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1
Frazao, Rodrigo José Albuquerque. "PMU based situation awareness for smart distribution grids." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT061/document.
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Une infrastructure robuste de surveillance basée sur des mesures numériques classiques est souvent utilisée pour permettre une gestion efficace du réseau de distribution électrique, néanmoins les mesures de phaseurs synchronisés, également connu comme synchrophaseurs, sont particulièrement efficaces pour améliorer la capacité de gestion et la surveillance de ces réseaux. Le synchrophaseur est un phaseur numériquement calculé à partir des échantillons de données en utilisant une source temporelle absolue pour un horodatage extrêmement précis des mesures effectuées.De ce fait, les applications des synchrophaseurs sont très nombreuses dans les réseaux électriques, en particulier dans les réseaux de transport. Ils permettent notamment de mesurer la différence angulaire entre les noeuds, l'estimation d'état linéaire, détecter l'îlotage, surveiller la stabilité oscillatoire, et détecter et identifier les défauts. Ainsi, nous pourrions être amenés à croire que pour apporter les avantages bien connus des mesures synchronisées vers les réseaux de distribution électriques, il serait seulement nécessaire de placer les Unités de Mesure de Phaseur, également connu par l'abréviation anglophone PMU, d'une manière directe dans l'environnement de la distribution électrique. Malheureusement, cette tâchen'est pas aussi évidente qu'elle n'y paraît.Les réseaux de distribution électriques et les réseaux de transport ont des caractéristiques opérationnelles différentes, donc les PMUs dédiées aux réseaux de distribution doivent avoir des caractéristiques différentes de celles consacrées aux réseaux haute tension. Les réseaux de distribution intelligents possèdent des longueurs de ligne plus courtes en produisant une ouverture angulaire plus petite entre les noeuds adjacents. En outre, le contenu harmonique élevé et la déviation en fréquence imposent aussi des défis pour l'estimation des phaseurs. Les appareils synchronisés avancés dédiés pour la surveillance du réseau de distribution doivent surmonter ces défis afin de mener la précision des mesures au-delà des exigences actuelles.Cette problématique globale est traitée et évaluée dans la présente thèse. La précision de l'estimation de phaseur est directement liée à la performance de l'algorithme utilisé pour traiter les données. Une grande robustesse contre les effets pernicieux qui peuvent dégrader la qualité des estimations est fortement souhaitée. De ce fait, trois algorithmes adaptifs en fréquence sont présentés en visant l'amélioration du processus d'estimation des mesures de phaseurs dans les réseaux de distribution actifs. Plusieurs simulations en utilisant des signaux corrompus sont réalisées pour évaluer leurs performances dans des conditions statiques et/ou dynamiques.Prenant en compte l'estimation précise des phaseurs, quatre applications potentielles sont présentées pour augmenter la perception, la compréhension et la projection des actions dans les réseaux de distribution. Des contributions sont apportées concernant le circuit équivalent de Thévenin vu par le point de couplage commun (PCC) entre la production décentralisée et les réseaux de distribution. Des contributions sont également apportées pour les équivalents dynamiques externes et l'évaluation de la chute de tension dans les réseaux moyenne-tension radiaux, ainsi que l'évaluation de la problématique des harmoniques pour l'amélioration de la méthode classique nomée PH (puissance active harmonique) pour détecter à la fois la principale source de pollution harmonique et le vrai flux de puissance harmonique sous déviation en fréquence.Le sujet des mesures de phaseurs synchronisés dans le réseaux électrique de distribution est encore peu exploré et les questionnements quant à son applicabilité sont communs, néanmoins cette thèse vise à fournir des propositions pour contribuer à l'avènement de mesures de phaseurs dans l'environnement de la distribution électriqueRobust metering infrastructure based on classical digital measurements has been used to enable a comprehensive power distribution network management, however synchronized phasor measurements, also known as synchrophasors, are especially welcome to improve the overall framework capabilities. Synchrophasor is a phasor digitally computed from data samples using an absolute and accuracy time source as reference. In this way, since the absolute time source has sufficient accuracy to synchronize voltage and current measurements at geographically distant locations, it is possible to extract valuable informations of the real grid operating status without full knowledge of its characteristics.Due to this fact, applications of synchronized phasor measurements in wide-area management systems (WAMSs) have been achieved. Angular separation, linear state estimation, islanding detection, oscillatory stability, and disturbance location identification are some of the several applications that have been proposed. Thus, we could be lead to believe that to bring the well-known benefits of the synchronized measurements toward electric distribution grids it is only required to place in a straightforward manner conventional Phasor Measurement Units (PMUs) into the electric distribution environment. Unfortunately, this is not as simple as it seems.Electric power distribution systems and high-voltage power systems have different operational characteristics, hence PMUs or PMU-enabled IEDs dedicated to distribution systems should have different features from those devoted to the high-voltage systems. Active distribution grids with shorter line lengths produce smaller angular aperture between their adjacent busbars. In addition, high harmonic content and frequency deviation impose more challenges for estimating phasors. Generally, frequency deviation is related to high-voltage power systems, however, due to the interconnected nature of the overall power system, frequency deviation can be propagated toward the distribution grid. The integration of multiple high-rate DERs with poor control capabilities can also impose local frequency drift. Advanced synchronized devices dedicated to smart monitoring framework must overcome these challenges in order to lead the measurement accuracy beyond the levels stipulated by current standard requirements.This overall problematic is treated and evaluated in the present thesis. Phasor estimation accuracy is directly related to the algorithm's performance used for processing the incoming data. Robustness against pernicious effects that can degrade the quality of the estimates is highly desired. Due to this fact, three frequency-adaptive algorithms are presented aiming to boost the phasor estimation process in active distribution grids. Several simulations using spurious and distorted signals are performed for evaluating their performances under static and/or dynamic conditions.Taking into account accurate phasor estimates, four potential applications are presented seeking to increase situational awareness in distribution environment. Contributions are presented concerning online Thévenin's equivalent (TE) circuit seen by the Point of Common Coupling (PCC) between DERs and the grid side, dynamic external equivalents and online three-phase voltage drop assessment in primary radial distribution grids, as well as assessment of harmonic issues for improving the classical PH method (harmonic active power) to detect both the main source of harmonic pollution and true power flow direction under frequency deviation.The issue of synchronized phasor measurements in electric power distribution systems is still underexplored and suspicions about its applicability are common, however this thesis aims to provide propositions to contribute with the advent of phasor measurements in electric distribution environment
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Vutsinas, Megan. "Contingency analysis using synchrophasor measurements." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1233080600/.
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Zhang, Yingchen. "New Methods for Synchrophasor Measurement." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77297.
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Recent developments in smart grid technology have spawned interest in the use of phasor measurement units to help create a reliable power system transmission and distribution infrastructure. Wide-area monitoring systems (WAMSs) utilizing synchrophasor measurements can help with understanding, forecasting, or even controlling the status of power grid stability in real-time. A power system Frequency Monitoring Network (FNET) was first proposed in 2001 and was established in 2004. As a pioneering WAMS, it serves the entire North American power grid through advanced situational awareness techniques, such as real-time event alerts, accurate event location estimation, animated event visualization, and post event analysis.
Traditionally, Phasor Measurement Units (PMUs) have utilized signals obtained from current transformers (CTs) to compute current phasors. Unfortunately, this requires that CTs must be directly connected with buses, transformers or power lines. Chapters 2, 3 will introduce an innovative phasor measurement instrument, the Non-contact Frequency Disturbance Recorder (NFDR), which uses the magnetic and electric fields generated by power transmission lines to obtain current phasor measurements.
The NFDR is developed on the same hardware platform as the Frequency Disturbance Recorder (FDR), which is actually a single phase PMU. Prototype testing of the NFDR in both the laboratory and the field environments were performed. Testing results show that measurement accuracy of the NFDR satisfies the requirements for power system dynamics observation.
Researchers have been developing various techniques in power system phasor measurement and frequency estimation, due to their importance in reflecting system health. Each method has its own pros and cons regarding accuracy and speed. The DFT (Discrete Fourier Transform) based algorithm that is adopted by the FDR device is particularly suitable for tracking system dynamic changes and is immune to harmonic distortions, but it has not proven to be very robust when the input signal is polluted by random noise. Chapter 4 will discuss the Least Mean Squares-based methods for power system frequency tracking, compared with a DFT-based algorithm.
Wide-area monitoring systems based on real time PMU measurements can provide great visibility to the angle instability conditions. Chapter 5 focuses on developing an early warning algorithm on the FNET platform.Ph. D.
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Ritzmann, Deborah. "Synchrophasor-based overhead line impedance monitoring." Thesis, University of Reading, 2017. http://centaur.reading.ac.uk/74320/.
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Thermal limits of overhead transmission lines create network constraints that can result in curtailment of renewable energy generation. Thermal limits are conventionally static and based on worst-case, non-cooling ambient weather conditions, leading to under-utilization of overhead lines. Utilization can be increased and network constraints reduced by rating overhead lines dynamically, based on actual conductor temperature. Installation and maintenance of temperature and weather sensors along an overhead line is expensive and laborious. A more cost-effective solution is to derive average conductor temperature from overhead line impedance parameters, which can be calculated from measurements of electrical signals at each line end. Synchronized phasor measurement technology is becoming increasingly available in substations to capture voltage and current signals with high accuracy and reporting rates. It is known that the substation instrumentation channel can introduce significant systematic errors to the phasor measurements, which in turn cause inaccurate line impedance parameter and temperature values. This thesis presents novel methods for accurate, real-time monitoring of overhead line impedance parameters using synchronized phasor measurements that have systematic errors. In contrast to previous research, the time-variance and temperature dependence of line resistance as well as compensation of systematic errors is taken into account in the system model to increase parameter estimation accuracy. In addition, an algorithm for the selection of the best parameter estimates from different measurement sets is given. The effectiveness of the novel methods is demonstrated in several case studies on measurement data from simulations and an actual overhead line. The results show that the identified correction factors compensate systematic measurement errors, leading to a reduction in impedance parameter estimation errors of at least one order of magnitude compared to existing methods. Furthermore, the accuracy of real-time estimation of average conductor temperature was increased by at least one order of magnitude relative to previously proposed methods.
