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1
Raak, Fredrik. "Investigation of Power Grid Islanding Based on Nonlinear Koopman Modes." Thesis, KTH, Elektriska energisystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-136834.
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To view the electricity supply in our society as just sockets mountedin our walls with a constant voltage output is far from the truth. Inreality, the power system supplying the electricity or the grid, is themost complex man-made dynamical system there is. It demands severecontrol and safety measures to ensure a reliable supply of electric power.Throughout the world, incidents of widespread power grid failures havebeen continuously reported. The state where electricity delivery to customersis terminated by a disturbance is called a blackout. From a stateof seemingly stable operating conditions, the grid can fast derail intoan uncontrollable state due to cascading failures. Transmission linesbecome automatically disconnected due to power flow redirections andparts of the grid become isolated and islands are formed. An islandedsub-grid incapable of maintaining safe operation conditions experiencesa blackout. A widespread blackout is a rare, but an extremely costlyand hazardous event for society.During recent years, many methods to prevent these kinds of eventshave been suggested. Controlled islanding has been a commonly suggestedstrategy to save the entire grid or parts of the grid from a blackout.Controlled islanding is a strategy of emergency control of a powergrid, in which the grid is intentionally split into a set of islanded subgridsfor avoiding an entire collapse. The key point in the strategy is todetermine appropriate separation boundaries, i.e. the set of transmissionlines separating the grid into two or more isolated parts.The power grid exhibits highly nonlinear response in the case oflarge failures. Therefore, this thesis proposes a new controlled islandingmethod for power grids based on the nonlinear Koopman Mode Analysis(KMA). The KMA is a new analyzing technique of nonlinear dynamicsbased on the so-called Koopman operator. Based on sampled data followinga disturbance, KMA is used to identify suitable partitions of thegrid.The KMA-based islanding method is numerically investigated withtwo well-known test systems proposed by the Institute of Electrical andElectronics Engineers (IEEE). By simulations of controlled islanding inthe test system, it is demonstrated that the grid’s response following afault can be improved with the proposed method.The proposed method is compared to a method of partitioning powergrids based on spectral graph theory which captures the structural propertiesof a network. It is shown that the intrinsic structural propertiesof a grid characterized by spectral graph theory are also captured by theKMA. This is shown both by numerical simulations and a theoreticalanalysis.
2
Zheng, Wei. "Control strategies enabling seamless switching to islanded operation." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/control-strategies-enabling-seamless-switching-to-islanded-operation(bbd0b08b-0a72-4c45-99de-c3b98f908058).html.
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Significant penetration of distributed generation (DG) and the increasing automation level available for distribution networks have opened an option of splitting a network into subsystems and operating each as an "autonomous island". This is particularly important when a major contingency occurs. However, there are issues and challenges that must be addressed before islanded operation becomes viable, among which, ensuring seamless switching of a distribution subsystem from grid-connected to islanded mode is critically important. Unless the subsystem is a predesigned microgrid, it is highly possible that the subsystem load demand will exceed the generation capacity of island DGs. Therefore, an appropriate load shedding scheme must be implemented to ensure the islanded subsystem is power balanced. In this thesis, a switching control strategy is designed to deliver seamless islanding switching. This strategy comprises a multiple-DG coordination method and a single-step load shedding scheme. Mathematical studies and time-domain simulations that investigate the transients observed during the islanding switching process are both conducted, and together, they are used to address the transient stability issues of an islanded subsystem. This thesis focuses on a distribution subsystem consisting of a mix of synchronous and inverter-based DGs and a combination of static and dynamic loads. DG modelling and control is first introduced, and based on that, various types of method to achieve multiple-DG coordination, including an innovative multiple-master strategy, are investigated. The widely accepted master-slave strategy is used to coordinate DGs when the subsystem is islanded. The strategy demands a single dispatchable and controllable DG, such as a synchronous generator, to be the master, whilst requires the others, such as intermittent renewable-based DGs, to be the slaves. Dynamic load modelling is another critical part of this thesis. The transient stability of dynamic loads after major disturbances is investigated and then used to design the stability-oriented load shedding priority. The single-step load shedding scheme calculates the load shedding amount based on the power flow at the point of common coupling (PCC) and the spinning reserve available in the island. This scheme is activated by the tripping event of the PCC circuit breaker between the grid and the island, and then priorities the load to be shed according to the priority predetermined from the stability perspective. Mathematical analysis is first conducted on a simple subsystem to investigate the impact of DG settings on the islanding transients. A full-scale subsystem is also simulated in PSCAD/EMTDC and used to verify the effectiveness of the switching control strategy. In time-domain simulations, the subsystem is islanded following either a routine switching event or a permanent grid fault. Various factors that may affect the transient performance are analysed, such as the severity of the fault, the DG penetration level, the fault clearance time and the switching control delay. This thesis concludes that based on the proposed switching control strategy, the concept of seamless switching from grid-connected to islanded operation is technically viable.
3
Huang, Ruth Christiana. "Designing Anti-Islanding Detection Using the Synchrophasor Vector Processor." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1001.
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ABSTRACT
Designing Anti-Islanding Detection Using the Synchrophasor Vector Processor
Ruth Huang
The need for distributed generation (DG) has become more and more popular because of the adverse effects of fossil fuels and the fear of running out of fossil fuels. By having DG, there are less transmission losses, voltage support, controllability of the system, decreased costs in transmission and distribution, power quality improvement, energy efficiency, and reduced reserve margin. The adverse effects of DG are voltage flicker, harmonics, and islanding. Islanding occurs when the DG continues to energize the power system when the main utility is disconnected. Detecting islanding is important for personnel safety, speedy restoration, and equipment protection. This paper describes the different islanding methods currently used and the benefits of combining two passive islanding detection methods, under/over voltage detection and voltage phase jump detection methods, using the synchrophasor vector processor (SVP).
4
Thacker, Timothy Neil. "Control of Power Conversion Systems for the Intentional Islanding of Distributed Generation Units." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/30814.
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Within the past decade, talk has arisen of shifting the utility grid from centralized, radial sources to a distributed network of sources, also known as distributed generation (DG); in the wake of deregulation, the California energy crisis, and northeastern blackouts.
Existing control techniques for DG systems are designed to operate a system either in the connected or disconnected (islanding) mode to the utility; thus not allowing for both modes to be implemented and transitioned between. Existing detection and re-closure algorithms can also be improved upon. Dependent upon the method implemented, detection algorithms can either cause distortions in the output or completely miss a disturbance. The present re-closure process to reconnect to the utility is to completely shutdown and wait five minutes. The proposed methods of this study improve upon existing methods, via simulation and hardware experimentation, for DG systems that can intentionally islanding themselves.
The proposed, â switched-modeâ , control allows for continuous operation of the system during disturbances by transitioning the mode of control to reflect the change in the system mode (grid-connected or islanding). This allows for zero downtimes without detrimental transients.
The proposed detection method can sense disturbances that other methods cannot; and within 25 ms (approximately 1.5 line-cycles at 60 Hz). This method is an improvement over other methods because it eliminates the need to purposely distort the outputs to sense a disturbance.
The proposed re-closure method is an improvement over the existing method due to the fact that it does not require the system to de-energize before re-synchronizing and reconnecting to the utility. This allows for DGs to continuously supply power to the system without having to shut down. Results show that the system is generally ready to reconnect after 2 to 5 line cycles.<br>Master of Science
5
Singh, Manish K. "Optimal Operation of Water and Power Distribution Networks." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/86860.
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Under the envisioned smart city paradigm, there is an increasing demand for the coordinated operation of our infrastructure networks. In this context, this thesis puts forth a comprehensive toolbox for the optimization of electric power and water distribution networks. On the analytical front, the toolbox consists of novel mixed-integer (non)-linear program (MINLP) formulations; convex relaxations with optimality guarantees; and the powerful technique of McCormick linearization. On the application side, the developed tools support the operation of each of the infrastructure networks independently, but also towards their joint operation. Starting with water distribution networks, the main difficulty in solving any (optimal-) water flow problem stems from a piecewise quadratic pressure drop law. To efficiently handle these constraints, we have first formulated a novel MINLP, and then proposed a relaxation of the pressure drop constraints to yield a mixed-integer second-order cone program. Further, a novel penalty term is appended to the cost that guarantees optimality and exactness under pre-defined network conditions. This contribution can be used to solve the WF problem; the OWF task of minimizing the pumping cost satisfying operational constraints; and the task of scheduling the operation of tanks to maximize the water service time in an area experiencing electric power outage. Regarding electric power systems, a novel MILP formulation for distribution restoration using binary indicator vectors on graph properties alongside exact McCormick linearization is proposed. This can be used to minimize the restoration time of an electric system under critical operational constraints, and to enable a coordinated response with the water utilities during outages.<br>Master of Science<br>The advent of smart cities has promoted research towards interdependent operation of utilities such as water and power systems. While power system analysis is significantly developed due to decades of focused research, water networks have been relying on relatively less sophisticated tools. In this context, this thesis develops Advanced efficient computational tools for the analysis and optimization for water distribution networks. Given the consumer demands, an optimal water flow (OWF) problem for minimizing the pump operation cost is formulated. Developing a rigorous analytical framework, the proposed formulation provides significant computational improvements without compromising on the accuracy. Explicit network conditions are provided that guarantee the optimality and feasibility of the obtained OWF solution. The developed formulation is next used to solve two practical problems: the water flow problem, that solves the complex physical equations yielding nodal pressures and pipeline flows given the demands/injections; and an OWF problem that finds the best operational strategy for water utilities during power outages. The latter helps the water utility to maximize their service time during power outages, and helps power utilities better plan their restoration strategy. While the increased instrumentation and automation has enabled power utilities to better manage restoration during outages, finding an optimal strategy remains a difficult problem. The operational and coordination requirements for the upcoming distributed resources and microgrids further complicate the problem. This thesis develops a computationally fast and reasonably accurate power distribution restoration scheme enabling optimal coordination of different generators with optimal islanding. Numerical tests are conducted on benchmark water and power networks to corroborate the claims of the developed formulations.
