To see the other types of publications on this topic, follow the link: Power system small-signal stability.
Dissertations / Theses on the topic 'Power system small-signal stability'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Power system small-signal stability.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
singhvi, vikas. "Small Signal Stability of an Unregulated Power System." MSSTATE, 2002. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11062002-140310/.
Full textAbstract:
Rotor angle stability is the ability of the interconnected synchronous machines of a power system to remain in synchronism. This stability problem is concerned with the behavior of one or more synchronous machine after they have been perturbed. These perturbations can be small or large depending upon the type of disturbances considered. The work presented in this thesis is focused on the power system behavior when subjected to small disturbances. The ?small signal? disturbances are considered sufficiently small for the linearization of system equations to be permissible for the purpose of the analysis. The first step in the small signal stability studies is to obtain initial steady state conditions using load flow solutions. After establishing initial conditions, an unregulated mathematical model of the power system is formed. The mathematical model obtained is a set of nonlinear coupled first order differential equations. The method of small changes, called the perturbation method, is used to linearize these nonlinear differential equations. The equations are then written in a linear state space model form. The eigenvalues and the participation factors are obtained from the state matrix and the contribution of a particular machine in a particular mode or oscillations (or eigenvalue) can be examined for the small signal stability studies.
2
McIlhagger, David. "Acceleration of power system small signal stability analysis." Thesis, Queen's University Belfast, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486529.
Full textAbstract:
Electric power networks comprise large complex interconnections of generation and loads. The generators, and their controllers, are non-linear dynamic systems which on interconnection form a very complex control problem. Traditionally the models used to capture the small signal Rtability of these systems were not highly detailed. This waR jURtified Rince the generation was provided by large centralized power Rtations, however with the current trend towards small scale and diRtributed generation, as provided by.wind farmR and diesel genRetR, the power system modelR require a greater level of detail. This means that the stability assessment of theRe models involves greater detail and requires greater computation time, thus rendering near future predictions obsolete. ThiR thesis studies the methods that are Ilsed to determine • power system small signal stability, in order to provide acceleration to this analysis. A method based on wavelet approximations to provide an approximate solution was developed and its effectiveneRs against the traditional QR algorithm waR investigated. The method was applied to a four generator RyRtem and the IEEE New England 39 bus Rystem. Alternative methods to form accelerating polynomials for eigenvalue methodR were developed and evaluated against the IEEE New England 39 bus system. A new algorithm, called the polygon polynomial Arnoldi method (PPAM) was developed and tested against the implicitly restarted Arnoldi method (IRAM), from the linear algebra literature. The effectiveness of both theRe methods was tested against the IEEE New England 39 bus system and the one area IEEE reliability test system along with that for the QR algorithm.
3
Rudraraju, Seetharama raju. "SMALL SIGNAL AND TRANSIENT STABILITY ANALYSIS OF MVDC SHIPBOARD POWER SYSTEM." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11052009-170217/.
Full textAbstract:
Recent developments in high power rated Voltage Source Converters (VSCs) have resulted in their successful application in Multi-Terminal HVDC (MTDC) transmission systems and also have potential in the Medium Voltage DC (MVDC) distribution systems. This work presents the findings of stability studies carried out on a zonal MVDC architecture for the shipboard power distribution system. The stability study is confined to rotor angle stability of the power system, i.e. the transient and small signal stability analysis. The MTDC ring structure similar to MVDC shipboard power system was implemented in MATLAB/Simulink to look at the transient behavior of the MVDC system. Small signal stability analysis has been carried out with the help of Power System Toolbox (PST) for both MVAC as well as MVDC architectures. Later, Participation Analysis has been carried out to address the small signal instability in the case of MVAC architecture and methods for enhancement were also presented.
4
Gu, Qun. "Flexible control of electrical power system to enhance small signal stability /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
Full text
5
Fourie, Gert. "Power system stabilizer and controlled series capacitor small-signal stability performance analysis." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53013.
Full textAbstract:
Thesis (MScEng)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: This thesis presents results of a study on the small-signal stability of a single-machine infinite-bus power system. Conditions of generator loading and network impedance are identified that require additional stability support. Two methods of stability enhancement are investigated, namely the power system stabilizer and the controlled series capacitor. Both stabilizers employ the conventional (classic) control structure, and parameters are evaluated for optimum performance using an integral-of-the-squared-error-based method. Results for damping capability versus generator loading and system impedance were generated. The ability of the power system stabilizer and controlled series capacitor to provide stability support is compared. This comparison is based on (a) the ability to provide more damping torque when needed, and (b) the amount of damping torque contributed by the stabilizer.
AFRIKAANSE OPSOMMING: Hierin word die resultate van 'n studie op die klein-sein stabiliteit van 'n enkel-masjien oneindige-bus kragstelsel weergegee. Kondisies van generator belasting en netwerk impedansie waar dempings-ondersteuning benodig word, word geïdentifiseer. Twee metodes van stabiliteits-verbetering word ondersoek, naamlik die kragstelstel stabiliseerder en die beheerde serie kapasitor. Beide stabiliseerders maak gebruik van die konvensionele (klassieke) beheerstruktuur, waarvan parameters geëvalueer word deur gebruik te maak van 'n integraal-van-die-vierkant-fout-gebaseerde metode. Resultate vir dempingsvermoë teenoor generator belasting en stelsel impedansie word verkry. Die vermoë van die kragstelsel stabiliseerder en beheerde serie kapasitor om stabiliteits-ondersteuning te verskaf, word vergelyk. Hierdie vergelyking is gebasseer op (a) die vermoë om meer dempingswrinkrag te voorsien wanneer benodig, en (b) die hoeveelheid dempingswrinkrag deur die stabiliseerder bygedra.
6
Mudau, Dovhani Selby. "Comparison of three power system software packages for small-signal stability analysis." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/8935.
Full textAbstract:
Includes bibliographical references (leaves 131-133).Many power system simulation tools exist for small-signal stability analysis. This is due to the rapid development of computer systems, higher industrial growth and the need for reliable power system simulation tools for efficient planning and control of electric power systems. Three power system small-signal stability simulation tools have been selected for comparison and these are: PSAT 2.1.2, MatNetEig and PacDyn 8.1.1. These combine both open and closed source code industrial-grade power system analysis tools. The objective of this thesis is to compare three simulation tools on power system small-signal stability analysis. Input formats, data output flexibility, dynamic components and synchronous machine saturation modelling in all three simulation tools were amongst other features investigated for comparative studies.
7
Kshatriya, Niraj. "Power System Controller Design by Optimal Eigenstructure Assignment." IEEE Transactions on Power System, 2010. http://hdl.handle.net/1993/4838.
Full textAbstract:
In this thesis the eigenstructure (eigenvalues and eigenvectors) assignment technique based algorithm has been developed for the design of controllers for power system applications. The application of the algorithm is demonstrated by designing power system stabilizers (PSSs) that are extensively used to address the small-signal rotor angle stability problems in power systems. In the eigenstructure assignment technique, the critical eigenvalues can be relocated as well as their associated eigenvectors can be modified. This method is superior and yield better dynamical performance compared to the widely used frequency domain design method, in which only the critical eigenvalues are relocated and no attempt is made to modify the eigenvectors.
The reviewed published research has demonstrated successful application of the eigenstructure assignment technique in the design of controllers for small control systems. However, the application of this technique in the design of controllers for power systems has not been investigated rigorously.
In contrast to a small system, a power system has a very large number state variables compared to the combined number of system inputs and outputs. Therefore, the eigenstructure assignment technique that has been successfully applied in the design of controllers for small systems could not be applied as is in the design of power system controllers. This thesis proposes a novel approach to the application of the eigenstructure assignment technique in the design of power system controllers. In this new approach, a multi-objective nonlinear optimization problem (MONLOP) is formulated by quantifying different design objectives as a function of free parametric vectors. Then the MONLOP is solved for the free parametric vectors using a nonlinear optimization technique. Finally, the solution of the controller parameters is obtained using the solved free parametric vectors.
The superiority of the proposed method over the conventional frequency domain method is demonstrated by designing controllers for three different systems and validating the controllers through nonlinear transient simulations. One of the cases includes design of a PSS for the Manitoba Hydro system having about 29,000 states variables, which demonstrates the applicability of the proposed algorithm for a practical real-world system.
8
Restrepo, Jaime Quintero. "A real-time wide-area control for mitigating small-signal instability in large electric power systems." Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Spring2005/j%5Fquintero%5F011905.pdf.
Full text
9
Zhang, Pei. "Co-ordination and control of power system damping controllers to enhance small signal stability." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321949.
Full text
10
Vance, Katelynn Atkins. "Evaluation of Stability Boundaries in Power Systems." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/78322.
Full textAbstract:
Power systems are extremely non-linear systems which require substantial modeling and control efforts to run continuously. The movement of the power system in parameter and state space is often not well understood, thus making it difficult or impossible to determine whether the system is nearing instability. This dissertation demonstrates several ways in which the power system stability boundary can be calculated. The power system movements evaluated here address the effects of inter-area oscillations on the system which occur in the seconds to minutes time period.
The first uses gain scheduling techniques through creation of a set of linear parameter varying (LPV) systems for many operating points of the non-linear system. In the case presented, load and line reactance are used as parameters. The scheduling variables are the power flows in tie lines of the system due to the useful information they provide about the power system state in addition to being available for measurement. A linear controller is developed for the LPV model using H₂/H∞ with pole placement objectives. When the control is applied to the non-linear system, the proposed algorithm predicts the response of the non-linear system to the control by determining if the current system state is located within the domain of attraction of the equilibrium. If the stability domain contains a convex combination of the two points, the control will aid the system in moving towards the equilibrium.
The second contribution of this thesis is through the development and implementation of a pseudo non-linear evaluation of a power system as it moves through state space. A system linearization occurs first to compute a multi-objective state space controller. For each contingency definition, many variations of the power system example are created and assigned to the particular contingency class. The powerflow variations and contingency controls are combined to run sets of time series analysis in which the Lyapunov function is tracked over three time steps. This data is utilized for a classification analysis which identifies and classifies the data by the contingency type. The goal is that whenever a new event occurs on the system, real time data can be fed into the trained tree to provide a control for application to increase system damping.Ph. D.
11
Whitlock, Rogers Jr. "Identification of Power System Stability Using Relevant Modes." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1384.
Full textAbstract:
The purpose of this investigation is to identify appropriate location of capacitor banks and sources of reactive power by studying power system stability in the vicinity of system equilibrium states. The locations for reactive power sources are determined by identifying those modes of the system that participate most in the system behavior in general and in dictating the final state of the system after experiencing faults or disturbances. To identify the relevant modes of the system that participate most in the system dynamic, we shall make use of modal and participation analysis for different system conditions. We also apply modal and participation analysis to a system in order to identify the components of greatest impact that result in the most efficient system control. The ideas developed in this study are used to analyze and identify weak boundaries of the IEEE 39- Bus system that contribute to the system’s instability.
12
Li, Chi. "Impedance-Based Stability Analysis in Power Systems with Multiple STATCOMs in Proximity." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85053.