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Agatep, Allan. "Voltage Stability Analysis Using Simulated Synchrophasor Measurements." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/957.
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An increase in demand for electric power has forced utility transmission systems to continuously operate under stressed conditions, which are close to instability limits. Operating power systems under such conditions along with inadequate reactive power reserves initiates a sequence of voltage instability points and can ultimately lead to a system voltage collapse. Significant research have been focused on time-synchronized measurements of power systems which can be used to frequently determine the state of a power system and can lead to a more robust protection, control and operation performance. This thesis discusses the applicability of two voltage stability synchrophasor-based indices from literature to analyze the stability of a power system. Various load flow scenarios were conducted on the BPA 10-Bus system and the IEEE 39-Bus System using PowerWorld Simulator. The two indices were analyzed and compared against each other along with other well-known methods. Results show that their performances are coherent to each other regarding to voltage stability of the system; the indices can also predict voltage collapse as well as provide insight on other locations within the system that can contribute to instability.
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Quint, Ryan David. "Response-Based Synchrophasor Controls for Power Systems." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50576.
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The electric power grid is operated with exceptionally high levels of reliability, yet recent large-scale outages have highlighted areas for improvement in operation, control, and planning of power systems. Synchrophasor technology may be able to address these concerns, and Phasor Measurement Units (PMUs) are actively being deployed across the Western Interconnection and North America. Initiatives such as the Western Interconnection Synchrophasor Program (WISP) are making significant investments PMUs with the expectation that wide-area, synchronized, high-resolution measurements will improve operator situational awareness, enable advanced control strategies, and aid in planning the grid.This research is multifaceted in that it focuses on improved operator awareness and alarming as well as innovative remedial controls utilizing synchrophasors. It integrates existing tools, controls, and infrastructure with new technology to propose applications and schemes that can be implemented for any utility. This work presents solutions to problems relevant to the industry today, emphasizing utility design and implementation. The Bonneville Power Administration (BPA) and Western Electricity Coordinating Council (WECC) transmission systems are used as the testing environment, and the work performed here is being explored for implementation at BPA. However, this work is general in nature such that it can be implemented in myriad networks and control centers.
A Phase Angle Alarming methodology is proposed for improving operator situational awareness. The methodology is used for setting phase angle limits for a two-tiered angle alarming application. PMUs are clustered using an adapted disturbance-based probabilistic rms-coherency analysis. While the lower tier angle limits are determined using static security assessment between the PMU clusters, the higher tier limits are based on pre-contingency operating conditions that signify poorly damped post-contingency oscillation ringdown. Data mining tools, specifically decision trees, are employed to determine critical indicators and their respective thresholds. An application is presented as a prototype; however, the methodology may be implemented in online tools as well as offline studies.
System response to disturbances is not only dependent on pre-contingency conditions but also highly dependent on post-contingency controls. Pre-defined controls such as Special Protection Schemes (SPSs) or Remedial Action Schemes (RAS) have a substantial impact on the stability of the system. However, existing RAS controls are generally event-driven, meaning they respond to predetermined events on the system. This research expands an existing event-driven voltage stability RAS to a response-based scheme using synchrophasor measurements. A rate-of-change algorithm is used to detect substantial events that may put the WECC system at risk of instability. Pickup of this algorithm triggers a RAS that provides high-speed wide-area reactive support in the BPA area. The controls have proved effective for varying system conditions and topologies, and maintain stability for low probability, high consequence contingencies generally dismissed in today\'s deterministic planning studies.
With investments being made in synchrophasor technology, the path of innovation has been laid; it\'s a matter of where it goes. The goal of this research is to present simple, yet highly effective solutions to problems. Doing so, the momentum behind synchrophasors can continue to build upon itself as it matures industry-wide.
Ph. D.
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Jones, Kevin David. "Synchrophasor-Only Dynamic State Estimation & Data Conditioning." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51548.
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A phasor-only estimator carries with it intrinsic improvements over its SCADA analogue with respect to performance and reliability. However, insuring the quality of the data stream which leaves the linear estimator is crucial to establishing it as the front end of an EMS system and network applications which employ synchrophasor data. This can be accomplished using a two-fold solution: the pre-processing of phasor data before it arrives at the linear estimator and the by developing a synchrophasor-only dynamic state estimator as a mechanism for bad data detection and identification. In order to realize these algorithms, this dissertation develops a computationally simple model of the dynamics of the power system which fits neatly into the existing linear state estimation formulation. The algorithms are then tested on field data from PMUs installed on the Dominion Virginia Power EHV network.Ph. D.
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Barik, Tapas Kumar. "Synchrophasor Based Centralized Remote Synchroscope for Power System Restoration." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/82849.
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The process of Synchronization between two buses in a power system plays a vital role, especially during blackstart or bulk power system restoration period. The synchronization process is primarily monitored in the presence of experienced personnel at the substation level, which might not control or even predict the after effects of synchronization as soon as the synchronizing breaker between the two buses respective to the two islands is closed. However, with the advent of phasor measurement units (PMUs) providing time synchronized synchrophasor data, synchroscope functionality can now be implemented at a centralized remote control platform, usually the control room of the specific utility. This thesis presents a technique along with the actual implementation of such a PMU Synchroscope analytic developed as a part of the Department of Energy sponsored open and Extensible Control and Analytics platform for synchrophasor data (openECA project). The challenges faced to realize this functionality at the centralized remote location along with methods to overcome these hurdles have been discussed in the document. Additional features in comparison to the conventional synchroscope device are also added to facilitate a smoother and successful synchronization, reducing error on behalf of the user /operator and thus, facilitating a faster power system restoration.Master of Science
Successful and proper synchronization between different nodes of a power system is one of the most crucial stages of restoring power after a major wide area electricity outage. Improper synchronization may lead to additional system outages and might delay the restoration process. In this regards, it is desired to perform this vital task at the electric utility’s central remote control room. This thesis develops an application to perform the successful reconnection between two nodes of a system overcoming the various challenges and incorporating system delays. The application designed is based on real-time measurements and is integrated with an open source framework platform for ease of the user.
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Huang, Ruth Christiana. "Designing Anti-Islanding Detection Using the Synchrophasor Vector Processor." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1001.
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ABSTRACT
Designing Anti-Islanding Detection Using the Synchrophasor Vector Processor
Ruth Huang
The need for distributed generation (DG) has become more and more popular because of the adverse effects of fossil fuels and the fear of running out of fossil fuels. By having DG, there are less transmission losses, voltage support, controllability of the system, decreased costs in transmission and distribution, power quality improvement, energy efficiency, and reduced reserve margin. The adverse effects of DG are voltage flicker, harmonics, and islanding. Islanding occurs when the DG continues to energize the power system when the main utility is disconnected. Detecting islanding is important for personnel safety, speedy restoration, and equipment protection. This paper describes the different islanding methods currently used and the benefits of combining two passive islanding detection methods, under/over voltage detection and voltage phase jump detection methods, using the synchrophasor vector processor (SVP).
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Retty, Hema. "Load Modeling using Synchrophasor Data for Improved Contingency Analysis." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/78328.
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For decades, researchers have sought to make the North American power system as
reliable as possible with many security measures in place to include redundancy. Yet the
increasing number of blackouts and failures have highlighted the areas that require
improvement. Meeting the increasing demand for energy and the growing complexity of the
loads are two of the main challenges faced by the power grid. In order to prepare for
contingencies and maintain a secure state, power engineers must perform simulations using
steady state and dynamic models of the system. The results from the contingency studies are
only as accurate as the models of the grid components. The load components are generally the most difficult to model since they are controlled by the consumer. This study focuses on
developing static and dynamic load models using advanced mathematical approximation
algorithms and wide area measurement devices, which will improve the accuracy of the system
analysis and hopefully decrease the frequency of blackouts.
The increasing integration of phasor measurement units (PMUs) into the power system
allows us to take advantage of synchronized measurements at a high data rate. These devices
are capable of changing the way we manage online security within the Energy Management
System (EMS) and can enhance our offline tools. This type of data helps us redevelop the
measurement-based approach to load modeling.
The static ZIP load model composition is estimated using a variation of the method of
least squares, called bounded-variable least squares. The bound on the ZIP load parameters
allows the measurement matrix to be slightly correlated. The ZIP model can be determined
within a small range of error that won't affect the contingency studies. Machine learning is used
to design the dynamic load model. Neural network training is applied to fault data obtained
near the load bus and the derived network model can estimate the load parameters. The neural network is trained using simulated data and then applied to real PMU measurements. A PMU algorithm was developed to transform the simulated measurements into a realistic
representation of phasor data. These new algorithms will allow us to estimate the load models
that are used in contingency studies.Ph. D.
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Almas, Muhammad Shoaib. "Synchrophasor Applications and their Vulnerability to Time Synchronization Impairment." Doctoral thesis, KTH, Elkraftteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217978.