6
NGUYEN, Ngoc Trung. "Study and development of innovative measurement methods and systems for anti-islanding protection in smart grids." Doctoral thesis, Università degli Studi di Palermo, 2014. http://hdl.handle.net/10447/90786.
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Gardner, Robert Matthew. "A Wide-Area Perspective on Power System Operation and Dynamics." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26779.
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Classically, wide-area synchronized power system monitoring has been an expensive task requiring significant investment in utility communications infrastructures for the service of relatively few costly sensors. The purpose of this research is to demonstrate the viability of power system monitoring from very low voltage levels (120 V). Challenging the accepted norms in power system monitoring, the document will present the use of inexpensive GPS time synchronized sensors in mass numbers at the distribution level. In the past, such low level monitoring has been overlooked due to a perceived imbalance between the required investment and the usefulness of the resulting deluge of information. However, distribution level monitoring offers several advantages over bulk transmission system monitoring. First, practically everyone with access to electricity also has a measurement port into the electric power system. Second, internet access and GPS availability have become pedestrian commodities providing a communications and synchronization infrastructure for the transmission of low-voltage measurements. Third, these ubiquitous measurement points exist in an interconnected fashion irrespective of utility boundaries. This work offers insight into which parameters are meaningful to monitor at the distribution level and provides applications that add unprecedented value to the data extracted from this level. System models comprising the entire Eastern Interconnection are exploited in conjunction with a bounty of distribution level measurement data for the development of wide-area disturbance detection, classification, analysis, and location routines.
The main contributions of this work are fivefold: the introduction of a novel power system disturbance detection algorithm; the development of a power system oscillation damping analysis methodology; the development of several parametric and non-parametric power system disturbance location methods, new methods of power system phenomena visualization, and the proposal and mapping of an online power system event reporting scheme.<br>Ph. D.
8
Mazloomzadeh, Ali. "Development of Hardware in the Loop Real-Time Control Techniques for Hybrid Power Systems Involving Distributed Demands and Sustainable Energy Sources." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1666.
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The future power grid will effectively utilize renewable energy resources and distributed generation to respond to energy demand while incorporating information technology and communication infrastructure for their optimum operation. This dissertation contributes to the development of real-time techniques, for wide-area monitoring and secure real-time control and operation of hybrid power systems.
To handle the increased level of real-time data exchange, this dissertation develops a supervisory control and data acquisition (SCADA) system that is equipped with a state estimation scheme from the real-time data. This system is verified on a specially developed laboratory-based test bed facility, as a hardware and software platform, to emulate the actual scenarios of a real hybrid power system with the highest level of similarities and capabilities to practical utility systems. It includes phasor measurements at hundreds of measurement points on the system. These measurements were obtained from especially developed laboratory based Phasor Measurement Unit (PMU) that is utilized in addition to existing commercially based PMU’s. The developed PMU was used in conjunction with the interconnected system along with the commercial PMU’s. The tested studies included a new technique for detecting the partially islanded micro grids in addition to several real-time techniques for synchronization and parameter identifications of hybrid systems.
Moreover, due to numerous integration of renewable energy resources through DC microgrids, this dissertation performs several practical cases for improvement of interoperability of such systems. Moreover, increased number of small and dispersed generating stations and their need to connect fast and properly into the AC grids, urged this work to explore the challenges that arise in synchronization of generators to the grid and through introduction of a Dynamic Brake system to improve the process of connecting distributed generators to the power grid.
Real time operation and control requires data communication security. A research effort in this dissertation was developed based on Trusted Sensing Base (TSB) process for data communication security. The innovative TSB approach improves the security aspect of the power grid as a cyber-physical system. It is based on available GPS synchronization technology and provides protection against confidentiality attacks in critical power system infrastructures.
9
Vieira, Junior Jose Carlos de Melo. "Metodologias para ajuste e avaliação do desempenho de reles de proteção anti-ilhamento de geradores sincronos distribuidos." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260506.
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Orientadores: Andre Luiz Morelato França, Walmir de Freitas Filho<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação<br>Made available in DSpace on 2018-08-06T02:54:55Z (GMT). No. of bitstreams: 1
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Previous issue date: 2006<br>Resumo: Uma das principais funções dos sistemas de proteção de geradores distribuídos conectados em redes de subtransmissão ou de distribuição de energia elétrica é desconectá-los tão logo uma situação de ilhamento seja detectada. O ilhamento ocorre quando parte da rede elétrica é desconectada do restante do sistema da concessionária, mas continua a ser energizada por um ou mais geradores distribuídos conectados a ela, formando um subsistema isolado da concessionária. Esta ocorrência deve ser evitada porque coloca em risco a segurança de pessoas e equipamentos e pode deteriorar a qualidade da energia suprida aos consumidores locais. Neste contexto, esta tese de doutorado propõe novas metodologias para avaliar de forma sistemática e ajustar alguns dos principais relés de proteção anti-ilhamento de geradores síncronos. As técnicas analisadas compreendem os relés de deslocamento de fase ou ¿salto de vetor¿, relés de taxa de variação de freqüência, relés de sub/sobrefreqüência convencionais e os relés de sub/sobretensão convencionais. A aplicação das metodologias desenvolvidas mostrou que elas são ferramentas eficientes para avaliar e determinar o desempenho desses relés quanto à detecção de ilhamentos, auxiliando na seleção dos esquemas de proteção e ajustes mais adequados<br>Abstract: One of the main functions of distributed generators¿ protection systems is the capability to disconnect the generators immediately after an islanding occurrence is detected. Islanding occurs when a portion of the distribution system is disconnected from the utility grid, yet remains energized by one or more distributed generators connected to it. This operating condition should be avoided because it poses safety risks to utility personnel and equipments as well as it can cause power quality problems to the local costumers. In this context, this thesis proposes new methodologies to systematically evaluate and adjust some anti-islanding techniques applied to synchronous generators. The techniques analyzed are the under/over frequency relays, the rate of change of frequency (ROCOF) relays, the vector surge or vector jump relays and the under/overvoltage relays. The results have shown that the proposed methodologies can be efficient tools to evaluate and to determine the performance of these anti-islanding relays, consequently, they can help protection engineers to select the most proper protection devices and their settings<br>Doutorado<br>Energia Eletrica<br>Doutor em Engenharia Elétrica
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Meira, Paulo César Magalhães 1985. "Análise da proteção antiilhamento de geradores de indução conectados em redes de distribuição de energia elétrica." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259993.
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Orientador: Walmir de Freitas Filho<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação<br>Made available in DSpace on 2018-08-15T23:24:26Z (GMT). No. of bitstreams: 1
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Previous issue date: 2010<br>Resumo: Em redes de distribuição, ilhamento ocorre quando parte da rede elétrica é desconectada do restante do sistema da concessionária, mas continua a ser energizada por um ou mais geradores distribuídos conectados a ela. Esta ocorrência deve ser evitada porque coloca em risco a segurança de pessoas e equipamentos. Diversos trabalhos têm sido desenvolvidos na análise do comportamento ilhado e da proteção antiilhamento de geradores síncronos e de geradores não-rotativos conectados via conversores eletrônicos. No entanto, pouca atenção tem sido dada aos casos envolvendo geradores de indução, sejam eles geradores duplamente alimentados ou com rotor tipo gaiola de esquilo. Portanto, o objetivo desta dissertação de mestrado é investigar o comportamento destes geradores durante ilhamentos, bem como analisar a eficiência dos relés baseados em medidas de freqüência e tensão para a realização de proteção antiilhamento. A ferramenta empregada para análise da proteção antiilhamento é a zona de não-detecção, a qual é definida como a região no espaço de desbalanço de potência reativa versus desbalanço de potência ativa em que o sistema de proteção antiilhamento não consegue detectar a situação de ilhamento dentro do tempo especificado. Tais zonas foram obtidas através de numerosas simulações de transitórios eletromagnéticos utilizando o programa PSCAD/EMTDC<br>Abstract: In distribution systems, islanding occurs when part of the electric system is disconnected from the remaining utility system, but continues to be fed by one or more distributed generators operating in the island. This occurrence should be avoided as it represents a safety risk to equipment and customers. There have been several research papers which analyze the islanding behavior and the anti-islanding protection of synchronous generators and non-rotating generators connected to the grid using electronic converters. Nonetheless, little attention has been spent to analyze the situations involving induction generators, either doubly-fed generators or squirrel-cage generators. Therefore, the objective of this dissertation is to investigate the behavior of these generators during islanded operation, as well as analyze the efficiency of anti-islanding protection schemes based on frequency and voltage relays. The analysis is conducted by using the non-detection zone, which is defined in the active versus reactive power imbalance space where the anti-islanding protection fails. These zones were determined by numerous electromagnetic transient simulations by using the software PSCAD/EMTDC<br>Mestrado<br>Energia Eletrica<br>Mestre em Engenharia Elétrica
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Wang, Minnan, and 王旻楠. "Islanding of systems of distributed generation using optimization methodology." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44914933.