Full textAbstract:
Multiple STATCOM units in proximity have been adopted in power transmission systems in order to obtain better voltage regulation and share burdens. Throughout stability assessment in this dissertation, it is shown, for the first time, that STATCOMs could interact with each other in a negative way in the small-signal sense due to their control, causing voltage instability, while loads and transmission lines showed small effects. Since this voltage stability problem is induced by STATCOMs, d-q frame impedance-based stability analysis was used, for the first time, to explore the inherent power system instability problem with presence of STATCOMs as it provides an accurate understanding of the root cause of instability within the STATCOM control system.
This dissertation first proposes the impedance model in d-q frame for STATCOMs, including dynamics from synchronization, current and voltage loops and reveals the significant features compared to other types of grid-tied converters that 1) impedance matrix strongly coupled in d and q channel due to nearly zero power factor, 2) different behaviors of impedances at low frequency due to inversed direction of reactive power and 3) coupled small-signal propagation paths on the voltage at point of common coupling from synchronization and ac voltage regulation.
Using the proposed impedance model, this dissertation identifies the frequency range of interactions in a viewpoint of d-q frame impedances and pinpointed that the ac voltage regulation was the main reason of instability, masking the effects of PLL in power transmission systems. Due to the high impedance of STATCOMs compared to that of transmission lines around the frequency range of interactions, STATCOMs were seen to interact with each other through the transmission lines. A scaled-down 2-STATCOM power grid was built to verify the conclusions experimentally.Ph. D.
13
Chompoobutrgool, Yuwa. "Concepts for Power System Small Signal Stability Analysis and Feedback Control Design Considering Synchrophasor Measurements." Licentiate thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103032.
Full textAbstract:
In the Nordic power network, the existence of poorly damped low-frequency inter-area oscillations (LFIOs) has long affected stability constraints, and thereby, limited power transfer capacity. Adequate damping of inter-area modes is, thus, necessary to secure system operation and ensure system reliability while increasing power transfers. Power system stabilizers (PSS) is a prevalent means to enhance the damping of such modes. With the advent of phasor measurement units (PMUs), it is expected that wide-area damping control (WADC), that is, PSS control using wide-area measurements obtained from PMUs, would effectively improve damping performance in the Nordic grid, as well as other synchronous interconnected systems. Numerous research has investigated one ``branch'' of the problem, that is, PSS design using various control schemes. Before addressing the issue of controller design, it is important to focus on developing proper understanding of the ``root'' of the problem: system-wide oscillations, their nature, behavior and consequences. This understanding must provide new insight on the use of PMUs for feedback control of LFIOs. The aim of this thesis is, therefore, to lay important concepts necessary for the study of power system small signal stability analysis that considers the availability of synchrophasors as a solid foundation for further development and implementation of ideas and related applications. Particularly in this study, the focus is on the application addressed damping controller design and implementation. After a literature review on the important elements for wide-area damping control (WADC), the thesis continues with classical small signal stability analysis of an equivalent Nordic model; namely, the KTH-NORDIC32 which is used as a test system throughout the thesis. The system's inter-area oscillations are identified and a sensitivity analysis of the network variables directly measured by synchrophasors is evaluated. The concept of network modeshapes, which is used to relate the dynamical behavior of power systems to the features of inter-area modes, is elaborated. Furthermore, this network modeshape concept is used to determine dominant inter-area oscillation paths, the passageways containing the highest content of the inter-area oscillations. The dominant inter-area paths are illustrated with the test system. The degree of persistence of dominant paths in the study system is determined through contingency studies. The properties of the dominant paths are used to construct feedback signals as input to the PSS. Finally, to exemplify the use of the dominant inter-area path concept for damping control, the constructed feedback signals are implemented in a PSS modulating the AVR error signal of a generator on an equivalent two-area model, and compared with that of conventional speed signals.
14
Cao, Jun. "Optimal and small-signal stability improvement of power system operation using multi-terminal VSC-HVDC." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602454.
Full textAbstract:
The thesis is essentially concerned with some theoretical aspects of the economic and stability studies of power systems with great penetration levels of renewable energy. In part I, firstly, the process of incorporation of VSC MTDC model in ACIDC state estimation is described in detail. The proposed approach simultaneously upgrades the estimated values of the state variables, for a unified solution in a single reference frame. The effectiveness of the proposed ACIMTDC state estimation algorithm and the bad data identification process is demonstrated and validated in modified IEEE test system. Secondly, the optimal power flow (OPF) of a meshed ACIDC power transmission network with Voltage Source Converter based Multi-terminal DC (VSC-MTDC) networks is presented in the thesis. The OPF problem is formulated to minimize the transmission loss of the whole ACIDC network with two different VSC control strategies considered. In addition, Grid Code compliance of wind farms is also embedded in the OPF formulation. The results of the proposed OPF demonstrate that the power losses of the meshed ACIDC power systems can be greatly reduced. In part Il, a novel emergency damping control (EDC) is proposed to suppress inter-area oscillations occurred as anticipated low-probability cases in power system operations. The proposed EDC combines the event-driven and response-based control strategy. It is tested and evaluated in a standard power system and a real large-scale power system in China to compute the optimal location, amount and applying time of generator decreasing and load shedding in order to suppress inter-area oscillations.
15
Zhao, Shuang. "FORWARD AND BACKWARD EXTENDED PRONY (FBEP) METHOD WITH APPLICATIONS TO POWER SYSTEM SMALL-SIGNAL STABILITY." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1480948469362031.
Full text
16
Lin, Qing. "Small-Signal Modeling and Stability Specification of a Hybrid Propulsion System for Aircrafts." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103515.
Full textAbstract:
This work utilizes the small-signal impedance-based stability analysis method to develop stability assessment criteria for a single-aisle turboelectric aircraft with aft boundary-layer propulsion (STARC-ABL) system. The impedance-based stability analysis method outperforms other stability analysis methods because it does not require detailed information of individual components for system integration, therefore, a system integrator can just require the vendors to make the individual components meet the impedance specifications to ensure whole system stability. This thesis presents models of a generator, motor, housekeeping loads, and battery all with power electronics interface which form an onboard electrical system and analyzes the relationship between the impedance shape of each component and their physical design and control loop design. Based on the developed small-signal model of the turbine-generator-rectifier subsystem and load subsystem, this thesis analyzes the impact of electromechanical dynamics of the turbofan passed through the generator on the dc distribution system, concluding that the rectifier can mitigate the impact. Finally, to ensure the studied system stable operation during the whole flying profile, the thesis provides impedance specifications of the dc distribution system and verifies the specifications with several cases in time-domain simulations.M.S.
Electric aircraft propulsion (EAP) technologies have been a trend in the aviation industry for their potential to reduce environmental emissions, increase fuel efficiency and reduce noise for commercial airplanes. Achieving these benefits would be a vital step towards environmental sustainability. However, the development of all-electric aircraft is still limited by the current battery technologies and maintenance systems. The single-aisle turboelectric aircraft with aft boundary-layer (STARC-ABL) propulsion concept is therefore developed by NASA aiming to bridge the gap between the current jet fuel-powered aircraft and future all-electric vehicles. The plane uses electric motors powered by onboard gas turbines and transfers the generated power to other locations of the airplane like the tail fan motor to provide distributed propulsion. Power electronics-based converter converts electricity in one form of electricity to another form, for example, from ac voltage to dc voltage. This conversion of power is very important in the whole society, from small onboard chips to Mega Watts level electrical power system. In the aircraft electrical power system context, power electronics converter plays an important role in the power transfer process especially with the recent trend of using high voltage dc (HVDC) distribution instead of conventional ac distribution for the advantage of increased efficiency and better voltage regulation. The power generated by the electric motors is in ac form. Power electronics converter is used to convert the ac power into dc power and transfer it to the dc bus. Because the power to drive the electric motor to provide distributed propulsion is also in ac form, the dc power needs to be converted back into ac power still through a power electronics converter. With a high penetration of power electronics into the onboard electrical power system and the increase of electrical power level, potential stability issues resulted from the interactions of each subsystem need to be paid attention to. There are mainly two stability-related studies conducted in this work. One is the potential cross-domain dynamic interaction between the mechanical system and the electrical system. The other is a design-oriented study to provide sufficient stability margin in the design process to ensure the electrical system’s stable operation during the whole flying profile. The methodology used in this thesis is the impedance-based stability analysis. The main analyzing process is to find an interface of interest first, then grouped each subsystem into a source subsystem and load subsystem, then extract the source impedance and load impedance respectively, and eventually using the Nyquist Criterion (or in bode plot form) to assess the stability with the impedance modeling results. The two stability-related issues mentioned above are then studied by performing impedance analysis of the system. For the electromechanical dynamics interaction study, this thesis mainly studies the rotor dynamics’ impact on the output impedance of the turbine-generator-rectifier system to assess the mechanical dynamics’ impact on the stability condition of the electrical system. It is found that the rotor dynamics of the turbine is masked by the rectifier; therefore, it does not cause stability problem to the pre-tuned system. For the design-oriented study, this thesis mainly explores and provides the impedance shaping guidelines of each subsystem to ensure the whole system's stable operation. It is found that the stability boundary case is at rated power level, the generator voltage loop bandwidth is expected to be higher than 300Hz, 60˚ to achieve a 6dB, 45˚ stability margin, and load impedance mainly depends on the motor-converter impedance.
17
Aree, Pichai. "Small-signal stability modelling and analysis of power systems with electronically controlled compensation." Thesis, University of Glasgow, 2000. http://theses.gla.ac.uk/2600/.
Full textAbstract:
Flexible AC Transmission Systems (FACTS) equipment is currently being incorporated into the power system for controlling key networks parameters aiming at improving the power system steady-state and dynamic performances. The vast array of power system analysis tools used by planners and system operators, on a daily basis, for the successful running of the network are to be upgraded to include comprehensive modelling for FACTS plant components. Commensurate with this global objective, this research work is aimed at developing comprehensive power system models of FACTS devices suitable for small-signal stability studies. The FACTS components covered in this research are the Static Var Compensator (SVC) and the Thyristor-Controlled Series Capacitor (TCSC). More specifically, the modelling of these devices combined with advanced modelling of synchronous generators has positioned the current work in the area of small-signal stability modelling and analysis of power systems with electronically controlled compensation. The work has been developed within the framework of the block-diagram methodology because it yields physical insight and offers the opportunity to gain fundamental knowledge of the dynamic interactions taking place between synchronous generators and FACTS plant components. The key issues of synchronous generator modelling, from the viewpoint of small-signal stability analysis, are addressed in this thesis. In particular, the impact of synchronous generator modelling order, with emphasis on system damping, is discussed in depth. Various representations of salient-pole synchronous generators are used to enable a variety of models suitable for small-signal stability studies. The models range from synchronous generators with no danger windings, to cases when one damper winding is included in each of the rotor axes, i.e. d and q-axis. The drive behind the study is to settle the issue of what is a suitable number of machine damper windings to be used in small-signal stability analysis that adequately represents the system model with a good level of reliability while keeping engineering complexity manageable.
18
Kanchanaharuthai, Adirak. "Small-Signal Stability, Transient Stability and Voltage Regulation Enhancement of Power Systems with Distributed Renewable Energy Resources." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1321988036.
Full text
19
Wenjuan, D. U. "Power System Small Signal Oscillation Stability as Affected by Static Synchronous Compensator (STATCOM) and Energy Storage System (ESS) Control." Thesis, University of Bath, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516943.
Full text
20
Mahmoud, G. A. "A new method of assessing power system stability." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372306.