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Recent years have seen the significance of utilizing time-synchronized, high resolution measurements from phasor measurement units (PMUs) to develop and implement wide-area monitoring, protection and control (WAMPAC) systems. WAMPAC systems aim to provide holistic view of the power system and enable detection and control of certain power system phenomena to enhance reliability and integrity of the grid. This thesis focuses on the design, development and experimental validation of WAMPAC applications, and investigates their vulnerability to time synchronization impairment. To this purpose, a state-of-the-art real-time hardware-in-the-loop (RT-HIL) test-bench was established for prototyping of synchrophasor-based applications. This platform was extensively used throughout the thesis for end-to-end testing of the proposed WAMPAC applications. To facilitate the development of WAMPAC applications, an open-source real-time data mediator is presented that parses the incoming synchrophasor stream and provides access to raw data in LabVIEW environment. Within the domain of wide-area protection applications, the thesis proposes hybrid synchrophasor and IEC 61850-8-1 GOOSE-based islanding detection and automatic synchronization schemes. These applications utilize synchrophasor measurements to assess the state of the power system and initiate protection / corrective action using GOOSE messages. The associated communication latencies incurred due to the utilization of synchrophasors and GOOSE messages are also determined. It is shown that such applications can have a seamless and cost-effective deployment in the field. Within the context of wide-area control applications, this thesis explores the possibility of utilizing synchrophasor-based damping signals in a commercial excitation control system (ECS). For this purpose, a hardware prototype of wide-area damping controller (WADC) is presented together with its interface with ECS. The WADC allows real-time monitoring and remote parameter tuning that could potentially facilitate system operators’ to exploit existing damping assets (e.g. conventional generators) when changes in operating conditions or network topology emerges. Finally the thesis experimentally investigates the impact of time synchronization impairment on WAMPAC applications by designing RT-HIL experiments for time synchronization signal loss and time synchronization spoofing. It is experimentally demonstrated that GPS-based time synchronization impairment results in corrupt phase angle computations by PMUs, and the impact this has on associated WAMPAC application.QC 20171121
smart transmission grid operation and control (STRONg2rid)
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Laverty, D. M. "Synchrophasor Measurement and Wireless Telecommunications in the Active Distribution Network." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527827.
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Zhu, Ruoxi. "Online Voltage Stability Monitoring and Control Using Limited Synchrophasor Measurements." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/97197.
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As the scale and complexity of an interconnected power grid has increased significantly, power systems can be operated close to the verge of voltage instability. With the application of Phasor Measurement Units (PMUs), dispatchers are able to monitor long term voltage stability in a real time operational environment. This research addresses the critical issues by proposing three different methods. Voltage Stability Assessment Index (VSAI) is a Thévenin Equivalent (TE) based method considering voltage dynamic mechanisms. To extend the model from one load bus to a critical load center, Optimal Power Flow-Loading limit (OPF-LI) is developed to assess the voltage stability margin. To utilize limited available PMU measurements, State Calculator (SC) is included in the algorithm to approximate the dynamic states at the buses where PMU measurements are not available. The online voltage regulating method in terms of On-load Tap Changer (OLTC) control is also investigated. The methods proposed in this research have been validated with the test cases from the WECC 179 bus system.M.S.
This thesis proposed a hybrid solution of voltage stability monitoring and control in a power system. For the performance of motors, heaters or other loads in the power system, it is important that the customers are supplied with stable voltage. The variation of the voltage may cause damages to the load. Therefore, the methods in this thesis provides a feasible solution to monitor voltage stability of load centers in a power system. In addition, a novel approach for voltage control is proposed to prevent a voltage collapse of the system. The simulation results illustrate that the approach introduced in this thesis is promising for real time application.
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Adewole, Adeyemi Charles. "Voltage stability assessment and wide area protection/control using synchrophasor measurements." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2380.
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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.Electric power systems are being operated closer to their designed stability limits due to the constraints caused by the continuous increase in system loading, and the lack of new power stations and transmission network infrastructure to support this increase in system loading. This coupled with the practice of long distance bulk power transmission and cascading contingencies, makes system instability and consequently blackouts inevitable. In such scenarios, system instabilities like voltage instability becomes a serious threat to the secure operation of the power system, and voltage collapse (system-wide blackouts) are prone to occur. This is often compounded by the unavailability of real-time system measurements for situational awareness from the existing Supervisory Control and Data Acquisition (SCADA)/Energy Management System (EMS) platforms which are usually based on unsynchronized SCADA measurements with a slow reporting rate of 1 measurement every 2-10 seconds. This Doctoral thesis proposes non-iterative algorithms and methods of solution based on the IEEE C37.118 synchrophasor measurements from Phasor Measurement Units (PMUs) with a high reporting rate of up to 200 measurements every second (200 fps) for voltage stability assessment and automated wide area Centralised Protection/Control (CPC) against catastrophic voltage instabilities/blackouts in power systems. Extended formulations are proposed for the Optimal Placement of PMUs (OPP) in power systems with respect to voltage stability assessment. The impact of zero injection buses, critical buses, and PMU redundancy is considered in the formulation of the OPP problem solution. The extended formulations made use of Binary Integer programming (BIP) and Modal Participation Factors (MPFs) derived from the eigenvalues of the power flow Jacobian.
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Chompoobutrgool, Yuwa. "Aspects of Wide-Area Damping Control Design using Dominant Path Synchrophasor Signals." Doctoral thesis, KTH, Elektriska energisystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-164251.
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The presence of inter-area oscillations has long affected stability constraints, and therefore, limited the power transfer capacity of interconnected power systems. Adequate damping of these inter-area oscillations is, thus, necessary to secure system operation and ensure system reliability while increasing power transfers. Power system stabilizers (PSS) are the most common devices used to enhance the damping of such oscillations. Many studies have demonstrated that PSSs using remote signals may perform better than using local signals. The advent of phasor measurement units (PMU) makes remote or wide-area signals become available, which enables various important applications. Of particular interest is wide-area damping control (WADC), which aims to utilize remote or wide-area measurements to damp the inter-area oscillations. However, two main challenges in WADC design are (1) feedback controller input signal selection (which PMU signal is best to use?), and (2) latency (which is inherent in the transmission of the measurements) considerations. In response to the first challenge, this thesis proposes a concept called dominant inter-area oscillation path, which serves to pinpoint a set of candidate signals that can be used as the feedback controller inputs by locating the interconnected corridors where the inter-area modal contents are the most observable. Derivation, identification, and use of the dominant inter-area oscillation paths are demonstrated throughout the thesis. Extensive analysis on the relationships between the proposed set of signals and system properties regarding stability and robustness is presented. To tackle the second challenge, the impacts of time delays on the system performance when using the dominant path signals are investigated. To date, several studies have proposed different control design methods using various oscillation dampers to design WADC. Nevertheless, neither a systematic method nor a concept that encompasses fundamental knowledge on power system dynamics has yet been offered. The objective of this thesis is, thus, to propose an analytical framework based on the dominant path concept which is built upon fundamental principles for feedback controller input signal selection in WADC. With this framework, a proper and systematic approach is developed. The proposed method allows to select appropriate signals and use them to effectively mitigate the inter-area oscillations that constrain power transfer capacity and affect system stability.QC 20150414
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Mthunzi, Everett Mondliwethu. "Performance analysis of a protection scheme based on P-class synchrophasor measurements." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2378.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.Power grid and system protection advancement greatly depend on technological advances. Advent technologies like digital microprocessor type protective relays facilitate paradigm shifts, providing inimitable beneficial engineering adaptations. Phasor measuring technology provides one such technological advance. The onset and rapid development of the Phasor Measuring Unit (PMU) provides an excellent platform for phasor-based, power system engineering. Power transmission constitutes a critical section in the electric power system. The power system transmission lines are susceptible to faults which require instant isolation to establish and maintain consistent system stability. This research focuses on the study of transmission line protection based on P-Class synchrophasor measurements. The IEEE C37.238-2011 Precision Time Protocol (PTP) paradigm shift facilitates practical application of synchrophasors in protection schemes. Synchrophasor procession and accurate data alignment over wide areas support the hypothesis of a phasor-based transmission line differential protection. This research aims to directly implement P-Class synchrophasors in transmission line differential protection, employing synchrophasors to determine fault conditions and administer corresponding protective actions in wide area transmission lines. The research also aims to evaluate the operational characteristics of the synchrophasor-based transmission line differential protection scheme. The research deliverables include a laboratory scale Test-bench that implements the PMU-based transmission line differential protection scheme, and a differential protection utility software solution that follows guidelines specified by the C37.118-2011 standard for synchrophasors. The findings stand to evaluate performance of the PMU-based line differential protection scheme, verifying the protection model as an alternate, practical and feasible backup protection solution. The research deliverables include a synchrophasor-based current differential algorithm, software utility for implementing the PMU-based protection scheme and a Test-bench for concept and feasibility validation.
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Bengtsson, Sebastian. "ESTIMATION OF ELECTROMECHANICAL OSCILLATIONS IN THE NORDIC POWER SYSTEM USING SYNCHROPHASOR MEASUREMENT DATA." Thesis, KTH, Elektriska energisystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-53701.
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Unstable electromechanical dynamics, or electromechanical modes, may cause large amplitude oscillations that may lead to system break-ups or partial blackouts. Thus, the monitoring and study of these modes are of prominent importance and can be of great help for system operators and planning engineers. In this thesis ambient data analysis has been applied on both simulated and synchronized phasor data from Phasor Measurement Units (PMUs) installed at the distribution network of the Nordic power system at Tampere, Lund and Luleå to estimate frequencies and damping ratios of electromechanical modes in the systems. Different spectral estimators (Yule-Walker, Multitaper and Welch) have been used and their performance has been evaluated. Damping estimates were obtained using an autoregressive Yule-Walker model and the half-power point method. Emphasis on general handling and preprocessing of PMU data is made throughout the thesis. The performed analysis indicates that within the measurement locations available, two main inter-area modes in the Nordic power system can be estimated at approximately 0.4 Hz and 0.5 Hz. In addition relevant system dynamics in the frequency range of 0.6-1.0 Hz can also be observed. Ambient data analysis techniques have great potential for monitoring electromechanical oscillations in power systems. However, there are issues related to data quality that need to be systematically addressed, especially when it comes to calculating accurate damping estimates, in the presence of undamped low amplitude sinusoids and forced oscillations.
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Dekhane, Kunal Shashikant. "The Virginia Tech Phasor Data Concentrator Analysis & Testing System." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/46332.
