Dissertations / Theses on the topic 'Power system dynamic'
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Hockenberry, James Richard. "Power system dynamic load modeling." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42594.
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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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Bousnane, Kafiha. "Real-time power system dynamic simulation." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6623/.
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The present day digital computing resources are overburdened by the amount of calculation necessary for power system dynamic simulation. Although the hardware has improved significantly, the expansion of the interconnected systems, and the requirement for more detailed models with frequent solutions have increased the need for simulating these systems in real time. To achieve this, more effort has been devoted to developing and improving the application of numerical methods and computational techniques such as sparsity-directed approaches and network decomposition to power system dynamic studies. This project is a modest contribution towards solving this problem. It consists of applying a very efficient sparsity technique to the power system dynamic simulator under a wide range of events. The method used was first developed by Zollenkopf (^117) Following the structure of the linear equations related to power system dynamic simulator models, the original algorithm which was conceived for scalar calculation has been modified to use sets of 2 * 2 sub-matrices for both the dynamic and algebraic equations. The realisation of real-time simulators also requires the simplification of the power system models and the adoption of a few assumptions such as neglecting short time constants. Most of the network components are simulated. The generating units include synchronous generators and their local controllers, and the simulated network is composed of transmission lines and transformers with tap-changing and phase-shifting, non-linear static loads, shunt compensators and simplified protection. The simulator is capable of handling some of the severe events which occur in power systems such as islanding, island re-synchronisation and generator start-up and shut-down. To avoid the stiffness problem and ensure the numerical stability of the system at long time steps at a reasonable accuracy, the implicit trapezoidal rule is used for discretising the dynamic equations. The algebraisation of differential equations requires an iterative process. Also the non-linear network models are generally better solved by the Newton-Raphson iterative method which has an efficient quadratic rate of convergence. This has favoured the adoption of the simultaneous technique over the classical partitioned method. In this case the algebraised differential equations and the non-linear static equations are solved as one set of algebraic equations. Another way of speeding-up centralised simulators is the adoption of distributed techniques. In this case the simulated networks are subdivided into areas which are computed by a multi-task machine (Perkin Elmer PE3230). A coordinating subprogram is necessary to synchronise and control the computation of the different areas, and perform the overall solution of the system. In addition to this decomposed algorithm the developed technique is also implemented in the parallel simulator running on the Array Processor FPS 5205 attached to a Perkin Elmer PE 3230 minicomputer, and a centralised version run on the host computer. Testing these simulators on three networks under a range of events would allow for the assessment of the algorithm and the selection of the best candidate hardware structure to be used as a dedicated machine to support the dynamic simulator. The results obtained from this dynamic simulator are very impressive. Great speed-up is realised, stable solutions under very severe events are obtained showing the robustness of the system, and accurate long-term results are obtained. Therefore, the present simulator provides a realistic test bed to the Energy Management System. It can also be used for other purposes such as operator training.
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Zhong, Zhian. "Power Systems Frequency Dynamic Monitoring System Design and Applications." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28707.
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Recent large-scale blackouts revealed that power systems around the world are far from the stability and reliability requirement as they suppose to be. The post-event analysis clarifies that one major reason of the interconnection blackout is lack of wide area information. Frequency dynamics is one of the most important parameters of an electrical power system. In order to understand power system dynamics effectively, accurately measured wide-area frequency is needed. The idea of building an Internet based real-time GPS synchronized wide area Frequency Monitoring Network (FNET) was proposed to provide the imperative dynamic information for the large-scale power grids and the implementation of FNET has made the synchronized observations of the entire US power network possible for the first time. The FNET system consists of Frequency Disturbance Recorders (FDR), which work as the sensor devices to measure the real-time frequency at 110V single-phase power outlets, and an Information Management System (IMS) to work as a central server to process the frequency data. The device comparison between FDR and commercial PMU (Phasor Measurement Unit) demonstrate the advantage of FNET. The web visualization tools make the frequency data available for the authorized users to browse through Internet.
The research work addresses some preliminary observations and analyses with the field-measured frequency information from FNET. The original algorithms based on the frequency response characteristic are designed to process event detection, localization and unbalanced power estimation during frequency disturbances. The analysis of historical cases illustrate that these algorithms can be employed in real-time level to provide early alarm of abnormal frequency change to the system operator. The further application is to develop an adaptive under frequency load shedding scheme with the processed information feed in to prevent further frequency decline in power systems after disturbances causing dangerous imbalance between the load and generation.Ph. D.
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Song, Xuefeng. "Dynamic modeling issues for power system applications." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1591.
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Power system dynamics are commonly modeled by parameter dependent nonlinear differential-algebraic equations (DAE) x p y x f ) and 0 = p y x g ) . Due to
(,, (,, the algebraic constraints, we cannot directly perform integration based on the DAE. Traditionally, we use implicit function theorem to solve for fast variables y to get a reduced model in terms of slow dynamics locally around x or we compute y numerically at each x . However, it is well known that solving nonlinear algebraic equations analytically is quite difficult and numerical solution methods also face many uncertainties since nonlinear algebraic equations may have many solutions, especially around bifurcation points. In this thesis, we apply the singular perturbation method to model power system dynamics in a singularly perturbed ODE (ordinary-differential equation) form, which makes it easier to observe time responses and trace bifurcations without reduction process. The requirements of introducing the fast dynamics are investigated and the complexities in the procedures are explored. Finally, we propose PTE (Perturb and Taylors expansion) technique to carry out our goal to convert a DAE to an explicit state space form of ODE. A simplified unreduced Jacobian matrix is also introduced. A dynamic voltage stability case shows that the proposed method works well without complicating the applications.
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Singhavilai, Thamvarit. "Identification of electric power system dynamic equivalent." Thesis, University of Strathclyde, 2011. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=15647.
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Geitner, Gert-Helge, and Guven Komurgoz. "Power Flow Modelling of Dynamic Systems." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-171305.