Full text
21
Tinsley, Carl Terrie III. "Modeling of Multi-Pulse Transformer/Rectifier Units in Power Distribution Systems." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34655.
Full textAbstract:
Multi-pulse transformer/rectifier systems are becoming increasingly popular in power distribution systems. These topologies can be found in aircraft power systems, motor drives, and other applications that require low total harmonic distortion (THD) of the input line current. This increase in the use of multi-pulse transformer topologies has led to the need to study large systems composed of said units and their interactions within the system. There is also an interest in developing small-signal models so that stability issues can be studied.
This thesis presents a procedure for the average model of multi-pulse transformer/rectifier topologies. The dq rotating reference frame was used to develop the average model and parameter estimation is incorporated through the use of polynomial fits. The average model is composed of nonlinear dependent sources and linear passive components. A direct benefit from this approach is a reduction in simulation time by two orders of magnitude. The average model concept demonstrates that it accurately predicts the dynamics of the system being studied. In particular, two specific topologies are studied, the 12-pulse hexagon transformer/rectifier (hex t/r) and the 18-pulse autotransformer rectifier unit (ATRU). In both cases, detailed switching model results are used to verify the operation of the average model. In the case of the hex t/r, the average model is further validated with experimental data from an 11 kVA prototype. The hex t/r output impedance, obtained from the linearized average model, has also been verified experimentally.Master of Science
22
Hodgson, J. E. "A comprehensive method to estimate power system stability constraint costs." Thesis, University of Bath, 1997. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362150.
Full text
23
Erlich, I. Fischer A. U. "Fast Assessment of Small-Signal Oscillatory Stability in Large Interconnected Power Systems, Balkan Power Conference BPC 2002, June 2002, Belgrade, Yugoslavia." Gerhard-Mercator-Universitaet Duisburg, 2003. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-04142003-140806/.
Full textAbstract:
This paper deals with suitable approaches for fast assessment of oscillatory stability of large interconnected power systems within power system operation. Beside voltage stability and transient stability, oscillatory stability has to be assessed, too. It can be shown, that parallel eigenvalue computation using a parallel variant of Arnoldi method can reduce the time necessary for eigenvalue computation of large power systems.
24
Kaberere, Keren Kanuthu. "Variations in modeling and algorithmic factors impacting on small-signal stability results : assessment of five industrial-grade power system simulation tools." Doctoral thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/5197.
Full textAbstract:
Includes bibliographical references.There are several industrial-grade simulation tools, used for small-signal stability studies, that are commercially available on the market. However, these tools differ in their components modeling and solution methodology. Therefore, different simulation tools can give different results for the same power system model. In this thesis, five industrial-grde simulation tools - PSS/E, PowerFactory, EUROSTAG, SSAT, and MatNetEig - are investigated. The features and capabilities of the five tools are compared based on componenets modeling, numerical methodology, and tool flexibility in terms of data input and output.
25
Bu, Siqi. "Probabilistic small-signal stability analysis and improved transient stability control strategy of grid-connected doubly fed induction generators in large-scale power systems." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580121.
Full textAbstract:
Growing numbers of large-scale wind farms have been recently established and connected to conventional power grid. With the rising level of penetration, the impact of wind power sources on the grid has extended from simple power quality problems to power grid security and stability, frequency and peak regulation, and economic dispatch issues. Therefore, it has significant theoretical and practical values to comprehensively investigate the effect of grid-connected wind power sources on the power system stability. In order to study the influence of considerable stochastic characteristic of wind power generation, probabilistic analysis of power system small-signal stability has been implemented. An analytical method of probabilistic analysis based on Gram-Charlier expansion is proposed to deal with the stochastic uncertainty and spatial correlation of multiple grid-connected wind power sources. Results of probabilistic stability analysis of the example power system demonstrate that the stochastic fluctuation of wind power generation certainly affects small-signal stability of the power system especially in a stressed load condition. Probabilistic stability changes significantly with the variation of wind power penetration level. Focusing on the examination of mechanism of terminal voltage dip during the grid fault, this thesis then develops an improved flux magnitude and angle control (IFMAC) strategy to enhance the grid fault ride-through (FRT) capability of grid-connected doubly fed induction generators (DFIGs). It is indicated by analysis that the significant increase of DFIG power angle stimulated by grid faults during the transient is the essential reason of DFIG voltage dip. IF MAC scheme is proposed with the aim to control the DFIG power angle. The theoretical analysis has also illustrated that the surrounding power system may benefit prominently in terms of transient stability margin by applying the proposed control strategy. Simulation results of the example system have validated the effectiveness and robustness of IF MAC controller in different operating conditions.
26
Men, Kun. "Long term voltage stability analysis for small disturbances." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2499.
Full text
27
Antoine, Olivier. "Wide area measurement-based approach for assessing the power flow influence on inter-area oscillations." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209368.
Full textAbstract:
Power systems have been historically designed at a time when the production wascentralized and the electricity had to be transmitted to the loads from the closest power
plant. Nowadays, there is an increasing integration of decentralized and intermittent pro-
duction. Moreover, the energy market coupling has enabled the transfer of electric power
for economical purposes. Also, former isolated power systems are now interconnected for
reliability and financial reasons.
All of these changes make difficult to predict the future behavior of the grid. Studies
are done in order to plan for the future needs of the system. However, building new in-
frastructures takes time and it is expected that these needs will not be completely fulfilled
in all the parts of the grid. Therefore, transmission of active power could be limited by
the existing infrastructure. For example, the presence of inter-area oscillations is often
the limiting factor when a high active power is transmitted on a long transmission line
between two groups of generators. Since higher levels of active power are exchanged on
longer distances, problems of inter-area oscillations may arise in power systems previously
not affected by this phenomenon.
In this work, a measurement-based approach, able to predict in the short-term the
future behavior of oscillations, is presented. This approach is complementary to the
long-term planning of the grid.
The mandatory first step towards a measurement-based approach is to have the ability
to extract useful information among a huge quantity of data. To face this issue, some
comparisons of data mining algorithms are performed. The proposed method combines
two decision tree algorithms to obtain both prediction accuracy and comprehensibility.
The second required step for building a measurement-based model is to take into
account the limitations of the measurements. Two types of wide area measurements are
used, synchronized measurements from PMUs and traditional unsynchronized data from
the SCADA/EMS system. Oscillation monitoring using PMUs is especially of interest
and an approach is presented to post-process damping estimates. This post-processing
method consists in a noise reduction technique followed by a damping change detection
algorithm.
Finally, the method, combining these two steps, is implemented to analyze the Con-
tinental European grid. This implementation takes place in the context of the European
project Twenties. The results, using several months of measurements, are described in
detail before being discussed.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
28
Wu, Zhongyu. "Wide Area Analysis and Application in Power System." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/36427.
Full textAbstract:
Frequency monitoring network (FNET) is an Internet based GPS synchronized wide-area frequency monitoring network deployed at distribution level. At first part of this thesis, FNET structure and characteristics are introduced. After analysis and smoothing FDR signals, the algorithm of event trigger is present with Visual C++ DLL programming.
Estimation of disturbance location method is discussed based on the time delay of arriving (TDOA) in the second part of this work. In this section, author shows the multiply method to calculate event time, which is important when deal with pre-disturbance frequency in TDOA part. Two event kinds are classified by the change of frequency and the linear relationship between change of frequency and imbalance of generation and load power is presented. Prove that Time Delay of Arrival (TDOA) is a good algorithm for estimation event location proved by real cases. At last, the interface of DLL module and the key word to import and export DLL variables and function is described. At last, PSS compensation optimization with a set of nonlinear differential algebraic equations (DAE) is introduced in detail. With combining the bifurcation theory of nonlinear system and the optimization theory, the optimal control of small-signal stability of power electric systems are solved. From the perspective of stability margin, global coordination of controller parameters is studied to ensure the stable operation of power grids. The main contents of this thesis include:
ï¼ 1ï¼ Models of power systems and test power electric systems. Tht5e dynamic and static models of the elements of power systems, such as generatorbbs, AVRs, PSSs, loads and FACTS controllers are presented. Method of power system linearization modeling is introduced. Three test power systems, WSCC 9-bus system, 2-area system, New England 39-bus system, are used in thesis.
ï¼ 2ï¼ Multi-objective optimizations based on bifurcation theory. The optimization models, damping control-Hopf bifurcation control, voltage control-damping control, are presented. Pareto combined with evolutionary strategy (ES) are used to solve multi-objective optimizations. Based on traditional PSS parameters optimizations, it can be formulated as a multi-objective problem, in which, two objectives should be taken into account. The minimum damping torque should be identified.
Master of Science
29
Cvetkovic, Igor. "Modeling and Control of Voltage-Controlling Converters for Enhanced Operation of Multi-Source Power Systems." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85850.
Full textAbstract:
The unconventional improvements in the power electronics field have been the primary reason for massive deployment of renewable energy sources in the electrical power grid over the past several decades. This needed trend, together with the increasing penetration of micro-, and nano- grids, is bringing significant improvements in system controllability, performance, and energy availability, but is fundamentally changing the nature of electronically-interfaced sources and loads, altering their conventionally mild aggregate dynamics, and inflicting low- and high- frequency dynamic interactions that never before existed at this magnitude. This problem is not restricted only to the grid; modern electronic power distribution systems built for airplanes, ships, electric vehicles, data-centers, and homes, comprise dozens, even hundreds of power electronics converters, produced by different manufacturers, who provide very limited details on converters' dynamic behavior - distinctiveness that has the highest impact on how two converters, or converter and a system interact. Consequently, substantial dispersion of power electronics into the future grid will significantly depend on engineers' capability to understand how to model and dynamically control power flow and subsystem interactions. It is therefore essential to continue developing innovative methods that allow easier system-level modeling, continuous monitoring of dynamic interactions, and advanced control concepts of power electronics converters and systems.
The dissertation will start with a "black box" approach to modeling of three-phase power electronics converters, introducing a method to remove source and load dynamics from in-situ measured terminated frequency responses. It will be then shown how converter, itself, can perform an online stability assessment knowing its own unterminated dynamics, and being able to measure all terminal immittances. The dissertation will further advance into an approach to control power electronics converters based on the electro-mechanical duality with synchronous machines, and end with selected examples of system-level operation, where small-signal instability in multi-source power systems can be mitigated using this concept.Ph. D.
30
Obradovic, Danilo. "Coordinated Frequency Control Between Interconnected AC/DC Systems." Licentiate thesis, KTH, Elkraftteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280156.
