziel der Arbeit3 1.4. Struktur der Arbeit 5 2. Normen und technische Rahmenbedingungen 6 2.1. DIN EN 50160 6 2.2. VDE-AR-N 41057 2.3. Technische Anschlussbedingungen 9 2.4. Erneuerbare-Energien-Gesetz 11 2.5. Zusammenfassung 12 3. Gliederung probabilistischer Lastflussverfahren 13 3.1. Punktschätzende und iterative Verfahren 14 3.2. Gliederung nach Stichprobenverfahren 15 3.3. Reduzierung des Grundraumes 16 3.3.1. Cluster-Analyse17 3.3.2. Ausreißerbehandlung 21 3.3.3. Wahrscheinlichkeits- und Verteilungsfunktion 21 3.4. Methode der Stichprobenziehung 22 3.4.1. Einfache Zufallsstichprobe 23 3.4.2. Systematische Stichprobe24 3.4.3. Geschichtete Zufallsstichprobe 25 3.5. Reduzierung des Stichprobenraumes 26 3.6. Invertierung von Stichproben 26 3.7. Zusammenfassung 27 4. Vergleich probabilistischer Verfahren 28 4.1. Nicht-Gaußsche Eingangsdaten 28 4.2. Bestimmung notwendiger Clusterzentren 29 4.3. Erstellung des Stichprobenraumes pro Kombination 31 4.4. Gütemaße und Effizienz von Stichprobenverfahren 33 4.4.1. Median 34 4.4.2. Median der absoluten Abweichung vom Median 37 4.4.3. Maximale normierte Perzentilsdifferenz 40 4.4.4. Zusammenfassung 43 4.5. Streuung der Stichprobenverfahren bei wiederholter Ausführung 44 4.5.1. Median 44 4.5.2. Median der absoluten Abweichung vom Median 45 4.5.3. Maximale normierte Perzentilsdifferenz 47 4.5.4. Zusammenfassung 49 4.6. Sensitivität bei unterschiedlicher Anzahl statistischer Netzknoten 52 4.6.1. Median 52 4.6.2. Median der absoluten Abweichung vom Median 54 4.6.3. Maximale normierte Perzentilsdifferenz 56 4.6.4. Zusammenfassung58 4.7. Notwendige Kombinationen für Ziel-Gütemaße 59 5. Software-basierte probabilistische Verteilnetzplanung 61 5.1. Struktur der entwickeltenSoftware 61 5.2. Last- und Erzeugungsprofile 63 5.2.1. Synthetische Haushaltslast 63 5.2.2. Elektrofahrzeug 64 5.2.3. Wärmepumpe 65 5.2.4. Photovoltaische Anlagen 66 5.2.5. Windenergieanlagen 66 5.3. Optimale Auswahl nach Regeleffizienz 67 5.4. DezentraleWirkleistungsregler 68 5.4.1. P(U)-Regler für Schnellladeinfrastruktur 68 5.4.2. P(U)-Regelung von Wärmepumpen gemäß thermischer Grenzen 69 5.5. Blindleistungsregler 72 5.5.1. Zentrale Steuerung 73 5.5.2. Dezentrale Regelung 75 5.5.3. Verteilte Regelung 79 5.6. Regelbarer Ortsnetztransformator 83 5.7. Automatisierte Netzausbauplanung 86 5.7.1. Transformatortausch 87 5.7.2. Vergrößerung des Leiterquerschnitts 89 5.7.3. Zusätzliche Stichleitung 89 5.7.4. Kostenberechnung 90 5.8. Zusammenfassung 91 6. Anwendungsfälle probabilistischer Planung 92 6.1. Verwendete Verteilnetzmodelle 94 6.2. Abschätzung der Auswirkung von PV-Anlagenausbau 95 6.2.1. Unterschiede der Planungsverfahren zur Schätzung der PVA-Nennleistung 95 6.2.2. Einfluss der Blindleistungsregelung auf mögliche Anlagenleistung 100 6.3. Abschätzung von Netzauslastungen in Wohngebieten 106 6.3.1. Annahmen und Szenarien 107 6.3.2. Auswertung der Knotenspannungen 110 6.3.3. Auswertung der Betriebsmittelauslastungen 116 6.4. Zusammenfassung 118 7. Zusammenfassung und Ausblick 119 Literaturverzeichnis 121 Anhang 135 A. Statistische Merkmale 135 A.1. Empirische Wahrscheinlichkeitsfunktion 135 A.2. Kumulative empirische Verteilungsfunktion 136 A.3. Quantile 136 A.4. Interquartilsabstand 137 B. PLF-Methoden 138 B.1. Veröffentlichte PLF-Methoden 138 B.2. Test Gaußsche Verteilung 138 C. Definitionen 140 C.1. Symbole für Flussdiagramme 140 C.2. Zählpfeilsystem 140 D. Ergänzende Ergebnisse 142 E. Danksagung 143 / Development of distributed energy units such as photovoltaic systems affects grid states significantly. It is uncertain, where and to what extent the development of these units is carried out in the future. It is now up to the distribution system operator to cope with todays grid challenges and to update grid planning and control for the future. A statistical method is developed, which incorporates quasi-stationary modeled ”smart grid” solutions such as reactive power controllers and on-load