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Wrinch, Michael C. "Negative sequence impedance measurement for distributed generator islanding detection." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/3418.
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This thesis presents a method of detecting electrical islands in low voltage distributed generator networks by measuring negative sequence impedance differences between islanded and utility connections. Extensive testing was conducted on a commercial building and 25 kV distributed generator fed network by measuring naturally occurring and artificially injected negative sequence components. Similarly, this technique was tested using the IEEE 399-1990 bus test case using the EMTP software. The practical measurements have been matched to simulations where further system performance characteristics of detecting power system islands has been successfully demonstrated. Measured results indicate that unbalanced load conditions are naturally occurring and readily measurable while deliberately unbalanced loads can increase the accuracy of negative sequence impedance islanding detection. The typically low negative sequence impedance of induction motors was found to have only a small effect in low voltage busses, though large machines can effect the threshold settings. Careful placement of the island detector is required in these situations. The negative sequence impedance measurement method is an improvement on previous impedance measurement techniques for islanding detection due to its accuracy, and distinctly large threshold window which have challenged previous impedance based islanding detection techniques.
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Hobbs, Ivan Kevin. "Evaluation and implementation of anti-islanding methods for converter-fed distributed generation." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1559.
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MScEng<br>Thesis (MScEng (Electrical and Electronic Engineering))--Univerity of Stellenbosch, 2009.<br>ENGLISH ABSTRACT: As the number of distributed generation units connected to a distribution network
increase, the possibility of island formation increases. An island is formed when
distributed generation units continue to energize local loads within a section of the grid,
which has been disconnected from the main distribution network. These islands pose
significant danger to maintenance personnel as well as to members of the public.
In this study, an investigation is done into various anti-islanding methods. The modes of
operation of these methods are discussed, as well as their strengths and weaknesses. The
slip-mode frequency shift method and the Sandia voltage shift method, in combination
with over/under voltage and frequency protection, are simulated and tested to confirm
their functionality. The results obtained show that it is possible to prevent distributed
generation units from energizing local loads when the grid is disconnected.<br>AFRIKAANSE OPSOMMING: Die moontlike toekomstige toename in die aantal verspreide generasie eenhede gekoppel
aan die verspreidings netwerk, verhoog die moontlikheid van eiland vorming. ‘n Eiland
word gevorm wanneer verspreide generasie eenhede energie aan lokale laste voorsien
nadat die netwerk ontkoppel is. Dit hou groot gevaar in vir onderhouds personeel asook
vir die publiek.
In die tesis word ‘n studie gedoen oor die verskillende metodes om die vorming van
ongewensde eilande te voorkom. Die glipmode-frekwensieskuif metode en die Sandia
spanningskuif metode word gekombineer met die oor/onder spanning en frekwensie
beskerming metodes. Die kombinasie van metodes word dan gesimuleer en
eksperimenteel getoets. Die verkrygde resultate toon dat dit moontlik is om die vorming
van ongewensde eilande effektief te voorkom.
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Sgarbossa, Riccardo. "Unintentional Islanding in Distribution Networks with Large Penetration of Power Electronics and Renewable Energy Systems." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3424898.
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The PhD thesis focus on the analysis and investigation of a crucial issue related to increasing number of distributed energy resources (DERs). This recent issue is the unintentional (i.e. uncontrolled) islanding operation in distribution network with large penetration of DERs based on power electronic converters. Particular focus has been addressed to the interaction between DERs, protection systems and new connection rules required by standard bodies. The aim of the research activity is the investigation on the causes and the influencing factors of unintentional islanding in medium and low voltage (MV and LV) distribution network.
The unintentional islanding issue has interested many studies and publications over the last decades. However, the literature research is lacking of considering the lately introduced European standards and technical specifications for DERs. Therefore, during the PhD research, novel aspects of how requirements and ancillary services influence the unintentional islanding operations have been studied, highlighting novel relevant factors, such as the role of the loads characteristics, the influence of the frequency measure and the inverter regulation speed.<br>The PhD thesis focus on the analysis and investigation of a crucial issue related to increasing number of distributed energy resources (DERs). This recent issue is the unintentional (i.e. uncontrolled) islanding operation in distribution network with large penetration of DERs based on power electronic converters. Particular focus has been addressed to the interaction between DERs, protection systems and new connection rules required by standard bodies. The aim of the research activity is the investigation on the causes and the influencing factors of unintentional islanding in medium and low voltage (MV and LV) distribution network.
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Bukhsh, Waqquas Ahmed. "Islanding model for preventing wide-area blackouts and the issue of local solutions of the optimal power flow problem." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9671.
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Optimization plays a central role in the control and operation of electricity power networks. In this thesis we focus on two very important optimization problems in power systems. The first is the optimal power flow problem (OPF). This is an old and well-known nonconvex optimization problem in power system. The existence of local solutions of OPF has been a question of interest for decades. Both local and global solution techniques have been put forward to solve OPF problem but without any documented cases of local solutions. We have produced test cases of power networks with local solutions and have collected these test cases in a publicly available online archive (http://www.maths.ed.ac.uk/optenergy/LocalOpt/), which can be used now by researchers and practitioners to test the robustness of their solution techniques. Also a new nonlinear relaxation of OPF is presented and it is shown that this relaxation in practice gives tight lower bounds of the global solution of OPF. The second problem considered is how to split a network into islands so as to prevent cascading blackouts over wide areas. A mixed integer linear programming (MILP) model for islanding of power system is presented. In recent years, islanding of power networks is attracting attention, because of the increasing occurrence and risk of blackouts. Our proposed approach is quite flexible and incorporates line switching and load shedding. We also give the motivation behind the islanding operation and test our model on variety of test cases. The islanding model uses DC model of power flow equations. We give some of the shortcomings of this model and later improve this model by using piecewise linear approximation of nonlinear terms. The improved model yields good feasible results very quickly and numerical results on large networks show the promising performance of this model.
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Kunte, Rohit S. "A wavelet transform-based islanding detection algorithm for inverter assisted distributed generators a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=8&sid=2&srchmode=1&vinst=PROD&fmt=6&startpage=-1&clientid=28564&vname=PQD&RQT=309&did=1786737271&scaling=FULL&ts=1250274536&vtype=PQD&rqt=309&TS=1250275236&clientId=28564.
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Norris, Sean William. "Preventing wide area blackouts in transmission systems : a new approach for intentional controlled islanding using power flow tracing." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10713/.
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A novel method to reduce the impact of wide area blackouts in transmission networks is presented. Millions of customers are affected each year due to blackouts. Splitting a transmission system into smaller islands could significantly reduce the effect of these blackouts. Large blackouts are typically a result of cascading faults which propagate throughout a network where Intentional Controlled Islanding (ICI) has the advantage of containing faults to smaller regions and stop them cascading further. Existing methodologies for ICI are typically calculated offline and will form pre-determined islands which can often lead to excessive splits. This thesis developed an ICI approach based on real time information which will calculate an islanding solution quickly in order to provide a ‘just-in-time’ strategy. The advantage of this method is that the island solution is designed based on the current operating point, but well also be designed for the particular disturbance location and hence will avoid unnecessary islanding. The new method will use a power flow tracing technique to find a boundary around a disturbance which forms the island that will be cut. The tracing method required only power flow information and so, can be computed quite quickly. The action of islanding itself can be a significant disturbance, therefore any islanding solution should aim to add as little stress as possible to the system. While methods which minimise the power imbalance and total power disrupted due to splitting are well documented, there has been little study into the effect islanding would have on voltage. There a new approach to consider the effects that islanding will have on the voltage stability of the system is developed. The ICI method is based on forming an island specific to a disturbance. If the location of a source is known along with information that a blackout is imminent, the methodology will find the best island in which to contain that disturbance. This is a slightly different approach to existing methods which will form islands independent of disturbance location knowledge. An area of influence is found around a node using power flow tracing, which consists of the strongly connected elements to the disturbance. Therefore, low power flows can be disconnected. This area of influence forms the island that will be disconnected, leaving the rest of the system intact. Hence minimising the number of islands formed. Finally the methodology is compared to the existing methods to show that the new tool developed in this thesis can find better solutions and that a new way of thinking about power system ICI can be put forward.
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Dong, Dong. "Ac-dc Bus-interface Bi-directional Converters in Renewable Energy Systems." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28495.
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This dissertation covers several issues related to the ac-dc bus-interface bi-directional converters in renewable energy systems.