Full textAbstract:
The development of Smart Grid and an increased emphasis on Wide Area Measurement,
Automation, Protection and Control (WAMPAC) has lead to the substantial increase in the
development and use of Synchrophasor Systems. The Department of Energy having realized its
importance in the Power System has encouraged its deployment through the Smart Grid
Investment Grant. With many utilities beginning to implement a large number of PMUs over
their respective power systems, Phasor Data Concentrators (PDCs) play a crucial part in
accurately relaying data from the point of measurement to the operators at the control center. The
current Synchrophasor standard, IEEE C37.118-2005 covers adequately the steady state
characterization of PMUs but does not specify requirements for PDCs. Having recognized the
need for such a standard for PDCs, the North American Synchrophasor Initiative (NASPI) has
developed a guide outlining some of its objectives, functions and tests requirements. Virginia
Tech has developed a PDC Test System under these guidelines and as per the requirements of the
PJM Synchrophasor Systems Deployment Project. This thesis focuses on the testing tools
developed and the procedures implemented in the Virginia Tech PDC Test System.Master of Science
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Peng, Jimmy Chih-Hsien. "Developing ringdown oscillation monitoring techniques using synchrophasor data with applications to New Zealand network." Thesis, University of Auckland, 2012. http://hdl.handle.net/2292/10852.
Full textAbstract:
This thesis improves the performance of Kalman Filter and Prony Analysis for tracking multiple ringdown oscillations in stressed transmission networks. Prior to the start of this research, there were no detailed comparisons between both methods. Hence, detailed investigations were first conducted to address the merits of each technique. Subsequently, a number of modifications for enhancing the approximation accuracy of each method have been outlined. Developments were primarily conducted using synthetic signals and, assumed the ambient noise of the applied systems is white. As a result, a sampling scheme has been integrated to traditional Prony Analysis resulting into an Enhanced Prony procedure. Instead of using a fixed sampling interval, the Enhanced Prony Analysis continuously selects a sampling interval appropriate to the network. This was achieved by utilizing a proposed condition number as a quality control index. Unlike the existing relative error approach, the condition number examines the adequacy of the sampling interval without prior knowledge of the values of the modal parameters. Overall, the Enhanced Prony Analysis has been shown to provide more reliable modal estimations. In addition to monitoring the dominant oscillation, the functionality of Kalman Filter was extended to detect multiple modes. By, firstly, redefining the state variables to directly represent the modal contents and, secondly, Hankel Singular Value Decomposition was applied to provide more accurate estimates of the initial state variables. Since network dynamics are not linear, the use of Extended Kalman Filter was also adopted. The improved Kalman Filter is subsequently known as Extended Complex Kalman Filter (ECKF). Unlike Kalman Filter, ECKF is designed to operate in a non-linear non-predetermined operational environment. Its monitoring performance was also verified using a New Zealand case study. Overall, the proposed ECKF technique provided an estimation accuracy at par with Prony Analysis while retaining Kalman's recursive nature of implementation. Although both improved methods are suitable for tracking multiple oscillations simultaneously, ECKF is considered to be the more attractive option for the New Zealand operation. Meanwhile, parallel-processing was applied to both detection methods. Compared with the traditional sequential computation, parallelizing the monitoring algorithms was able to achieve faster computing speeds. Hence, it was identified as a suitable implementation solution for realizing future monitoring algorithms. Lastly, this thesis investigated the operation of Power System Stabilizers (PSS) to damp the inter-area oscillations when utilizing the remote synchrophasor measurements. The objective was to examine the degradation of the damping performance under different load characteristics. Overall, the use of the remote phasor data offered a better observability for the controller. Damping performance was improved when compared with conventional design. PSS, using a combination of remote and local signals, are less affected by the attributes of the load. The worst damping performance was identified under constant power load while the best damping performance occurred under the constant impedance.
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Tauro, Yvonne Agnes Pearl. "An Iterative Technique for Instrument Transformer Calibration and Line Parameter Estimation with Synchrophasor Measurements." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/77706.
Full textAbstract:
The introduction of synchrophasor technology to the realm of power systems has presented a myriad of novel approaches to age-old problems. In this thesis, the questions of instrument transformer calibration and transmission line parameter estimation have been examined. With synchrophasors offering real-time data for analysis, a solution to each individual problem seems feasible. A quandary however arises due to the fact that calibration methods depend on accurate knowledge of line parameters, and estimation of these parameters depend on calibrated measurements. Traditional methods of determining the parameters may not be the most accurate due to a variety of fluctuations possible on the system, which is why real-time estimation could prove beneficial. This work analyzes each problem and a feasible solution and proposes a method to achieve transducer calibration as well as parameter estimation together, while employing synchronized phasor measurements.Master of Science
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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.
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Zora, Leydi Tatiana. "Thesis PMU Applications Prioritization Based in Wide Area Disturbance Events." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/71829.
Full textAbstract:
Synchrophasor Measurement Units (PMUs) are devices that can not only measure but also time stamp voltage, current, frequency, among others. PMUs take these synchronized measurements as fast as 60 times per second; compared with the traditional 2-4 second SCADA measurements, PMUs bring a much clear and real-time picture of what is happening in the power system. PMUs have been increasingly deployed across transmission power grids worldwide. In the USA this is primarily done by utilities through projects sponsored mainly by SIGS and Smart Grid grants. There are different applications that synchrophasors can provide, including off-line and real-time applications. However, due to budget constraints, technology development and characteristics specific to each system, not all applications are equally suitable and essential for all electric power systems. This thesis provides a method for PMU applications prioritization based on the analysis and results of wide area disturbance events.Master of Science
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Lowe, Bradley Shayne. "A New Method of Determining the Transmission Line Parameters of an Untransposed Line using Synchrophasor Measurements." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/56607.
Full textAbstract:
Transmission line parameters play a significant role in a variety of power system applications. The accuracy of these parameters is of paramount importance. Traditional methods of determining transmission line parameters must take a large number of factors into consideration. It is difficult and in most cases impractical to include every possible factor when calculating parameter values. A modern approach to the parameter identification problem is an online method by which the parameter values are calculated using synchronized voltage and current measurements from both ends of a transmission line.
One of the biggest problems facing the synchronized measurement method is line transposition. Several methods have been proposed that demonstrate how the line parameters of a transposed line may be estimated. However, the present case of today's power systems is such that a majority of transmission lines are untransposed. While transposed line methods have value, they cannot be applied in real-world scenarios. Future efforts of using synchronized measurements to estimate transmission line parameters must focus on the development and refining of untransposed line methods.
This thesis reviews the existing methods of estimation transmission line parameters using synchrophasor measurements and proposes a new method of estimating the parameters of an untransposed line. After the proposal of this new method, a sensitivity analysis is conducted to determine its performance when noise is present in the measurements.Master of Science
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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.
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Retty, Hema A. "Evaluation and Standardizing of Phasor Data Concentrators." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/32064.
Full textAbstract:
The power grid is interconnected in many ways; so that when disturbances occur in a small region, their effects can be seen across large areas causing major blackouts. In order to isolate the fault, measurements taken at different times throughout the blackout need to be collected and analyzed. With each measurement device having its own time source, time alignment can be a quite tedious and lengthy process. The need for a new time synchronized measurement device has arrived. The Phasor Measurement Units (PMU) is not only GPS time synchronized, but it also takes measurements as voltage and current phasors.
PMUs are becoming an integral part in many power system applications from load flow analysis and state estimation to analyzing blackout causes. Phasor Data Concentrators (PDC) collect and process PMU data. As such, it is important that PMU and PDC communication is seamless. PDCs are set up at multiple utilities and power authorities and also need to be able to communicate and send data to one another seamlessly to encompass analysis of large measurement systems. If these devices are not working similarly when processing and sending/receiving data, unnecessary problems may arise. Therefore it is important that there is an expectation as to how they should work. However, what is expected from these devices is not entirely clear. For this reason, standards such as IEEE C37.118.2-2011 [5] have been proposed to help make operation as uniform as possible. Unfortunately, the standards for PDCs are lacking and tend to only set up communication protocols. To help normalize PDCs, these standards need to be expanded to include all PDC operations and give little room for discrepancy as to what a PDC should do in any given situation. Tests have been performed on PDCs not only to see how they match up to current standards but on how they act outside of the standards.Master of Science
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Li, Meiyan. "Transient Stability Prediction based on Synchronized Phasor Measurements and Controlled Islanding." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/52623.
Full textAbstract:
Traditional methods for predicting transient stability of power systems such as the direct method, the time domain approach, and the energy function methods do not work well for online transient stability predictions problems. With the advent of Phasor Measurement Units (PMUs) in power systems, it is now possible to monitor the behavior of the system in real time and provide important information for transient stability assessment and enhancement. Techniques such as the rotor oscillation prediction method based on time series have made the prediction of system stability possible for real-time applications. However, methods of this type require more than 300 milliseconds after the start of a transient event to make reliable predictions. The dissertation provides an alternate prediction method for transient stability by taking advantage of the available PMUs data. It predicts transient stability using apparent impedance trajectories obtained from PMUs, decision trees, and FLDSD method. This method enables to find out the strategic locations for PMUs installation in the power system to rapidly predict transient stability. From the simulations performed, it is realized that system stability can be predicted in approximately 200 milliseconds (12 cycles). The main advantage of this method is its simplicity as the PMUs can record the apparent impedance trajectories in real-time without any previous calculations. Moreover, using decision trees built in CART, transient stability prediction becomes straightforward and computationally very fast. The optimum locations for PMUs placement can also be determined using this technique.
After the transient instability prediction by the apparent impedance trajectories, a slow- coherency based intelligent controlled islanding scheme is also developed to restore the stability of system. It enables the generators in the same island to stay in synchronism and the imbalance between the generators and load demand is minimized.Ph. D.
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Becci, Andrea. "Comparison between fault location methods in distribution grid using PMU measurements." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22602/.
Full textAbstract:
The introduction of Phasor Measurement Unit (PMU) in distribution network has an
important innovation that brings the possibility of having in real time the complete
knowledge of the full network with higher accuracy.
In the following chapters is analized the possibility to derive the position of a fault along
a line using measurements performed by a limited number of PMU connected to strategic
nodes.
