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Holm, Gustav. "Automated Model Transformation for Cyber-Physical Power System Models." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214750.
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Standardized information and mathematicalmodels, which model the characteristics of the power generationand power transmission systems, are requirements for futuredevelopment and maintenance of different applications tooperate the electrical grid. Available databases such as Nordpoolprovides large amounts of data for power supply and demand [1].The typical misconception with open availability of data is thatexisting power system software tools can interact and process thisdata. Difficulties occur mainly because of two reasons. The firston is the amount of data produced. When the topology of theelectrical grid changes e.g. when a switch opens or closes, the flowof electrical power changes. This event produce changes ingeneration, transmission and distribution of the energy anddifferent data sets are produced. The second problem is therepresentation of information [2]. There are a limited number ofsoftware tools that can analyze this data, but each software toolrequires a specific data format structure to run. Dealing withthese difficulties requires an effective way to transform theprovided data representation into new data structures that canbe used in different execution platforms. This project aims tocreate a generic Model-to-Text (M2T) transformation capable oftransforming standardized power system information modelsinto input files executable by the Power System Analysis Tool(PSAT). During this project, a working M2T transformation wasnever achieved. However, missing functionality in someprograms connected to sub processes resulted in unexpectedproblems. This led to a new task of updating the informationmodel interpreter PyCIM. This task is partially completed andcan load basic power system information models.
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Anderson, Sharon Lee. "Reduced order power system models for transient stability studies." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09052009-040743/.
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Hammer, Anders. "Analysis of IEEE Power System Stabilizer Models." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14035.
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Student:Anders HammerSupervisor:Kjetil UhlenContact:Daniel MotaCollaboration with:Voith HydroProblem descriptionIEEE (Institute of Electrical and Electronics Engineers) presented in 2005 a new PSS structure named IEEE PSS4B (Figure 0 1). Voith Hydro wants to analyse the pros and cons of using this new type compared to older structures. The PSS4B is a multi-band stabilizer that has three separate bands and is specially designed to handle different oscillation frequencies in a wide range. Until now, Voith Hydro has used the common PSS2B in their installations, but in the future they will probably start to implement the new PSS4B. This master thesis will seek to find an answer on following questions:•How should the PSS4B be tuned to give the best damping of the local and inter-area oscillation mode?•Will an implementation of PSS4B give a better result compared to PSS2B?•What are the pros and cons of PSS2B and PSS4B? Figure 0 1: The multi-band stabilizer, IEEE PSS4B [1].MethodIn order to test and compare different PSS models, a simple two-area network model is created in a computer simulation programme (SIMPOW). One of the generating units is a hydro generator, which has a model of a static excitation system made by Voith Hydro. This network is characterised by a poorly damped inter-area oscillation mode, and in addition some local oscillation modes related to each machine. Different PSS structures (PSS2B and PSS4B) are then tuned and installed in the excitation system of the hydro generator, in order to improve the stability of the network. Different tuning methods of the PSS4B are designed, tested and later compared with the more common stabilizer the PSS2B. Simplifications are made where parts of the stabilizer is disconnected in order to adapt the control structure to the applied network and its oscillations. Totally 5 different tuning methods are presented, and all these methods are based on a pole placement approach and tuning of lead/lag-filters. ResultsInitial eigenvalues of the different setups are analysed and several disturbances are studied in time domain analysis, in order to describe the robustness of the system. Figure 2 illustrates the rotor speed of the generator, where the different PSS’s are implemented. PSS4B is clearly resulting in increased damping of all speed oscillations in this network. The same results can also be seen in an eigenvalue analysis.Conclusion The best overall damping obtained in this master thesis occurs when the high frequency band of the PSS4B is tuned first, and in order to maximize the damping of the local oscillation mode in the network. The intermediate frequency band is then tuned as a second step, according to the inter-area oscillation mode. Results of this tuning technique show a better performance of the overall damping in the network, compared to PSS2B. The improvement of the damping of the inter-area oscillation mode is not outstanding, and the reason is that the applied machine is relative small compared to the other generating units in the network. The oscillation modes in the network (local and inter-area) have a relative small frequency deviation. A network containing a wider range of oscillation frequencies will probably obtain a greater advantage of implementing a multi-band stabilizer.
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Scruggs, James N. "Power system availability determination through Petri net simulation." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1178910568.
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Persson, Jonas. "Linear models of non-linear power system components." Licentiate thesis, KTH, Electrical Systems, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1415.
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Cresswell, Charles. "Steady state load models for power system analysis." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/3846.
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The last full review of load models used for power system studies occurred in the 1980s. Since then, new types of loads have been introduced and system load mix has changed considerably. The examples of newly introduced loads include drive-controlled motors, low energy consumption light sources and other modern power electronic loads. Their numbers have been steadily increasing in recent years, a trend which is expected to escalate. Accordingly, the majority of load models used in traditional power system studies are becoming outdated, as they are unable to accurately represent power demand characteristics of existing and future loads. Therefore, in order to accurately predict both active and non-active power demand characteristics of aggregated modern power system loads in different load sectors (e.g. residential, commercial or industrial), existing load models should be updated and new models developed. This thesis aims to fill this gap by developing individual, generic and aggregated steady state models of the most common loads in use today, as well as of those expected to show significant growth in the future. The component-based approach is adopted for load modelling, where individual load models are obtained in detailed simulations of physical devices. Whenever possible, the developed individual load models are validated by measurements. These detailed individual load models are then simplified and expressed as equivalent circuit and analytical models, which allowed the establishment of generic load models that can be easily aggregated. It should be noted that since all non-active power characteristics are correctly represented, the developed aggregated load models allow for a full harmonic analysis, which is not the case with the standard steady state load models. Therefore, the proposed load models form an extensive library of comprehensive load models that are suitable for use in multiple areas of power system research. Based on the results of research related to typical domestic/residential sector load mix, the newly developed load models are aggregated and then applied to a typical UK/Scotland distribution network. Considerable differences are seen between network characteristics of newly proposed and previously developed models. The voltage distortion of a typical distribution system bus is investigated, and it is shown that distortion of the system voltage is likely to increase significantly in the future. The results of the presented research also suggest that neglecting the harmonic characteristics from the set of general load attributes may introduce errors in standard load flow studies.
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Nteka, Makhetsi Flora. "Development and assessment of reduced order power system models." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1088.
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Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2013<br>The demand for electrical energy has kept on increasing, thus causing power systems to be more complex and bringing the challenging problems of electrical energy generation, transmission, stability, as well as storage to be examined more thoroughly.
With the advent of high-speed computation and the desire to analyze increasingly complex behaviour in power systems, simulation techniques are gaining importance and prevalence. Nevertheless, while simulations of large, interconnected complex power systems are feasible, they remain time-consuming. Moreover, the models and parameters used in simulations are uncertain, due to measurement uncertainty, the need to represent a complex behaviour with low-order models, and the inherent changing nature of the power system.
This research explores the use of a model reduction technique and the applications of a Real-Time Digital Simulator (RTDS) to reduce the uncertainty in large-scale complex power system models. The main goal of the research is to develop a reduced order model and to investigate the applications of the RTDS simulator in reduction of large, interconnected power systems models. The first stage of the study is to build and simulate the full model of the power system using the DigSILENT and RTDS simulators. The second phase is to apply model reduction technique to the full model and to determine the parameters in the reduced-order model as well as how the process of reduction increases this model uncertainty. In the third phase the results of the model reduction technique are compared based on the results of the original model - IEEE standard benchmark models has been used. The RTDS was used for comparative purposes.
The thesis investigations use a particular model reduction technique as Coherency based Method. Though the method ideas are applicable more generally, a concrete demonstration of its principles is instructive and necessary. Further, while this particular technique is not relevant to every system, it does apply to a broad class of systems and illustrates the salient features of the proposed methodology.
The results of the thesis can be used in the development of reduced models of complex power systems, simulation in real-time during power system operation, education at universities, and research.
Keywords: IEEE benchmark models, reduced models, Coherency based Method, DigSILENT, RTDS, model uncertainty, power system stability
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Raoofsheibani, Davood [Verfasser]. "Online Power System Security Analysis and State Prediction : Enhanced Power System Models and Tools / Davood Raoofsheibani." Düren : Shaker, 2021. http://d-nb.info/1240853947/34.
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Demiray, Turhan Hilmi. "Simulation of power system dynamics using dynamic phasor models /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17607.
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Persson, Jonas. "Bandwidth-reduced Linear Models of Non-continuous Power System Components." Doctoral thesis, Stockholm : Electric Power Systems, School of Electrical Engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3984.