Full textAbstract:
With ambitions of reducing the environmental pollution, power systems integrate larger shares of Renewable Energy Sources (RES) to phase out conventional thermal and nuclear generators. Since RES (such as wind and solar power) are connected to the grid through power electronics devices, they do not inherently contribute to system inertia. With decreasing inertia, the Instantaneous Frequency Deviation (IFD), which follows a power unbalance, is significantly impacted. Frequency Containment Reserves (FCR) are designed to provide a fast dynamic response, counteract power imbalances and stabilize the frequency within a short time interval. Besides inertia, the significant factors affecting frequency behavior are the available amount of FCR and the capability of their fast and stable response. System operators define the list of requirements that a generating unit has to satisfy to participate in FCR. Generators, which are the major part of FCR, have different governors and turbines properties. This study assesses the dynamical performance of typical generators in both open-loop testing and closed-loop varying inertia systems. The goal is to evaluate if specific FCR requirements present a sufficient condition for the desired response, and which governor properties are capable of satisfying them. As an additional, and sometimes necessary, support to FCR, HVDC interconnections are utilized in the form of Emergency Power Control (EPC). This thesis investigates which of the EPC methods performs appropriately in terms of IFD improvement, closed-loop stability, and power and energy provided. The analysis is a continuation from the previous investigation on FCR, and mainly compare two EPC methods related to Nordic Power System (NPS) test case: ramp/step method which is currently implemented in the NPS, and droop frequency-based EPC, proposed by this study for the future operation in the NPS. Apart from ensuring a proper system frequency response, the influence of implemented HVDC supplementary active power control is analyzed to rotor angle stability. In further, this thesis presents a comprehensive analysis of the impact that proposed HVDC supplementary power control has on the linearized dynamics of power systems. By building a generic system, this analytical study is the first of its kind that includes both higher order generator dynamics, and local angle/frequency input of the controller. The methodological approach here analytically formulates the impact the HVDC supplementary control has mainly on the generator synchronizing and damping torque components. The positive impact of the droop frequency-based HVDC power support is highlighted using both single and multi-machine systems. In that way, the implementation of desired droop frequency-based HVDC control to mainly improve system frequency is motivated furthermore. It shows that a proper HVDC supplementary control may impose the various positive impacts for future variable and low inertia scenarios, and ensure a proper power system sustainability.QC 20200907
multiDC - Advanced Control and Optimization Methods for AC and HVDC Grids
31
Almada, Leandro Momenté [UNESP]. "O modelo de injeção de potência do TCSC e sua aplicação no estudo da estabilidade a pequenas perturbações." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/87103.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0
Previous issue date: 2012-06-01Bitstream added on 2014-06-13T19:08:06Z : No. of bitstreams: 1
almada_lm_me_ilha.pdf: 552123 bytes, checksum: bb24b3e82f3436a173c7b23090715999 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O principal objetivo deste trabalho é a utilização do modelo de injeção de potência do dispositivo FACTS TCSC (Thyris-tor Controlled Series Capacitor) na análise da estabilidade a pequenas perturbações de sistemas elétricos de potência. Para atingir este objetivo é deduzido o modelo de injeção de potência do TCSC, cujo equacionamento é adicionado ao Modelo de Sensibilidade de Po-tência (MSP), utilizado para representar o sistema elétrico de potência (SEP). Para o amortecimento das oscilações eletromecânicas de baixa frequência do SEP são utilizados dois modelos para os controladores, um que considera somente um ganho proporcional e outro comumente chamado na literatura de controlador suplementar de amortecimento (POD – Power Oscillation Damping) que contém também blocos de avanço- atraso de fase. Ambos os controladores devem atuar em conjunto com o TCSC para fornecer amortecimento ao SEP. Neste trabalho o sinal de entrada para os dois controladores é a variação da potência ativa na linha de transmissão de instalação do TCSC e seus parâmetros são ajustados de duas formas: pelo método dos resíduos e utilizando o toolbox rltool (SISO) do software MATLAB. Para a validação do equacionamento desenvolvido foram realizadas simulações em um sistema de potência simétrico, de duas áreas, composto de 4 geradores e 10 barras
This work presents a power injection model for the Thyristor Controlled Series Compensator (TCSC), a Flexible AC Transmission Systems (FACTS) device, for small signal stability analysis in the electric power systems. To achieve such goal, the TCSC injection power model equations are summed up to the Power Sensitivity Model (PSM) which is used to represent the electric power system (EPS). For the low frequency electromechanical oscillation damping, two models are used to represent the controller: 1. A proportional control and; 2. A supplementary control known as Power Oscillation Damping (POD), which also comprehends lead-lag blocks. Both controllers, previously cited, must work together with the TCSC to damp oscillations in the EPS. In this work, the input signal for both controllers is the real power flow variation in the transmission line where the TCSC is placed and the controllers parameters are adjusted using the residues method and the Matlab toolbox rltool (SISO). Several simulations in a symmetrical, two areas power system, composed of four generators and ten busses, are provided in way to validate the power injection model and are discussed in this work
32
Louganski, Konstantin P. "Modeling and Analysis of a Dc Power Distribution System in 21st Century Airlifters." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35514.
Full textAbstract:
A DC power distribution system (PDS) of a transport aircraft was modeled and analyzed using MATLAB/Simulink software. The multi-level modeling concept was used as a modeling approach, which assumes modeling subsystem of the PDS at three different levels of complexity. The subsystem models were implemented in Simulink and combined into the whole PDS model according to certain interconnection rules. Effective modeling of different scenarios of operation was achieved by mixing subsystem models of different levels in one PDS model. Linearized models were obtained from the nonlinear PDS model for stability analysis and control design.
The PDS model was used to examine the system stability and the DC bus power quality under bidirectional power flow conditions. Small-signal analysis techniques were employed to study stability issues resulting from subsystem interactions. The DC bus stability diagram was proposed for predicting stability of the PDS with different types of loads without performing an actual stability test based on regular stability analysis tools. Certain PDS configurations and operational scenarios leading to instability were identified. An analysis of energy transfer in the PDS showed that a large energy storage capacitor in the input filter of a flight control actuator is effective for reduction of the DC bus voltage disturbances produced by regenerative action of the actuator. However, energy storage capacitors do not provide energy savings in the PDS and do not increase its overall efficiency.Master of Science
33
Alahmad, Bashar. "The role of location of low inertia in power systems." Thesis, Uppsala universitet, Institutionen för elektroteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-444863.
Full textAbstract:
The plans to reduce the energy-related greenhouse gas emissions stimulate the deployment of electronically interfaced renewable resources. The increased penetration of such intermittent sources together with phasing conventional power plants out and the installation of High Voltage Direct Current (HVDC) links for long-distance more efficient transmission, reduces the stored inertia in any electrical grid. This leads to a more vulnerable power system and increases the significance of studying the corresponding stability aspects. Decreasing the inertial response of a power system deteriorates the quality of both frequency and rotor-angle stability which are the dynamics of interest in this study. The thesis explores the role of the location of low inertia on varying the power system’s dynamics. This is to be conducted in isolation of all other factors that could affect the study outcomes, such as dealing with the same system’s inertia value upon lowering the inertia in different locations. To accomplish this objective, it is essential to analyze the inertia distribution of the examined power system following the alterations of inertia reduction location. Accordingly, an inherently previous work methodology, that estimates the relative distance of the system’s components to Center Of Inertia (COI), is utilized throughout this study. Both frequency response and small-signal stability are analyzed in light of the inertia distribution results. The thesis examines two different power systems, a small two-area model and a bigger more realistic power system. The former model, known as Kundur model, helps in building a conceptual process to apply the methodology and to benchmark the dynamics of interest. While the latter is a reduced model of the Swedish transmission grid, known as Nordic 32 model. Different scenarios of low inertia are considered to capture the current trend of integrating more Renewable Energy Sources (RES) and phasing out more conventional plants. DIgSILENT Powerfactory is the weapon of choice in this study. It is utilized to assess both the frequency stability by performing electromechanical transients’ simulations, and small-signal stability following modal analysis simulations. Results show that the alterations of low inertia location are associated with variations in Instantaneous Frequency Deviation (IFD), Rate Of Change Of Frequency (ROCOF) and the damping ratio of the most critical inter-area oscillation mode. These variations have different levels of significance. Variations of the latter two metrics have the most considerable effects from the stability’s perspective. They can be utilized to prioritize the phasing out process of the conventional power plants, and to choose one of the scenarios of a specific low inertia location over the others. This helps in fulfilling proper long-term planning and short-term operation from the system operator’s perspective.
34
Nasri, Amin. "On the Dynamics and Statics of Power System Operation : Optimal Utilization of FACTS Devicesand Management of Wind Power Uncertainty." Doctoral thesis, KTH, Elektriska energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154576.
Full textAbstract:
Nowadays, power systems are dealing with some new challenges raisedby the major changes that have been taken place since 80’s, e.g., deregu-lation in electricity markets, significant increase of electricity demands andmore recently large-scale integration of renewable energy resources such aswind power. Therefore, system operators must make some adjustments toaccommodate these changes into the future of power systems.One of the main challenges is maintaining the system stability since theextra stress caused by the above changes reduces the stability margin, andmay lead to rise of many undesirable phenomena. The other important chal-lenge is to cope with uncertainty and variability of renewable energy sourceswhich make power systems to become more stochastic in nature, and lesscontrollable.Flexible AC Transmission Systems (FACTS) have emerged as a solutionto help power systems with these new challenges. This thesis aims to ap-propriately utilize such devices in order to increase the transmission capacityand flexibility, improve the dynamic behavior of power systems and integratemore renewable energy into the system. To this end, the most appropriatelocations and settings of these controllable devices need to be determined.This thesis mainly looks at (i) rotor angle stability, i.e., small signal andtransient stability (ii) system operation under wind uncertainty. In the firstpart of this thesis, trajectory sensitivity analysis is used to determine themost suitable placement of FACTS devices for improving rotor angle sta-bility, while in the second part, optimal settings of such devices are foundto maximize the level of wind power integration. As a general conclusion,it was demonstrated that FACTS devices, installed in proper locations andtuned appropriately, are effective means to enhance the system stability andto handle wind uncertainty.The last objective of this thesis work is to propose an efficient solutionapproach based on Benders’ decomposition to solve a network-constrained acunit commitment problem in a wind-integrated power system. The numericalresults show validity, accuracy and efficiency of the proposed approach.The Doctoral Degrees issued upon completion of the programme are issued by Comillas Pontifical University, Delft University of Technology and KTH Royal Institute of Technology. The invested degrees are official in Spain, the Netherlands and Sweden, respectively.QC 20141028
35
Gianto, Rudy. "Coordination of power system controllers for optimal damping of electromechanical oscillations." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0056.
Full textAbstract:
This thesis is devoted to the development of new approaches for control coordination of PSSs (power system stabilisers) and FACTS (flexible alternating current transmission system) devices for achieving and enhancing small-disturbance stability in multi-machine power systems. The key objectives of the research reported in the thesis are, through optimal control coordination of PSSs and/or FACTS devices, those of maintaining satisfactory power oscillation damping and secure system operation when the power system is subject to persisting disturbances in the form of load demand fluctuations and switching control. Although occurring less frequently, fault disturbances are also considered in the assessment of the control coordination performance. Based on the constrained optimisation method in which the eigenvalue-based objective function is minimised to identify the optimal parameters of power system damping controllers, the thesis first develops a procedure for designing the control coordination of PSSs and FACTS devices controllers. The eigenvalue-eigenvector equations associated with the selected electromechanical modes form a set of equality constraints in the optimisation. The key advance of the procedure is that there is no need for any special software system for eigenvalue calculations, and the use of sparse Jacobian matrix for forming the eigenvalue-eigenvector equations leads to the sparsity formulation which is essential for large power systems. Inequality constraints include those for imposing bounds on the controller parameters. Constraints which guarantee that the modes are distinct ones are derived and incorporated in the control coordination formulation, using the property that eigenvectors associated with distinct modes are linearly independent. The robustness of the controllers is achieved very directly through extending the sets of equality constraints and inequality constraints in relation to selected eigenvalues and eigenvectors associated with the state matrices of power systems with loading conditions and/or network configurations different from that of the base case. On recognising that the fixed-parameter controllers, even when designed with optimal control coordination, have an inherent limitation which precludes optimal system damping for each and every possible system operating condition, the second part of ii the research has a focus on adaptive control techniques and their applications to power system controllers. In this context, the thesis reports the development of a new design procedure for online control coordination which leads to adaptive PSSs and/or supplementary damping controllers (SDCs) of FACTS devices for enhancing the stability of the electromechanical modes in a multi-machine power system. The controller parameters are adaptive to the changes in system operating condition and/or configuration. Central to the design is the use of a neural network synthesised to give in its output layer the optimal controller parameters adaptive to system operating condition and configuration. A novel feature of the neural adaptive controller is that of representing the system configuration by a reduced nodal impedance matrix which is input to the neural network.