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As tools for dynamic system modelling both conventional methods such as transfer function or state space representation and modern power flow based methods are available. The latter methods do not depend on energy domain, are able to preserve physical system structures, visualize power conversion or coupling or split, identify power losses or storage, run on conventional software and emphasize the relevance of energy as basic principle of known physical domains. Nevertheless common control structures as well as analysis and design tools may still be applied. Furthermore the generalization of power flow methods as pseudo-power flow provides with a universal tool for any dynamic modelling. The phenomenon of power flow constitutes an up to date education methodology. Thus the paper summarizes fundamentals of selected power flow oriented modelling methods, presents a Bond Graph block library for teaching power oriented modelling as compact menu-driven freeware, introduces selected examples and discusses special features.
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Newham, Nikki. "Power System Investment Planning using Stochastic Dual Dynamic Programming." Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/1975.
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Generation and transmission investment planning in deregulated markets faces new challenges
particularly as deregulation has introduced more uncertainty to the planning problem. Tradi-
tional planning techniques and processes cannot be applied to the deregulated planning problem
as generation investments are profit driven and competitive. Transmission investments must
facilitate generation access rather than servicing generation choices. The new investment plan-
ning environment requires the development of new planning techniques and processes that can
remain flexible as uncertainty within the system is revealed.
The optimisation technique of Stochastic Dual Dynamic Programming (SDDP) has been success-
fully used to optimise continuous stochastic dynamic planning problems such as hydrothermal
scheduling. SDDP is extended in this thesis to optimise the stochastic, dynamic, mixed integer
power system investment planning problem. The extensions to SDDP allow for optimisation of
large integer variables that represent generation and transmission investment options while still
utilising the computational benefits of SDDP. The thesis also details the development of a math-
ematical representation of a general power system investment planning problem and applies it to
a case study involving investment in New Zealand’s HVDC link. The HVDC link optimisation
problem is successfully solved using the extended SDDP algorithm and the output data of the
optimisation can be used to better understand risk associated with capital investment in power
systems.
The extended SDDP algorithm offers a new planning and optimisation technique for deregulated
power systems that provides a flexible optimal solution and informs the planner about investment
risk associated with uncertainty in the power system.
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Wu, Qiang. "Tap changing dynamic modeling and its effects on power system voltage behavior." Thesis, The University of Sydney, 1998. https://hdl.handle.net/2123/27640.
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This thesis presents research results on the effects of tap changing dynamic modeling
on power system mid-to-long term voltage behavior.
The modeling of tap changing dynamics in voltage stability studies is first addressed.
The dynamic operation of an on-load-tap—changing transformer is represented by a
highly nonlinear, discrete and time—delay embedded model, which is suitable to
mid-to—long term voltage stability studies. Different discrete tap models and their
continuous approximations with respect to time and tap position are introduced.
The initial emphasis is on studying the influences of different discrete and continuous
tap models on voltage stability properties. Combining the tap changer dynamics
with the detailed load dynamics, the impacts of different tap models on system
voltage behavior are illustrated via theoretical analysis and simulation. It is shown
that different stability regions are associated with different continuous tap models
and significantly influence the system/voltage behavior, especially under heavily
loaded system conditions. The Lyapunov stability method is used to predict the
stability region. Limit cycle phenomena are observed in systems with discrete tap
models due to the inherent nonlinearities present in these models, the tap dynamics
and its interaction with the load dynamics. Conditions for existence of limit cycles
are derived via the describing function method. Cases when discrete tap models
and their corresponding continuous approximations result in different and / or similar
system behavior are also illustrated.
Further, a detailed study is given on. the voltage oscillation phenomenon in power
systems with on-load—tap—changers. Two kinds of oscillations are considered, namely
the well-known voltage oscillations due to tap hunting and oscillations due to tap—
load interactions. The focus is on the limit cycle caused by the tap-load interaction.
The effects of tap deadband and other parameters such as tap delay time and load
recovery time on the existence of system cyclic behavior are carefully investigated.
It. is shown that whether or not the limit cycle can be avoided by adjusting the tap
deadband depends mainly on the load characteristics. Trajectory sensitivity analysis
offers useful information on the influence of parameters on system cyclic behavior.
Next, consideration is given to the coordination of a tap changer, as a voltage
control device, with other controls, such as a switching capacitor. Using the results
of voltage stability analysis as a framework, a new approach for the coordination
of dissimilar control actions is derived for arresting voltage collapse. The benefits
of coordination of tap locking and capacitor switching are demonstrated foi two
possible situations. Firstly, prior capacitor switching at some buses is shown to
expand the stability regioh and provide sufficient time for successful tap locking.
Secondly, locking taps at some buses can slow the system deterioration and provides
time for capacitor switching.
The results obtained not only highlight the importance of tap dynamics modeling
in voltage behavior studies, but also give an insight into system voltage stability
evaluatiofi and control involving on—load-tap—changer dynamics.
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Troullinos, George. "Estimating order reduction for dynamic systems with applications to power system equivalents." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/13449.
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Singh, Ravindra. "A Novel Approach for Tuning of Power System Stabilizer Using Genetic Algorithm." Thesis, Indian Institute of Science, 2004. http://hdl.handle.net/2005/65.
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The problem of dynamic stability of power system has challenged power system engineers since over three decades now. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system, which exhibits an oscillatory behaviour around the equilibrium state, following any disturbance, such as sudden change in loads, change in transmission line parameters, fluctuations in the output of turbine and faults etc. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of low frequency oscillations. The oscillations, which are typically in the frequency range of 0.2 to 3.0 Hz, might be excited by the disturbances in the system or, in some cases, might even build up spontaneously. These oscillations limit the power transmission capability of a network and, sometimes, even cause a loss of synchronism and an eventual breakdown of the entire system.
The application of Power System Stabilizer (PSS) can help in damping out these oscillations and improve the system stability. The traditional and till date the most popular solution to this problem is application of conventional power system stabilizer (CPSS). However, continual changes in the operating condition and network parameters result in corresponding change in system dynamics. This constantly changing nature of power system makes the design of CPSS a difficult task.
Adaptive control methods have been applied to overcome this problem with some degree of success. However, the complications involved in implementing such controllers have restricted their practical usage.