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Branney, Sean J. "Comparison and development of hurricane electrical power system damage models." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5657.
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Thesis (M.S.)--University of Missouri-Columbia, 2008.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 25, 2008) Includes bibliographical references.
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Hockenberry, James Richard. "Evaluation of uncertainty in dynamic, reduced-order power system models." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/46685.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.<br>Includes bibliographical references (leaves 209-213).<br>With the advent of high-speed computation and the desire to analyze increasingly complex behavior in power systems, simulation techniques are gaining importance and prevalence. However, while simulations of large, interconnected power systems are feasible, they remain time-consuming. Additionally, the models and parameters used in simulations are uncertain, due to measurement uncertainty, the need to approximate complex behavior with low-order models and the inherent changing nature of the power system. This thesis explores the use of model reduction techniques to enable the study of uncertainty in large-scale power system models. The main goal of this thesis is to demonstrate that uncertainty analyses of transient simulations of large, interconnected power systems are possible. To achieve this, we demonstrate that a basic three stage approach to the problem yields useful results without significantly increasing the computational burden. The first stage is to reduce the order of the original power system model, which reduces simulation times and allows the system to be simulated multiple times in a reasonable time-frame. Second, the mechanics of the model reduction are closely studied; how uncertainties affect the reduction process and the parameters in the reduced-order model as well as how the process of reduction increases uncertainty are of particular interest. Third, the reduced-order model and its accompanying uncertainty description are used to study the uncertainty of the original model. Our demonstration uses a particular model reduction technique, synchronic modal equivalencing (SME), and a particular uncertainty analysis method, the probabilistic collocation method (PCM). Though our ideas are applicable more generally, a concrete demonstration of the principle is instructive and necessary. Further, while these particular techniques are not relevant to every system, they do apply to a broad class of systems and illustrate the salient features of our methodology. As mentioned above, a detailed analysis of the model reduction technique, in this case SME, is necessary. As an ancillary benefit of the thesis work, interesting theoretical results relevant to the SME algorithm, which is still under development, are derived.<br>by James R. Hockenberry.<br>Ph.D.
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Altamirano, Chavez Armando. "An efficient algorithm using Householder's formulas for the solution of faulted power systems." Thesis, Kansas State University, 1986. http://hdl.handle.net/2097/9896.
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Dong, Zhao Yang. "Advanced methods for small signal stability analysis and control in modern power systems." Phd thesis, School of Electrical and Information Engineering, Graduate School of Engineering, 1998. http://hdl.handle.net/2123/6416.
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廖德寧 and Te-Ning Liao. "A vertical axial-field generator and its stability in power system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1986. http://hub.hku.hk/bib/B31207789.
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Farahmand, Hossein. "Integrated Power System Balancing in Northern Europe - Models and Case Studies." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16864.
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Maintaining a continuous balance between generation and load is crucial for the safeguarding of the power systems. In order to effectively deal with the various uncertainties that contribute to the real-time imbalance in liberalised power systems, Transmission System Operators (TSOs) procure and employ the so-called balancing services through balancing markets. In Europe, though such mechanisms are well in place at the national level, the potential of multinational balancing markets has not been fully exploited (with the exception of the Nordic system and various pilot projects). This thesis analyses the potential for integrating the balancing power markets in northern Europe, including the Nordic system, Germany and the Netherlands. It addresses the twin issues of the procurement and employment of cross-border balancing services by using mathematical models. Beginning with an outline of the role of balancing markets in Europe, an overview of existing balancing markets in the northern European system is presented. A discussion on the cross-border balancing arrangements is then carried out, paving the way for quantitative analysis. A quantitative analyses of the multinational balancing markets are carried out, both in terms of attainable socio-economic cost savings, and their effect on the exchange of regional balancing services and generation dispatch. In this respect, two cases of balancing market integration are analysed: the current state with separate balancing markets, and the anticipated state of full integration of these markets. In the proposed modelling approach a two-step model is used, representing the day-ahead and balancing markets, respectively. First, the day-ahead market is modelled as a common market for the whole European continent. Simultaneously, reserve procurement for northern Europe is modelled. Available transmission capacity is allocated implicitly to the balancing services exchange, based on the trade-off between day-ahead energy and balancing capacity exchange. Next, the balancing energy market is modelled as a real-time power dispatch on the basis of the day-ahead market clearing results and simulated imbalances. Detailed results illustrate the consequences of market integration between two synchronous areas on procured and activated reserves, dispatch of generators, and power flows. The profitability of balancing market integration is quantified by the observed cost savings obtained due to the use of cheaper balancing resources and less activation of reserves caused by imbalance netting. The implementation of cross-border balancing entails both qualitative and quantitative analyses of different balancing exchange scenarios. This thesis focuses on the qualitative studies of cross-border balancing arrangements together with the quantitative analysis of cross-border balancing. The methodology developed in the thesis enables the study of the benefits of integrating the northern European balancing markets, and the resulting exchange of balancing services among the Nordic countries, Germany and the Netherlands. The multinational balancing market can be adapted to capture the effect of different market integration scenarios. The presented modelling approach includes a flow-based market model, which takes into account physical power flows and loop flows, especially suitable for the European systems with highly meshed transmission grids. A four tiered sequential approach is used to organize the primary contributions of the research work, as highlighted by the four distinct publications arising out of it. Tier 1: An optimal methodology for reserve activation in the Nordic system is established. Tier 2: Using the first tier as the basis, a cross-border reserves procurement algorithm is proposed for an integrated European system. Superimposing Tier 2 on Tier 1 results in a bottom-up approach of capturing the full spectrum of reserve procurement and activation for integrated balancing markets. Tier 3: The profitability of balancing market integration is brought forward through both weekly and yearly analysis on the basis of mathematical models developed in Tier 1 and 2. Tier 4: It is shown that the flexibility concerns warranted by penetration of renewable energy resources can be well addressed by using the developed framework of cross-border balancing market integration. A case study of a future power system (in 2030) with wind energy penetration has been employed in this regard. The results include the optimal distribution of balancing reserve capacity allocations for procurement among the constituent countries, and the optimal exchange of balancing energy that ensues upon activating these capacity reserves. An annual analysis of the post-integration scenario results demonstrates the significant cost savings that are achievable under the framework of multinational balancing markets. The results also demonstrate the potential for increased production flexibility, in light of increased wind energy penetration in the future operation of power systems through the mechanism of multinational balancing markets.
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Guo, Song. "Adaptive parameter estimation of power system dynamic models using modal information." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10576/.
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Knowledge of the parameter values of the dynamic generator models is of paramount importance for creating accurate models for power system dynamics studies. Traditionally, power systems consists of a relatively limited numbers of large power stations and the values of generator parameters were provided by manufacturers and validated by utilities. Recently however, with the increasing penetration of distributed generation, the accuracy of these models and parameters cannot be guaranteed. This thesis addresses the above concerns by developing a methodology to estimate the parameter values of a power system dynamic model online, employing dynamic system modes, i.e. modal frequencies and damping. The dynamic modes are extracted from real-time measurements. The aim of the proposed methodology is to minimise the differences between the observed and modelled modes of oscillation. It should be emphasised that the proposed methodology does not aim to develop the dynamic model itself but rather modify its parameter using WAMS measurements. The developed methodology is general and can be used to identify any generator parameters., However, thesis concentrates on the estimation of generator inertia constants. The results suggest that the proposed methodology can estimate inertias and replicate the dynamic behaviour of the power system accurately, through the inclusion of pseudo-measurements in the optimisation process. The pseudo-measurements not only improves the accuracy of the parameter estimation but also the robustness of it. Observability, a problem when there are fewer numbers of measurements than the numbers of parameters to be estimated, has also been successfully tackled. It has been shown that the damping measurements do not influence the accuracy and robustness of generator inertia estimation significantly.
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Ly, Cuong. "Reliability study of the Callide power station electrical system." Thesis, Queensland University of Technology, 1997. https://eprints.qut.edu.au/36023/1/36023_Ly_1997.pdf.
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The reliable operation of the electrical system at Callide Power Station is of extreme importance to the
normal everyday running of the Station.
The electrical system configuration and hardware are inherently very reliable. However, in all cases the
failure of components such as circuit breakers, switchboards, and transformers would directly or indirectly
effect the Station's capability to generate at full load capacity and hence maximise revenue.
This study has applied the principles of reliability and has utilised a reliability software package to do an
analysis on the electrical system at Callide Power Station.