36
Pupin, Carlos Eduardo [UNESP]. "Estudo da estabilidade a pequenas perturbações de sistemas elétricos multimáquinas com dispositivos FACTS do tipo SSSC e controladores suplementares (POD e PSS)." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/87113.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0
Previous issue date: 2009-05-28Bitstream added on 2014-06-13T20:08:35Z : No. of bitstreams: 1
pupin_ce_me_ilha.pdf: 1801957 bytes, checksum: 06dbcbacdd038bf23cf8b0bfc982dbeb (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Este trabalho apresenta estudos referentes à estabilidade a pequenas perturbações do sistema elétrico de potência, considerando a atuação de FACTS para o amortecimento das oscilações eletromecânicas de baixa freqüência. É abordado o dispositivo FACTS SSSC (Static Synchronous Series Compensator). Para este fim o sistema elétrico é modelado, modificando-se o Modelo de Sensibilidade de Potência para se inserir o compensador. Para melhorar a estabilidade do sistema desenvolvido, controladores são propostos para maximizar o desempenho do dispositivo SSSC, e dessa forma introduzir amortecimento ao sistema elétrico. Acrescenta-se ao modelo desenvolvido os Estabilizadores de Sistemas de Potência (ESP ou PSS – Power System Stabilizers) e o Power Oscillation Damping (POD), para atuação conjunta com o SSSC. Utilizando os fatores de participação e teoria de resíduos é possível encontrar a melhor localização para instalação dos dispositivos e realizar o ajuste dos parâmetros dos controladores. Simulações são realizadas para dois sistemas teste; um de quatro e outro de dez geradores. A partir dos resultados obtidos conclui-se pela potencialidade da utilização do SSSC para a melhoria da estabilidade a pequenas perturbações do sistema elétrico de potência.
This work presents studies to provide damping to low frequencies oscillations of the electrical power systems by FACTS devices, considering SSSC (Static Synchronous Series Compensator). This is developed and implemented using the Power Sensitivity Model for multimachine systems. Afterwards, the SSSC devices are introduced as well as the controllers. The PSS (Power Systems Stabilizers) and POD (Power Oscillation Damping) controllers has been included using the participation factor and residue number theory to examine their best allocation on the electrical power systems. The study is based on modal analysis and time domain simulations using two test systems: four and ten generators. The simulation results show the capability of this method for small signal stability improvement for the electric power systems.
37
Almada, Leandro Momenté. "O modelo de injeção de potência do TCSC e sua aplicação no estudo da estabilidade a pequenas perturbações /." Ilha Solteira: [s.n.], 2012. http://hdl.handle.net/11449/87103.
Full textAbstract:
Orientador: Percival Bueno de AraujoBanca: Laurence Duarte Colvara
Banca: Gideon Villar Leandro
Resumo: O principal objetivo deste trabalho é a utilização do modelo de injeção de potência do dispositivo FACTS TCSC (Thyris-tor Controlled Series Capacitor) na análise da estabilidade a pequenas perturbações de sistemas elétricos de potência. Para atingir este objetivo é deduzido o modelo de injeção de potência do TCSC, cujo equacionamento é adicionado ao Modelo de Sensibilidade de Po-tência (MSP), utilizado para representar o sistema elétrico de potência (SEP). Para o amortecimento das oscilações eletromecânicas de baixa frequência do SEP são utilizados dois modelos para os controladores, um que considera somente um ganho proporcional e outro comumente chamado na literatura de controlador suplementar de amortecimento (POD - Power Oscillation Damping) que contém também blocos de avanço- atraso de fase. Ambos os controladores devem atuar em conjunto com o TCSC para fornecer amortecimento ao SEP. Neste trabalho o sinal de entrada para os dois controladores é a variação da potência ativa na linha de transmissão de instalação do TCSC e seus parâmetros são ajustados de duas formas: pelo método dos resíduos e utilizando o toolbox rltool (SISO) do software MATLAB. Para a validação do equacionamento desenvolvido foram realizadas simulações em um sistema de potência simétrico, de duas áreas, composto de 4 geradores e 10 barras
Abstract: This work presents a power injection model for the Thyristor Controlled Series Compensator (TCSC), a Flexible AC Transmission Systems (FACTS) device, for small signal stability analysis in the electric power systems. To achieve such goal, the TCSC injection power model equations are summed up to the Power Sensitivity Model (PSM) which is used to represent the electric power system (EPS). For the low frequency electromechanical oscillation damping, two models are used to represent the controller: 1. A proportional control and; 2. A supplementary control known as Power Oscillation Damping (POD), which also comprehends lead-lag blocks. Both controllers, previously cited, must work together with the TCSC to damp oscillations in the EPS. In this work, the input signal for both controllers is the real power flow variation in the transmission line where the TCSC is placed and the controllers parameters are adjusted using the residues method and the Matlab toolbox rltool (SISO). Several simulations in a symmetrical, two areas power system, composed of four generators and ten busses, are provided in way to validate the power injection model and are discussed in this work
Mestre
38
Loen, Ida Larsen. "Stability Analysis of Small Hydro Power Plants : Model Verification and Analysis of the Impacts of the Voltage Regulation System." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-24330.
Full textAbstract:
This master thesis concerns stability problems and protection related to small hydro distributed generation. Behavior related to the voltage regulator and the excitation limiters is the main focus in this report. The report consists of two main parts. Part one concerns laboratory studies with focus on the characteristics of the laboratory model, and system modeling and validation. In the other part of the thesis, the validated model is used to study the effect of the excitation limiters and their influence on the system response and performance. These studies are useful to obtain knowledge considering operation close to the power system limits.The laboratory model considered in this thesis is a motor-generator set in the NTNU/SINTEF renewable energy laboratory, representing a small hydro power plant. The characteristics of this model are studied through laboratory measurements, and the system is modeled in Simulink and validated by laboratory testing. The final simulation model of the laboratory system has a response very similar to the actual model. The response of the simulation model has some deviations from the laboratory model, but these are considered small and it is concluded that the model is valid for further studies of excitation limiters for these master thesis.Studies and measurements in the laboratory have given important information about the model and its characteristics and performance. The motor drive operating as a turbine governing system for the laboratory model does not seem to give a realistic representation of a hydraulic turbine governing system. The motor drive responds fast and efficient to disturbances, and contributes greatly to a well damped system with a high stability margin. The motor drive should respond more slowly to give a more realistic representation of the relatively slow response of hydro turbine governors. The excitation system parameters have a great influence on the behavior of the synchronous generator in the laboratory model. The details concerning the excitation system structure are partly unknown, which makes it challenging to find the exact parameters for the voltage regulator implemented in the Simulink model. The parameters found through studying the simulated response seems to be satisfying, as the voltage response of the simulation model is regulated similarly as for the laboratory model. For the cases evaluated in this report, the laboratory model seems to have better small signal stability characteristics when operating underexcited. Whether the stability margin is higher for under- or overexcited operation seems to depend on the characteristics of the generator.The dynamic field current limiters implemented in the simulation model seem to be a close representation of the excitation limiters in the laboratory model. The limiters, controlled by PI controllers are activated as the field current has exceeded a given limit for a certain amount of time. The field current response in field current limiting operation mode depends on the proportional- and integral gain of the PI controller. It is shown that changes of these parameters affect the response significantly. Further studies are needed to draw any conclusions if, and for which cases, this can provoke instability when the field current limiters are activated.
39
Pupin, Carlos Eduardo. "Estudo da estabilidade a pequenas perturbações de sistemas elétricos multimáquinas com dispositivos FACTS do tipo SSSC e controladores suplementares (POD e PSS) /." Ilha Solteira : [s.n.], 2009. http://hdl.handle.net/11449/87113.
Full textAbstract:
Orientador: Percival Bueno de AraujoBanca: Francisco Villarreal Alvarado
Banca: Élcio Precioso de Paiva
Resumo: Este trabalho apresenta estudos referentes à estabilidade a pequenas perturbações do sistema elétrico de potência, considerando a atuação de FACTS para o amortecimento das oscilações eletromecânicas de baixa freqüência. É abordado o dispositivo FACTS SSSC (Static Synchronous Series Compensator). Para este fim o sistema elétrico é modelado, modificando-se o Modelo de Sensibilidade de Potência para se inserir o compensador. Para melhorar a estabilidade do sistema desenvolvido, controladores são propostos para maximizar o desempenho do dispositivo SSSC, e dessa forma introduzir amortecimento ao sistema elétrico. Acrescenta-se ao modelo desenvolvido os Estabilizadores de Sistemas de Potência (ESP ou PSS - Power System Stabilizers) e o Power Oscillation Damping (POD), para atuação conjunta com o SSSC. Utilizando os fatores de participação e teoria de resíduos é possível encontrar a melhor localização para instalação dos dispositivos e realizar o ajuste dos parâmetros dos controladores. Simulações são realizadas para dois sistemas teste; um de quatro e outro de dez geradores. A partir dos resultados obtidos conclui-se pela potencialidade da utilização do SSSC para a melhoria da estabilidade a pequenas perturbações do sistema elétrico de potência.
Abstract: This work presents studies to provide damping to low frequencies oscillations of the electrical power systems by FACTS devices, considering SSSC (Static Synchronous Series Compensator). This is developed and implemented using the Power Sensitivity Model for multimachine systems. Afterwards, the SSSC devices are introduced as well as the controllers. The PSS (Power Systems Stabilizers) and POD (Power Oscillation Damping) controllers has been included using the participation factor and residue number theory to examine their best allocation on the electrical power systems. The study is based on modal analysis and time domain simulations using two test systems: four and ten generators. The simulation results show the capability of this method for small signal stability improvement for the electric power systems.
Mestre
40
Warichet, Jacques. "From the measurement of synchrophasors to the identification of inter-area oscillations in power transmission systems." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209511.
Full textAbstract:
In the early 1980s, relaying engineers conceived a technology allowing a huge step forward in the monitoring of power system behavior: the synchrophasor, i.e. the estimation of a phasor representation - amplitude and phase - of a sinusoidal waveform at a given point in time thanks to highly accurate time synchronization of a digital relay. By measuring synchrophasors across the power system several times per second, and centralizing the appropriate information in a hierarchical way through a telecommunication network link, it is now possible to continuously monitor the state of very large systems at a high refresh rate. At the beginning, the phase angle information of synchrophasors was used to support or improve the performance of classic monitoring applications, such as state estimation and post-mortem analysis. Later, synchrophasors were found to be valuable for the detection and analysis of phenomena that were not monitored previously, such as system islanding and angular stability. This allows a better understanding of system behavior and the design of remedial actions in cases where system security appears to be endangered. Early detection and even prediction of instabilities, as well as validation and improvement of the dynamic models used for studies, have thus become possible.