In recent years there has been a growing interest in robust stabilization and disturbance attenuation problem. H∞ control theory provides a powerful tool to deal with robust stabilization and disturbance attenuation problem. However the standard H∞ control theory does not guarantee robust performance under the presence of all the uncertainties in the power plants.
This thesis provides a method for designing fixed parameter controller for system to ensure robustness under model uncertainties. Minimum performance required of PSS is decided a priori and achieved over the entire range of operating conditions.
A new method has been proposed for tuning the parameters of a fixed gain power system stabilizer. The stabilizer places the troublesome system modes in an acceptable region in the complex plane and guarantees a robust performance over a wide range of operating conditions. Robust D-stability is taken as primary specification for design. Conventional lead/lag PSS structure is retained but its parameters are re-tuned using genetic algorithm (GA) to obtain enhanced performance. The advantage of GA technique for tuning the PSS parameters is that it is independent of the complexity of the performance index considered. It suffices to specify an appropriate objective function and to place finite bounds on the optimized parameters. The efficacy of the proposed method has been tested on single machine as well as multimachine systems. The proposed method of tuning the PSS is an attractive alternative to conventional fixed gain stabilizer design as it retains the simplicity of the conventional PSS and still guarantees a robust acceptable performance over a wide range of operating and system condition.
The method suggested in this thesis can be used for designing robust power system stabilizers for guaranteeing the required closed loop performance over a prespecified range of operating and system conditions. The simplicity in design and implementation of the proposed stabilizers makes them better suited for practical applications in real plants.
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Snowdon, David Computer Science & Engineering Faculty of Engineering UNSW. "Operating system directed power management." Awarded By:University of New South Wales. Computer Science & Engineering, 2010. http://handle.unsw.edu.au/1959.4/44747.
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Energy is a critical resource in all types of computing systems from servers, where energy costs dominate data centre expenses and carbon footprints, to embedded systems, where the system's battery life limits the device's functionality. In their efforts to reduce the energy use of these system's hardware manufacturers have implemented features which allow a reduced energy consumption under software control. This thesis shows that managing these settings is a more complex problem than previously considered. Where much (but not all) of the previous academic research investigates unrealistic scenarios, this thesis presents a solution to managing the power on varying hardware. Instead of making unrealistic assumptions, we extract a model from empirical data and characterise that model. Our models estimate the effect of different power management settings on the behaviour of the hardware platform, taking into account the workload, platform and environmental characteristics, but without any kind of a-priori knowledge of the specific workloads being run. These models encapsulate a system's knowledge of the platform. We also developed a \emph{generalised energy-delay} policy which allows us to quickly express the instantaneous importance of both performance and energy to the system. It allows us to select a power management strategy from a number of options. This thesis shows, by evaluation on a number of platforms, that our implementation, Koala, can accurately meet energy and performance goals. In some cases, our system saves 26\% of the system-level energy required for a task, while losing only 1\% performance. This is nearly 46\% of the dynamic energy. Taking advantage of all energy-saving opportunities requires detailed platform, workload and environmental information. Given this knowledge, we reach the exciting conclusion that near optimal power management is possible on real operating systems, with real platforms and real workloads.
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Liu, Xiaopeng. "Power system dynamic vulnerability under extreme transmission line contingencies." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18782.
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Power systems around the world may be under the threat of extreme conditions such as natural disasters and terrorist attacks. To find the most severe condition in the static sense, systematic methods based on optimization have been developed. However, until now, there is no systematic way to find the most severe contingency in the dynamic sense. The thesis proposes such a systematic approach. The method adopts a two-step “screening-and-ranking” procedure similar to the one employed in conventional dynamic security analysis. In the “screening” step, transmission lines are screened using two criteria. The first criterion is based on critical eigen-sensitivity with respect to single line outages. A transmission line is selected only if one of the critical eigenvalues has a large sensitivity to the outage of this line. The second criterion is based on a topology analysis searching for cut-sets in the system. A transmission line is selected if it is a member of a system cut-set with high power imbalance ratio. In the “ranking” step, time-domain analysis is performed on all the combinations of the lines screened by the first step, to determine their real dynamic impact on the system. Relays for generators, loads, and transmission lines are set-up so as to capture possible cascading events after the initial disturbance. Test results on the One Area IEEE96 system show that the set of critical lines selected by the proposed screening scheme is dependent on the system operating conditions. The screening step can reduce the contingency number significantly, which will alleviate the computation burden in the ranking step by a large margin. The most severe contingencies in term of load shedding were in most cases identified by the proposed method. The merit of the method is its simplicity, which makes it applicable to the analysis of N-2 and N-3 transmission line contingencies. Limitations of the method, such as the possibility of missing the more disruptive cLes réseaux électriques peuvent être sous la menace de conditions extrêmes, tels que désastres naturels et attentats terroristes. Pour déterminer la condition la plus sévère en état stationnaire, des méthodes systématiques utilisant des techniques d'optimisations ont été développées. Jusqu'à présent il n'existe cependant pas de méthodes systématiques pour déterminer quel défaut est le plus sévère en régime dynamique. Cette thèse propose une telle méthode. Elle utilise une approche en deux étapes, « triage et classement », similaire à celle utilisée dans une analyse de sécurité dynamique conventionnelle. Dans l'étape de triage, les lignes de transport d'électricité sont sélectionnées selon deux critères. Le premier est basé sur la sensibilité critique des valeurs propres par rapport à la perte d'une seule ligne. Une ligne de transport est sélectionnée seulement si une des valeurs propres critiques a une sensibilité élevée à la perte de cette ligne. Le second critère est basé sur une analyse topologique et recherche des ensembles de coupure dans le système. Une ligne de transport est sélectionnée si elle appartient à un ensemble de coupure avec un déséquilibre de puissance élevé. Dans l'étape de classement, une analyse temporelle est effectuée sur toutes les combinaisons possibles des lignes de transport sélectionnées dans la première étape, afin de déterminer leurs véritables impacts dynamiques sur le réseau électrique. Les relais de protection sont représentés. Les résultats des simulations sur le système test IEEE96 démontrent que l'étape de triage peut réduire le nombre de défauts de manière significative, ce qui peut alléger considérablement le fardeau de calcul dans l'étape de classement. Les défauts les plus sévères en termes de délestage étaient identifiés dans la plupart des cas par la méthode proposée. L'intérêt de la méthode réside dans sa simplicité,$
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Cui, Yinan. "Dynamic State Estimation Assisted Power System Monitoring and Protection." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25851.