The study analyses other possible system configurations that could increase the reliability of the Station.
The study identifies priority maintenance on load points displaying high reliability indices. An analysis
was done on the impact of unusual system configurations such as Boiler Feed Pump motor startups.
Using the results from the study an appropriate level of maintenance was suggested for the current
Callide electrical system configuration and recommendations on the replacement of some 41 SV circuit
breaker tripping toggles was made.
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Schürmans, Stefan [Verfasser], Rainer [Akademischer Betreuer] Leupers, and Tobias [Akademischer Betreuer] Gemmeke. "Power Estimation on Electronic System Level using Linear Power Models / Stefan Schürmans ; Rainer Leupers, Tobias Gemmeke." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1171323808/34.
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PIRES, Robson Celso. "Complex-Valued Steady-State Models as Applied to Power Flow Analysis and Power System State Estimation." reponame:Repositório Institucional da UNIFEI, 2018. http://repositorio.unifei.edu.br/xmlui/handle/123456789/1359.
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Previous issue date: 2018-06<br>Nonlinear systems of equations in complex domain are frequently encountered in applied mathematics, e.g., power systems, signal processing, control theory, neural networks and biomedicine, to name a few. The solution of these problems often requires a first- or second-order approximation of these nonlinear functions to generate a new step or descent direction to meet the solution iteratively. However, such methods cannot be applied to real functions of complex variables because they are necessarily non-analytic in their argument, i.e., the Taylor series expansion in their argument alone does not exist. To overcome this problem, the nonlinear function is usually redefined as a function of the real and imaginary parts of its complex argument so that standard methods can be applied. Although not widely known, it is possible to build an expansion of these nonlinear functions in its original complex variables by noting that functions of complex variables can be analytic in their argument and its complex conjugate as a whole. This property lies in the fact that if a function is analytic in the space spanned by ℜ{} and ℑ{}in ℝ, it is also analytic in the space spanned by and * in ℂ. The main contribution of this work is the application of this methodology to a complex Taylor series expansions aiming algorithms commonly used for solving complex-valued nonlinear systems of equations emerged from power systems problems. In our proposal, a complex-valued power ow analysis (CV PFA) model solved by Newton-Raphson method is revisited and enhanced. Nonetheless, especially emphasis is addressed to Gauss-Newton method when derived in complex domain for solving power system state estimation (CV PSSE) problems, whichever they are applied in transmission or distribution systems. The factorization method of the complex Jacobian matrices emerged from CV PFA and CV PSSE approaches is the Three Angle Complex Rotation (TACR) algorithm that comes from the Givens Rotations algorithm in real domain. In this research one demonstrates that Wirtinger derivatives can lead to greater insights in the structure of both problems, i.e., CV PFA & CV PSSE. Moreover, it can often be exploited to mitigate computational overhead, storage cost and enhance the network's component modeling as FACTS devices, e.g., STATCOM, VSC-HVDC, besides easily handle PMU measurements and embedding new technologies towards smart grids. Finally, in order to add numerical robustness, a fourth-order Levenberg-Marquardt algorithm is employed to the CV PFA & CV PSSE approaches because of its nice bi-quadratic convergence property, instead of the well-known quadratic convergence property of the classical Newton-Raphson and Gauss-Newton algorithms. Recall that these latter algorithms are prone to collapse when the power system network is ill-conditioned, i.e., it is heavily loaded or presents branches with high R/X ratio. These results are partially presented in this thesis because they are still under study and development. But most of them will appear in forthcoming papers submitted to IEEE-PES Transactions on Power Systems and coming up Top Conferences.
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Tong, Y.-K. "Circuit models and simulations of surge attentuation on HV transmission system." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235205.
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Abrahamsson, Lars. "Optimal Railroad Power Supply System Operation and Design : Detailed system studies, and aggregated investment models." Doctoral thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107037.
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Railway power supply systems (RPSSs) differ mainly from public power systems from that the loads are moving. These moving loads are motoring trains. Trains can also be regenerating when braking and are then power sources. These loads consume comparatively much power, causing substantial voltage drops, not rarely so big that the loads are reduced. By practical reasons most RPSSs are single-phase AC or DC. Three-phase public grid power is either converted into single-phase for feeding the railway or the RPSS is compartmentalized into separate sections fed individually from alternating phase-pairs of the public grid. The latter is done in order not to overload any public grid phase unnecessarily much. This thesis summarizes various ways of optimally operating or designing the railway power supply system. The thesis focuses on converter-fed railways for the reasons that they are more controllable, and also has a higher potential for the future. This is also motivated in a literature-reviewing based paper arguing for the converter usage potential. Moreover, converters of some kind have to be used when the RPSS uses DC or different AC frequency than the public grid. The optimal operation part of this thesis is mainly about the optimal power flow controls and unit commitments of railway converter stations in HVDC-fed RPSSs. The models are easily generalized to different feeding, and they cope with regenerative braking. This part considers MINLP (mixed integer nonlinear programming) problems, and the main part of the problem is non-convex nonlinear. The concept is presented in one paper. The subject of how to model the problem formulations have been treated fully in one paper. The thesis also includes a conference article and a manuscript for an idea including the entire electric train driving strategy in an optimization problem considering power system and mechanical couplings over time. The latter concept is a generalized TPSS (Train Power Systems Simulator), aiming for more detailed studies, whereas TPSS is mainly for dimensioning studies. The above optimal power flow models may be implemented in the entire electric train driving strategy model. The optimal design part of this thesis includes two aggregation models for describing reduction in train traffic performance. The first one presented in a journal, and the second one, adapted more useful with different simulation results was presented at a conference. It also includes an early model for optimal railway power converter placements. The conclusions to be made are that the potential for energy savings by better operation of the railway power system is great. Another conclusion is that investment planning models for railway power systems have a high development potential. RPSS planning models are computationally more attractive, when aggregating power system and train traffic details.<br><p>QC 20121206</p>
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Abur, Ali. "Knowledge-based power flow models and array processor-based power flow solutions for fast prediction of system states /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487261553057511.
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Le, Dantec Jorge I. (Jorge Ignacio). "Assessing business models arising from the integration of distributed energy systems in the Chilean electric power system." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90714.
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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2014.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 83-84).<br>Electric power systems are more than just networks of generation, transmission and distribution assets. They are socio-technical systems, involving regulation, markets and technology availability. Presently, the dynamic relation among these aspects is creating new consumer needs in many power systems around the world, which incumbent electricity utilities do not seem well suited to meet at the required pace. In this context, the integration of Distributed Energy Systems (DESs) and their related business models appears as a flexible and often more affordable option to deliver value, by fulfilling the unmet needs of both consumers and utilities. To advice Chilean electric power system's stakeholders about the adequacy of a set of DES-related business models to Chilean needs, this document presents a systematic analysis, which focuses on the interrelation between business model attributes, involved DES technologies, and stakeholder needs. Specifically, an analytic framework is developed and applied to some business models currently operative in other markets, measuring their adequacy to meet stakeholders' needs in a set of envisioned scenarios of Chile's power system. This work provides a systematic tool for decision-making processes in selecting business models, when the decision must be made with qualitative data. Moreover, the evaluation in the Chilean system of actual business models shows results that should be valuable for consumers, utilities, and regulators.<br>by Jorge I. Le Dantec.<br>S.M. in Engineering and Management
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Mazumdar, Joy. "System and method for determining harmonic contributions from nonlinear loads in power systems." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/23215.
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The objective of this research is to introduce a neural network based solution for the problem of measuring the actual amount of harmonic current injected into a power network by an individual nonlinear load. Harmonic currents from nonlinear loads propagate through the system and cause harmonic pollution. As a result, voltage at the point of common coupling (PCC) is rarely sinusoidal. The IEEE 519 harmonic standard provides customer and utility harmonic limits and many utilities are now requiring their customers to comply with IEEE 519. Measurements of the customer’s current at the PCC are expected to determine the customer’s compliance with IEEE 519. However, results in this research show that the current measurements at the PCC are not always reliable in that determination. In such a case, it may be necessary to determine what the customer’s true current harmonic distortions would be if the PCC voltage could be a pure sinusoidal voltage. However, establishing a pure sinusoidal voltage at the PCC may not be feasible since that would mean performing utility switching to reduce the system impedance. An alternative approach is to use a neural network that is able to learn the customer’s load admittance. Then, it is possible to predict the customer’s true current harmonic distortions based on mathematically applying a pure sinusoidal voltage to the learned load admittance. The proposed method is called load modeling. Load modeling predicts the true harmonic current that can be attributed to a customer regardless of whether a resonant condition exists on the utility power system. If a corrective action is taken by the customer, another important parameter of interest is the change in the voltage distortion level at the PCC due to the corrective action of the customer. This issue is also addressed by using the dual of the load modeling method. Topologies of the neural networks used in this research include multilayer perceptron neural networks and recurrent neural networks. The theory and implementation of a new neural network topology known as an Echo State Networks is also introduced. The proposed methods are verified on a number of different power electronic test circuits as well as field data. The main advantages of the proposed methods are that only waveforms of voltages and currents are required for their operation and they are applicable to both single and three phase systems. The proposed methods can be integrated into any existing power quality instrument or can be fabricated into a commercial standalone instrument that could be installed in substations of large customer loads, or used as a hand-held clip on instrument.