The dissertation explores a dc-electronic distribution system for residential and commercial applications with a focus on the design of an ac-dc bi-directional converter for such application. This converter is named as the â Energy Control Centerâ due to its unique role in the system. First, the impact of the unbalanced power from the ac grid, especially the single-phase grid, on the dc system operation is analyzed. Then, a simple ac-dc two-stage topology and an advanced digital control system is proposed with a detailed design procedure. The proposed converter system significantly reduces the dc-link capacitor volume and achieves a dynamics-decoupling operation between the interfaced systems. The total volume of the two-stage topology can be reduced by upto three times compared with the typical design of a full-bridge converter. In addition, film capacitors can be used instead of electrolytic capacitors in the system, and thus the whole system reliability is improved.
A set of ac passive plus active filter solutions is proposed for the ac-dc bus-interface converter which significantly reduces the total power filter volume but still eliminate the total leakage current and the common-mode conducted EMI noises by more than 90%. The dc-side low-frequency CM voltage ripple generated by the unbalanced ac voltages can be eliminated as well. The proposed solution features a high reliability and fits three types of the prevalent low-voltage ac distribution systems.
Grid synchronization, a critical interface control in ac-dc bus-interface converters, is discussed in detail. First, a novel single-phase grid synchronization solution is proposed to achieve the rejection of multiple noises as well as the capability to track the ac voltage amplitude. Then, a comprehensive modeling methodology of the grid synchronization for three-phase system is proposed to explain the output frequency behaviors of grid-interface power converters at the weak grid, at the islanded condition, and at the multi-converter condition. The proposed models provide a strong tool to predict the grid synchronization instabilities raised from industries under many operating conditions, which is critical in future more-distributed-generation power systems.
Islanding detection issues in ac-dc bus-interface converters are discussed in detail. More than five frequency-based islanding detection algorithms are proposed. These solutions achieve different performances and are suitable for different applications, which are advantageous over existing solutions. More importantly, the detailed modeling, trade-off analysis, and design procedures are given to help completely understand the principles. In the end, the effectiveness of the proposed solutions in a multiple-converter system are analyzed. The results drawn from the discussion can help engineers to evaluate other existing solutions as well.<br>Ph. D.
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Biswas, Shuchismita. "Power Grid Partitioning and Monitoring Methods for Improving Resilience." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104684.
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This dissertation aims to develop decision-making tools that aid power grid operators in mitigating extreme events. Two distinct areas are focused on: a) improving grid performance after a severe disturbance, and b) enhancing grid monitoring to facilitate timely preventive actions. The first part of the dissertation presents a proactive islanding strategy to split the bulk power transmission system into smaller self-adequate islands in order to arrest the propagation of cascading failures after an event. Heuristic methods are proposed to determine in what sequence should the island boundary lines be disconnected such that there are no operation constraint violations. The idea of optimal partitioning is further extended to the distribution network. A planning problem for determining which parts of the existing distribution grid can be converted to microgrids is formulated. This partitioning formulation addresses safety limits, uncertainties in load and generation, availability of grid-forming units, and topology constraints such as maintaining network radiality. Microgrids help maintain energy supply to critical loads during grid outages, thereby improving resilience. The second part of the dissertation focuses on wide-area monitoring using Phasor Measurement Unit (PMU) data. Strategies for data imputation and prediction exploiting the spatio-temporal correlation in PMU measurements are outlined. A deep-learning-based methodology for identifying the location of temporary power systems faults is also illustrated. As severe weather events become more frequent, and the threats from coordinated cyber intrusions increase, formulating strategies to reduce the impact of such events on the power grid becomes important; and the approaches outlined in this work can find application in this context.<br>Doctor of Philosophy<br>The modern power grid faces multiple threats, including extreme-weather events, solar storms, and potential cyber-physical attacks. Towards the larger goal of enhancing power systems resilience, this dissertation develops strategies to mitigate the impact of such extreme events. The proposed schemes broadly aim to- a) improve grid performance in the immediate aftermath of a disruptive event, and b) enhance grid monitoring to identify precursors of impending failures. To improve grid performance after a disruption, we propose a proactive islanding strategy for the bulk power grid, aimed at arresting the propagation of cascading failures. For the distribution network, a mixed-integer linear program is formulated for identifying optimal sub-networks with load and distributed generators that may be retrofitted to operate as self-adequate microgrids, if supply from the bulk power systems is lost. To address the question of enhanced monitoring, we develop model-agnostic, computationally efficient recovery algorithms for archived and streamed data from Phasor Measurement Units (PMU) with data drops and additive noise. PMUs are highly precise sensors that provide high-resolution insight into grid dynamics. We also illustrate an application where PMU data is used to identify the location of temporary line faults.
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Arguence, Olivier. "Modélisation des ilots non-intentionnels et caractérisation des méthodes passives de détection d’ilotage." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT045/document.
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Un ilot non-intentionnel peut se former lorsque d’une petite partie du réseau est déconnectée du reste du système électrique, et continue pourtant de fonctionner à l’insu du gestionnaire de réseau en raison de la présence de générateurs locaux. Cet événement n’est pas voulu : le comportement des ilots n’est pas maitrisé, ce qui entraîne des risques potentiels pour les personnes et équipements électriques. L’ilotage non-intentionnel est un phénomène complexe et mal connu, aujourd’hui considéré comme rare, mais dont la probabilité d’apparition tend actuellement, a priori, à s’accroître progressivement. Cet accroissement est dû à l’effet conjugué de plusieurs phénomènes : premièrement, le développement des installations de production de petite et moyenne puissance, raccordées directement au réseau de distribution ; deuxièmement, l’élargissement des seuils de détection qui sont utilisés dans leurs protections de découplage ; et troisièmement, l’implémentation dans ces installations d’automatismes de régulation de puissance active et réactive. Dans ce contexte, la chaire industrielle Smartgrid d’Enedis a financé ces travaux de thèse afin de mieux caractériser ces phénomènes d’ilotage et d’améliorer leur détection.Afin d’atteindre ces objectifs, une première priorité de la thèse a été d’améliorer la compréhension des ilots non-intentionnels au travers d’une approche analytique. Celle-ci a notamment permis la résolution formelle d’un modèle simple capable d’expliquer le comportement en fréquence d’un îlot. Ces résolutions ont été enrichies par de nombreuses expérimentations en laboratoire et par des simulations numériques. Les modèles ont fait l’objet d’une étude bibliographique approfondie, notamment pour le choix des modèles de charge.Une seconde priorité de la thèse a été d’estimer l’efficacité des méthodes passives de détection d’ilotage au travers du calcul de la zone de non-détection (ZND). L'influence de plusieurs charges sur la ZND a été analysé, ce qui a permis d’améliorer la compréhension du phénomène complexe que sont les ilots non-intentionnels. L’efficacité des nouvelles protections anti-ilotage utilisant des seuils sur la dérivée en fréquence (ROCOF) a aussi fait l’objet d’évaluations approfondies. Enfin, les méthodes de calcul de ZND ont été améliorés par rapport aux méthodes préexistantes, ce qui a permis de radicalement améliorer l’estimation faite de l'impact des nouvelles régulations de puissance P(f) et Q(U)<br>Unintentional islands might appear when a subpart of the grid is disconnected from the power system and keeps working because of local generation. These events are unwanted: their behavior is not controlled and leads to potential risks for people and for electric equipment. Unintentional islanding is a complex phenomenon and badly understood. Nowadays it is considered to be rare, but a priori its occurrence probability is currently steadily increasing. This rising is the consequence of several phenomena: firstly, the development of distributed generation of small and average size directly connected to the distribution grid; secondly, the enlargement of frequency thresholds used by isolating protections; and thirdly, the implementation of power regulations of active and reactive power in the generation unit. Within this context, the Smart Grid chair of Enedis financed this PhD thesis in order to better characterize these islanding phenomena and to improve their detection.To achieve these targets, a first priority of the PhD was to improve the comprehension of unintentional islanding through symbolic calculation. This approach makes it possible to solve a simple model and to explain the evolution of the frequency during an island. These results are completed with several laboratory experiments and by numeric simulations. Models are designed based on a thorough bibliography, in particular for load modeling.A second priority of the PhD was to estimate the efficiency of anti-islanding protections through the computation of non-detection zone (NDZ). The impact of several loads on the NDZ is analyzed to improve the understanding of unintentional islanding, which is a complex phenomenon. The efficiency of new anti-islanding protections using thresholds on the rate of change of frequency (ROCOF) is also thoroughly evaluated. It is shown that the computation method used by the protection plays a key role. At last, the calculation methods of the NDZ is improved regarding previous methods. Among other things, it allows to radically change the estimations of the impact of new power regulations P(f) and Q(U)
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Barik, Tapas Kumar. "Modern Adaptive Protection and Control Techniques for Enhancing Distribution Grid Resiliency." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103644.
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Power distribution systems have underwent a lot of significant changes in the last two
decades. Wide-scale integration of Distributed Energy Resources (DERs) have made the
distribution grid more resilient to abnormal conditions and severe weather induced outages.