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The advent of phasor measurement units (PMUs) has unlocked several novel methods to monitor, control, and protect bulk electric power systems. This thesis introduces the concept of ?Dynamic State Estimation? (DSE), aided by PMUs, for wide-area monitoring and protection of power systems. Unlike traditional State Estimation where algebraic variables are estimated from system measurements, DSE refers to a process to estimate the dynamic states associated with synchronous generators. This thesis first establishes the viability of using particle filtering as a technique to perform DSE in power systems. The utility of DSE for protection and wide-area monitoring are then shown as potential novel applications. The work is presented as a collection of several journal and conference papers. In the first paper, we present a particle filtering approach to dynamically estimate the states of a synchronous generator in a multi-machine setting considering the excitation and prime mover control systems. The second paper proposes an improved out-of-step detection method for generators by means of angular difference. The generator's rotor angle is estimated with a particle filter-based dynamic state estimator and the angular separation is then calculated by combining the raw local phasor measurements with this estimate. The third paper introduces a particle filter-based dual estimation method for tracking the dynamic states of a synchronous generator. It considers the situation where the field voltage measurements are not readily available. The particle filter is modified to treat the field voltage as an unknown input which is sequentially estimated along with the other dynamic states. The fourth paper proposes a novel framework for event detection based on energy functions. The key idea is that any event in the system will leave a signature in WAMS data-sets. It is shown that signatures for four broad classes of disturbance events are buried in the components that constitute the energy function for the system. This establishes a direct correspondence (or mapping) between an event and certain component(s) of the energy function. The last paper considers the dynamic latency effect when the measurements and estimated dynamics are transmitted from remote ends to a centralized location through the networks.National Science Foundation, NSF (Award #1544621)
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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.
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FURNAS CENTRAIS ELÉTRICAS S.AEsta 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.
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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張旭健 and Yuk-kin Cheung. "Auto-retuning of power system stabilizers for dynamic stability improvement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31212207.
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Cheung, Yuk-kin. "Auto-retuning of power system stabilizers for dynamic stability improvement /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19669136.
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Smith, Mark Allen. "Improved dynamic stability using FACTS devices with phasor measurement feedback /." This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-05022009-040702/.
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Mabeta, Simon Jorums. "Open Conductor Faults and Dynamic Analysis of a Power System." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18994.
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The overall goal of this thesis is to study and understand Open Conductor Faults and to assess their impact on the stability of a power system. In particular, the thesis has investigated the effect of this type of the fault on the dynamic electromechanical behavior of synchronous machine. The thesis has also focused on the effect of generator and transformer grounding as well as the effect of transformer winding configuration on the stability of the power system during this type of fault.Open conductor faults are series faults which involve a break in one or two of the three conductors of a three phase power system. As such, the fault is an unsymmetrical fault and thus, the theory of symmetrical components was revisited. Symmetrical components and symmetrical circuits have been used to analyze both types of open conductor faults in order to understand the phenomenon and ease calculations. A dual approach to this study has been undertaken. The phenomenon is treated analytically through calculations and then the calculated results are confirmed through computer simulations using SIMPOW, a power system simulation software. In either approach, it is evidently clear, through the use of Eigen values and calculated damping coefficients, that the damping of the machine in an open conductor situation is worse than the for the normal case without the fault. A research in to the developed equations for damping has been undertaken. The theory of induction motors is applied in development of both the positive and negative damping power. The equation for negative damping power is developed first, using the symmetrical component concept and secondly, using the single phasing concept. In the investigation of transformer winding configurations and the grounding generators and transformers, different scenarios have been considered and simulated in order to show their effect during the fault. Finally the two open conductor case has also been investigated analytically and through computer simulation. The effect of grounding is shown in the results obtained. It shows that power transfer only occurs when there is a return path from the point of the fault to the generator.
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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.Includes bibliographical references (leaves 209-213).
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.
by James R. Hockenberry.
Ph.D.
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Krishnan, Venkat Kumar. "Coordinated static and dynamic reactive power planning against power system voltage stability related problems." [Ames, Iowa : Iowa State University], 2007.
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Beeravolu, Nagendrakumar. "Predicting Voltage Abnormality Using Power System Dynamics." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1722.
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The purpose of this dissertation is to analyze dynamic behavior of a stressed power system and to correlate the dynamic responses to a near future system voltage abnormality. It is postulated that the dynamic response of a stressed power system in a short period of time-in seconds-contains sufficient information that will allow prediction of voltage abnormality in future time-in minutes. The PSSE dynamics simulator is used to study the dynamics of the IEEE 39 Bus equivalent test system. To correlate dynamic behavior to system voltage abnormality, this research utilizes two different pattern recognition methods one being algorithmic method known as Regularized Least Square Classification (RLSC) pattern recognition and the other being a statistical method known as Classification and Regression Tree (CART). Dynamics of a stressed test system is captured by introducing numerous contingencies, by driving the system to the point of abnormal operation, and by identifying those simulated contingencies that cause system voltage abnormality.
Normal and abnormal voltage cases are simulated using the PSSE dynamics tool. The results of simulation from PSSE dynamics will be divided into two sets of training and testing set data. Each of the two sets of data includes both normal and abnormal voltage cases that are used for development and validation of a discriminator. This research uses stressed system simulation results to train two RLSC and CART pattern recognition models using the training set obtained from the dynamic simulation data. After the training phase, the trained pattern recognition algorithm will be validated using the remainder of data obtained from simulation of the stressed system. This process will determine the prominent features and parameters in the process of classification of normal and abnormal voltage cases from dynamic simulation data.