However, a power system is rarely stationary and the assumptions behind the definition of “phasor” are not completely fulfilled because the waveforms' frequency and amplitude are not constant over a signal cycle at fundamental frequency. Therefore, accuracy of synchrophasor measurements during dynamic events is an important performance criterion. Furthermore, when discontinuities (phase jumps and high magnitude variations) and harmonics disturb the measured analog signals as a consequence of switching actions or external disturbances, measurements provided to the “user” (the operator or the algorithms that will take decisions such as triggering alarms and remedial actions) require a certain robustness.
The efforts underpinning this thesis have lead to the development of a method that ensures the robustness of the measurement. This scheme is described and tested in various conditions. In order to achieve a closer alignment between required and actual measurement performance, it is recommended to add an online indicator of phasor accuracy to the phasor data.
Fast automated corrective actions and closed-loop control schemes relying on synchrophasors are increasingly deployed in power systems. The delay introduced in the measurement and the telecommunication can have a negative impact on the efficiency of these schemes. Therefore, measurement latency is also a major performance indicator of the synchrophasor measurement.
This thesis illustrates the full measurement chain, from the measurement of analog voltages and currents in the power system to the use of these measurements for various purposes, with an emphasis on real-time applications: visualization, triggering of alarms in the control room or remedial actions, and integration in closed-loop controls. It highlights the various elements along this chain, which influence the availability, accuracy and delay of the data.
The main focus is on the algorithm to estimate synchrophasors and on the tradeoff between accuracy and latency that arises in applications for which measurements are taken during dynamic events and the data must be processed within a very limited timeframe.
If both fast phasors and slower, more accurate phasors are made available, the user would be able to select the set of phasors that are the most suitable for each application, by giving priority to either accuracy or a short delay.
This thesis also tentatively identifies gaps between requirements and typical measurements in order to identify current barriers and challenges to the use of wide area measurement systems.
A specific application, the continuous monitoring of oscillatory stability, was selected in order to illustrate the benefits of synchrophasors for the monitoring, analysis and control of power system behavior. This application requires a good phasor accuracy but can allow for some measurement delay, unless phasor data are used in an oscillation damping controller. In addition, it also relies on modal estimators, i.e. techniques for the online identification of the characteristics of oscillatory modes from measurements. This field of ongoing research is also introduced in this thesis.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
41
Furini, Marcos Amorielle [UNESP]. "Estudo da estabilidade a pequenas perturbações de sistemas elétricos de potência multimáquinas sob a ação dos controladores FACTS TCSC e UPFC." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/87215.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0
Previous issue date: 2008-01-25Bitstream added on 2014-06-13T20:09:50Z : No. of bitstreams: 1
furini_ma_me_ilha.pdf: 1020610 bytes, checksum: d3a4a2f6ec4cb8559c7d3d6b770ec955 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
O objetivo desta Dissertação de Mestrado é apresentar a possibilidade de fornecer amortecimento às oscilações de baixa freqüência do sistema elétrico de potência através dos dispositivos FACTS (Flexible Alternating Current Transmission System) TCSC (Thyristor Controlled Series Capacitor) e UPFC (Unified Power Flow Controller). Para isso realiza-se o desenvolvimento e implementação do Modelo de Sensibilidade de Potência para sistemas multmáquinas. Na seqüência são introduzidos os dispositivos TCSC e UPFC, bem como os seus controladores. Apresentam-se resultados de acordo com a evolução dos modelos que representam os dispositivos FACTS, ou seja, parte-se de uma compensação fixa, passando para um modelo dinâmico de primeira ordem e por fim, é incluído o controlador POD (Power Oscillation Damping). A utilização de sinais locais e remotos para entrada do controlador POD também é analisada. Além disso são mostrados os resultados obtidos pela técnica clássica de introdução de amortecimento através de sinais suplementares (os estabilizadores de sistemas de potência – PSS: Power System Stabilizers). O projeto dos controladores POD e PSS é baseado no método da compensação de fase, utilizando a teoria de controle clássico. Fatores de participação, autovetores, autovalores e resíduos de funções de transferência são utilizados como índices para examinar a melhor alocação dos controladores POD e PSS no sistema elétrico de potência.
The objective of this work is to present the possibility to provide damping to low frequencies oscillations of the electrical power systems by FACTS devices (Flexible Alternating Current Transmission System): TCSC (Thyristor Controlled Series Capacitor) and UPFC (Unified Power Flow Controller). This is developed and implemented using the Power Sensitivity Model for multimachine systems. Afterwards, the TCSC and UPFC devices are introduced as well as the controllers. Results are presented according to the evolution of the models that represent the FACTS devices, i.e., it starts with a fixed compensation, passing through a first order dynamic model and finally, it is included a POD controller (Power Oscillation Damping). It is also analyzed the inclusion of local and remote signals for the input of the POD controller. Besides, results obtained by classical techniques of introducing damping by supplementary signals (Power Systems Stabilizer – PSS) are shown. The project of POD and PSS controllers are based on the Phase Compensation Method using the classical control theory. Participation Factor like eigenvalues, eigenvectors and transfer function residues are used as index to examine the best allocation of the POD and PSS controllers on the electrical power systems.
42
Pina, Aline Petean [UNESP]. "Comparação entre modelos do dispositivo FACTS STATCOM para o estudo da estabilidade a pequenas perturbações." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/87089.
Full textAbstract:
Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0
Previous issue date: 2010-05-28Bitstream added on 2014-06-13T19:06:57Z : No. of bitstreams: 1
pina_ap_me_ilha.pdf: 797000 bytes, checksum: d243ccbbde4d3e77f76b36fd34886251 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Este trabalho apresenta estudos referentes à modelagem do dispositivo FACTS STATCOM para posterior inclusão nas equações do Modelo de Sensibilidade de Potência multimáquinas. O objetivo final da modelagem é o estudo da estabilidade a pequenas perturbações de sistemas elétricos de potência. São considerados dois modelos para o dispositivo: um primeiro modelo permite apenas a compensação de potência reativa, enquanto que num segundo modelo é possível a compensação tanto de potência ativa como de potência reativa. Também são sugeridos controladores para o dispositivo FACTS STATCOM e, neste trabalho, estes controladores são descritos por blocos de primeira ordem. Com o equacionamento do sistema elétrico realizado, seu modelo é implementado computacionalmente para se efetuar simulações para se avaliar a estabilidade a pequenas perturbações. As simulações estão baseadas na análise no domínio do tempo e no domínio da frequência, utilizando os dois modelos desenvolvidos para o STATCOM. A partir dos resultados obtidos pelas simulações, análises são realizadas, e discutidos os principais aspectos referentes à estabilidade a pequenas perturbações de sistemas elétricos de potência
This work presents studies referred to the modeling of the FACTS STATCOM device to include in multi-machine Power Sensitivity Model equations. The aim is to study electrical system stability under small perturbations. Two models are considered for the device: the first one allows only the reactive power compensation, while the other one allows the reactive or active compensation. Controllers for the FACTS STATCOM device are also suggested, and in this work they are described by first order blocks. As the electrical system equations are finalized, the model is computationally implemented to effectuate simulations and evaluate the stability under small perturbations. The simulations are based on the time and frequency domain using the two models developed for the FACTS STATCOM device. Considering the results obtained by the simulations the analysis are realized and discussed the principal aspects referred to the electrical Power system stability under small perturbations
43
Furini, Marcos Amorielle. "Estudo da estabilidade a pequenas perturbações de sistemas elétricos de potência multimáquinas sob a ação dos controladores FACTS TCSC e UPFC /." Ilha Solteira : [s.n.], 2008. http://hdl.handle.net/11449/87215.
Full textAbstract:
Orientador: Percival Bueno de AraujoBanca: Antonio Padilha Feltrin
Banca: Wellington Santos Mota
Resumo: O objetivo desta Dissertação de Mestrado é apresentar a possibilidade de fornecer amortecimento às oscilações de baixa freqüência do sistema elétrico de potência através dos dispositivos FACTS (Flexible Alternating Current Transmission System) TCSC (Thyristor Controlled Series Capacitor) e UPFC (Unified Power Flow Controller). Para isso realiza-se o desenvolvimento e implementação do Modelo de Sensibilidade de Potência para sistemas multmáquinas. Na seqüência são introduzidos os dispositivos TCSC e UPFC, bem como os seus controladores. Apresentam-se resultados de acordo com a evolução dos modelos que representam os dispositivos FACTS, ou seja, parte-se de uma compensação fixa, passando para um modelo dinâmico de primeira ordem e por fim, é incluído o controlador POD (Power Oscillation Damping). A utilização de sinais locais e remotos para entrada do controlador POD também é analisada. Além disso são mostrados os resultados obtidos pela técnica clássica de introdução de amortecimento através de sinais suplementares (os estabilizadores de sistemas de potência - PSS: Power System Stabilizers). O projeto dos controladores POD e PSS é baseado no método da compensação de fase, utilizando a teoria de controle clássico. Fatores de participação, autovetores, autovalores e resíduos de funções de transferência são utilizados como índices para examinar a melhor alocação dos controladores POD e PSS no sistema elétrico de potência.
Abstract: The objective of this work is to present the possibility to provide damping to low frequencies oscillations of the electrical power systems by FACTS devices (Flexible Alternating Current Transmission System): TCSC (Thyristor Controlled Series Capacitor) and UPFC (Unified Power Flow Controller). This is developed and implemented using the Power Sensitivity Model for multimachine systems. Afterwards, the TCSC and UPFC devices are introduced as well as the controllers. Results are presented according to the evolution of the models that represent the FACTS devices, i.e., it starts with a fixed compensation, passing through a first order dynamic model and finally, it is included a POD controller (Power Oscillation Damping). It is also analyzed the inclusion of local and remote signals for the input of the POD controller. Besides, results obtained by classical techniques of introducing damping by supplementary signals (Power Systems Stabilizer - PSS) are shown. The project of POD and PSS controllers are based on the Phase Compensation Method using the classical control theory. Participation Factor like eigenvalues, eigenvectors and transfer function residues are used as index to examine the best allocation of the POD and PSS controllers on the electrical power systems.
Mestre
44
Pina, Aline Petean. "Comparação entre modelos do dispositivo FACTS STATCOM para o estudo da estabilidade a pequenas perturbações /." Ilha Solteira : [s.n.], 2010. http://hdl.handle.net/11449/87089.