Aim of this thesis is to analize and compare different possible use of PMU for fault
location and undestrand which are the problematics that have to be solved for real implementation.
Firstly is provided an introduction on the main features of the instrument
focusing on the definition of the synchrophasor and because it is important to improve
the quality of the measurements providing some accuracy indexes used to define such
parameter.
Then, different methods for fault location in distribution network are described concentrating
the discussion on the algorithm provided for the calculation and finally, is introduced
a method for stategic PMU positioning inside the network and then a comparison
between the methods is performed emphasizing the advantages and disadvantages brings
from each method, focusing on the limitations that can occur due to not easily accessible
input data,
exibility of each method to different types of fault and extension of the
theorical model to a real network with different components and higher vastity.
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Farantatos, Evangelos. "A predictive out-of-step protection scheme based on PMU enabled distributed dynamic state estimation." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45863.
Full textAbstract:
Recent widespread blackouts have indicated the need for more efficient and accurate power system monitoring, control and protection tools. Power system state estimation, which is the major tool that is used nowadays for providing the real-time model of the system, has significant biases resulting mainly from the complexity and geographic spread and separation of an electric power system. Synchrophasor technology is a promising technology that has numerous advantages compared to conventional metering devices. PMUs provide synchronized measurements, where synchronization is achieved via a GPS clock which provides the synchronizing signal with accuracy of 1 μsec. As a result, the computed phasors have a common reference (UTC time) and can be used in local computations, thus distributing the state estimation process. The first part of the work presents a PMU enabled dynamic state estimator (DSE) that can capture with high fidelity the dynamics of the system and extract in real time the dynamic model of the system. The described DSE is performed in a decentralized way, on the substation level based on local measurements which are globally valid. The substation based DSE uses data from relays, PMUs, meters, FDRs etc in the substation only, thus avoiding all issues associated with transmission of data and associated time latencies. This approach enables very fast DSE update rate which can go up to more than 60 executions per second.
The distributed state estimation architecture that synchrophasor technology enables, along with the fast sampling rate and the accuracy of the measurements that PMUs provide, enable the computation of the real-time dynamic model of the system and the development of numerous power system applications for more efficient control and protection of the system. In the second part of the work, a transient stability monitoring scheme is presented that utilizes the information given by the dynamic state estimation and enables real-time monitoring of the transient swings of the system and characterizes the stability of the system in real time. In particular, the real-time dynamic model of the system, as given by the DSE, is utilized to evaluate the system's energy function based on Lyapunov's direct method and extract stability properties from the energy function. The two major components of the scheme are a) the calculation of the center of oscillations of the system and b) the derivation of an equivalent, reduced sized model which is used for the calculation of the potential and kinetic energy of the system based on which the stability of the system is determined. Finally, as an application of the transient stability monitoring scheme, an energy based out-of-step protection scheme is proposed. The energy of the generator is continuously monitored and if it exceeds a predefined threshold then instability is asserted and a trip signal can be sent to the generator. The major advantage of the scheme is that the out-of-step condition is predicted before its occurrence and therefore relays can act much faster than today's technology. The scheme is compared to presently available state of the art out-of-step protection schemes in order to verify its superiority.
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Junior, Shigueru Nagao. "Unidade eletrônica microprocessada para tratamento de sinais de transformadores de instrumentação ópticos e convencionais para aplicações metrológicas in situ." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-17032017-143745/.
Full textAbstract:
As elevadas perdas existentes no setor elétrico tem causado preocupação nas empresas de distribuição, aliadas ainda a necessidade crescente de um desenvolvimento econômico sustentável. Neste cenário a calibração periódica dos instrumentos destinados a medição (entre eles os transformadores de instrumentos) tornam-se essenciais e tais procedimentos encontram-se previstos no novo modelo de operação do setor elétrico. Porém, as dificuldades logísticas e operacionais de transporte a laboratórios metrológicos credenciados dificultam a execução de tais serviços. As técnicas e métodos desenvolvidos nesse trabalho visam a implementação de uma unidade eletrônica capaz de aquisitar e processar dados provenientes de transformadores de instrumentos, de natureza indutiva (denominado de convencional) e ópticos, bem como seus subsistemas de apoio, como ferramentas de medição e calibração portátil, móvel, para execução dos serviços metrológicos in situ nos ambientes das subestações e cabines primárias. Estes serviços, apesar de estarem em estágio incipiente, são de extremo interesse para empresas de energia elétrica. Este projeto está baseado no estado da arte de componentes da eletrônica analógica e digital, onde destacam-se conversores analógico/digital (A/D), microprocessadores, osciladores, FPGA e técnicas computacionais para processamento digital de sinais. São apresentadas as formas de implementação tanto em hardware como em software para esta unidade eletrônica de forma a atender aos requisitos funcionais especificados e às normas do INMETRO e normas internacionais equivalentes para aplicações metrológicas. A validação é baseada em testes comparativos dos fasores na frequência fundamental dos sinais obtidos, analisando os valores de amplitude (para cálculo de erro de relação) e de fase ( para cálculo de erro de fase) entre transformadores ópticos e convencionais, sendo que estes últimos podem ser de referência ou não.The high losses in the electricity sector have caused concern in distribution companies, together with the growing need for sustainable economic development. In this scenario the periodic calibration of instruments intended for measurement (including instrument transformers) become essential and such procedures are provided for in the new model of operation of the electric sector. However, the logistical and operational difficulties of transportation to accredited metrological laboratories make it difficult to perform such services. The techniques and methods developed in this work are aimed at the implementation of an electronic unit capable of acquiring and processing data from instrument transformers of an inductive (conventional) and optical nature, as well as its supporting subsystems, such as portable and mobile measuring and calibration tools for the execution of on-site metrological services in the substations and primary cabins. These services, although in an incipient stage, are of extreme interest to electric energy companies. This project is based on the state-of-the-art components of analog and digital electronics, including analog/digital (A/D) converters, microprocessors, oscillators, FPGA and computational techniques for digital signal processing. The forms of implementation in both hardware and software for this electronic unit are presented in order to meet the functional requirements specified and the standards of the Instituto Nacional de Metrologia (INMETRO) and equivalent international standards for metrological applications. The validation is based on comparative tests of the phasors at the fundamental frequency of the obtained signals, analyzing the amplitude (for ratio error calculation) and phase (for phase error calculation) between optical and conventional transformers, the last one can be reference or not.
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Aleixo, Renato Ribeiro. "Proposta e implementação de uma Micro-PMU." Universidade Federal de Juiz de Fora (UFJF), 2018. https://repositorio.ufjf.br/jspui/handle/ufjf/6641.
Full textAbstract:
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Este trabalho tem como objetivo a proposta de uma Unidade de Medição Fasorial (do inglês, Phasor Measurement Unit)(PMU), de baixo custo, voltada para o monito-ramento da distribuição de energia elétrica. O medidor proposto pode ser conectado à rede de baixa tensão, possibilitando assim o monitoramento dos sistemas de dis-tribuição e transmissão de energia. O algoritmo de estimação fasorial que compõe o software embarcado do equipamento faz uso do filtro Savitzky-Golay como aproxima-ção da derivada, necessária no processo de estimação da frequência do componente fundamental do sinal. O hardware utilizado é composto pelo microprocessador ARM TM4C1294NCPDT da Texas Instruments, um módulo GPS NEO-6M da uBlox, um módulo Wi-Fi ESP8266, além de um circuito de condicionamento do sinal analógico. O sincronismo das medições realizadas é garantido graças ao sinal composto por um pulso por segundo fornecido pelo GPS. Para o envio dos dados gerados pelo medidor pro-posto, o protocolo definido na norma vigente para PMUs foi utilizado. As estimações podem ser armazenadas e vizualizadas em tempo real através de um software monitor de dados de sincrofasores. Os resultados contemplam os testes exigidos pela norma, avaliando-se o erro total da estimação do fasor, o erro de frequência e o erro de taxa de variação da frequência. Por último, a fim de se reafirmar o sincronismo existente entre as medições realizadas por mais de um equipamento, estimou-se os fasores e a frequência em pontos distintos do sistema 4 Barras do IEEE, simulado em tempo real no RTDS, onde pode-se observar a estimação correta da defasagem entre duas barras desse sistema.
The present work proposes of a low cost Phasor Measurement Unity (PMU), for monitoring the power distribution system. The proposed meter can be connected at the low voltage level, making possible the monitoring of the distribution system and the transmission system. The algorithm used to compute the phasor estimation that composes the embedded software in the equipment uses the Savitzky-Golay filter to approximate the differentiation process, necessary in the frequency estimation of the fundamental component of the signal. The hardware of the equipment is composed by a microprocessor AMR TM4C1294NCPDT of Texas Instruments, a uBlox GPS NEO-6M module, a Wi-Fi ESP8266 module and an analog conditioning circuit. The synchronism of the measurements is guaranteed due to a pulse per second signal from the GPS module. For the transmission of the data generated by the PMU, the protocol suggested by the standard is used. The estimated parameters can be visualized in real time through the Synchrophasor Data Monitor Software. The results contemplate the tests required by the IEEE standard C37.118.1 and the analyses of the total vector error, frequency error and rate of change of frequency error. Finally, to attest the synchronism between different PMUs, a test in a Real Time Digital Simulator (RTDS) was made, where the 4 bus IEEE system was simulated. The difference of the angles estimated for different buses was computed and the obtained values were according to the expected.
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Vianna, João Tito Almeida. "Métodos determinísticos para detecção e localização por área de faltas monofásicas de alta impedância sustentadas nos circuitos primários de sistemas de distribuição desequilibrados." Universidade Federal de Juiz de Fora (UFJF), 2016. https://repositorio.ufjf.br/jspui/handle/ufjf/4039.