Each of the algorithmic or statistical pattern recognition methods have their advantages and disadvantages and it is the intention of this dissertation to use them only to find correlations between the dynamic behavior of a stressed system in response to severe contingencies and the outcome of the system behavior in a few minutes into the future.
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Parchure, Abhineet Himanshu. "Towards Three-Phase Dynamic Analysis of Large Electric Power Systems." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/54574.
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This thesis primarily focuses on studying the impact of Distributed Generation (DG) on the electromechanical transients in the electric grid (distribution, transmission or combined transmission and distribution (TandD) systems) using a Three Phase Dynamics Analyzer (hereafter referred to as TPDA). TPDA includes dynamic models for electric machines, their controllers, and a three-phase model of the electric grid, and performs three-phase dynamic simulations without assuming a positive sequence network model. As a result, TPDA can be used for more accurate investigation of electromechanical transients in the electric grid in the presence of imbalances.
At present, the Electromagnetic Transient Program (EMTP) software can be used to perform three-phase dynamic simulations. This software models the differential equations of the entire electric network along with those of the machines. This calls for solving differential equations with time constants in the order of milliseconds (representing the fast electric network) in tandem with differential equations with time constants in the order of seconds (representing the slower electromechanical machines). This results in a stiff set of differential equations, making such an analysis extremely time consuming. For the purpose of electromechanical transient analysis, TPDA exploits the difference in the order of time constants and adopts phasor analysis of the electric network, solving differential equations only for the equipment whose dynamics are much slower than those of the electric network. Power Flow equations are solved using a graph trace analysis based approach which, along with the explicit partitioned method adopted in TPDA, can eventually lead to the use of distributed computing that will further enhance the speed of TPDA and perhaps enable it to perform dynamic simulation in real time .
In the work presented here, first an overview of the methodology behind TPDA is provided. A description of the object oriented implementation of TPDA in C++/C# is included. Subsequently, TPDA is shown to accurately simulate power system dynamics of balanced networks by comparing its results against those obtained using GE-PSLF®. This is followed by an analysis that demonstrates the advantages of using TPDA by highlighting the differences in results when the same problem is analyzed using a three-phase network model with unbalances and the positive sequence network model as used in GE-PSLF®. Finally, the impact of rapidly varying DG generation is analyzed, and it is shown that as the penetration level of DG increases, the current and voltage oscillations throughout the transmission network increase as well. Further, rotor speed deviations are shown to grow proportionally with increasing DG penetration.Master of Science
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Jones, Kevin David. "Synchrophasor-Only Dynamic State Estimation & Data Conditioning." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51548.
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A phasor-only estimator carries with it intrinsic improvements over its SCADA analogue with respect to performance and reliability. However, insuring the quality of the data stream which leaves the linear estimator is crucial to establishing it as the front end of an EMS system and network applications which employ synchrophasor data. This can be accomplished using a two-fold solution: the pre-processing of phasor data before it arrives at the linear estimator and the by developing a synchrophasor-only dynamic state estimator as a mechanism for bad data detection and identification. In order to realize these algorithms, this dissertation develops a computationally simple model of the dynamics of the power system which fits neatly into the existing linear state estimation formulation. The algorithms are then tested on field data from PMUs installed on the Dominion Virginia Power EHV network.Ph. D.
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Fang, Yong Jie. "Dynamic and transient system control using fast acting quadrature boosters." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244084.
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Elkington, Katherine. "The Dynamic Impact of Large Wind Farms on Power System Stability." Doctoral thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93220.
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As the installed capacity of wind power increases across the world, its impact on power systems is becoming more important. To ensure the reliable operation of a power system which is significantly fed by wind power, the dynamics of the system must be understood. The purpose of this study is to analyse the dynamic impact of large-scale wind farms on the stability of a power grid, and to investigate the possibility of improving the stabilisation and damping of the grid by smart control strategies for wind turbines. When unconventional types of generators are used in a power system, the system behaves differently under abnormal dynamic events. For example, new types of generators such as doubly fed induction generators (DFIGs) cause different modes of oscillation in the system. In order to damp oscillations in the system, it is necessary to understand the equipment causing these oscillations, and the methods of optimally damping the oscillations. Large power oscillations can occur in a power system as a result of disturbances. Ordinarily these oscillations are slow and, in principle, it is possible to damp them with the help of wind power. This suggests the use of a power oscillation damping (POD) controller for a DFIG, similar to a power system stabiliser (PSS) for a synchronous generator. To demonstrate this concept, we design PODs for DFIGs in a wind farm. Voltage stability is another important aspect of the safe operation of a power system. It has been shown that the voltage stability of a power system is affected by induction generators and also DFIGs. The voltage stability must therefore also be analysed in order to guard against a power system collapse. In this study we develop models and control strategies for large wind farms comprising DFIGs, and study the impact of the wind farms on power systems. The design of multiple PODs in a wind farm is performed using linear matrix inequalities (LMIs), and the impact of the wind turbines is investigated through the use of linear and dynamic simulations. It has been demonstrated that DFIGs can be used for damping oscillations, and that they can also improve the critical clearing time of some faults. However, they may have an adverse impact on power systems after large voltage disturbances.QC 20120419
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Henschel, Sebastian. "Analysis of electromagnetic and electromechanical power system transients with dynamic phasors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0014/NQ38894.pdf.
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Nguyen, Dat. "Dynamic feedback pulse shaping for high power chirped pulse amplification system." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5826.