Full textAbstract:
Orientador: Percival Bueno de AraujoBanca: Anna Diva Plasencia Lotufo
Banca: Igor Kopcak
Resumo: Este trabalho apresenta estudos referentes à modelagem do dispositivo FACTS STATCOM para posterior inclusão nas equações do Modelo de Sensibilidade de Potência multimáquinas. O objetivo final da modelagem é o estudo da estabilidade a pequenas perturbações de sistemas elétricos de potência. São considerados dois modelos para o dispositivo: um primeiro modelo permite apenas a compensação de potência reativa, enquanto que num segundo modelo é possível a compensação tanto de potência ativa como de potência reativa. Também são sugeridos controladores para o dispositivo FACTS STATCOM e, neste trabalho, estes controladores são descritos por blocos de primeira ordem. Com o equacionamento do sistema elétrico realizado, seu modelo é implementado computacionalmente para se efetuar simulações para se avaliar a estabilidade a pequenas perturbações. As simulações estão baseadas na análise no domínio do tempo e no domínio da frequência, utilizando os dois modelos desenvolvidos para o STATCOM. A partir dos resultados obtidos pelas simulações, análises são realizadas, e discutidos os principais aspectos referentes à estabilidade a pequenas perturbações de sistemas elétricos de potência
Abstract: This work presents studies referred to the modeling of the FACTS STATCOM device to include in multi-machine Power Sensitivity Model equations. The aim is to study electrical system stability under small perturbations. Two models are considered for the device: the first one allows only the reactive power compensation, while the other one allows the reactive or active compensation. Controllers for the FACTS STATCOM device are also suggested, and in this work they are described by first order blocks. As the electrical system equations are finalized, the model is computationally implemented to effectuate simulations and evaluate the stability under small perturbations. The simulations are based on the time and frequency domain using the two models developed for the FACTS STATCOM device. Considering the results obtained by the simulations the analysis are realized and discussed the principal aspects referred to the electrical Power system stability under small perturbations
Mestre
45
Gamino, Bruno Rafael. "Análise da estabilidade a pequenas perturbações considerando a atuação dos controladores suplementares de amortecimento ESP e TCSC-POD ajustados por um algoritmo BVNS /." Ilha Solteira, 2018. http://hdl.handle.net/11449/157402.
Full textAbstract:
Orientador: Percival Bueno de AraujoResumo: Neste trabalho, uma técnica baseada na Busca em Vizinhança Variável Básica é apresentada para realizar o ajuste coordenado dos parâmetros dos controladores suplementares de amortecimento Thyristor Controlled Series Capacitor - Power Oscillation Damping e Estabilizadores de Sistemas de Potência, a fim de garantir a estabilidade a pequenas perturbações de sistemas elétricos de potência. A estratégia do método de ajuste proposto consiste em explorar sistematicamente estruturas de vizinhança atrelada a uma etapa de busca local, tornando possível a obtenção de soluções ótimas e a manutenção da capacidade de evitar a estagnação em um ótimo local. Um modelo do TCSC por injeção de corrente é apresentado e seus coeficientes de sensibilidade de corrente são deduzidos para incorporação ao Modelo de Sensibilidade de Corrente, que é utilizado para representar o sistema elétrico de potência. Com a inclusão da modelagem dos controladores de amortecimento, simulações são realizadas em dois sistemas testes, conhecidos como sistema Simétrico de Duas Áreas e sistema New England. Os resultados obtidos são analisados para melhor compreensão do comportamento do sistema elétrico de potência quando submetido a uma pequena perturbação e da influência dos controladores de amortecimento neste cenário. Os parâmetros dos controladores são ajustados pelo algoritmo Particle Swarm Optimization, por um Algoritmo Genético e, também, pelo método proposto neste trabalho. Os desempenhos individuais dos métodos d... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In this work, a technique based on Basic Variable Neighborhood Search is presented to perform the coordinated tuning of the parameters of the supplementary damping controllers Thyristor Controlled Series Capacitor - Power Oscillation Damping and Power System Stabilizers in order to guarantee the small-signal stability of the electric power systems. The strategy of the proposed tuning method consists in systematically exploring neighborhood structures followed by a local search stage, making it possible to obtain optimal solutions and to maintain the ability to avoid stagnation in a local optimum. A current injection model for the TCSC is presented and its current sensitivity coefficients are deduced for incorporation into the Current Sensitivity Model, which is used to represent the electric power system. With the inclusion of the damping controllers modeling, simulations are performed on two test systems, known as the Two-Area Symmetric system and New England system. The results obtained are analyzed to better understand the behavior of the electric power system when subjected to a small disturbance and the influence of the damping controllers in this scenario. The controllers parameters are tuned by the Particle Swarm Optimization algorithm, by a Genetic Algorithm and also by the method proposed in this work. The individual performances of the tuning methods are compared in order to conclude on the technique best suited for this type of problem, including the analysis of a ... (Complete abstract click electronic access below)
Doutor
46
Rodrigues, Carolina Ribeiro. "Utilização da modelagem politópica para a avaliação da margem de estabilidade a pequenas perturbações em sistemas de potência." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-04092007-083807/.
Full textAbstract:
O presente trabalho propõe a utilização conjunta dos conceitos de modelagem politópica e estabilidade quadrática para avaliação da robustez de desempenho de estabilizadores de sistemas de potência (ou PSSs, do inglês, Power System Stabilizers). Controladores de amortecimento do tipo PSS têm sido amplamente utilizados em sistemas elétricos de potência desde o final da década de 60. A maioria destes estabilizadores que hoje estão em operação foi projetada segundo uma abordagem clássica, que envolve a linearização das equações do sistema em torno de um ponto de equilíbrio e controle através de um compensador de avanço-atraso de fase. Este procedimento de projeto é bastante difundido devido à facilidade do uso de tais técnicas e ao baixo custo de implementação. No entanto, uma das principais desvantagens inerentes a essa abordagem vem justamente da linearização, pois a validade do controle projetado fica restrita a uma vizinhança do ponto de operação no qual o sistema foi linearizado. Sendo assim, não há garantia formal de desempenho satisfatório do controlador, uma vez que as condições operativas do sistema variam normalmente ao longo do dia. Mesmo que o desempenho seja verificado, após o projeto, para pontos de operação diferentes daquele no qual foi feito a linearização (procedimento que é tipicamente empregado em estudos de estabilidade a pequenas perturbações), o mesmo estará garantido formalmente apenas nas proximidades dos pontos verificados. A presente pesquisa busca o preenchimento desta lacuna referente à falta de garantia formal de desempenho em condições não nominais de operação. Com o intuito de garantir formalmente a robustez de desempenho dos controladores, utilizou-se o conceito de estabilidade quadrática associado a uma modelagem politópica do sistema de potência para verificação do fator de amortecimento mínimo dentre todos os modos de oscilação do sistema (o qual é usualmente adotado em sistemas de potência como critério de desempenho ou, equivalentemente, como indicador de margem de estabilidade a pequenas perturbações). A modelagem politópica é usada como alternativa para a obtenção de um modelo de sistema dinâmico que leva em conta as incertezas referentes ao ponto de operação. Neste tipo de modelagem, ao invés de se considerar apenas um ponto de operação nominal, leva-se em conta um conjunto particular de pontos de operação típicos do sistema (os quais comporão os vértices de um conjunto convexo, chamado de politopo). Posteriormente, com base no conceito de estabilidade quadrática, pode-se garantir que um controlador projetado para garantir um desempenho mínimo aos vértices de um politopo estenderá tal garantia também a qualquer ponto de operação que tiver uma descrição linearizada pertencente a este politopo. Os resultados obtidos demonstram que a associação desses dois conceitos fornece uma alternativa viável e vantajosa para a avaliação da robustez de estabilidade e desempenho em sistemas de potência. O procedimento proposto pode ser usado de maneira complementar ao cálculo de autovalores tipicamente empregado na indústria, estendendo a garantia formal de robustez a um conjunto mais amplo de pontos de operação.The present work proposes the joint use of polytopic modeling and quadratic stability concepts to evaluate the performance robustness of power systems stabilizers (or PSSs). PSS-type damping controllers have been widely used in electric power systems since the end of 6th decade of this century. The majority of these stabilizers, which are in operation nowadays, were designed according to a classical control approach. This method involves linearization of the system equations around an equilibrium point and control through a lead-lag phase compensator. This procedure has a widespread application in power systems due to the simplicity of the technique and the low implementation cost. However, one of the main disadvantages inherent to this method lies exactly in the linearization, since the validity of the designed control is restricted to a neighborhood of the operation point in which the linearization has been done. Since the system operating condition changes throughout the day, we cannot have a formal guarantee of a satisfactory controller performance. Even if the controller performance is checked for different operating points after the design, the performance will be formally guaranteed only in the neighborhoods of the verified points. The present research aims to fill this gap associated to the lack of a formal performance guarantee in an off-nominal operation condition. With the objective of formally guaranteeing the controller performance, the concept of quadratic stability, associated to a polytopic modeling of the system, was used to check the minimum damping factor among all system modes of oscillation (which is usually adopted in power systems as a performance criteria or, equivalently, as an index of small-signal stability margin). The polytopic modeling is used as an alternative to obtain the dynamic system model that accounts for the uncertainty in the operating point. In this type of modeling, instead of considering only one nominal operating point, a particular set of typical system operating points is chosen (which will compose the vertices of a convex set, called polytope). Later, based on the quadratic stability concept, it is possible to guarantee that a controller designed to achieve a minimum performance index at the vertices of the polytopic set will extend this property to any operation point belonging to this set. The obtained results show that the association of these two concepts provides a viable and advantageous alternative for the evaluation of the stability and performance robustness in power systems. The proposed procedure can be used as a complement to the eigenvalue calculation used in the industry, extending the formal robustness guarantee to a broader set of operating points.
47
Magne, Pierre. "Contribution à l'étude de la stabilité et à la stabilisation des réseaux DC à récupération d'énergie." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0119/document.
Full textAbstract:
Ce mémoire est consacré à l'étude du phénomène d'instabilité pouvant apparaître sur les bus continus des réseaux DC. En effet, l'interaction entre les différents sous-systèmes électriques (source, charge, filtre) composant le réseau DC peut conduire, sous certaines conditions, à l'instabilité du système. A partir de la modélisation des charges sous forme de "Charge à Puissance Constante" (notée CPL), des méthodes d'études permettant l'analyse de la stabilité "petit-signal" et "grand-signal" des systèmes électriques sont présentées. Celles-ci permettent de mettre en évidence le fait qu'un réseau DC ne peut pas fournir n'importe quelle puissance à ses charges sans devenir instable. Ces puissances limites dépendent à la fois de la structure du réseau et des valeurs de ses éléments passifs et de sa tension de bus. Afin de pouvoir augmenter l'amortissement/les marges de stabilité du système, des méthodes de stabilisation sont présentées dans ce mémoire. Elles proposent d'adapter les commandes des charges de manière à assurer sa stabilité. Ceci se fait grâce à l'addition d'un signal stabilisant sur la référence de chaque charge. Ce signal n'est visible que durant les régimes transitoires de la charge afin de ne pas modifier le point de fonctionnement demandé. Néanmoins, plus on voudra stabiliser une charge et plus son signal stabilisant sera important. Un bon compromis doit donc être trouvé afin d'assurer la stabilité du système sans altérer les performances dynamiques des charges. Deux approches différentes sont proposées afin de générer ces commandes stabilisantes. La première se base sur la mise en place d'un stabilisateur centralisé. Deux méthodes centralisées sont alors proposées : la première s'appuie sur la théorie des multimodèles de Takagi-Sugeno alors que la seconde s'appuie sur la théorie de Lyapunov. Cette dernière permettra d'orienter les efforts de stabilisation sur les charges souhaitées pour par exemple, les diriger principalement vers les organes de récupération d'énergie. La seconde approche se base sur la mise en place d'un système de stabilisation multi-agent. Celui-ci présente une structure décentralisée où chaque agent correspond à un bloc de stabilisation. Ceux-ci vont compenser localement les impacts déstabilisants de leur charge respective et leurs actions combinées permettront d'assurer la stabilité du système. De plus, on propose d'utiliser un algorithme d'optimisation sous contraintes qui permettra de donner un dimensionnement du système minimisant les efforts de stabilisation tout en considérant des cas de défaut tels que la perte de l'un des agents ou la reconfiguration du réseauThis thesis is devoted to the analysis of the instability phenomenon that may appear on the DC bus of DC microgrids. Indeed, interaction between the different electrical subsystems of the grid (source, load, filters) can lead, under certain conditions, to the system instability. From the "Constant Power Load" (CPL) hypothesis for the loads, this thesis presents studying methods for "small-signal" and "large-signal" stability analysis of electrical systems. This highlights that a DC microgrid cannot power the loads more than a maximum limit without becoming unstable. This power limitation depends on the structure of the grid, the value of its passive components, and its bus voltage. In order to improve the microgrid stability, stabilization methods are presented in this thesis. They propose to adapt the loads control to ensure the system stability. This is achieved by the addition of a stabilizing signal to the reference of each load. This signal is only visible during the load power transient mode to not change the requested operating point. However, a good trade-off must be found to ensure system stability without affecting the dynamic performance of its loads. Two approaches are investigated to generate the stabilizing commands. The first one is based on the establishment of a centralized stabilization block. Two centralized methods have been developed: the first one is based on the Takagi-Sugeno theory while the second is based on the Lyapunov theory. This latest permits to guide the stabilizing effort on the desired loads. For example, stabilizing effort can be oriented on the energy storage device. The second approach is based on the establishment of a multi-agent stabilizing system. It consists of a decentralized structure in which each agent corresponds to a stabilization block. These will locally compensate the destabilizing impact of their respective load on the microgrid, and their combined actions ensure the system stability. To design the system, the use of a constrained optimization algorithm is proposed. This permits to minimize stabilization efforts while considering faulty events such as the failure of one of the agents or a reconfiguration of the microgrid
48
Oliveira, Ricardo Vasques de. "Projeto de controladores de amortecimento para sistemas elétricos de potência." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-02072006-192756/.