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Stefopoulos, Georgios Konstantinos. "Quadratic power system modeling and simulation with application to voltage recovery and optimal allocation of VAr support." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29695.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.<br>Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Deng, Shijie; Committee Member: Divan, Deepakraj; Committee Member: Harley, Ronald; Committee Member: Taylor, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Bakkabulindi, Geofrey. "Planning Models for Single Wire Earth Return Power Distribution Networks." Licentiate thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-107160.
Full textAbstract:
The high cost of grid extension to rural areas, often characterized by scattered communities with low load densities, requires the use of low cost electrification technologies to ensure economic viability. In Single Wire Earth Return (SWER) power distribution networks, the earth itself forms the current return path of the single phase system leading to significant cost savings on conductors, poles and poletop hardware compared to conventional systems. However, challenges exist in SWER with regard to earthing and safety as well as the dependence on earth conductivity to supply consumer loads. This work presents models for the optimal planning of SWER distribution networks. The earth return path is modeled as a conductor based on the Carson line model taking into consideration specific ground properties of the considered location. A load flow algorithm for radial SWER networks is subsequently formulated whereby both overhead line and ground voltages and currents are determined. First, heuristic planning models are developed based on the SWER load flow model. The objective of the heuristic models is to determine the optimum feeder configuration and overhead conductor subject to SWER load flow constraints and load growth over several time periods. Whereas the resulting solutions are good, they may not necessarily be globally optimum. Optimization models are then developed using mixed integer non-linear programming (MINLP) with the aim of obtaining global solutions to the SWER network planning problem. Since the MINLP formulations are limited to the accurate analysis of limited size networks, considerations and approximations for the analysis of larger networks are presented. The developed models are applied to a case study in Uganda to test their practical application. In addition, comparative studies are done to determine how the proposed optimization models compare with previous distribution planning models. The numerical analysis includes the impact of deterministic distributed generation on the SWER planning problem. Results showed consistent performance of the proposed heuristic and optimization models, which also compared well with conventional models. The optimization models gave more cost-effective solutions to the SWER planning problem than the heuristic models. However, the former models had higher computational cost than the latter. The inclusion of distributed generation allowed for cheaper network solutions to be obtained. The models are applicable to the planning of Single Wire Earth Return networks for isolated mini-grids, grid-extension to previously un-electrified rural areas as well as the upgrade of SWER feeders in existing installations.<br><p>QC 20121207</p><br>Sustainable Technological Development in the Lake Victoria Region
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Song, Shuaiwen. "Power, Performance and Energy Models and Systems for Emergent Architectures." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19316.
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Massive parallelism combined with complex memory hierarchies and heterogeneity in high-performance computing (HPC) systems form a barrier to efficient application and architecture design. The performance achievements of the past must continue over the next decade to address the needs of scientific simulations. However, building an exascale system by 2022 that uses less than 20 megawatts will require significant innovations in power and performance efficiency.<br /> A key limitation of past approaches is a lack of power-performance policies allowing users to quantitatively bound the effects of power management on the performance of their applications and systems. Existing controllers and predictors use policies fixed by a knowledgeable user to opportunistically save energy and minimize performance impact. While the qualitative effects are often good and the aggressiveness of a controller can be tuned to try to save more or less energy, the quantitative effects of tuning and setting opportunistic policies on performance and power are unknown. In other words, the controller will save energy and minimize performance loss in many cases but we have little understanding of the quantitative effects of controller tuning. This makes setting power-performance policies a manual trial and error process for domain experts and a black art for practitioners. To improve upon past approaches to high-performance power management, we need to quantitatively understand the effects of power and performance at scale.<br /> In this work, I have developed theories and techniques to quantitatively understand the relationship between power and performance for high performance systems at scale. For instance, our system-level, iso-energy-efficiency model analyzes, evaluates and predicts the performance and energy use of data intensive parallel applications on multi-core systems. This model allows users to study the effects of machine and application dependent characteristics on system energy efficiency. Furthermore, this model helps users isolate root causes of energy or performance inefficiencies and develop strategies for scaling systems to maintain or improve efficiency. I have also developed methodologies which can be extended and applied to model modern heterogeneous architectures such as GPU-based clusters to improve their efficiency at scale. <br /><br>Ph. D.
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Li, Xiaojuan. "Estimations of power system frequency, phasors and their applications for fault location on power transmission lines." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0125.
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The thesis is devoted to the development of new algorithms for estimation of system frequency, power system phasors and transmission line fault location in the context of power system protection and control. A z-transform signal model combined with a nonlinear post-filtering scheme to estimate the operating frequency in a power system is first developed in the thesis. The signal model parameters are identified by an optimisation method in which the error between the model output and the actual signal that represents a voltage or current in the power system is minimised. The form and the structure of the signal model do not require iterations in the optimisation process for parameter identification. The system operating frequency is directly evaluated from the model parameters. Effects of noise and any frequency components other than the operating or supply-frequency on the accuracy are countered very effectively by applying a median post-filtering on the time series representing the frequency estimates derived from the model. Extensive simulation studies and comparisons with previously-published frequency estimation techniques confirm the high performance of the method developed in the thesis in terms of accuracy and time delay. With respect to power system phasor estimation, a method is developed based on waveform interpolation in the discrete time-domain to counter the spectral leakage errors arising in forming, by discrete Fourier transform (DFT), the supply frequency phasors representing power system voltages and currents when there are system frequency deviations from the nominal value. The interpolation scheme allows DFT evaluation to be performed with a time window length which is exactly equal to the fundamental period of the voltage or current waveform. Comparative studies presented in the thesis confirm the improvements achieved by the method proposed over other previouslypublished techniques in terms of accuracy and computing time. With the availability of accurate operating frequency and phasor estimates, an optimal fault location method based on multi-conductor distributedparameter line model is developed. The method is a general one which is applicable to any transmission line configurations, including multi-terminal lines. The fault location method is based on the minimisation of an objective function in which the fault distance is a variable. The objective function is formed from combining the phase-variable distributed-parameter equations of individual line sections from the fault point to the line terminals. The multivariable minimisation leads to high accuracy and robustness of the fault location algorithm in which any voltage/current measurement errors, including sampling time synchronisation errors, are represented in the estimation procedure as variables in addition to the fault distance. Extensive simulation studies are performed to verify that the method developed is highly accurate and robust. The thesis is supported by two international publications of which the candidate is a joint author.
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Liu, Xinghua, and 刘兴华. "Power system operation integrating clean energy and environmental considerations." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085866.
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Skogberg, Ronny. "Railway power supply system models for static calculations in a modular design implementation." Thesis, KTH, Elektriska energisystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170726.