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The topic of this proposal is the development of high peak power laser sources with a focus on linearly chirped pulse laser sources. In the past decade chirped optical pulses have found a plethora of applications such as photonic analog-to-digital conversion, optical coherence tomography, laser ranging, etc. This dissertation analyzes the aforementioned applications of linearly chirped pulses and their technical requirements, as well as the performance of previously demonstrated parabolic pulse shaping approaches. The experimental research addresses the topic of parabolic pulse generation in two distinct ways. First, pulse shaping technique involving a time domain approach is presented, that results in stretched pulses with parabolic profiles with temporal duration of 15 ns. After pulse is shaped into a parabolic intensity profile, the pulse is compressed with DCF fiber spool by 100 times to 80 ps duration at FWHM. A different approach of pulse shaping in frequency domain is performed, in which a spectral processor based on Liquid Crystal on Silicon technology is used. The pulse is stretched to 1.5 ns before intensity mask is applied, resulting in a parabolic intensity profile. Due to frequency to time mapping, its temporal profile is also parabolic. After pulse shaping, the pulse is compressed with a bulk compressor, and subsequently analyzed with a Frequency Resolved Optical Gating (FROG). The spectral content of the compressed pulse is feedback to the spectral processor and used to adjust the spectral phase mask applied on the pulse. The resultant pulse after pulse shaping with feedback mechanism is a Fourier transform, sub-picosecond ultrashort pulse with 5 times increase in peak power. The appendices in this dissertation provide additional material used for the realization of the main research focus of the dissertation. Specification and characterization of major components of equipment and devices used in the experiment are present. The description of Matlab algorithms that was used to calculate required signals for pulse shaping are shown. A brief description of the Labview code used to control the spectral processor will also be illustrated.Ph.D.
Doctorate
Physics
Sciences
Physics
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CANTERA, JOSE MARIA CALVO. "DETECTION AND IDENTIFICATION OF ANOMALIES IN POWER SYSTEM DYNAMIC STATE ESTIMATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1987. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9891@1.
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ELETROBRAS - CENTRAIS ELÉTRICAS BRASILEIRAS S. A.Este trabalho apresenta uma comparação entre o desempenho dos estimadores dinâmicos e rastreador, em sistemas de potência operando sob condições quase-estacionárias, considerando suas características de previsão e filtragem. A partir desta comparação, propõe-se um estimador dinâmico que incorpora as principais vantagens dos estimadores previamente mencionados. Além disso, apresenta-se um novo esquema de detecção e identificação de anormalidades (erros grosseiros nas medidas, mudanças brusca no ponto de operação do sistema e erros na configuração da rede), esquema este apropriadamente construído para algoritmos de estimação dinâmica. Resultados numéricos ilustram o desempenho deste novo algoritmo sob diferentes condições operativas.
This work presents a comparison between the performance of dynamic and tracking estimators, in power systems operating under quasi-static conditions, concerning their characteristics of forecasting and filtering. From this comparison, a new dynamic estimator which incorporates the main advantages of the previous estimators is proposed. Also, a new scheme of detection and identification of anomalies (gross errors in the measurements, sudden changes in the system operating point and errors in the network configuration) is presented. This scheme is properly built for dynamic algorithms. Numerical results showing the performance of the new algorithm under different operational conditions are discussed.
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Grzejewski, Jerzy Marek. "Implementation of distributed software environments for dynamic power system security assessment." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760685.
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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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Fan, Dawei. "Synchronized Measurements And Applications During Power System Dynamics." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26115.
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Synchronized phasor measurements during dynamics tend to be affected by prevailing system frequency. Some major blackouts in power systems are indeed featured with very large frequency disturbance. Quantitative study done in this dissertation shows that small frequency disturbance may lead to measurement errors, and large frequency disturbance may lead to wrong measurements as well as catastrophic results if applied in system protection and control. The purpose of this dissertation is to bring up this issue, point to some possible solutions and application examples.
A synchronized frequency measurement method, which has better dynamic performance, is proposed in this dissertation. Based on this accurate synchronized frequency, a phasor compensation algorithm is proposed to correct the errors due to frequency disturbance in legacy PMUs or as alternative frequency tracking algorithm in new PMUs. Phasor positioning and unbalance issues are also investigated in this dissertation. With these improved synchronized measurements, wide area protection and control can be achieved with higher reliability. As an application example, traditional preset out-of-step protection could be replaced by the adaptive out-of-step protection using wide area measurements. Real-time swing curve and real-time EEAC based adaptive out-of-step protection schemes are developed respectively in this dissertation. Numerical Simulations are performed for validation of the proposed concepts.Ph. D.
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Kook, Kyung Soo Soo. "Dynamic Model Based Novel Findings in Power Systems Analysis and Frequency Measurement Verification." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27761.
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This study selects several new advanced topics in power systems, and verifies their usefulness using the simulation. In the study on ratio of the equivalent reactance and resistance of the bulk power systems, the simulation results give us the more correct value of X/R of the bulk power system, which can explain why the active power compensation is also important in voltage flicker mitigation. In the application study of the Energy Storage System(ESS) to the wind power, the new model implementation of the ESS connected to the wind power is proposed, and the control effect of ESS to the intermittency of the wind power is verified. Also this study conducts the intensive simulations for clarifying the behavior of the wide-area power system frequency as well as the possibility of the on-line instability detection.
In our POWER IT Laboratory, since 2003, the U.S. national frequency monitoring network (FNET) has been being continuously operated to monitor the wide-area power system frequency in the U.S. Using the measured frequency data, the event of the power system is triggered, and its location and scale are estimated. This study also looks for the possibility of using the simulation technologies to contribute the applications of FNET, finds similarity of the event detection orders between the frequency measurements and the simulations in the U.S. Eastern power grid, and develops the new methodology for estimating the event location based on the simulated N-1 contingencies using the frequency measurement.
It has been pointed out that the simulation results can not represent the actual response of the power systems due to the inevitable limit of modeling power systems and different operating conditions of the systems at every second. However, in the circumstances that we need to test such an important infrastructure supplying the electric energy without taking any risk of it, the software based simulation will be the best solution to verify the new technologies in power system engineering and, for doing this, new models and better application of the simulation should be proposed.
Conducting extensive simulation studies, this dissertation verified that the actual X/R ratio of the bulk power systems is much lower than what has been known as its typical value, showed the effectiveness of the ESS control to mitigate the intermittence of the wind power from the perspective of the power grid using the newly proposed simulation model of ESS connected to the wind power, and found many characteristics of the wide-area frequency wave propagation. Also the possibility of using the simulated responses of the power system for replacing the measured data could be confirmed and this is very promising to the future application of the simulation to the on-line analysis of the power systems based on the FNET measurements.Ph. D.