Full textAbstract:
O presente trabalho propõe, como inovação, o limite superior para a energia da saída do sistema em malha fechada como índice de desempenho a ser usado no projeto de controladores robustos para amortecer oscilações eletromecânicas de baixa freqüência em sistemas de potência. A saída do sistema em malha fechada é especificada de forma que a energia da saída corresponda ao valor acumulado do desvio da energia cinética do sistema. O índice de desempenho proposto mostrou-se adequado ao problema de oscilações eletromecânicas. Tal índice de desempenho é utilizado na formulação de uma metodologia sistemática de projeto. O problema de controle é estruturado na forma de desigualdades matriciais lineares, permitindo a obtenção de uma solução numérica para o problema. A obtenção da solução do problema de controle proposto (energia da saída como índice de desempenho) exige menos dispêndio computacional, quando comparado com o tradicional fator de amortecimento mínimo na forma de posicionamento regional de pólos. Tal característica pode ser significativa para o tempo computacional requerido pelo projeto de controladores envolvendo modelos sistemas de potência de ordem elevada. O projeto de controladores de amortecimento robustos, baseados em modelos multimáquinas que dispensem a hipótese de existência de um barramento infinito, constitui a segunda parte da pesquisa proposta. Os problemas inerentes à hipótese do barramento infinito são resolvidos pelo uso de duas abordagens que não adotam tal hipótese. A primeira abordagem adotada refere-se ao uso de um modelo multimáquinas com o ângulo de uma das máquinas do sistema como referência angular. A segunda alternativa proposta é a incorporação do sistema primário de controle de velocidade no modelo multimáquinas referente à primeira alternativa. Além de resolver o problema referente ao uso do barramento infinito, o presente trabalho também propõe análises da influência da hipótese de tal barramento no projeto de controladores de amortecimento. A influência da hipótese do barramento infinito no projeto dos controladores é delineada por meio dos fundamentos expostos e dos resultados obtidos com as diferentes alternativas utilizadasThe present work proposes, as innovation, an upper bound for the output energy of the closed loop system to be used as a performance index in the design of robust controllers to damp low-frequency electromechanical oscillations in electric power systems. The output of the closed loop system is specified so that the output energy corresponds to the accumulated value of the kinetic energy deviation of the closed loop system. The performance index used in the procedure has shown to be suitable to the oscillation problem. The proposed performance index is used in the formulation of a systematic design methodology. The control problem is structured in the form of linear matrix inequalities, allowing a numerical solution to the control problem. The adopted performance index is less costly in terms of computational effort when compared with the traditional minimum damping ratio (performance index usually accepted in power system as small signal stability margin) via regional pole placement in the LMI formulation. This characteristic may be significant to the computational time required for the controller design involving large power system models. The robust damping controller design, based on multimachine models without the infinite-bus assumption, constitutes the second part of this research proposal. The problems inherent to the infinte-bus assumption are solved by means of two approaches which do not use such assumption. The first proposed approach refers to the use of a multimachine model adopting one machine angle of the system as angular reference. The second adopted approach is the incorporation of the primary speed control in the multimachine model regarding to the first approach. Besides solving the problem regarding to the use of infinite-bus assumption, the present work also proposes analyses of such assumption influence in the design of damping controllers. The influence of such assumption, in the design of the controllers, is outlined by means of exposed fundamentals and results obtained with the proposed approaches
49
Miotto, Ednei Luiz. "Aplicação do algoritmo bioinspirado Novel Bat Algorithm na parametrização dos controladores suplementares de amortecimento e dispositivo FACTS GUPFC." Ilha Solteira, 2018. http://hdl.handle.net/11449/157493.
Full textAbstract:
Orientador: Percival Bueno de AraujoResumo: Este trabalho apresenta o Novel Bat Algorithm com uma nova técnica para realizar o ajuste coordenado dos parâmetros de controladores suplementares de amortecimento (Estabilizadores de Sistemas de Potência e do conjunto Generalized Unified Power Flow Controller – Power Oscillation Damping) em sistemas elétricos de potência multimáquinas. O objetivo principal é inserir amortecimento adicional aos modos oscilatórios de baixa frequência e, consequentemente, garantir a estabilidade do sistema elétrico frente a pequenas perturbações. Para representar o sistema elétrico de potência será utilizado o Modelo de Sensibilidade de Potência. Desse modo, todos os seus dispositivos e componentes foram modelados por injeções de potência. Análises estáticas e dinâmicas foram realizadas em dois sistemas teste, sendo: o Sistema Simétrico de Duas Áreas e o Sistema New England. A eficiência do dispositivo FACTS Generalized Unified Power Flow Controller atuando em conjunto com uma estrutura de controle baseada em controladores Proporcional – Integral foi criteriosamente avaliada para o controle de fluxos de potências ativa e reativa, para a melhoria do perfil de tensão do sistema elétrico e na redução das perdas no sistema de transmissão. O desempenho do Novel Bat Algorithm, no que concerne ao ajuste dos parâmetros dos controladores, foi comparado a outros quatro algoritmos bio-inspirados bastante difundidos na literatura: Particle Swarm Optimization, Bacterial Foragim Optimization, Bat Algorithm e... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This work presents the Novel Bat Algorithm as a new technique for the to perform the coordinated tuning of the parameters of the supplementary damping controllers (Power Systems Stabilizers and Generalized Unified Power Flow Controller - Power Oscillation Damping) in multi-machine electric power systems. The main objective is to insert damping to low-frequency oscillations and thus ensure the stability of the electrical system against minor disturbances. The Power Sensitivity Model is used to represent the system. Thus, all devices and their components are modeled by power injection. Static and dynamic analyzes were performed in the two systems: the two-areas symmetric, and the New England. The performance of the proposed methodology (Novel Bat Algorithm), for tuning of the parameters of the controllers was compared to four other algorithms, presented in the literature: The Particle Swarm Optimization method, Bacterial Foraging Optimization method, Bat Algorithm method and a Genetic Algorithm with elitism. The results demonstrated that the Novel Bat Algorithm was more effective than the other techniques presented, generating robust solutions when variations on the scenarios of loads were considered, and therefore accredited it as a tool in the analysis of the study of small-signal stability.
Doutor
50
Qoria, Taoufik. "Nouvelles lois de contrôle pour former des réseaux de transport avec 100% d’électronique de puissance." Thesis, Paris, HESAM, 2020. http://www.theses.fr/2020HESAE041.
Full textAbstract:
Le développement rapide de la production d'énergie renouvelable intermittente et des liaisons HVDC entraîne une augmentation importante du taux de pénétration des convertisseurs statiques dans les réseaux de transport. Aujourd'hui, les convertisseurs statiques ont pour fonction principale d'injecter une puissance dans le réseau tout en s'appuyant sur des machines synchrones qui garantissent tous les besoins du système électrique. Ce mode de fonctionnement est appelé «Grid-following». Les convertisseurs contrôlés en Grid-following ont plusieurs limitations: leur incapacité à fonctionner en mode autonome, leurs problèmes de stabilité dans des réseaux faibles et en cas de défaut ainsi que leur effet négatif sur l'inertie équivalent du système. Pour relever ces défis, le contrôle en Grid-forming est une bonne solution pour répondre aux besoins du système électrique et permettre un fonctionnement stable et sûr du système même avec un taux de pénétration des convertisseurs statique de 100%. Tout d'abord, trois stratégies de contrôle en Grid-forming sont proposées pour garantir quatre fonctionnalités principales: contrôle de tension, contrôle de puissance, émulation d'inertie et le support de la fréquence. La dynamique et la robustesse du système basées sur chaque contrôle ont été analysées et discutées. Ensuite, selon la topologie du convertisseur, la connexion avec le réseau AC peut nécessiter des filtres et des boucles de contrôle supplémentaires. Dans le cadre de cette thèse, deux topologies de convertisseur ont été envisagées (VSC à 2-niveaux et VSC-MMC) et l'implémentation associée à chacune a été discutée. Enfin, les questions de la protection des convertisseurs Grid-forming contre les surintensités et leur synchronisation post-défaut ont été étudiées, puis, des algorithmes de limitation de courant et de resynchronisation ont été proposés pour améliorer la stabilité transitoire du système. Un banc d'essai a été développé pour confirmer les approches théoriques proposéesThe rapid development of intermittent renewable generation and HVDC links yields an important increase of the penetration rate of power electronic converters in the transmission systems. Today, power converters have the main function of injecting power into the main grid, while relying on synchronous machines that guaranty all system needs. This operation mode of power converters is called "Grid-following". Grid-following converters have several limitations: their inability to operate in a standalone mode, their stability issues under weak-grids and faulty conditions and their negative side effect on the system inertia.To meet these challenges, the grid-forming control is a good solution to respond to the system needs and allow a stable and safe operation of power system with high penetration rate of power electronic converters, up to a 100%. Firstly, three grid-forming control strategies are proposed to guarantee four main features: voltage control, power control, inertia emulation and frequency support. The system dynamics and robustness based on each control have been analyzed and discussed. Then, depending on the converter topology, the connection with the AC grid may require additional filters and control loops. In this thesis, two converter topologies have been considered (2-Level VSC and VSC-MMC) and the implementation associated with each one has been discussed. Finally, the questions of the grid-forming converters protection against overcurrent and their post-fault synchronization have been investigated, and then a hybrid current limitation and resynchronization algorithms have been proposed to enhance the transient stability of the system. At the end, an experimental test bench has been developed to confirm the theoretical approach