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Several previous theses and reports have shown that voltage variations, and other types of supply changes, can influence the performance and movements of trains. As part of a modular software package for railway focused calculations, the need to take into account for the electrical behavior of the system was needed, to be used for both planning and operational uses. In this thesis, different static models are presented and used for train related power flow calculations. A previous model used for converter stations is also extended to handle different configurations of multiple converters. A special interest in the train type IORE, which is used for iron ore transports along Malmbanan, and the power systems influence to its performance, as available modules, for mechanical calculations, in the software uses the same train type. A part of this project was to examine changes in the power systems performance if the control of the train converters were changed, both during motoring and regenerative braking. A proposed node model, for the static parts of a railway power system, has been used to simplify the building of the power system model and implementation of the simulation environment. From the results it can be concluded that under normal conditions, for the used train schedule, the voltage variation should not restrict the trains traction performance. It can also be seen from the results that a more optimized power factor control with a higher regenerative brake power or generation of reactive power could be used to limit the need for investments in infrastructure or to increase the traffic for a given system layout.<br>I ett flertal tidigare undersökningar och rapporter har konstaterats att spänningsvariationer, och andra förändringar, hos strömförsörjningen till tåg kan påverka dess prestanda och dess färd längs rälsen. Som en del av ett modulärt programpaket för tågrelaterade beräkningar uppstod därför ett behov av elkraftsberäkningar, både för planering och operativ drift. I denna rapport sammanställs och används ett antal olika statiska modeller för tågrelaterade effektflödesberäkningar. Modellen för omformarstationer har även utökats för att hantera konfigurationer då olika typer av omformare används. Ett särskilt intresse för tågtypen IORE, som används för malmtransporter längs Malmbanan, och dess påverkan av en förändrad strömförsörjning, har funnits då olika typer av mekaniska beräkningar för denna tågtyp utförs i andra befintliga moduler. En del av projektet bestod i att undersöka förändringar i elförsörjningen, på grund av en ändrad styrning av tågens omformare, både vid återmatning och motordrift. En föreslagen nodmodell för den statiska delen av elnätet har använts för att förenkla elsystemsmodellen och uppbyggnaden av simuleringsmiljön. Av resultaten från simuleringarna kan man anta att under normala förhållanden, och med det använda körschemat, bör ej spänningen vara en begränsande faktor för tågens drift. Övriga simuleringar visar också att en mer optimerad effektfaktor för högre återmatad bromseffekt eller för generering av reaktiv effekt kan användas för att slippa investeringar i infrastrukturen, eller för att utöka trafikmängden för ett givet system.
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Shafiee, Leila. "Validation of Models for Analysis of the Flexibility of the Swedish Power System." Thesis, KTH, Elektriska energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153950.
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The Swedish parliament has passed a planning framework to increase wind power production and have the annual production of 30 TWh wind power in 2020. The expansion of a continuously varying generation would result in an increased need for the capability of power system to keep the balance between generation and consumption. Therefore, it is important to study the flexibility of Swedish power system. Two models of Swedish power system are studied in this thesis work. The first model is a model of Swedish hydro power system which has been developed at KTH. The KTH model is formulated as a large linear optimization problem simulated in GAMS platform. It has a detailed representation of large hydro power plants but presents a simple model of electricity market and trading to other areas. The other model is Apollo which is developed by Sweco Company. Apollo is also formulated as an optimization problem and is a market model which uses a simplified model of hydro power system. The objective of this thesis work is to exchange data between the two models in order to compare, validate and if possible improve the models. To exchange data, the inputs and some outputs of Apollo are used as the inputs of KTH model and finally the outputs of KTH model is compared with the corresponding outputs of Apollo. There are some differences between the two models that must be removed in order to exchange data. All of differences except one of them are removed by data adjustment. The different methods that are used to remove those differences are discussed in the report. Due to the remaining difference and different efficiencies in the two models, scenarios cannot be directly transformed from Apollo to the KTH model. Therefore, three methods are introduced as compensation for the remaining differences. After applying those methods the same results can be obtained in the two models. As a result of the work on the data exchange some improvements are implemented in the KTH model and some improvements are identified and proposed for future work. The improvements are toward removing all the differences between the two models and make the models more similar to the real Swedish hydro power system. It is also concluded from the results that the Apollo hydro power schedules are feasible according to KTH model of hydro power system. This shows that Apollo does not overestimate the flexibility of Swedish hydro power system in the tested scenarios.<br>Riksdagen har beslutat om ett planeringsmål för ökad vindkraftproduktion upp till 30 TWh vindkraft år 2020. En utbygnnad av kontinuerligt varierande produktion skulle medföra ett ökat behov för elsystemets förmåga att balansera produktion och konsumtion. Därför är det viktigt att studera flexibiliteten i det svenska elsystemet. Två modeller av det svenska elsystemet studeras i detta examensarbete. Den första modellen, som är utvecklad på KTH, är en modell av det svenska vattenkraftsystemet. KTH-modellen är formulerad som ett stort linjärt optimeringsproblem som simuleras i GAMS-plattformen. Modellen har en detaljerad representation av större vattenkraftverk, medan modellen av elmarknaden och handeln med andra områden är mycket förenklad. Den andra modellen heter Apollo och är utvecklad av konsultföretaget Sweco. Apollo är också formulerad som ett optimeringsproblem, och är en marknadsmodell som använder en förenklad modell av vattenkraftsystemet. Målsättningen med detta arbete är att utbyta data mellan de två modellerna för att jämföra, validera och om möjligt förbättra de två modellerna. För att utbyta data används indata och vissa utdata från Apollo som indata till KTH-modellen och slutligen jämförs utdata från KTH-modellen med motsvarande utdata från Apollo. Det finns en del skillnader mellan de två modellerna som måste hanteras för att datautbytet ska vara möjligt. Alla skillnader utom en hanteras genom att modifiera data. De olika metoder som används för att hantera dessa skillnader diskuteras i rapporten. På grund av den återstående skillnaden och olika verkningsgrader i de två modellerna så kan inte scenarier överföras direkt från Apollo till KTH-modellen. Därför föreslås tre metoder för att kompensera de återstående skillnaderna. Med hjälp av dessa metoder kan samma resultat erhållas från de två modellerna. Till följd av arbetet med datautbytet har några förbättringar av KTH-modellen implementerats och ytterligare förbättringar har identifierats och föreslagits som framtida arbete. Dessa förbättringar syftar till att ta bort skillnaderna mellan de två modellerna och att göra de modellerna mer lika det verkliga svenska vattenkraftsystemet. En slutsats från projektet är också att de produktionsplaner för vattenkraften som erhålls från Apollo är genomförbara enligt KTH:s modell av vattenkraften. Detta visar att Apollo i de testade scenarierna inte överskattar flexibiliteten i det svenska vattenkraftsystemet.
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ALBUQUERQUE, MARCOS ANTONIO. "DYNAMIC AGGREGATION OF DUAL-INPUT POWER SYSTEM STABILIZER MODELS TO CALCULATE DYNAMIC EQUIVALENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3278@1.
Full textAbstract:
FURNAS CENTRAIS ELÉTRICAS S.A<br>Esta dissertação trata do problema da agregação dinâmica de
modelos de estabilizadores com dupla entrada, aplicados em
reguladores de tensão de unidades geradoras coerentes,
visando o cálculo de equivalentes dinâmicos precisos para
estudos de estabilidade transitória de sistemas de energia
elétrica. A metodologia utilizada para o cálculo de
equivalentes dinâmicos é baseada em coerência de geradores,
e apresenta três etapas básicas: a identificação de
unidades geradoras coerentes, a redução estática da rede
externa, e a agregação dinâmica dos geradores de cada grupo
formado. A agregação dinâmica de um grupo de unidades
geradoras coerentes permite a formação de uma ou mais
unidades geradoras equivalentes. Haverá um modelo
equivalente para cada componente da unidade geradora, ou
seja, modelos equivalentes de máquina síncrona, sistema de
excitação, estabilizador, turbina e regulador de
velocidade. O ajuste numérico dos parâmetros lineares da
função de transferência equivalente é feito pelo método de
Levenberg-Marquardt, de modo a minimizar o erro entre a
resposta em freqüência desta função e a da função de
transferência agregada, que representa a soma das funções
de transferência individuais das unidades de cada
grupo. Isto caracteriza um problema de otimização
multivariável. As respostas em freqüência são apresentadas
em diagramas de Bode (módulo e fase). A avaliação do
desempenho dinâmico dos equivalentes é feita no sistema
teste New England, comparando-se as curvas de oscilação dos
geradores do sistema interno obtidas em simulações com a
rede completa e com o equivalente. Os modelos de
estabilizadores com dupla entrada utilizados são do banco
de dados do sistema elétrico brasileiro.<br>This dissertation deals with the problem of dynamic
aggregation of dualinput stabilizer models applied on
voltage regulators of coherent generating units
to calculate dynamic equivalents for power system transient
stability studies. The methodology used for the calculation
of coherency-based dynamic equivalents has three basic
steps: the identification of the coherent groups of
generating units, the network reduction and the dynamic
aggregation of coherent generator models. The dynamic
aggregation of a group of coherent generating units
attached to a common busbar consists of the representation
of this group by one or more equivalent generating units.
There will be an equivalent model for each component of the
generating unit, i.e., an equivalent model for the
synchronous machine, other one for the excitation system,
and so on. The linear parameters of the equivalent transfer
function are numerically adjusted to match the frequency
response of the corresponding aggregated transfer function
which represents the sum of the individual transfer
functions for each coherent group. This characterises a
multivariable optimization problem. The frequency responses
are presented in Bode diagrams (magnitude and phase). The
dynamic equivalents are evaluated in the New England
system. The swing curves of the internal system generators
obtained with the complete system are compared with those
obtained with the equivalent system. The dual-input power
system stabilizer models considered in this work are in the
Brazilian system stability database.