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Withee, Jon E. "Fully coupled dynamic analysis of a floating wind turbine system." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1471.
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CIVINSThe use of wind power is in a period of rapid growth worldwide and wind energy systems have emerged as a promising technology for utilizing offshore wind resources for the large scale generation of electricity Drawing upon the maturity of wind turbine and floater technologies developed by the wind energy and oil and gas industries, respectively, large offshore wind energy systems have been developed and are being proposed for operation in offshore areas where environmental restrictions are less restrictive, large wind resources exist, and open sea areas are available for wind farm development. A fully coupled dynamic analysis/technique was developed to predict the response of a floating wind turbine system in a stochastic wind and wave environment This technique incorporated both non-linear wave loading on the submerged floater and the aerodynamic loading on the wind turbine A tension leg spar buoy was designed to support the wind turbine This design was chosen due to its relatively small size and hence lower potential cost per wind turbine The system's tethers were attached to the ends of spokes which radiated out from the spar cylinder This arrangement of lines and spokes promised to be very stiff in the roll and pitch modes of motion.
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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 SUPERIORO 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.
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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Lammert, Gustav [Verfasser]. "Modelling, Control and Stability Analysis of Photovoltaic Systems in Power System Dynamic Studies / Gustav Lammert." Kassel : Kassel University Press, 2019. http://d-nb.info/1196034125/34.
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HUANG, ZHONG-GING, and 黃鐘慶. "Long-term power system dynamic analysis." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/32645466904050563900.
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WANG, LI, and 王醴. "Analysis of power system dynamic stability." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/45625016847724142637.
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Singh, Mohit 1982. "Dynamic models for wind power plants." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-08-3809.
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Manufacturer-specific models of wind turbines are favored for use in wind power interconnection studies. While they are detailed and accurate, their usages are limited to the terms of the non-disclosure agreement, thus stifling model sharing. The primary objective of the work proposed is to develop universal manufacturer-independent wind power plant models that can be shared, used, and improved without any restrictions by project developers, manufacturers, and engineers. Each of these models includes representations of general turbine aerodynamics, the mechanical drive-train, and the electrical characteristics of the generator and converter, as well as the control systems typically used. In order to determine how realistic model performance is, the performance of the one of the models (doubly fed induction generator model) has been validated using real-world wind power plant data. This work also documents selected applications of these models.text
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Liu, Chuan Sheng, and 劉傳聖. "Excitation system identification and power system dynamic stability enhancement." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/44995610095729487814.
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Wu, Shang-Wei, and 吳尚瑋. "Effects of Large Power Plant on Power System Dynamic Stability." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/51793288745215208727.
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碩士國立臺灣海洋大學
電機工程學系
96
The main objective of this thesis is to study the dynamic stability characteristics of a power system with a large power plant installed for operation. The method of frequency domain analysis is utilized for the study with which the eigenstructure (eigenvalues with associated eigenvectors and participation factors) of each electromechanical oscillation mode can be computed for the analysis of system dynamic stability. Electromechanical oscillations include inter-area mode and intra-area (local and intra-plant) mode of oscillations. The inter-area mode often has lower frequency and damping ratio and affects relatively more numbers of generators. In this thesis, the eigenstructures of all electromechanical oscillation mode of the studied power system, with longitudinal structure and four geographic (northern, central, southern, and eastern) areas, are first computed. The results show that the system damping conforms to the criterion of dynamic stability under both peak load and light load operations. There is relatively more power imbalance between areas under light load since a net power is transferred from the northern area to the central area due to the operation of pumped storage units, and thus the damping ratio of the system under light load is lower than that under peak load. It is recommended that the inter-area oscillation mode be the focus of dynamic stability study for the studied system.
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Lin, Sheng Feng, and 林勝風. "Dynamic Behavior of an Island Power System." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/54382611511029877554.
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碩士國立高雄應用科技大學
電機工程系博碩士班
101
ABSTRACT This study investigated the dynamic behavior of an island power system. This system comprises three diesel-engine power generation sets, three fixed-speed variable-pitch wind turbines, a small-hydro power generation set, and other components. This study first established mathematical models for system components, and then used the developed models based on Matlab/Simulink to conduct simulation analysis. Three simulations were conduced including diesel-engine output power variation, system operating under random wind speed, and operating with high green energy penetration. The results suggested that the system can operate steadily in these modes. This study can serve as an important reference for planning, operation, and expansion of an island power system.
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Falahi, Milad. "Dynamic Reactive Power Control of Isolated Power Systems." Thesis, 2012. http://hdl.handle.net/1969.1/148126.
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This dissertation presents dynamic reactive power control of isolated power systems. Isolated systems include MicroGrids in islanded mode, shipboard power systems operating offshore, or any other power system operating in islanded mode intentionally or due to a fault. Isolated power systems experience fast transients due to lack of an infinite bus capable of dictating the voltage and frequency reference. This dissertation only focuses on reactive control of islanded MicroGrids and AC/DC shipboard power systems. The problem is tackled using a Model Predictive Control (MPC) method, which uses a simplified model of the system to predict the voltage behavior of the system in future. The MPC method minimizes the voltage deviation of the predicted bus voltage; therefore, it is inherently robust and stable. In other words, this method can easily predict the behavior of the system and take necessary control actions to avoid instability. Further, this method is capable of reaching a smooth voltage profile and rejecting possible disturbances in the system.
The studied MicroGrids in this dissertation integrate intermittent distributed energy resources such as wind and solar generators. These non-dispatchable sources add to the uncertainty of the system and make voltage and reactive control more challenging. The model predictive controller uses the capability of these sources and coordinates them dynamically to achieve the voltage goals of the controller. The MPC controller is implemented online in a closed control loop, which means it is self-correcting with the feedback it receives from the system.
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HUANG, PEI-HUA, and 黃培華. "Power system dynamic stability study via eigenstructure analysis." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/84469538477923789035.