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O presente trabalho tem por objetivo o desenvolvimento de alternativas para detecção de faltas de alta impedância (HIFs) sustentadas em sistemas de distribuição. Como a maioria destas faltas é monofásica, enfoque foi dado para este tipo de falta no desenvolvimento do trabalho. Devido ao desequilíbrio e a variação da carga dos sistemas de distribuição, a proteção tradicional dos mesmos apresenta dificuldades na detecção destas faltas, que acabam se sustentando no sistema. Isso acarreta um risco de segurança pública, na medida em que estruturas externas ao sistema elétrico são mantidas energizadas representando risco a vidas que entrem em contato com elas. Características da topologia típica de sistemas de distribuição brasileiros (conhecida como do “tipo europeu”) foram exploradas de forma a se elaborar duas propostas de métodos de detecção e localização de HIFs. Ambos os métodos se baseiam na alocação de medidores alocados ao longo do sistema de distribuição, cujas medidas são integradas a uma central de dados via rede de comunicação. Nesta central, as medidas recebidas são analisadas de forma a diagnosticar a presença e localização de faltas monofásicas de alta impedância no sistema e emitir alarmes que descrevam a situação atual do mesmo. O primeiro método, o PDSZ, baseia-se em medições fasoriais sincronizadas e, além da detecção e localização, conta com um algoritmo de classificação das fases envolvidas na falta. Já o segundo (PQDSZ) baseia-se em medições não fasoriais e não possui esta última funcionalidade. Ambos os métodos são implementados em laboratório e simulados com o uso de um Simulador Digital de Tempo Real (RTDS), o que permite uma validação bem próxima da aplicação dos métodos em um sistema real. Tais simulações comprovam a aplicabilidade dos métodos propostos e todos os resultados são analisados de forma a confirmar este fato.
This work aims to develop alternatives for the detection of sustained high impedance faults (HIFs) on distribution power systems. As the majority of these faults are single phase ones, the development was focused on this kind of fault. Due to load unbalance and variation of the distribution systems, the traditional protectiontechniques presents problems on detecting these faults, which are kept sustained on the system. This situation represents a serious public hazard, because the external electrical system structure remains energized, representing a risk to lives that eventually get in touch with it. There is also the risk of starting a fire from this fault point. Topologycal features of Brasilian distribution systems (known as “european type”) were exploited in order to elaborate two methods for detection and localization of HIFs. Both methods are based on the use of meters alocated along the distribution system, whose measurements are sent to a central data concentrator, through a network communication. Then, the received measurements are analysed in order to diagnose the ocurrence of single phase high impedance faults on the system and send alarms that describe the current system situation. The first method, named PDSZ, is based on Phasor Measurement Units (PMUs) and besides detecting and locating the fault, can also classify it, showing which phaseis involved. The second one, the PQDSZ, is based on non-synchronized measurements and can not classify the fault. Both methods were implemented on laboratory and tested using real equipament and a Real Time Digital Simulator (RTDS), which allows a very precise evaluation of the proposed methods, emulating conditions very similar the real ones. The simulations prove the aplicability of the proposed methods and the results are analysed in order to show the effectiveness of the proposed methods.
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"Transmission Line Parameter Estimation using Synchrophasor Data." Master's thesis, 2018. http://hdl.handle.net/2286/R.I.51696.
Full textAbstract:
abstract: Transmission line parameters play an important role in state estimation, dynamic line rating, and fault analysis. Because of this, several methods have been proposed in the literature for line parameter estimation, especially using synchrophasor data. However, success of most prior research has been demonstrated using purely synthetic data. A synthetic dataset does not have the problems encountered with real data, such as invariance of measurements and realistic field noise. Therefore, the algorithms developed using synthetic datasets may not be as effective when used in practice. On the other hand, the true values of the line parameters are unknown and therefore the algorithms cannot be directly implemented on real data. A multi-stage test procedure is developed in this work to circumvent this problem.
In this thesis, two popular algorithms, namely, moving-window total least squares (MWTLS) and recursive Kalman filter (RKF) are applied on real data in multiple stages. In the first stage, the algorithms are tested on a purely synthetic dataset. This is followed by testing done on pseudo-synthetic datasets generated using real PMU data. In the final stage, the algorithms are implemented on the real PMU data obtained from a local utility. The results show that in the context of the given problem, RKF has better performance than MWTLS. Furthermore, to improve the performance of RKF on real data, ASPEN data are used to calculate the initial estimates. The estimation results show that the RKF algorithm can reliably estimate the sequence impedances, using ASPEN data as a starting condition. The estimation procedure is repeated over different time periods and the corresponding results are presented.
Finally, the significance of data drop-outs and its impact on the use of parameter estimates for real-time power system applications, such as state estimation and dynamic line rating, is discussed. To address the problem (of data drop-outs), an auto regressive integrated moving average (ARIMA) model is implemented. The ability of this model to predict the variations in sequence impedances is demonstrated.Dissertation/Thesis
Masters Thesis Electrical Engineering 2018
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"Analysis of Synchronization and Accuracy of Synchrophasor Measurements." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.15780.
Full textAbstract:
abstract: In electric power systems, phasor measurement units (PMUs) are capable of providing synchronized voltage and current phasor measurements which are superior to conventional measurements collected by the supervisory control and data acquisition (SCADA) system in terms of resolution and accuracy. These measurements are known as synchrophasor measurements. Considerable research work has been done on the applications of PMU measurements based on the as-sumption that a high level of accuracy is obtained in the field. The study in this dissertation is conducted to address the basic issue concerning the accuracy of actual PMU measurements in the field. Synchronization is one of the important features of PMU measurements. However, the study presented in this dissertation reveals that the problem of faulty synchronization between measurements with the same time stamps from different PMUs exists. A Kalman filter model is proposed to analyze and calcu-late the time skew error caused by faulty synchronization. In order to achieve a high level of accuracy of PMU measurements, inno-vative methods are proposed to detect and identify system state changes or bad data which are reflected by changes in the measurements. This procedure is ap-plied as a key step in adaptive Kalman filtering of PMU measurements to over-come the insensitivity of a conventional Kalman filter. Calibration of PMU measurements is implemented in specific PMU instal-lation scenarios using transmission line (TL) parameters from operation planning data. The voltage and current correction factors calculated from the calibration procedure indicate the possible errors in PMU measurements. Correction factors can be applied in on-line calibration of PMU measurements. A study is conducted to address an important issue when integrating PMU measurements into state estimation. The reporting rate of PMU measurements is much higher than that of the measurements collected by the SCADA. The ques-tion of how to buffer PMU measurements is raised. The impact of PMU meas-urement buffer length on state estimation is discussed. A method based on hy-pothesis testing is proposed to determine the optimal buffer length of PMU meas-urements considering the two conflicting features of PMU measurements, i. e. un-certainty and variability. Results are presented for actual PMU synchrophasor measurements.Dissertation/Thesis
Ph.D. Electrical Engineering 2012
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Zheng, Ce. "Power System Online Stability Assessment using Synchrophasor Data Mining." Thesis, 2013. http://hdl.handle.net/1969.1/149456.
Full textAbstract:
Traditional power system stability assessment based on full model computation shows its drawbacks in real-time applications where fast variations are present at both demand side and supply side.
This work presents the use of data mining techniques, in particular the Decision Trees (DTs), for fast evaluation of power system oscillatory stability and voltage stability from synchrophasor measurements. A regression tree-based approach is proposed to predict the stability margins. Modal analysis and continuation power flow are the tools used to build the knowledge base for off-line DT training. Corresponding metrics include the damping ratio of critical electromechanical oscillation mode and MW-distance to the voltage instability region. Classification trees are used to group an operating point into predefined stability state based on the value of corresponding stability indicator. A novel methodology for knowledge base creation has been elaborated to assure practical and sufficient training data. Encouraging results are obtained through performance examination.
The robustness of the proposed predictor to measurement errors and system topological variations is analyzed. A scheme has been proposed to tackle the problem of when and how to update the data mining tool for seamless online stability monitoring. The optimal placement for the phasor measurement units (PMU) based on the importance of DT variables is suggested.
A measurement-based voltage stability index is proposed and evaluated using field PMU measurements. It is later revised to evaluate the impact of wind generation on distribution system voltage stability.
Next, a new data mining tool, the Probabilistic Collocation Method (PCM), is presented as a computationally efficient method to conduct the uncertainty analysis. As compared with the traditional Monte Carlo simulation method, the collocation method could provide a quite accurate approximation with fewer simulation runs.
Finally, we show how to overcome the disadvantages of mode meters and ringdown analyzers by using DTs to directly map synchrophasor measurements to predefined oscillatory stability states. The proposed measurement-based approach is examined using synthetic data from simulations on IEEE test systems, and PMU measurements collected from field substations. Results indicate that the proposed method complements the traditional model-based approach, enhancing situational awareness of control center operators in real time stability monitoring and control.
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Kai, Moses An. "Implementation and lessons learned from the Texas Synchrophasor Network." 2012. http://hdl.handle.net/2152/19468.
Full textAbstract:
For decades, power engineers have used simulations to predict grid stability and
voltage phase angles. Only recently have equipment been available to actually measure
phase angle at points hundreds of miles away. A few of these systems are presently
operating in the US by electric grids including the Electric Reliability Council of Texas
(ERCOT) and California Independent System Operator (ISO). However, the systems are
in their infancy and are far from being used to improve grid reliability. This thesis
describes the only independent synchronized phasor network that exists in the US.
Thanks to Schweitzer Engineering Laboratories (SEL), we are streaming in points from
three locations plus the University of Texas at Austin (UT Austin) as of January 2009.
This thesis will describe this network and grid analysis done this far.text
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Rangel, Werdene Alexandro. "Synchrophasor events in the Western Electricity Coordinating Council (WECC) grid." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-2725.
Full textAbstract:
Synchronized phasor measurements, or synchrophasors, allow the measurement of voltage phase angle and frequency, and through the comparison of two or more phasor the stability of the grid can be studied. The acquisition of synchrophasors in possible using Phasor Measurement Units (PMUs) and Global Positioning System Technology (GPS).