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Radesjö, Fanny. "Parameter Identification and Information Modeling of Gas Turbine Models for Power System Simulations." Thesis, KTH, Industriell ekologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210738.
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In the future renewable generation sources will have to co-exist with traditional generation sources that can overcome their limitations in providing secure power supply to society, such as gas turbines. In this project we proposed to substitute a simple model of a gas turbine by a detailed model to simulate the turbine´s behavior in a real system. Parameter identification of a simple gas turbine model was performed based on measurements from a detailed model. By this, the project contributes to a library of electric grid component models. The library is meant to allow operators and engineers to predict the system behavior by simulations. This can facilitate to anticipate possible instability in the grid and thereby contribute to the transition to the Smart Grid. Further, another gas turbine model was in the Modelica language was represented using the Unified Modeling Language (UML). This is a standard form of modelling that simplifies exchange of model information between project groups.
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Mirsad, Ćosović. "Distributed State Estimation in Power Systems using Probabilistic Graphical Models." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=108459&source=NDLTD&language=en.
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We present a detailed study on application of factorgraphs and the belief propagation (BP) algorithm to thepower system state estimation (SE) problem. We startfrom the BP solution for the linear DC model, for whichwe provide a detailed convergence analysis. Using BPbasedDC model we propose a fast real-time stateestimator for the power system SE. The proposedestimator is easy to distribute and parallelize, thusalleviating computational limitations and allowing forprocessing measurements in real time. The presentedalgorithm may run as a continuous process, with eachnew measurement being seamlessly processed by thedistributed state estimator. In contrast to the matrixbasedSE methods, the BP approach is robust to illconditionedscenarios caused by significant differencesbetween measurement variances, thus resulting in asolution that eliminates observability analysis. Using theDC model, we numerically demonstrate the performanceof the state estimator in a realistic real-time systemmodel with asynchronous measurements. We note thatthe extension to the non-linear SE is possible within thesame framework.Using insights from the DC model, we use two differentapproaches to derive the BP algorithm for the non-linearmodel. The first method directly applies BP methodology,however, providing only approximate BP solution for thenon-linear model. In the second approach, we make a keyfurther step by providing the solution in which the BP isapplied sequentially over the non-linear model, akin towhat is done by the Gauss-Newton method. The resultingiterative Gauss-Newton belief propagation (GN-BP)algorithm can be interpreted as a distributed Gauss-Newton method with the same accuracy as thecentralized SE, however, introducing a number ofadvantages of the BP framework. The thesis providesextensive numerical study of the GN-BP algorithm,provides details on its convergence behavior, and gives anumber of useful insights for its implementation.Finally, we define the bad data test based on the BPalgorithm for the non-linear model. The presented modelestablishes local criteria to detect and identify bad datameasurements. We numerically demonstrate that theBP-based bad data test significantly improves the baddata detection over the largest normalized residual test.<br>Glavni rezultati ove teze su dizajn i analiza novihalgoritama za rešavanje problema estimacije stanjabaziranih na faktor grafovima i „Belief Propagation“ (BP)algoritmu koji se mogu primeniti kao centralizovani ilidistribuirani estimatori stanja u elektroenergetskimsistemima. Na samom početku, definisan je postupak zarešavanje linearnog (DC) problema korišćenjem BPalgoritma. Pored samog algoritma data je analizakonvergencije i predloženo je rešenje za unapređenjekonvergencije. Algoritam se može jednostavnodistribuirati i paralelizovati, te je pogodan za estimacijustanja u realnom vremenu, pri čemu se informacije moguprikupljati na asinhroni način, zaobilazeći neke odpostojećih rutina, kao npr. provera observabilnostisistema. Proširenje algoritma za nelinearnu estimacijustanja je moguće unutar datog modela.Dalje se predlaže algoritam baziran na probabilističkimgrafičkim modelima koji je direktno primenjen nanelinearni problem estimacije stanja, što predstavljalogičan korak u tranziciji od linearnog ka nelinearnommodelu. Zbog nelinearnosti funkcija, izrazi za određenuklasu poruka ne mogu se dobiti u zatvorenoj formi, zbogčega rezultujući algoritam predstavlja aproksimativnorešenje. Nakon toga se predlaže distribuirani Gaus-Njutnov metod baziran na probabilističkim grafičkimmodelima i BP algoritmu koji postiže istu tačnost kao icentralizovana verzija Gaus-Njutnovog metoda zaestimaciju stanja, te je dat i novi algoritam za otkrivanjenepouzdanih merenja (outliers) prilikom merenjaelektričnih veličina. Predstavljeni algoritam uspostavljalokalni kriterijum za otkrivanje i identifikacijunepouzdanih merenja, a numerički je pokazano daalgoritam značajno poboljšava detekciju u odnosu nastandardne metode.
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Amakali, Simaneka. "Development of models for short-term load forecasting using artificial neural networks." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/1070.
Full textAbstract:
Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Discipline Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2008<br>Optimal daily operation of electric power generating plants is very essential for any power utility
organization to reduce input costs and possibly the prices of electricity in general. For a fossil fuel –
fired power plant for example, the benefits of power generation optimalization (i.e. generate what is
reasonably required) extends even to environmental issues such as the subsequent reduction in air
pollution. Now to generate “what is reasonably required” one needs forecast the future electricity
demands. Because power generation relies heavily on the electricity demand, the consumers are also
practically speaking required to wisely manage their loads to consolidate the power utility’s optimal
power generation efforts. Thus, for both cases, accurate and reliable electric load forecasting systems
are absolutely required.
To date, there are numerous forecasting methods developed primarily for electric load forecasting.
Some of these forecasting techniques are conventional and often less favoured.
To get a broad picture of the problem at hand, a literature survey was first conducted to identify
possible drawbacks of the existing forecasting techniques including the conventional one. Artificial
neural networks (ANNs) approach for short-term load forecasting (STLF) has been recently proposed
by a majority of researchers. But there still is a need to find optimal neural network structures or
convenient training approach that would possibly improve the forecasting accuracy.
This thesis developed models for STLF using ANNs approach. The evolved models are intended to
be a basis for real forecasting application. These models are tested using actual load data of the Cape
Peninsula University of Technology (CPUT) Bellville campus reticulation network and weather data
to predict the load of the campus for one week in advance.
The models were divided into two classes: first, forecasting the load for a whole week at once was
evaluated, and then hourly models were studied. In both cases, the inclusion of weather data was
considered. The test results showed that the hour-by-hour approach is more suitable and efficient for
a forecasting application. The work suggests that incremental training approach of a neural network
model should be implemented for on-line testing application to acquire a universal final view on its
applicability.
Keywords – power system operations, load forecasting, artificial neural networks, training mode,
accuracy
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Sharifnia, Hamidreza. "Safety related model and studies of Trojan Nuclear Power Plant electrical distribution system." PDXScholar, 1988. https://pdxscholar.library.pdx.edu/open_access_etds/3875.
Full textAbstract:
The most important requirement for running a nuclear power plant safely is having a reliable safety system, especially during the emergency shutdown condition. For performing a scrutiny load flow and voltage drop study a detailed and comprehensive electrical model for the emergency electrical distribution system of the Trojan Nuclear Power Plant has been developed. This model includes the representation of the transformers, circuit breakers, motors, cables and load data from 4160 volts level down to the individual 480 volts loads.
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Zhu, Huiyu. "New Multi-Phase Diode Rectifier Average Models for AC and DC Power System Studies." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/30188.
Full textAbstract:
More power semiconductors are applying to the aircraft power system to make the system smaller, lighter and more reliable. Average models provide a good solution to system simulation and can also serve as the basis to derive the small signal model for system-level study using linear control theory.
A new average modeling approach for three-phase and nine-phase diode rectifiers with improved ac and dc dynamics is proposed in this dissertation. The key assumption is to model the load current using its first-order Taylor Series expansion throughout the entire averaging time span. A thorough comparison in the time domain is given of this model and two additional average models that were developed based on different load current assumptions, using the detailed switching models as the benchmark. The proposed average model is further verified by experimental results.
In the frequency domain, the output impedance of a nine-phase diode rectifier is derived, and the sampling effect in the average model is investigated by Fourier analysis. The feeder's impedance before the rectifier is modeled differently in the output impedance in contrast in the equivalent commutation inductance.