These DERs enhance the reliability of the system to bounce back from an abnormal situation
rather quickly. However, the conventional notion of a radial system with unidirectional
power flow does not hold true due to the addition of these DERs. Bidirectional power flow
has challenged the conventional protection schemes in place. The most notable effects on
the protection schemes can be seen in the field of islanding or Loss of Mains(LOM) detection
and general fault identification and isolation. Adaptive protection schemes are needed to
properly resolve these issues. Although, previous works in this field have dealt with this
situation, a more comprehensive approach needs to be taken considering multiple topologies
for developing adaptive protection schemes. The most common protective devices widely
deployed in the distribution system such as overcurrent relays, reverse power relays at Point
of Common Coupling(PCC), fuses, reclosers and feeder breakers need to studied in implementing
these schemes.
The work presented in this dissertation deals with simulation based and analytical approaches
to tackle the issues of islanding and adaptive protection schemes. First we propose a multiprinciple
passive islanding detection technique which relies on local PCC measurements, thus
reducing the need of additional infrastructure and still ensuring limited Non Detection Zone
(NDZ). The next step to islanding detection would be to sustain a islanded distribution
system in order to reduce the restoration time and still supply power to critical loads. Such
an approach to maintain generator load balance upon islanding detection is studied next by
appropriate shedding of non-critical and low priority critical loads based upon voltage sensitivity
analysis. Thereafter, adaptive protection schemes considering limited communication
dependency is studied with properly assigning relay settings in directional overcurrent relays
(DOCRs), which are one of the most widely deployed protective devices in distribution
systems by catering to multiple topologies and contingencies. A simulation based technique
is discussed first and then an analytical approach to solve the conventional optimal relay
coordination problem using Mixed Integer Linear Programming (MILP) with the usage of
multiple setting groups is studied. All these approaches make the distribution more robust
and resilient to system faults and ensure proper fault identification and isolation, ensuring
overall safety of system.<br>Doctor of Philosophy<br>With widespread integration of inverter-based distributed energy resources (DERs) in the
distribution grid, the conventional protection and control schemes no longer hold valid.
The necessity of an adaptive protection scheme increases as the DER penetration in the
system increases. Apart from this, changes in system topology and variability in DER
generation, also change the fault current availability in the system in real-time. Hence, the
protection schemes should be able to adapt to these variations and modify their settings for
proper selectivity and sensitivity towards faults in the system, especially in systems with high
penetration of DERs. These protection schemes need to be modified in order to properly
identify and isolate faults in the network as well as correctly identify Loss of Mains (LOM)
or islanding phenomenon. Special attention is needed to plan the next course of action after
the islanding occurrence. Additionally, the protective devices in distribution system should
be utilized to their maximum capability to create an adaptive and smart protection system.
This document elaborately explains the research work pertaining to these areas.
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Souza, Paulo Victor Lameira de. "Um método grafo-algébrico para projeto de ilhamento controlado em Sistemas Elétricos de Potência." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-18072014-095619/.
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Neste trabalho, um novo método grafo-algébrico para o projeto de ilhamento intencional é proposto. O ilhamento intencional é um dos últimos recursos utilizados pelos operadores para evitar um colapso total do sistema elétrico. Ele objetiva dividir um sistema elétrico em dois ou mais subsistemas estáveis quando não é possível garantir a estabilidade do sistema interligado. O método desenvolvido é uma extensão de um método grafo-algébrico, baseado na fatoração da matriz incidência ramo-nó e que foi desenvolvido para a identificação de ilhamento não intencional, para o problema de projeto de ilhamento intencional. A aplicação da fatoração da matriz incidência ramo-nó no problema de projeto de ilhamento é contribuição inédita deste trabalho. O método proposto identifica os conjuntos de corte, compostos por linhas de transmissão/transformadores (ramos), aptos a dividir um sistema elétrico de potência conexo em dois ou mais subsistemas (ilhas), sob a condição de um número mínimo, previamente estabelecido, de ramos interrompidos ou uma interrupção mínima de fluxo de potência ativa. A identificação dos conjuntos de cortes é realizada por meio de uma fatoração ordenada da matriz incidência nó-ramo e por um processo de regularização de cortes. O método foi testado com resultados promissores em alguns sistemas elétricos de pequeno e médio porte. Apresentou boas características que sugerem que o mesmo seja adequado para aplicações em tempo real. O método fornece a informação das barras que formam cada ilha, adapta-se facilmente a mudanças na topologia e pode ser facilmente implementado com rotinas já existentes nos programas de computador comumente utilizados para análise de sistemas elétricos de potência. Trabalhos futuros são necessários para testar a metodologia em sistemas de maior porte, para avaliar a eficiência computacional do método e comparar com a eficiência de outros métodos relatados na literatura.<br>In this work , a new graph-algebraic method for the design of intentional islanding is proposed. Intentional islanding is one of the last resources used by the Power Electrical System Operators to avoid a total collapse of the electrical system. It aims to divide a power system into two or more stable subsystems when it is not possible to guarantee the stability of the interconnected system. The developed method is an extension of a graph-algebraic method, which is based on a factorization of the branch-node incidence matrix and which was developed to identify unintended islanding, to the problem of intended. The unprecedented contribution of this work is the application of the factorization of the incidence branch-node matrix in the design of islanding control. The proposed method identifies the cutsets, composed of transmission lines / transformers (branches) , able to divide a connected Electrical Power System in two or more subsystems (islands), under the constraint of a minimum number of interrupted branches or minimal interruption of power flow. The identification of cutsets are made through an ordered factorization of the incidence branch node matrix and a regularization process of cutsets. The method has been tested with promising results in some electrical systems of small and medium size. It has shown good characteristics which suggests that it is suitable for real-time applications. The method automatically provides the set of buses that form each island, it easily adapts to changes in topology and can be easily implemented with routines that are already developed in existing computer programs commonly used for analysis of electric power systems. Further work is needed to test the methodology in larger systems to evaluate the computational efficiency of the method and compare with the efficiency of other methods reported in the literature.
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Cesar, Thaissa de Melo. "Uso da transformada wavelet para análise dinâmica de um sistema fotovoltaico conectado à rede e sua interação com a rede elétrica." Universidade Federal de Goiás, 2018. http://repositorio.bc.ufg.br/tede/handle/tede/8265.
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Previous issue date: 2018-03-09<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>This work presents a study on the application of the wavelet transform in the monitoring and
analysis of the power quality and in the detection of islanding conditions in distributed generation
systems, addressing a grid connected photovoltaic system as a case study. Initially, an introduction
about distributed generation systems, standards and requirements for operation was made. Next,
the concepts and parameters related to electric power quality and islanding conditions are
presented. Then a review of the wavelet transform is presented, showing the concept of
multiresolution analysis and the main applications in the topic addressed. The wavelet transform is
an important contribution to time-frequency localization methods for the analysis of transient
signals. A multiresolution analysis was proposed through the discrete wavelet transform for
voltage analysis at the common coupling point between the generation system and the electric grid.
The standard deviation and the variation of the details coefficients of the wavelet transform were
used for the detection and classification of disturbances. In the application of the method, pure
sine-wave voltages with different types of disturbances were considered: voltage sag, voltage
sweel, interruption, oscillatory transients and noise. And three cases of dynamic island detection
were simulated with a grid connected photovoltaic system. The results obtained are presented and
discussed for validation of the wavelet transform application in the analysis of grid connected
photovoltaic systems.<br>Este trabalho apresenta um estudo sobre a aplicação da transformada wavelet no
monitoramento e análise da qualidade da energia elétrica e na detecção de ilhamento em
sistemas de geração distribuída, abordando como estudo de caso um sistema fotovoltaico
conectado à rede elétrica. Inicialmente é feita uma introdução sobre os sistemas de geração
distribuída, as normas e requisitos para operação. Em seguida são apresentados os conceitos
e parâmetros relativos à qualidade de energia elétrica e condições de ilhamento. Depois é
mostrada uma revisão da transformada wavelet, apresentando o conceito de análise
multirresolução e as principais aplicações no tema abordado. A transformada wavelet é uma
importante contribuição para métodos de localização tempo-frequência na análise de sinais
transitórios. Foi proposta uma análise multirresolução através da transformada wavelet
discreta para análise da tensão no ponto de acoplamento comum entre o sistema de geração
e a rede. O desvio padrão e a variação dos coeficientes de detalhes da transformada foram
utilizados para a detecção e a classificação dos distúrbios. Na aplicação do método, foram
consideradas tensões senoidais puras e com diferentes tipos de distúrbios: afundamento,
elevação, interrupção, transitórios oscilatórios e ruídos. E foram simulados três casos de
detecção de ilhamento dinâmica em um sistema fotovoltaico conectado à rede. Os resultados
obtidos validam a proposta de aplicação da transformada wavelet na análise de sistemas
fotovoltaicos conectados à rede.
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Theodoro, Edson Aparecido Rozas. "Desenvolvimento de uma ferramenta computacional para análise de segurança dinâmica, no contexto da estabilidade transitória, de sistemas elétricos de potência via métodos diretos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-20042010-100251/.