tap-changers. Uncertainties such as location, size and power profiles of energy systems are integrated into the grid model by sampling. This method is known as probabilistic load flow and is evaluated by quality measures at low combinations. Examples on probabilistic grid planning of different grid topologies are presented.:Abbildungsverzeichnis iv Tabellenverzeichnis viii Abkürzungsverzeichnis viii Formelzeichen x 1. Einleitung 1 1.1. Definition der Herausforderung 1 1.2. Netzplanung 2 1.3. Ziel der Arbeit3 1.4. Struktur der Arbeit 5 2. Normen und technische Rahmenbedingungen 6 2.1. DIN EN 50160 6 2.2. VDE-AR-N 41057 2.3. Technische Anschlussbedingungen 9 2.4. Erneuerbare-Energien-Gesetz 11 2.5. Zusammenfassung 12 3. Gliederung probabilistischer Lastflussverfahren 13 3.1. Punktschätzende und iterative Verfahren 14 3.2. Gliederung nach Stichprobenverfahren 15 3.3. Reduzierung des Grundraumes 16 3.3.1. Cluster-Analyse17 3.3.2. Ausreißerbehandlung 21 3.3.3. Wahrscheinlichkeits- und Verteilungsfunktion 21 3.4. Methode der Stichprobenziehung 22 3.4.1. Einfache Zufallsstichprobe 23 3.4.2. Systematische Stichprobe24 3.4.3. Geschichtete Zufallsstichprobe 25 3.5. Reduzierung des Stichprobenraumes 26 3.6. Invertierung von Stichproben 26 3.7. Zusammenfassung 27 4. Vergleich probabilistischer Verfahren 28 4.1. Nicht-Gaußsche Eingangsdaten 28 4.2. Bestimmung notwendiger Clusterzentren 29 4.3. Erstellung des Stichprobenraumes pro Kombination 31 4.4. Gütemaße und Effizienz von Stichprobenverfahren 33 4.4.1. Median 34 4.4.2. Median der absoluten Abweichung vom Median 37 4.4.3. Maximale normierte Perzentilsdifferenz 40 4.4.4. Zusammenfassung 43 4.5. Streuung der Stichprobenverfahren bei wiederholter Ausführung 44 4.5.1. Median 44 4.5.2. Median der absoluten Abweichung vom Median 45 4.5.3. Maximale normierte Perzentilsdifferenz 47 4.5.4. Zusammenfassung 49 4.6. Sensitivität bei unterschiedlicher Anzahl statistischer Netzknoten 52 4.6.1. Median 52 4.6.2. Median der absoluten Abweichung vom Median 54 4.6.3. Maximale normierte Perzentilsdifferenz 56 4.6.4. Zusammenfassung58 4.7. Notwendige Kombinationen für Ziel-Gütemaße 59 5. Software-basierte probabilistische Verteilnetzplanung 61 5.1. Struktur der entwickeltenSoftware 61 5.2. Last- und Erzeugungsprofile 63 5.2.1. Synthetische Haushaltslast 63 5.2.2. Elektrofahrzeug 64 5.2.3. Wärmepumpe 65 5.2.4. Photovoltaische Anlagen 66 5.2.5. Windenergieanlagen 66 5.3. Optimale Auswahl nach Regeleffizienz 67 5.4. DezentraleWirkleistungsregler 68 5.4.1. P(U)-Regler für Schnellladeinfrastruktur 68 5.4.2. P(U)-Regelung von Wärmepumpen gemäß thermischer Grenzen 69 5.5. Blindleistungsregler 72 5.5.1. Zentrale Steuerung 73 5.5.2. Dezentrale Regelung 75 5.5.3. Verteilte Regelung 79 5.6. Regelbarer Ortsnetztransformator 83 5.7. Automatisierte Netzausbauplanung 86 5.7.1. Transformatortausch 87 5.7.2. Vergrößerung des Leiterquerschnitts 89 5.7.3. Zusätzliche Stichleitung 89 5.7.4. Kostenberechnung 90 5.8. Zusammenfassung 91 6. Anwendungsfälle probabilistischer Planung 92 6.1. Verwendete Verteilnetzmodelle 94 6.2. Abschätzung der Auswirkung von PV-Anlagenausbau 95 6.2.1. Unterschiede der Planungsverfahren zur Schätzung der PVA-Nennleistung 95 6.2.2. Einfluss der Blindleistungsregelung auf mögliche Anlagenleistung 100 6.3. Abschätzung von Netzauslastungen in Wohngebieten 106 6.3.1. Annahmen und Szenarien 107 6.3.2. Auswertung der Knotenspannungen 110 6.3.3. Auswertung der Betriebsmittelauslastungen 116 6.4. Zusammenfassung 118 7. Zusammenfassung und Ausblick 119 Literaturverzeichnis 121 Anhang 135 A. Statistische Merkmale 135 A.1. Empirische Wahrscheinlichkeitsfunktion 135 A.2. Kumulative empirische Verteilungsfunktion 136 A.3. Quantile 136 A.4. Interquartilsabstand 137 B. PLF-Methoden 138 B.1. Veröffentlichte PLF-Methoden 138 B.2. Test Gaußsche Verteilung 138 C. Definitionen 140 C.1. Symbole für Flussdiagramme 140 C.2. Zählpfeilsystem 140 D. Ergänzende Ergebnisse 142 E. Danksagung 143