The purpose of this research is to study synchrophasor events in the Western Electricity Coordinating Council (WECC) grid. Several studies have been made in the Texas grid, and that allows a comparison of events in both grids.
During this study, five different types of synchrophasor events were observed. The first type of events, which consist of a change in phase angle difference value followed by damped oscillations has also been observed in the Texas grid; however, the other 4 types of events are not common occurrences in the Texas grid. The characteristics of each of the five types of synchrophasor events have been analyzed in this thesis.text
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KONARA, MUDIYANSELAGE ANUPAMA. "Synchrophasor-based robust power system stabilizer design using eigenstructure assignment." 2015. http://hdl.handle.net/1993/30973.
Full textAbstract:
Power system stabilizers (PSSs) provide the most economical way to improve damping of electro-mechanical oscillations in electrical power systems. Synchrophasor technology enables the use of remotely measured signals in the PSS allowing for greater flexibility in the design of the PSS.
Issues related to the transmission of remote signals should be addressed before implementing such systems in practice. This study investigates two of the data transmission issues: (i) delays, and (ii) data dropout; using a synchrophasor-based PSS designed for a two-area four-generator power system model. A time delayed system is modeled using discrete transformation and the effect of the constant delay on the control action of improving damping of an electro-mechanical oscillation is determined analytically. The effect of random delays and data dropout is investigated using non-linear simulations considering viable remedies to overcome these effects.
This research also identifies effective means of using synchrophasor signals for improving the performance of PSSs. Primarily, this research introduces a novel control design algorithm based on eigenstructure assignment that could utilize remotely measured signals to design a robust PSS considering different operating conditions at the design stage. Remote signals could be used as additional inputs to the controller, which introduces extra degrees of freedom. In eigenstructure assignment, these additional degrees of freedom are used to assign eigenvalues and eigenvectors to have adequate damping performance of the system over different operating conditions. The algorithm is formulated as a derivative-free non-linear optimization problem and solved using a single step of optimization by eliminating the use of eigenvalue sensitivities.
The proposed algorithm is tested for the 68 bus model of the interconnected New England test system and New York power system. Three different control configurations that use local and remote signals are considered in the design. The algorithm is solved using non-linear simplex optimization considering different initial points for seeking a global solution. Delays in the remote signals are also incorporated into the design. The designed controllers are verified in a non-linear simulation platform. Finally, the reliability of synchrophasor-based PSS is discussed in brief.February 2016
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Berry, Brian. "Evaluation of a rotor angle measurement technique using synchrophasor methods." Thesis, 2016. http://hdl.handle.net/10539/20064.
Full textAbstract:
All power systems are prone to electromechanical oscillations between generators which can
become unstable under certain conditions. This instability can have catastrophic consequences
such as plant damage or loss of power supply and it is therefore important to monitor these
oscillations and ensure that the risks are mitigated through corrective operational actions or
automatic control. Whilst this behaviour can be observed in a generators’ terminal voltage
phase and magnitude, the internal rotor angle (load angle) of a synchronous machine is useful
for understanding the true severity and interaction of electromechanical oscillations in a power
system. Both the Chinese and IEEE PMU standards mention a proposed method of measuring
the rotor angle directly using a phasor measurement unit (PMU) on the machine terminals and a
KeyPhasor measurement system [1,2]. KeyPhasors are usually installed on the turbine of large
synchronous machines as an aid to vibration monitoring. Whilst this measurement method is
mentioned in these standards, little is currently documented around its physical
implementation and accuracy. This research aims to evaluate the viability of such a method
within both simulation and laboratory environments. Laboratory tests using a miniature
synchronous generator and typical relay techniques were executed and the results proved
positive, but exposed challenges around the sampling resolution of the KeyPhasor signal. A
simulation environment was then used to improve these results and a sufficient method of
mitigating the resolution issue was proposed with accurate results to prove this method. The
rotor angle produced yields an error of around ±0.03°, which is well below the TVE requirement
of ±0.573° as per the IEEE C37.118.1-2011 standard.
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"Real-Time Power System Topology Monitoring Supported by Synchrophasor Measurements." Doctoral diss., 2015. http://hdl.handle.net/2286/R.I.36018.
Full textAbstract:
abstract: ABSTRACT
This dissertation introduces a real-time topology monitoring scheme for power systems intended to provide enhanced situational awareness during major system disturbances. The topology monitoring scheme requires accurate real-time topology information to be effective. This scheme is supported by advances in transmission line outage detection based on data-mining phasor measurement unit (PMU) measurements.
A network flow analysis scheme is proposed to track changes in user defined minimal cut sets within the system. This work introduces a new algorithm used to update a previous network flow solution after the loss of a single system branch. The proposed new algorithm provides a significantly decreased solution time that is desired in a real- time environment. This method of topology monitoring can provide system operators with visual indications of potential problems in the system caused by changes in topology.
This work also presents a method of determining all singleton cut sets within a given network topology called the one line remaining (OLR) algorithm. During operation, if a singleton cut set exists, then the system cannot withstand the loss of any one line and still remain connected. The OLR algorithm activates after the loss of a transmission line and determines if any singleton cut sets were created. These cut sets are found using properties of power transfer distribution factors and minimal cut sets.
The topology analysis algorithms proposed in this work are supported by line outage detection using PMU measurements aimed at providing accurate real-time topology information. This process uses a decision tree (DT) based data-mining approach to characterize a lost tie line in simulation. The trained DT is then used to analyze PMU measurements to detect line outages. The trained decision tree was applied to real PMU measurements to detect the loss of a 500 kV line and had no misclassifications.
The work presented has the objective of enhancing situational awareness during significant system disturbances in real time. This dissertation presents all parts of the proposed topology monitoring scheme and justifies and validates the methodology using a real system event.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2015
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Ren, Jinfeng. "Synchrophasor Measurement Using Substation Intelligent Electronic Devices: Algorithms and Test Methodology." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10388.
Full textAbstract:
This dissertation studies the performance of synchrophasor measurement obtained using substation Intelligent Electronic Devices (IEDs) and proposes new algorithms and test methodology to improve and verify their performance when used in power system applications.
To improve the dynamic performance when exposed to sinusoidal waveform distortions, such as modulation, frequency drift, abrupt change in magnitude, etc, an adaptive approach for accurately estimating phasors while eliminating the effect of various transient disturbances on voltages and currents is proposed. The algorithm pre-analyzes the waveform spanning the window of observation to identify and localize the discontinuities which affect the accuracy of phasor computation. A quadratic polynomial signal model is used to improve the accuracy of phasor estimates during power oscillations. Extensive experimental results demonstrate the advantages. This algorithm can also be used as reference algorithm for testing the performance of the devices extracting synchronized phasor measurements.
A novel approach for estimating the phasor parameters, namely frequency, magnitude and angle in real time based on a newly constructed recursive wavelet transform is developed. This algorithm is capable of estimating the phasor parameters in a quarter cycle of an input signal. It features fast response and achieves high accuracy over a wide range of frequency deviations. The signal sampling rate and data window size can be selected to meet desirable application requirements, such as fast response, high accuracy and low computational burden. In addition, an approach for eliminating a decaying DC component, which has significant impact on estimating phasors, is proposed using recursive wavelet transform.
This dissertation develops test methodology and tools for evaluating the conformance to standard-define performance for synchrophasor measurements. An interleaving technique applied on output phasors can equivalently increase the reporting rate and can precisely depict the transient behavior of a synchrophasor unit under the step input. A reference phasor estimator is developed and implemented. Various types of Phasor Measurement Units (PMUs) and PMU-enabled IEDs (Intelligent Electronic Devices) and time synchronization options have been tested against the standards using the proposed algorithm. Test results demonstrate the effectiveness and advantages.
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Mohan, Deepak. "Synchrophasor based methods for computing the thevenin equivalent impedance of a transmission network between the University of Texas at Austin and the University of Texas PanAm." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-08-4056.
Full textAbstract:
With the increase in complexity of modern electricity grids, the implementation of state-estimators has become a vital aspect of stability and contingency analyses for stable and secure power system operation. Transmission line reactance is an important component in the computation of state-estimators. Two models utilizing real-time synchrophasor data and ERCOT load information are proposed to compute Thevenin equivalent reactance. This thesis presents the results of implementing these methods to estimate the equivalent reactance of a transmission network between The University of Texas at Austin and The University of Texas, PanAm.text
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Sant, Aprajita. "Screening procedure to identify power system events of the Texas Synchrophasor Network." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5257.
Full textAbstract:
This work presents a method for screening synchrophasor data to search for power system events of interest. The method employs prony algorithm to perform modal analysis and estimate mode amplitude, frequency, and damping ratio on the data obtained from the Texas Synchrophasor Network. The procedure uses seven different Linear Prediction Model (LPM) orders, plus a 10 second window width that slides in steps of 1 second, to minimize the possibility of overlooking events of interest. Further, the algorithm is extended to include user defined modal characteristics thresholds, window length and step size to capture specific power system events.text
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Cai, Yaojie. "Development of a synchrophasor based power systems monitoring software with a fault locator application for multi-terminal transmission lines." 2017. http://hdl.handle.net/1993/32044.
Full textAbstract:
Synchrophasor technology is widely available embedded in modern power grid protection, metering, and recording devices. Utilizing synchrophasor measurements, a novel algorithm is proposed for fault location in multi-terminal transmission lines. In order to implement real-time synchrophasor applications, a software platform called “PhasorEye” was developed in this research. PhasorEye facilitates collecting synchrophasor data stream, visualization of decoded data, and implementation of synchrophasor applications as analysis tools. A laboratory setup involving a RTDS real-time digital simulator and a synchrophasor communication network was assembled to demonstrate and validate the use of the software and the proposed new fault location technique. Tests revealed several challenges in practical application of synchrophasor data for fault location and showed that the proposed fault location algorithm can accurately identify the faulted line segment and fault location. Additionally, several other synchrophasor applications developed by other University of Manitoba researchers were implemented and integrated into the software.February 2017
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Allen, Alicia Jen. "Analysis of transmission system events and behavior using customer-level voltage synchrophasor data." 2013. http://hdl.handle.net/2152/21878.