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O presente trabalho tem como objetivo desenvolver um programa computacional para análise de contingências, no contexto da estabilidade transitória, capaz de identificar as contingências críticas do sistema elétrico de potência via métodos diretos. A análise de estabilidade é realizada em diversas etapas, onde serão aplicados diversos filtros, baseados em métodos de análise de ilhamento, não existência de pontos de equilíbrio, PEBS, BCU e simulação computacional, no domínio do tempo, do sistema. Em cada etapa da análise, os casos serão classificadas como sendo estáveis, instáveis ou incertos segundo diferentes critérios, restando portanto, ao fim de cada etapa, um conjunto menor de possíveis contingências críticas. A metodologia proposta foi desenvolvida para modelos de SEPs com rede reduzida, porém as técnicas discutidas neste trabalho aplicam-se também a modelos que preservam a estrutura do sistema de transmissão.<br>The main objective of this work is to design a transient stability screening contingency program that is able to identify all critical contingencies in an electric power system using direct methods. The stability assessment is performed through several steps by mean of filters based on islanding detection, nonexistence of equilibrium points, PEBS, BCU and time-domain simulation of the power system. In each step of the analysis, all cases are classified as stable, unstable or uncertain cases by different criteria, resulting at the end of each step in a small number of possible critical contingencies. The proposed methodology was designed for reduced models of electric power systems, but all the techniques discussed in this work are also suitable for preserving structure models.
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Fredriksson, Jonatan. "Anpassning av småskaliga vattenkraftverk för ö-drift av lokalt elnät." Thesis, Uppsala universitet, Elektricitetslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388143.
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This master thesis examines technical requirements for small hydro power plants (HPP) to operate proximate parts of the power grid in island mode. The work examines how small hydropower can be modified and complemented with additional technologies to achieve sufficient frequency control capabilities. A case study was performed within the concession area of power grid operator Ålem Energy. One of the HPPs, located in Skälleryd, is owned by Ålem Energy and became the focal point of the study. Relevant parts of the concession area were surveyed for properties such as system inertia, electric load and available power. Furthermore, a model of Kaplan turbine 1 in Skälleryd HPP was created with the purpose of studying the benefits of bypassing regulation control from the wicket gates directly to the runner. The method was tested in an off-grid islanding test. Frequency control of the turbine was tested powering electric heaters and, using a new method, controlling a virtual power grid. Finally, a theory was developed to estimate the transient disturbance resilience (TDR) of a power grid. The theory was applied to the HPP in Skälleryd to suggest modifications for the plant to achieve sufficient islanding capabilities. The survey of the power system revealed a promising potential for the HPPs to operate in island mode, especially at later stages when the grid spans several HPPs for more system inertia. The available power from the HPPs was however strongly seasonal which imposes flexibility on a future plan of action for engaging the grid in island mode. The method of controlling the turbine power from the runner proved to have several difficulties. Firstly, the current hydraulics system was not able to freely control the runner as the hydrodynamic forces on the runner blades were too large. Secondly, the method was found to be unstable due to inherent amplification of speed deviations. Furthermore, the low inertia at Skälleryd is likely detrimental to the lone frequency control of the turbine. Therefore other methods for improving frequency control were suggested. The developed theory for TDR was used to create charts describing the TDR for various combinations of system inertia and regulation speed. By studying the proprieties of Skälleryd HPP in the charts the necessary modifications could be rationally chosen. A frequency regulating dummy load was found to be the simplest option. A control scheme was suggested with the dummy load performing primary frequency control and the turbines at Skälleryd performing secondary control, restoring the dummy load to its nominal state.
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Lin, Chung-Hsin, and 林仲信. "Islanding Prevention with Grid-Connected PV Power System." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/40548180575950049753.
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碩士<br>國立中正大學<br>電機工程所<br>94<br>A grid-connected PV power system with islanding prevention is proposed in this thesis. The proposed PV power system co¬n¬sists of a power stage and a control stage. In the power stage, a boost dc/dc converter incorporated with the perturba-tion-and-observation algorithm can draw the maxi¬mum power from the PV array. Then, a full-bridge dc/ac inverter will deliver real power to the utility line. Also the RLC parallel load for islanding test described in IEEE 929 and UL 1741 are estab-lished. In the control stage, the control circuit is realized by using two microcon-trollers. One is used to achieve the maximum power point tracking for the PV array by using the perturbation-and-observation algorithm. The other one is used to im-plement the function of grid-connection. Finally, experimen¬tal re¬sults have been conducted to verify the performance of the grid-connected PV power system with islanding prevention.
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Joshi, Swarup Ranjan. "Algorithm for Islanding Detection in Distributed Generation System." Thesis, 2015. http://ethesis.nitrkl.ac.in/7281/1/Algorithm_Joshi_2015.pdf.
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Power industry has been emphasizing more importance on distributed generation because there are new technology like fuel cell, wind turbine and power electronic use for advancement of power system has been evolved so much which cannot be possible without distributed generation. Hence distributed generation (DG) has become an inseparable part in power system and gained so much importance because of economical and environmental purpose. Islanding is a situation where a part of the distributed generation system containing a distributed generator gets electrically isolated from the remainder of the power system still continues to energise the network where the situation has occurred. Thus it has become important that the portion where islanding has occurred must detect this situation immediately for safety purpose. If tripping doesn’t occur in time there can be various and critical problem. Currently in industry practice we disconnect all distributed generators after islanding has occurred. Generally a distributed generator should be disconnected within 0.1s to 0.3s after loss of grid/main supply. To achieve this, each distributed generator must be supplied with an anti-islanding device which detect islanding like vector surge relay and ROCOF relay.
In this thesis we have discussed about current practices and development of power system through distributed generation, Islanding and other problems in distributed generation system, importance of islanding detection , islanding detection techniques which are used in common, Wavelet transform and hybrid technology developed in islanding detection, New method based on negative sequence component’s like voltage and current for islanding detection of wind turbines using the wavelet transform, Usage of both active and passive method and how it eliminates most of the non-detective zone, The coefficient at d-1 separation through daubechies wavelet transform localizes the corresponding islanding events and the change in energy and standard deviation at d-1 levelfor one cycle gives the threshold comparing which we conclude about the islanding condition , The usage of positive feedback and continuous feedback method and the implementation of DQ model of electrical machine for hybrid detection technology, simulation on islanding detection based these two techniques using SIMULINK and MATLAB is done. Finally a case-study of distributed Generation System containing 9 MW wind farms, 500 kW resistive loads and ,9MVAR filters, are considered for wavelet transform method and results are shown on islanding detection using those data and for hybrid method the same is done using feedback method and dq implementation for active method and checking the parameter through passive method with and without the controller. For islanding and nonislanding condition different conditions are checked so that islanding conditions can be clearly distinguished from the non-islanding condition. Sudden load change, line trip, islanding and normal condition for wavelet transform and detection of islanding with and without controller in hybrid method found to be highly effective in islanding detection. These two methods are then compared according to their stability and importance in different condition of power syste.
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Huang, Tsungfu, and 黃琮富. "Islanding Detection and Prevention of Green Power DC-Microgrid System." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/06039966084716348377.
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碩士<br>國立中正大學<br>電機工程研究所<br>99<br>Due to abnormal operation of electricity grid, a green power supply system may supply power to load independently and becomes islanding when it operates in grid-connection mode, affecting the power quality and causing damage to equipment and the safety of power distribution system. Therefore, the islanding should be excluded as soon as it is detected. This thesis combines the passive detection of abnormal voltage and frequency ranges, and the active detection of current phase shift to achieve islanding prevention. Using MATLAB/Simulink as system simulation platform, this thesis also presents the simulation of simulates islanding with the testing load of full-bridge inverter proposed by IEEE 1547.1. Finally, experimental results have been conducted to verify the performance of the islanding detection and prevention.
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Ke, Ming-Te, and 柯明德. "Improved Active Islanding Detection Methods for Distributed Power Generation System." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/98326821738474262567.
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碩士<br>國立高雄應用科技大學<br>電機工程系<br>97<br>“Security” is the major priority of distributed generation system connected in parallel with the utility grid. Therefore, effective detection of islanding operation has long been the main concern. In this thesis, the notion of periodical disturbing apply to active islanding detection methods is proposed, including the current amplitude disturbing method and the active frequency drift detection method with periodical disturbing are examined. These modified islanding detection methods aim to make a balance between maintaining the quality of power supply and increasing the performance of islanding detection. In the thesis, Matlab/Simulink/SimPowerSystems is adopted to establish the simulated power system composed of distribution generation and utility grid, and the performance of islanding detection methods are studied. Simulation results positively show that applying the notion of periodical disturbing to active islanding detection methods greatly enhances the efficacy on balancing the effectiveness of islanding detection and the quality of power supply.
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Talwar, Saurabh. "Islanding detection in distribution system embedded with renewable-based distributed generation." Thesis, 2012. http://hdl.handle.net/10155/290.
Full textAbstract:
Classical view of power system is characterized by a unidirectional power flow from
centralized generation to consumers. Power system deregulation gave impetus to a
modern view by introducing distributed generations (DGs) into distribution systems,
leading to a bi-directional power flow. Several benefits of embedding DGs into
distribution systems, such as increased reliability and reduced system losses, can be
achieved. However, when a zone of the distribution system remains energized after being
disconnected from the grid, DGs become islanded and early detection is needed to avoid
several operational issues.