The average model is applied to the resonance study in a system composed of a synchronous generator, a nine-phase diode rectifier and a motor drive. The Thevenin's and Norton's equivalent circuits are derived to construct a linearized system. The equivalent impedance are derived from the average models, and the source are obtained from the switching circuit by short-circuit or open-circuit. Transfer functions are derived from the harmonic sources to the bus capacitor voltage for resonance study. The relationship between the stability and the resonance is analyzed, and the effect of controllers on the resonance is investigated.
Optimization is another system-level application of the average model. A half-bridge circuit with piezoelectric actuator as its load is optimized using genetic algorithm. The optimization provides the possibility to design the actuator and its driving circuit automatically.<br>Ph. D.
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Jordan, Rhonda LeNai. "Incorporating endogenous demand dynamics into long-term capacity expansion power system models for Developing countries." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79547.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2013.<br>Page 163 blank. Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 129-137).<br>This research develops a novel approach to long-term power system capacity expansion planning for developing countries by incorporating endogenous demand dynamics resulting from social processes of technology adoption. Conventional capacity expansion models assume exogenous demand growth; however, literature suggests that this assumption is not appropriate for developing countries. The planning approach presented in this research explicitly represents the links between the social and technical components of the power system. As potential customers without electricity select between various supply options to meet their power needs and as existing customers alter their consumption in reaction to the price of electricity and the perceived performance of the grid, the demand for grid power is directly impacted. This thesis demonstrates that neglecting these feedbacks and resorting to simplified assumptions can result in suboptimal investment strategies. By comparing the investment strategies identified using this novel approach to that of more conventional approaches, this research highlights cases in which the incorporation of endogenous demand impacts capacity expansion planning. More specifically, this work proves that incorporating endogenous electricity demand is important when there is a large fraction of the population without access to power or when the improvement in reliability afforded by capacity expansion is large. Employing traditional capacity expansion methods in such cases may lead to the selection of inferior expansion strategies. This research has both academic and applied contributions. Methodologically, this research extends state-of-the-art power system models by combining two generally separate modeling approaches, system dynamics and optimization. These methods are integrated to capture both the technical details of power grid operation and endogenous electricity demand dynamics in order to simulate the performance and evolution of the electric power grid. This research also demonstrates a holistic approach to centralized power planning that enables a more realistic representation of grid demand in developing countries and the identification of strategies that, in some cases, perform better than the strategies identified using traditional approaches. Finally, while this research was inspired by the case of Tanzania, the approach was developed with the flexibility to be applied to other countries with similar power system structure and contextual features.<br>by Rhonda LeNai Jordan.<br>Ph.D.
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Gao, Wenzhong. "New methodology for power system modeling and its application in machine modeling and simulation." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/14732.
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Ventura, Cristina. "Theoretical and Experimental Development of a Photovoltaic Power System for Mobile Robot Applications." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1102.
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The primary goal of this work is the theoretical and experimental development of micro and mini systems for the photovoltaic production and the energy storage.
Robotics platforms should be, as much as possible, autonomous and self-sufficient, also from the energetic point of view. To this aim, up to now, the best compromise appears to be the use of micro solar power systems with rechargeable batteries. The use of this strategy for supplying systems with limited size and mass, but nevertheless high power requirements, such as a mobile robot, has been first studied. The system taken as test-bed in the experiment is a bio-inspired mobile robot, called TriBot.
First of all, a preliminary analysis of the feasibility of a photovoltaic system with batteries to supply this mobile robot has been done, considering the different solutions to place the PV cells on the robot structure, the different photovoltaic technologies and the power consumption of the robot, the conclusion is that, using the photovoltaic system here proposed, it is possible to increase the autonomy of the robot.
Since in the PV system here analyzed few solar cells can be employed, a very efficient charging system is an essential requisite. To this aim, a novel photovoltaic charge regulator, which uses the Fractional Open-Circuit Voltage MPPT method, is proposed.
A typical stand-alone photovoltaic system includes a solar array, batteries, regulator and load. In order to model the whole system and to evaluate its performance, a Simulink model in Matlab environment has been developed. In the simulator, measured values of the radiation and the temperature have been used, Anyhow, it will be possible also to use predicted values of radiation and temperature.
In this work, data given us by a weather forecast provider have been used. First of all the accuracy of these predicted data have been determined. Then, a method to classify each minute of a day as variable, cloudy, slightly cloudy or clear has been implemented. Using a neural network, a correlation between the classification of a specific day and the error done has been found. The knowledge of the available energy, in fact, should allow to implement power saving strategies, optimizing the activities of the robot.
Forecast and measured solar radiation are relative to the horizontal plane. However, the PV panel exposition is not assumed to be a control variable due to the fact that the robot can change its posture operating on uneven terrains. For these reasons, models are required to estimate the solar radiation on the plane of the PV array starting from the radiation on the horizontal plane. To this aim, Perez and Klucher models have been developed, these models require information at the same time on the global and the direct or diffuse radiation on the horizontal surface. Moreover, a neural network that allows to evaluate the global solar radiation on the tilted surface directly from the global solar radiation measured on the horizontal plane, without the need to slit it into the direct and diffuse components, has been developed.
Once that the solar radiation, measured or forecast, at any inclination and orientation are estimated; the power consumption of the robot and the efficiency of the charge regulator are known, all these information can be used in the Simulink model that, therefore, can become a very helpful tool to estimate the power production of the photovoltaic system and therefore the increase of the autonomy of the embedded systems used as load.
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Yang, Fang. "A Comprehensive Approach for Bulk Power System Reliability Assessment." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14488.
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Abstract
The goal of this research is to advance the state of the art in bulk power system reliability assessment. Bulk power system reliability assessment is an important procedure at both power system planning and operating stages to assure reliable and acceptable electricity service to customers. With the increase in the complexity of modern power systems and advances in the power industry toward restructuring, the system models and algorithms of traditional reliability assessment techniques are becoming obsolete as they suffer from nonrealistic system models and slow convergence (even non-convergence) when multi-level contingencies are considered and the system is overstressed. To allow more rigor in system modeling and higher computational efficiency in reliability evaluation procedures, this research proposes an analytically-based security-constrained adequacy evaluation (SCAE) methodology that performs bulk power system reliability assessment.
The SCAE methodology adopts a single-phase quadratized power flow (SPQPF) model as a basis and encompasses three main steps: (1) critical contingency selection, (2) effects analysis, and (3) reliability index computations. In the critical contingency selection, an improved contingency selection method is developed using a wind-chime contingency enumeration scheme and a performance index approach based on the system state linearization technique, which can rank critical contingencies with high accuracy and efficiency. In the effects analysis for selected critical contingencies, a non-divergent optimal quadratized power flow (NDOQPF) algorithm is developed to (1) incorporate major system operating practices, security constraints, and remedial actions in a constrained optimization problem and (2) guarantee convergence and provide a solution under all conditions. This algorithm is also capable of efficiently solving the ISO/RTO operational mode in deregulated power systems. Based on the results of the effects analysis, reliability indices that provide a quantitative indication of the system reliability level are computed. In addition, this research extends the proposed SCAE framework to include the effects of protection system hidden failures on bulk power system reliability.
The overall SCAE methodology is implemented and applied to IEEE reliability test systems, and evaluation results demonstrate the expected features of proposed advanced techniques. Finally, the contributions of this research are summarized and recommendations for future research are proposed.
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Pourbeik, Pouyan. "Design and coordination of stabilisers for generators and FACTS devices in multimachine power systems /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09php877.pdf.
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SOUZA, FABIO LUIZ DE. "DYNAMIC AGGREGATION OF POWER SYSTEM STABILIZER MODELS APPLIED IN VOLTAGE REGULATORS AND CALCULATION OF DYNAMIC EQUIVALENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7314@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR<br>O cálculo de equivalentes dinâmicos baseados em coerência
apresenta três etapas básicas: a identificação de
geradores coerentes, a redução estática da rede e a
agregação dinâmica dos modelos das unidades geradoras
coerentes.
Esta dissertação trata do problema da agregação dinâmica
de modelos de estabilizadores aplicados em reguladores de
tensão de geradores coerentes, visando o cálculo de
equivalentes dinâmicos precisos para estudos de
estabilidade transitória de sistemas de energia elétrica.
A determinação de um critério de escolha do melhor modelo
equivalente, para uma dada composição de modelos de
estabilizadores num grupo de geradores coerentes, é o
objetivo principal.