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Chia-WeiChang and 張家瑋. "Design of Dynamic Power Management for Android System." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/71078256885321539448.
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"Trajectory Sensitivity Based Power System Dynamic Security Assessment." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.14694.
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abstract: Contemporary methods for dynamic security assessment (DSA) mainly re-ly on time domain simulations to explore the influence of large disturbances in a power system. These methods are computationally intensive especially when the system operating point changes continually. The trajectory sensitivity method, when implemented and utilized as a complement to the existing DSA time domain simulation routine, can provide valuable insights into the system variation in re-sponse to system parameter changes. The implementation of the trajectory sensitivity analysis is based on an open source power system analysis toolbox called PSAT. Eight categories of sen-sitivity elements have been implemented and tested. The accuracy assessment of the implementation demonstrates the validity of both the theory and the imple-mentation. The computational burden introduced by the additional sensitivity equa-tions is relieved by two innovative methods: one is by employing a cluster to per-form the sensitivity calculations in parallel; the other one is by developing a mod-ified very dishonest Newton method in conjunction with the latest sparse matrix processing technology. The relation between the linear approximation accuracy and the perturba-tion size is also studied numerically. It is found that there is a fixed connection between the linear approximation accuracy and the perturbation size. Therefore this finding can serve as a general application guide to evaluate the accuracy of the linear approximation. The applicability of the trajectory sensitivity approach to a large realistic network has been demonstrated in detail. This research work applies the trajectory sensitivity analysis method to the Western Electricity Coordinating Council (WECC) system. Several typical power system dynamic security problems, in-cluding the transient angle stability problem, the voltage stability problem consid-ering load modeling uncertainty and the transient stability constrained interface real power flow limit calculation, have been addressed. Besides, a method based on the trajectory sensitivity approach and the model predictive control has been developed for determination of under frequency load shedding strategy for real time stability assessment. These applications have shown the great efficacy and accuracy of the trajectory sensitivity method in handling these traditional power system stability problems.Dissertation/Thesis
Ph.D. Electrical Engineering 2012
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Wang, Chun-Chieh, and 王俊傑. "Frequency Domain Analysis for Power System Dynamic Equivalencing." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/17227102863821729563.
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碩士國立臺灣海洋大學
電機工程學系
100
Recently, power system analysis is becoming more complicated because of the increase of system expansion. The use of coherency-based dynamic equivalent methods to simplify model can effectively reduce the scale of the external system model and hence remarkably alleviate the computation needed for system dynamic studies. The main purpose of this thesis is to use frequency domain analysis, i.e. eigen-structure (eigenvalues and eigenvectors) calculation in the study of power system dynamic equivalencing. The system is first divided into the study area and the external system. The main characteristics is to be maintained in the original study area. The method of eigenstructure analysis is used for the identification of coherent groups of generating units in the external system. Then the parameters of generators in a coherent group are aggregated by the weighting method, and these generators are reduced into a single unit. Buses are simplified with the method of equivalent power flows. Therefore, an equivalent system is obtained for representing the external system. From the results of dynamic responses comparisons on a practical power system, it is observed that the dynamic equivalent system is similar to the original system and can alleviate the computational burden needed for system dynamic studies.
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Fu, Chun-Kai, and 傅駿凱. "Time Domain Analysis for Power System Dynamic Equivalencing." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/16579311358972564184.
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碩士國立臺灣海洋大學
電機工程學系
100
In the analysis of large-scale power system, we are interested only in some local system which is the study system and the rest part of the system is referred to as the external system. In order to reduce the computational time and burden, a coherency-based simplified dynamic model is often used to represent the external system. Among those methods of power system dynamic equivalencing, the coherency method is the most fundamental one which is based on the similarity of rotor swing curves of generating units. This method requires the swing curves of generators of the original external system and the swing curves of generators of the equivalent external system have similar rotor swing curves when the study system is subject to a disturbance. In this thesis, coherent generator groups are first identified based on the similarity of generator rotor swing curves under a major disturbance, with the generators having similar rotor swing curves classified into a group. Then, by summing the capacities and aggregating the weighted parameters of generators in the coherent group, we obtain the simplified dynamic model for the external system. Results from studies on a sample power system are demonstrated to verify the feasibility of the method of coherency-based dynamic equivalencing.
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Liu, Jia-Rong, and 劉家榮. "Dynamic Analysis of Power System with Wind Farm." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/wdf773.
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碩士國立臺灣海洋大學
電機工程學系
105
Power system low-frequency oscillations are caused by electromechanical energy imbalance of the generating units, and may decrease system power transfer capability and deteriorate power system security. With the capacity increase of wind farm, more influence will be exerted on the power system. A Low-frequency oscillating phenomena often occurs in power system with large-capacity wind turbines and will prevent the transmission of power between regions and may result in system instability. Therefore, small signal stability of the power system with wind farm becomes an important issue. The main purpose of this thesis is to investigate the dynamic analysis of power system with wind farm. The study systems include a two-area power system and Changpin area of Taiwan power system in which wind turbines are installed as part of power source. The damping and frequency of the electromechanical oscillation modes are calculated through frequency domain analysis. The study results show that the small signal stability of power system is affected by the capacity and the point of interconnection of wind farms.
50
Kulasza, Matthew. "Generalized dynamic phasor-based simulation for power systems." 2015. http://hdl.handle.net/1993/30217.
Full textAbstract:
This thesis presents a new general purpose power system simulation technique based on dynamic phasors and conventional power system simulation methods. The method developed in this work converts time-domain circuits to equivalent dynamic phasor representations. These dynamic phasor equivalents are then simulated using nodal analysis and numerical integrator substitution. Simple linear circuit models are presented first in order to demonstrate that the new method is capable of accurately simulating small systems. The method developed in this work is then expanded to include control systems, power electronic converters, and synchronous machines. Visual comparisons with simulation results obtained using time-domain electromagnetic transient simulators demonstrate that the new dynamic phasor-based technique is capable of accurately simulating power system components.