In response to this call, a wavelet-based approach that uses the mean voltage index is
proposed in this work to detect islanding operation in distribution systems embedding
DGs. The proposed approach has been tested in several islanding and non-islanding
scenarios using IEEE 13-bus distribution system. The results have shown the
effectiveness of the proposed approach compared to other islanding approaches
previously published in the literature.<br>UOIT
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Huang, Ming-Chien, and 黃明茜. "A Study of Detection of Islanding Events for Taiwan Power System." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/66381190176311972978.
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碩士<br>國立臺灣大學<br>電機工程學研究所<br>104<br>Power system islanding disturbance is one of the most severe consequences of wide-area system failures. The purpose of this thesis is to propose an islanding contingency detecting and warning scheme to detect whether there is an islanding scenario in the power grid. The islanding contingency detecting and warning scheme can help power monitoring personnel detect the islanding operation immediately. It also enhances the power stability of the Taiwan grid. The proposed system in this study is based on the information collected by phasor measurement units which is applied to the islanding operation detection algorithm to detect the fault. The standard of phasor measurement unit and optimal PMU placement are analyzed and discussed. The PSS/E software is employed to simulate the islanding scenarios in Taiwan power grid and develop the algorithm in Matlab for judgment of the islanding operation.
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Li, Chia Huang, and 李佳遑. "Real-Time Simulation of Micro-Grid Energy Management and Islanding Detection with Power Condition System." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/92833424539758006774.
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碩士<br>國立聯合大學<br>電機工程學系碩士班<br>103<br>Based on real-time simulation system, which constructs the dynamic models of distributed generation (solar cell, wind-driven generation, diesel-driven generator), converter (including controller), vanadium redox flow battery energy storage system, and power conditioner in micro-grid systems with Matlab/SimPowerSystems as well as relevant energy management systems, dynamic smooth intermittent renewable energy generation designed with double fuzzy control rules is applied to prevent supply mains from extreme power fluctuation. Moreover, the micro-grid energy management system receives the micro-grid dynamic simulation state from the real-time simulator every one hour and plans the grid generating capacity in 24 hours with linear programming in order to achieve the optimal economical benefit of micro-grid.
In addition to above dynamic control/response of micro-grid and the economical benefit of energy management, a new-style passive islanding detection is also proposed in this study. In comparison with other passive methods, the proposed method presents the advantages of simple design and accurate and fast detection of islanding occurrence.
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Chang, Jen-Chien, and 張仁謙. "Islanding Detection Techniques for Wind Power Generation Systems." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/53092952277566792014.
Full textAbstract:
碩士<br>中原大學<br>電機工程研究所<br>92<br>Renewable energy has been drawing more attention since the advent of global warming effects. Multiple energy sources have currently become one of the goals for the energy policy of the developed countries around the world. Over the last decades, an increased percentage of the installation of dispersed mall-scaled generators, such as battery energy storage systems, photovoltaic systems, wind generation, and cogeneration, have been operated effectively in parallel with utility networks.
Islanding operation is a situation in which the dispersed power system keeps supplying electric power to a distribution network even when the utility grid loses power due to fault or maintenance. When the islanding operation occurs, the islanding detection systems should detect it and disconnect from the grid immediately.
The existing of the categories of islanding detection methods, are generally classified into passive and active techniques. Nevertheless, it has been demonstrated that “non-detection zones” still exist for some specific load impedances. Hence, a new algorithm using differential voltage correlation method is proposed in this paper to alleviate this problem. The DVC method injects a perturbing periodic signal into the inverter output current to the power system and monitors the correlation function between the periodic signal and the perturbed voltage at the connection point. Through the proposed method, an islanding detection index can be evaluated that serves as a useful reference to activate the protective relays.
To verify the proposed approach for islanding detection of dispersed wind power generation systems, the method has been implemented in Matlab programming tools. This approach has been evaluated under different scenarios, which include both loss of grid interconnection and parallel operation. Impacts of wind speed abrupt change and power-quality disturbances on the detection performance are also examined. From the test results, the effectiveness of the approach to reduce non-detection zone and improve the diagnosis accuracy has been demonstrated.
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Saikia, Himanshu Jyoti. "Development of a Fuzzy Based Algorithm for Islanding Detection of a Grid Connected DG." Thesis, 2017. http://ethesis.nitrkl.ac.in/8911/1/2017_MT_HJSaikia.pdf.
Full textAbstract:
In recent years, the demand for power has increased and there has been a growing demand for Renewable Energy generating units such as the wind, water, fuel cell, photovoltaic units. These energy units produce low pollution in comparison to fossil fuels. With the introduction of such Distributed Generation units, an improvement in electricity service, reliability and power quality in comparison to the power availed from the grid alone has been observed. Such environmental concerns and deregulation in market power has caused the DG units into momentum. The DG also provides a relative low capital cost in response to incremental changes in power, while placing the power source within the already existing network and sending the power back to the grid when required. Islanding occurs when a part of the distribution system turns out to be electrically disconnected from the rest of the power system, yet keeps on being energized by the DG associated with the subsystem. The formation of such power island may compromise service operation, reliability, deterioration in power and pose as a threat to the load utility. Current IEEE interconnection standards (IEEE 1547) mandate that the control and protection measures should be in place to lessen the probability of an unintentional island, and to minimize the duration of an islanding condition, if one should occur. In order to prevent such situations, the power system networks are installed with islanding detection devices. In this work a fuzzy logic controller based on islanding detection methods have been proposed and a comparison with the traditional passive islanding methods has been done to detect the Major Island formation during loss of mains. Furthermore, the controller has been configured to incorporate multi DG interfacing to the power system network attributing to detection of Minor Island formation. The controller has been configured for distinction between the load change and the islanding.
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Li, Yan. "Power management of power electronics interfaced low-voltage microgrid in islanding operation." Master's thesis, 2010. http://hdl.handle.net/10048/951.
Full textAbstract:
Thesis (M.Sc.)--University of Alberta, 2010.<br>A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Power Engineering and Power Electronics, Department of Electrical and Computer Engineering. Title from pdf file main screen (viewed on June 13, 2010). Includes bibliographical references.
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Tseng, Ying-Chuan, and 曾映銓. "Study of the Defense Mechanism and Wind Power Penetration Effects on Islanding Power Systems." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/28158973381834047607.
Full textAbstract:
碩士<br>國立中正大學<br>電機工程研究所<br>103<br>This thesis develops an intelligent defense mechanism, the maximum wind penetration, and system protection planning, as well as establishes an alarm strategy for isolated island systems. This thesis takes Penghu, Kinmen and Mazu systems as examples to identify the feasibility of the proposed defense system, wind penetration and the forecasting accuracy. First, this thesis uses the actual operational data measured in Penghu, Kinmen and Mazu systems; then creates an online database by implementing various simulation analyses under different operational patterns. The software, namely PSS/E, was utilized to perform the simulation, and we design a number of diesel generator tripping accidents to acquire the results of frequency responses by simulation. Next, this thesis designs the intelligent forecasting system by using back propagation artificial neuron network (BPANN) that can effectively predict system frequency response once all of wind turbines tripping or a diesel generator tripping occurs. The forecasting results can assist in planning corresponding system protection strategies, including generator rescheduling, increase of the number of diesel generator units, increase or reduce the number of wind turbines into the grid , or performing optimized low-frequency load shedding strategy.
The main target of this thesis is to improve the system stability on the remote island systems. The simulation results show that the proposed BPANN can accurately estimate frequency nadir, rate of frequency change, the minimum load shedding amount under stable operation, and the maximum wind penetration. The results of the thesis can provide the system operator with a reference relative to the preventive dispatch and the plan of load shedding.
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Lin, Feng-Yi, and 林峰誼. "Study on Islanding Detection for Distributed Type Photovoltaic Power Generation Systems." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/46244887490766642134.
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碩士<br>國立臺灣科技大學<br>電機工程系<br>97<br>This thesis presents the modeling of a photovoltaic power generation system and islanding detecting methods by using Matlab/Simulink simulation software. First of all, the study carried out modeling, simulation, and analysis for output characteristics of the solar cell modeling under the environment of different temperatures and sunlight intensities. Moreover, the study built solar power tracking model by using the DC/DC boost conve rter and perturbation & observation algorithm. Finally, the system can operate in a grid-connected mode for supplying A.C. source to the loads.
The islanding phenomenon resulted from the system in a grid-connected mode that has hazards to load, inverter and personnel security, so all grid-connected inverters should have the ability to detect islanding status and stop the run mode of grid-connect. This thesis introduces the background of islanding detection of grid-connect inverter and the system equivalent mode. And the study deeply discuss the principle of current disturbance and frequency drift method between active islanding detection system and inverter. By analyzing the simulation result, the islanding phenomenon can also be detected under the condition of power matching.
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Ju, Yi-Jyh, and 朱翊誌. "Islanding Operation Strategy of Micro-Grid Systems with Wind Power Generator." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/p55dt9.