Full textAbstract:
The research topics presented in this dissertation focus on validation of customer-level voltage synchrophasor data for transmission system analysis, detection and categorization of power system events as measured by phasor measurement units (PMUs), and identification of the influence of power system conditions (wind power, daily and seasonal load variation) on low-frequency oscillations. Synchrophasor data can provide information across entire power systems but obtaining the data, handling the large dataset and developing tools to extract useful information from it is a challenge. To overcome the challenge of obtaining data, an independent synchrophasor network was created by taking synchrophasor measurements at customer-level voltage. The first objective is to determine if synchrophasor data taken at customer-level voltage is an accurate representation of power system behavior. The validation process was started by installing a transmission level (69 kV) PMU. The customer-level voltage measurements were validated by comparison of long term trends and low-frequency oscillations estimates. The techniques best suited for synchrophasor data analysis were identified after a detailed study and comparison. The same techniques were also applied to detect power system events resulting in the creation of novel categories for numerous events based on shared characteristics. The numerical characteristics for each category and the ranges of each numerical characteristic for each event category are identified. The final objective is to identify trends in power system behavior related to wind power and daily and seasonal variations by utilizing signal processing and statistical techniques.text
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LEE, YU-JU, and 李育儒. "Design of Synchrophasor-Based Fault Location Algorithm for Multi-Terminal Nonhomogeneous Transmission Lines." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/z26j4x.
Full textAbstract:
博士國立臺灣大學
電機工程學研究所
107
In this dissertation, there are two synchrophasor-based fault location techniques for multi-terminal nonhomogeneous transmission lines and three-terminal nonhomogeneous transmission lines with one off-service line branch proposed. The synchronized voltage and current data sets are provided by intelligent electronic devices (IEDs) or phasor measurement units (PMUs) which are deployed on buses. These two fault location methods are explained briefly as below. For multi-terminal nonhomogeneous transmission lines, the method uses two-terminal fault location technique as the basis to locate the exact fault point by distinguishing the faulty line branch in multi-terminal nonhomogeneous transmission lines. The graph theory is adopted to represent the connection relationship among buses and junction points. Based on the connection relationship, the represented voltage and current phasors of junction points can be obtained orderly so as to identify the faulty line branch. For enhancing accuracy, an appropriate calculation data window is also proposed to mitigate the undesirable influence caused by DC decay and arcing phenomenon. This three-terminal nonhomogeneous transmission lines with one off-service line branch is also taken into account in this dissertation. This algorithm also uses two-terminal fault location technique to identify the faulty line branch and locate the fault point when a fault exist on one of in-service line branches. Contrarily, the two-terminal fault location technique only can point out that a fault exists at the junction point even if the real fault point is on the off-service line branch. Therefore, an advanced fault location index is proposed by using the apparent reactance of the junction point P and sequence network to locate the exact fault point which occurs on the off-service line branch. Two proposed fault location techniques and the appropriate calculation data window are demonstrated by MATLAB/Simulink, the results show that proposed methods can calculate the exact fault point within minor calculation error regardless of the different fault types and fault resistance. The result of the proposed calculation data window is also verified by realistic cases of TPC (Taiwan Power Company), the calculation error derived by using the proposed calculation data window is lower than the results which provided by installed digital relays apparently.
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Almiron, Rubens E. "Development of a laboratory synchrophasor network and an application to estimate transmission line parameters in real time." 2013. http://hdl.handle.net/1993/22016.
Full textAbstract:
The development of an experimental synchrophasors network and application of synchrophasors for real-time transmission line parameter monitoring are presented in this thesis. In the laboratory setup, a power system is simulated in a RTDS real-time digital simulator, and the simulated voltages and currents are input to hardware phasor measurement units (PMUs) through the analog outputs of the simulator. Time synchronizing signals for the PMU devices are supplied from a common GPS clock. The real time data collected from PMUs are sent to a phasor data concentrator (PDC) through Ethernet using the TCP/IP protocol. A real-time transmission line parameter monitoring application program that uses the synchrophasor data provided by the PDC is implemented and validated. The experimental synchrophasor network developed in this thesis is expected to be used in research on synchrophasor applications as well as in graduate and undergraduate teaching.
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Kowley, Puja Ajay. "Synchrophasor based method for computing the Thevenin equivalent impedance seen by a concentrated wind farm region." 2010. http://hdl.handle.net/2152/9014.
Full textAbstract:
Transmission line reactance is an important parameter in carrying out stability studies. The model proposed here utilizes available real time synchrophasor data and information about the generation in the ERCOT grid to determine the Thevenin equivalent reactance of a line. Synchrophasors provide the advantage of synchronized measurements of phase angles which are essential in determining the transmission line reactance. This thesis provides the results of applying this model to estimate the Thevenin equivalent line reactance between McDonald Observatory in West Texas and The University of Texas at Austin.text
48
"A Data Analytics Framework for Smart Grids: Spatio-temporal Wind Power Analysis and Synchrophasor Data Mining." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.18169.
Full textAbstract:
abstract: Under the framework of intelligent management of power grids by leveraging advanced information, communication and control technologies, a primary objective of this study is to develop novel data mining and data processing schemes for several critical applications that can enhance the reliability of power systems. Specifically, this study is broadly organized into the following two parts: I) spatio-temporal wind power analysis for wind generation forecast and integration, and II) data mining and information fusion of synchrophasor measurements toward secure power grids. Part I is centered around wind power generation forecast and integration. First, a spatio-temporal analysis approach for short-term wind farm generation forecasting is proposed. Specifically, using extensive measurement data from an actual wind farm, the probability distribution and the level crossing rate of wind farm generation are characterized using tools from graphical learning and time-series analysis. Built on these spatial and temporal characterizations, finite state Markov chain models are developed, and a point forecast of wind farm generation is derived using the Markov chains. Then, multi-timescale scheduling and dispatch with stochastic wind generation and opportunistic demand response is investigated. Part II focuses on incorporating the emerging synchrophasor technology into the security assessment and the post-disturbance fault diagnosis of power systems. First, a data-mining framework is developed for on-line dynamic security assessment by using adaptive ensemble decision tree learning of real-time synchrophasor measurements. Under this framework, novel on-line dynamic security assessment schemes are devised, aiming to handle various factors (including variations of operating conditions, forced system topology change, and loss of critical synchrophasor measurements) that can have significant impact on the performance of conventional data-mining based on-line DSA schemes. Then, in the context of post-disturbance analysis, fault detection and localization of line outage is investigated using a dependency graph approach. It is shown that a dependency graph for voltage phase angles can be built according to the interconnection structure of power system, and line outage events can be detected and localized through networked data fusion of the synchrophasor measurements collected from multiple locations of power grids. Along a more practical avenue, a decentralized networked data fusion scheme is proposed for efficient fault detection and localization.Dissertation/Thesis
Ph.D. Electrical Engineering 2013
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Liu, Jian-Hong, and 劉建宏. "Applications of Wide-Area Synchrophasor Measurements and Distributed Computation Techniques for Real-Time Voltage Stability Assessment in Smart Power Grids." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/70423332340788312944.
Full textAbstract:
博士國立清華大學
電機工程學系
102
As the power system becomes more stressed and the penetration of renewable energies increases, voltage stability assessment (VSA) becomes a key issue for monitoring and controlling the security of modern bulk power grids. For security considerations, system operators require powerful tools to analyze voltage security of the bulk power system in real-time environments. Traditionally, the VSA is accomplished based on model-based approaches. Although various analytical approaches have been proposed along this direction, their computational complexities may impede their real-time applications. In recent years, with advances of wide-area synchrophasor measurements and distributed computation techniques, these new technologies have opened new perspectives for developing real-time tools for VSA. To this end, this dissertation aims to develop new methodologies for enhancing the real-time voltage stability by using wide-area synchrophasor measurements and distributed computation techniques. First, based on real-time PMU measurements of individual load bus, a modified coupled single-port model will be proposed for measurement-based VSA. This model will improve underestimations of existing coupled single-port models since the reactive power response extracted from the extended Ward-type equivalent is explored to compensate the reactive power mismatch in the existing coupled single-port model. Then, a mitigation factor based on this reactive power response will be defined to provide a direction for adjusting circuit parameters of the current model, and modified models can be constructed accordingly. In addition, based on this modified coupled single-port model, several voltage stability indicators are developed for real-time VSA. Second, the phenomenon of the short-term voltage instability of induction generators will be investigated. This phenomenon will lead to over-accelerations of induction generators such that the induction generators with the high slip may not return to the pre-fault equilibrium point. In order to identify this short-term voltage instability of induction generators in real-time manners, a synchrophasor-based short-term voltage stability indicator will be developed by incorporating induction generator equivalent models into modified coupled single-port models. Third, multi-area Available Transfer Capability (ATC) assessments will be investigated in the distributed computation environments. Three distributed schemes, including (i) Predictor-Corrector Proximal Multiplier Method, (ii) Auxiliary Problem Principle Method, and (iii) Alternative Direction Multiplier Method, will be applied to distributed ATC assessments. System partition with non-overlapping and boundary sub-systems will be employed to a distributed system for implementing proposed iterative distributed algorithms in a distributed manner. Finally, probabilistic load margin predictions under large-scale penetration of wind generations will be studied. Under wind speed variations, a new computational framework will be proposed to conduct probabilistic load margin estimations. A distributed bi-directional sweep method will be employed in multiple wind generators connected to the main grid for power flow computations. A modified direct method will be presented such that conventional 2N + 1 non-linear equations can be replaced by N + 1 equations for load margin calculations. Accordingly, corresponding probabilistic estimations can be calculated by integrating both modified direct method and Gram-Charlier expansions. Simulations on several IEEE test systems have been used to validate the feasibility and the accuracy of our proposed techniques.