O ajuste dos parâmetros dos modelos equivalentes de
estabilizadores dos grupos coerentes é realizado, a partir
das respostas em freqüência dos modelos individuais de
cada grupo, utilizando-se o método de Levenberg-Marquardt,
o que caracteriza um problema de otimização multivariável.
O desempenho dinâmico dos equivalentes calculados com a
metodologia adotada é avaliado em um sistema teste.<br>The calculation of coherency-based dynamic equivalents has
three main steps: the identification of coherent
generators, the network reduction and the dynamic
aggregation of the coherent generating unit models.
This dissertation deals with the problem of dynamic
aggregation of power system stabilizer models to calculate
coherency-based dynamic equivalents for power system
transient stability studies. The determination of a
criteria to choose the best equivalent model for a given
composition of power system stabilizer models in a group
of coherent generators is the main objective.
The parameters of the power system stabilizer equivalent
models for each group of coherent generating units are
adjusted to match the frequency response of the individual
models. This multivariable optimization problem is solved
using the Levenberg-Marquardt method.
The dynamic performance of the equivalents is evaluated in
a test system.
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Chandler, Shawn Aaron. "Global Time-Independent Agent-Based Simulation for Transactive Energy System Dispatch and Schedule Forecasting." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2212.
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Electricity service providers (ESP) worldwide have increased their interest in the use of electrical distribution, transmission, generation, storage, and responsive load resources as integrated systems. Referred to commonly as "smart grid," their interest is driven by widespread goals to improve the operations, management and control of large-scale power systems. In this thesis I provide research into a novel agent-based simulation (ABS) approach for exploring smart grid system (SGS) dispatch, schedule forecasting and resource coordination. I model an electrical grid and its assets as an adaptive ABS, assigning an agent construct to every SGS resource including demand response, energy storage, and distributed generation assets. Importantly, real time is represented as an environment variable within the simulation, such that each resource is characterized temporally by multiple agents that reside in different times. The simulation contains at least as many agents per resource as there are time intervals being investigated. These agents may communicate with each other during the simulation, but only agents assigned to represent the same unique resource may exchange information between time periods. Thus, confined within each time interval, each resource agent may also interact with other resource agents. As with any agent-based model, the agents may also interact with the environment, in this case, containing forecasted environment, load and price information specific to each time interval. The resulting model is a time-independent global approach capable of: (1) capturing time-variant local grid conditions and distribution grid load balancing constraints; (2) capturing time-variant resource availability and price constraints, and finally, (3) simulating efficient unit-commitment real-time dispatches and schedule forecasts considering time-variant forecasted transactive market prices. This thesis details the need for such a system, discusses the form of the ABS, and analyzes the predictive behavior of the model through a critical lens by applying the resulting proof-of-concept simulation to a set of comprehensive validation scenarios. The resulting analysis demonstrates ABS as an effective tool for real-time dispatch and SGS schedule forecasting as applied to research, short-term economic operations planning and transactive systems alike. The model is shown to converge on economic opportunities regardless of the price or load-forecast shape and to correctly perform least-cost dispatch and schedule forecasting functionality.
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Jain, Himanshu. "Dynamic Simulation of Power Systems using Three Phase Integrated Transmission and Distribution System Models: Case Study Comparisons with Traditional Analysis Methods." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/74234.
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Solar PV-based distributed generation has increased significantly over the last few years, and the rapid growth is expected to continue in the foreseeable future. As the penetration levels of distributed generation increase, power systems will become increasingly decentralized with bi-directional flow of electricity between the transmission and distribution networks. To manage such decentralized power systems, planners and operators need models that accurately reflect the structure of, and interactions between the transmission and distribution networks. Moreover, algorithms that can simulate the steady state and dynamics of power systems using these models are also needed. In this context, integrated transmission and distribution system modeling and simulation has become an important research area in recent years, and the primary focus so far has been on studying the steady state response of power systems using integrated transmission and distribution system models.
The primary objective of this dissertation is to develop an analysis approach and a program that can simulate the dynamics of three phase, integrated transmission and distribution system models, and use the program to demonstrate the advantages of evaluating the impact of solar PV-based distributed generation on power systems dynamics using such models. To realize this objective, a new dynamic simulation analysis approach is presented, the implementation of the approach in a program is discussed, and verification studies are presented to demonstrate the accuracy of the program. A new dynamic model for small solar PV-based distributed generation is also investigated. This model can interface with unbalanced networks and change its real power output according to the incident solar irradiation. Finally, application of the dynamic simulation program for evaluating the impact of solar PV units using an integrated transmission and distribution system model is discussed.
The dissertation presents a new approach for studying the impact of solar PV-based distributed generation on power systems dynamics, and demonstrates that the solar PV impact studies performed using the program and integrated transmission and distribution system models provide insights about the dynamic response of power systems that cannot be obtained using traditional dynamic simulation approaches that rely on transmission only models.<br>Ph. D.
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Du, Zhaobin, and 杜兆斌. "Area COI-based slow frequency dynamics modeling, analysis and emergency control for interconnected power systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B4175783X.
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Dresch, Rodolfo de Freitas Valle. "Análise do efeito da modelagem da carga nas estimativas de perdas elétricas em sistemas de distribuição." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/103754.
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As perdas elétricas, que no Brasil giram em torno de 14,4%, são prejudiciais ao desempenho técnico e financeiro das concessionárias de energia elétrica, principalmente em um cenário de uma eminente crise energética e alta regulação. A mitigação das perdas elétricas está diretamente relacionada com sua correta estimação. Para operar um sistema de energia elétrica, é de fundamental importância definir a correta modelagem dos elementos do sistema. As metodologias de estimação das perdas de energia, para sistemas de distribuição, vigentes não levam em conta possíveis erros na correta modelagem das cargas conectadas. Desta forma, este trabalho tem o objetivo de analisar a influência causada pela utilização dos modelos de carga, na estimação das perdas elétricas em sistemas de distribuição. Esta análise abrange as metodologias de fluxo de carga backward-forward sweep por soma de corrente, por soma de potência e Newton-Raphson. A perda de energia é calculada pela diferença entre a energia injetada no sistema, menos a energia entregue. O estudo de caso é realizado em um sistema de distribuição teste de 13 barras da IEEE. No caso proposto, são realizados cálculos das perdas de energia para o sistema de distribuição, considerando diferentes modelos de carga. Desta maneira, o trabalho estimou a diferença no cálculo das perdas para cada tipo de modelo de carga, em relação a perdas calculadas com o padrão original das cargas. Outro ponto analisado foi o desempenho das metodologias de fluxo de carga, frente à alteração dos modelos de carga. Os resultados demonstram que a alteração dos modelos de carga influência a estimação das perdas elétricas nos sistemas de distribuição, e o desempenho dos fluxos de carga.<br>Electrical losses, which in Brazil are around 14.4%, are harmful to the technical and financial performance of electric utilities, especially in a scenario of an imminent energy crisis and high regulation. Mitigation of electrical losses is directly related to its correct estimation. To operate an electric power system, it is of fundamental importance to define the correct model of the system elements. The methodologies for estimating energy losses, for the existing distribution systems, do not take into account possible errors in the correct model of connected loads. Thus, this study aims to examine the influence caused by the use of different load models, in the estimation of electrical losses in distribution systems. This analysis covers the backward-forward sweep load flow methodologies by the sum of current, by the sum of power and Newton-Raphson. The energy loss is calculated by the difference between the energy injected into the system, minus the energy delivered. The case study is performed on the IEEE 13 Node Test Feeder. In the proposed case, calculations of energy losses in the distribution system are performed considering different load models. Therefore, the study has estimated the difference in the calculation of energy loss for each type of load model, for the losses calculated with the original pattern of loads. Another point discussed is the performance of load flow methodologies, related to the change of load models. The results have shown that the change in load models influence the estimation of electrical losses in distribution systems and in the performance of load flows.
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Yu, Chang, and 余暢. "An investigation of subsynchronous oscillation of AC/DC power systems: modeling and analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37151885.
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Ciechanowicz, David [Verfasser], Thomas [Akademischer Betreuer] Hamacher, Alois C. [Gutachter] Knoll, and Thomas [Gutachter] Hamacher. "A Power System Planning and Power Flow Simulation Framework for Generating and Evaluating Power Network Models : Investigating the Impact of Large-Scale Road Transportation Electrification on Urban Power Systems / David Ciechanowicz ; Gutachter: Alois C. Knoll, Thomas Hamacher ; Betreuer: Thomas Hamacher." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1162621079/34.
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