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碩士<br>國立中山大學<br>電機工程學系研究所<br>97<br>To increase the allowable capacity of wind generation and system reliability of distribution system for islanding operation, an actual Taipower feeder has been selected for computer simulation. The voltage enhancement of distribution feeders with fixed speed wind generator has been obtained by using the static synchronous compensator(STATCOM). The model of
Doubly-Fed induction generator(DFIG) in Matlab/Simulink has also been applied in the feasibility study of islanding operation for Taipower feeder. The critical clearing time of fault contingency is solved by considering the low voltage ride through (LVRT) capability of wind generators (WG) and the CBEMA curve of sensitive loads. In this way, feeder circuit breaker(CB) can be tripped in time to achieve islanding operation of distribution feeders without causing the tripping of WG due to voltage disturbance for the system fault contingency. To restore the stable operation of distribution feeders after being isolated from the rest of the power system, an adaptive load shedding scheme has been presented to disconnect the proper amount of system loading to achieve the balance of wind power generation and load demand according to the variations of feeder load profile and wind speed. It is found that system voltage sag problem due to severe fault contingency can be mitigated effectively by using the STATCOM for the support of low voltage ride through capability of WG. With the proper design of protection relay settings for feeder CB tripping and load shedding scheme, the WG and critical loads can be prevented from tripping during transient disturbance to ensure the successful islanding operation of distribution system.
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Chiu, Chia-Lung, and 邱嘉隆. "Development of Maximum Power Point Tracking and Islanding Detection Technologies for Photovoltaic Power Generation Systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/76437001457681216142.
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碩士<br>國立勤益科技大學<br>電機工程系<br>98<br>The purpose of this thesis is to develope a maximum power point tracking (MPPT) technique and an islanding phenomenon detection technique for improving the performance of photovoltaic(PV) power generation systems. First, the PSIM software was used to establish a 516W grid-connected PV system for completing the simulation of the proposed MPPT method and islanding detection method. To make full utilization of PV array output power which depends on irradiances, an intelligent MPPT method is developed in this thesis. The proposed MPPT method based on extension theory can automatically adjust the step size to track the PV array maximum power point. Moreover, this thesis proposed an islanding phenomenon detection technique based on the extension theory. The proposed technique can correctly differentiate the islanding operation of a PV power generation system and disconnect the load from the photovoltaic power generation system quickly. Some simulation results are made to demonstrate the validities of the proposed extension maximum power point tracking method and the extension islanding detection method of photovoltaic system. In addition, a maximum power point tracker is implemented using programmable system on chip (PSoC) to reduce the hardware circuit size. Some experimental results are also made to verify that the proposed extension maximum power point tracking method can provide a good dynamic response and steady-state performance for a photovoltaic power generation system.
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"Distributed Photovoltaic Generation in Residential Distribution Systems: Impacts on Power Quality and Anti-islanding." Master's thesis, 2013. http://hdl.handle.net/2286/R.I.17741.
Full textAbstract:
abstract: The past few decades have seen a consistent growth of distributed PV sources. Distributed PV, like other DG sources, can be located at or near load centers and provide benefits which traditional generation may lack. However, distribution systems were not designed to accommodate such power generation sources as these sources might lead to operational as well as power quality issues. A high penetration of distributed PV resources may lead to bi-directional power flow resulting in voltage swells, increased losses and overloading of conductors. Voltage unbalance is a concern in distribution systems and the effect of single-phase residential PV systems on voltage unbalance needs to be explored. Furthermore, the islanding of DGs presents a technical hurdle towards the seamless integration of DG sources with the electricity grid. The work done in this thesis explores two important aspects of grid inte-gration of distributed PV generation, namely, the impact on power quality and anti-islanding. A test distribution system, representing a realistic distribution feeder in Arizona is modeled to study both the aforementioned aspects. The im-pact of distributed PV on voltage profile, voltage unbalance and distribution sys-tem primary losses are studied using CYMDIST. Furthermore, a PSCAD model of the inverter with anti-island controls is developed and the efficacy of the anti-islanding techniques is studied. Based on the simulations, generalized conclusions are drawn and the problems/benefits are elucidated.<br>Dissertation/Thesis<br>M.S. Electrical Engineering 2013
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Liou, Kang-Jian, and 劉康健. "Application of Extension and Chaotic Synchronization Methods to Detect Islanding Effect of Photovoltaic Power Systems." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/03974857563109413614.
Full textAbstract:
碩士<br>國立勤益科技大學<br>電機工程系<br>103<br>The detection of islanding effect is one of the important issues for photovoltaic (PV) power system, the islanding effect occurs when the distributed power source is disconnected from the mains supply, and the power is still supplied in partial load area, which may injure the maintenance personnel or damage equipments. The novelty of this study is combining Extension and Chaos synchronization (CS) on islanding detection, and use non-autonomous Chua's circuit for detection platform. Simulation and experimental designs through PSIM were applied to mimic PV power system, and demonstrate the effectiveness of the proposed method. Results show that the accuracy of the proposed methods achieves 98% on detecting the islanding effect in PV power system.
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Σταθόπουλος, Κωνσταντίνος. "Μελέτη/κατασκευή υβριδικού συστήματος (κυψέλη υδρογόνου και PV στοιχείων) και της συμπεριφοράς των διατάξεων προστασίας". Thesis, 2013. http://hdl.handle.net/10889/6025.
Full textAbstract:
Η ενεργειακή κρίση που προκάλεσε η χρήση των υδρογονανθράκων ως κύρια πηγή παραγωγής ενέργειας, η προσπάθεια κάθε κράτους για απεξάρτηση του από τις πετρελαιοπαραγωγικές χώρες αλλά και η ανάγκη για μορφές ενέργειας χωρίς αρνητική επίδραση στο περιβάλλον οδήγησαν στην ανάπτυξη των ανανεώσιμων μορφών ενέργειας.
Για την εμπορική τους, όμως, εκμετάλλευση ήταν απαραίτητη η επίλυση των τεχνικών προβλημάτων που εμφανίστηκαν, ιδιαίτερα όσο αναφορά τη σύνδεση κατανεμημένων παραγωγών με το υπάρχον ηλεκτρικό δίκτυο.
Tο φαινόμενο της νησιδοποίησης (islanding), δηλαδή η μη διακοπή της παροχής ηλεκτρικού ρεύματος στο διασυνδεδεμένο δίκτυο από το κατανεμημένο παραγωγό όταν αυτός έχει αποσυνδεθεί από το κεντρικό δίκτυο, με κίνδυνο για τους εργαζόμενους και τις εκάστοτε συνδεδεμένες σε αυτόν συσκευές, πρέπει να αντιμετωπίζεται άμεσα.
Σκοπός της εργασίας αυτής είναι η θεωρητική σύγκριση των προτεινόμενων τεχνικών ελέγχου νησιδοποίησης, η επιλογή και η προσομοίωση στο ATP-EMTP της καταλληλότερης από αυτές.
Στο πρώτο κεφάλαιο αναλύεται η σημερινή κατάσταση όσο αναφορά την παραγωγή ενέργειας από την κάθε ανανεώσιμη πηγή ενέργειας και τονίζεται η εξέχουσα θέση και η επικράτηση της ηλιακής ενέργειας και των φωτοβολταϊκών συστημάτων.
Στο δεύτερο κεφάλαιο αναπτύσσεται το φαινόμενο της νησιδοποίησης και μια σειρά από προτεινόμενες τεχνικές ανίχνευσης και διακοπής της νησιδοποίησης.
Στο τρίτο κεφάλαιο αναλύονται οι τεχνικές με χρήση άεργου ισχύος και γίνεται θεωρητική ανάλυση της επιλεγμένης RPV μεθόδου.
Στο τέταρτο και πέμπτο κεφάλαιο περιγράφονται οι δυνατότητες του ATP-EMTP, η προσομοίωση της μεθόδου και τα αποτελέσματα που προέκυψαν. Τέλος η εργασία ολοκληρώνεται από τα συμπεράσματα μετά την προσομοίωση σχετικά με την επιλογή της συγκεκριμένης μεθόδου και το φαινόμενο της νησιδοποίησης.<br>The energy crisis caused by the use of oil as a primary source of energy, the effort of each state to detox from oil-producing countries and the need for energy without negative impact on the environment has led to the development of renewable sources of energy.
For their commercial exploitation though, it was necessary to solve the technical problems that occurred, particularly about connecting distributed generation with the existing power grid.
The phenomenon of islanding (islanding), the electrical supply from distributed generation is not interrupted when it is disconnected from the main-grid, with a risk for employees and equipment connected on this, should be dealt with.
The purpose of this work is the theoretical comparison of the proposed islanding control techniques, selection and simulation in ATP-EMTP of the one that is the most appropriate of them.
In the first chapter the present status report of energy production from each renewable energy source and highlights the prominence and prevalence of solar energy and photovoltaics are analyzed.
During the second chapter the phenomenon of islanding is described and a number of proposed techniques for detecting and preventing islanding.
In the third chapter the techniques using reactive power are analyzed and the theoretical analysis of the selected RPV method is presented.
In the fourth and fifth chapter the possibilities of ATP-EMTP are described, the simulation method and its results are presented. Finally the work is concluded by the results after the simulation on the selection of this particular method and the phenomenon of islanding.