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Fernandez, Javier Oscar. "The Virginia Tech Calibration System." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/32669.
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Phasor measurement unit (PMU) applications on power grid monitoring systems have been implemented since the early ninetyâ s. Large monitoring system network performance relies on the consistent measurements of PMUs across the system. This has become a major challenge for designers since large networks use PMUs from various manufacturers who likely implement different synchrophasor technologies to perform the phasor estimations. The current synchrophasor standard, the IEEE C37.118-2005 Synchrophasor Standard, covers adequately the steady-state characterization of PMUs but does not specify transient condition requirements. The North American Synchrophasor Initiative (NASPI) has developed a guide outlining the several tests required for dynamic characterization of PMUs. The National Institute of Standards and Technology (NIST) developed two PMU testing stands for steady-state conformance with the current standard and for dynamic performance testing. Since May 2010, Virginia Tech has been working closely with the NIST in developing a PMU testing system similar to the NIST designs for commercial testing of PMUs and research purposes, the Virginia Tech Calibration System. This thesis focuses on assessing the system accuracy differences between the designs, and the software interface modifications to adapt the new hardware.Master of Science
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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.
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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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Culliss, Jerel Alan. "A Method for PMU-Based Reconfigurable Monitoring." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/35646.
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Given an increasing tendency towards distributed generation and alternative energy sources, the power grid must be more carefully monitored in order to ensure stability. Phasor Measurement Units (PMUs) provide very good observation of a small area of a network, but their relatively high cost prevents them from being deployed at every point. Therefore, to monitor an entire network, State Estimation is still required. By combining these two techniques, the accuracy and speed of power network monitoring can be improved. This thesis presents a method for achieving this goal from both hardware and computational perspectives. Practical considerations for PMU placement are discussed, such as instrument transformer calibration, and an algorithm is developed to apply this technique to any power system. The resulting method is termed reconfigurable monitoring - computationally isolated areas which may be grouped as necessary to allow for flexibility in power system monitoring.Master of Science
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Du, Xiaochen. "PMU applications in system integrity protection scheme." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/pmu-applications-in-system-integrity-protection-scheme(82592e7a-c56d-47f0-8b64-c9a7b9d15ea9).html.
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This thesis has proposed two types of real time System Integrity Protection Schemes(SIPS) using Emergency Single Machine Equivalent (E-SIME) and Model PredictiveControl (MPC) approaches respectively. They are aiming to resolve the transientstability problems in power systems. Synchronous measurements, fast communicationnetwork and FACTS are deployed in the two SIPSs. The Thyristor Controlled SeriesCompensation (TCSC) is applied as the control action in both SIPSs.In the E-SIME based SIPS, the SIME approach is used to evaluate the transient stabilityof the system and then a decision is made about the control actions needed to stabilizethe system. During emergency conditions, a fast response time is very important andthis requires a security guideline to be used in the decision making process. Theguideline is developed by analyzing offline multiple fault scenarios using an automaticlearning approach. This ensures appropriate control actions can be performed withoutcompromising the response time required on a real system.The MPC based SIPS optimizes the control action at every discrete time instant byselecting the control action that leads to the minimized cost function value. Automaticlearning (AL) is utilized to predict power system dynamics by assuming each controlaction has been taken. Furthermore, a feature selection technique, that chooses themost relevant variables, is used to improve the performance of the AL prediction. Themodel predictive control (MPC) technique is performed every discrete time interval, sothe optimal control action is always selected.Two types of SIPS are tested and verified in the benchmark systems. Simulation resultsshow they can effectively protect the system from loss of synchronism in the aftermathof a large disturbance. This thesis also compares the two SIPSs and concludes thebenefits and shortcomings of each approach.
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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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Bueno, James. "A direct measurement of pmu xi from muon decay." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/23724.
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The asymmetry of the positron distribution in polarised muon decay provides confirmation that the weak interaction maximally violates parity conservation. Since 1957 the quantity Pmu xi has been measured with increasing precision, where Pmu is the polarisation of the muon, and xi is a parameter describing the asymmetry. Thus far the results have been consistent with the standard model using a (V-A) interaction.
A new measurement of pmu xi using the TRIUMF Weak Interaction Symmetry Test (TWIST) spectrometer is presented in this thesis. The result is pmu xi = 1.00084 +- 0.00035 (stat.) -0.00063,+0.00165 (syst.), which is a factor of 3.2 more precise than a previous TWIST direct measurement, and a factor of 7.0 more precise than the pre-TWIST value. New limits are set on physics beyond the standard model, including the weak decay of right-handed muons, and left-right symmetric models where a (V+A) current is introduced to conserve parity at higher energies.
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Brueni, Dennis J. "Minimal PMU placement for graph observability : a decomposition approach /." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-10312009-020314/.
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Altman, James Ross. "A Practical Comprehensive Approach to PMU Placement for Full Observability." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31200.
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In recent years, the placement of phasor measurement units (PMUs) in electric transmission systems has gained much attention. Engineers and mathematicians have developed a variety of algorithms to determine the best locations for PMU installation. But often these placement algorithms are not practical for real systems and do not cover the whole process. This thesis presents a strategy that is practical and addresses three important topics: system preparation, placement algorithm, and installation scheduling. To be practical, a PMU strategy should strive for full observability, work well within the heterogeneous nature of power system topology, and enable system planners to adapt the strategy to meet their unique needs and system configuration. Practical considerations for the three placement topics are discussed, and a specific strategy based on these considerations is developed and demonstrated on real transmission system models.Master of Science
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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.
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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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Landford, Jordan. "Event Detection Using Correlation within Arrays of Streaming PMU Data." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3031.
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This thesis provides a synchrophasor data analysis methodology that leverages both statistical correlation techniques and a statistical distribution in order to identify data inconsistencies, as well as power system contingencies. This research utilizes archived Phasor Measurement Unit (PMU) data obtained from the Bonneville Power Administration in order to show that this methodology is not only feasible, but extremely useful for power systems monitoring, decision support, and planning purposes.
By analyzing positive sequence voltage angles between a pair of PMUs at two different substation locations, an historic record of correlation is established. From this record, a Rayleigh distribution of correlation coefficients is calculated. The statistical parameters of this Rayleigh distribution are used to infer occurrences of power system and data events.
To monitor an entire system, a simple solution would be observing each of these parameters for every PMU combination. One issue with this approach is that correlation of some PMU pairs may be redundant or yield little value to monitoring capabilities. Additionally, this approach quickly encounters scalability issues as each additional PMU adds considerably to computation - for example, if the system contains n PMUs the amount of computations will be n(n-1)/2. System-wide monitoring of these parameters in this fashion is cumbersome and inefficient.
To address these issues, an alternative scheme is proposed which involves monitoring only a subset of PMUs characterized by electrically coupled zones, or clusters, of PMUs. These clusters include both electrically-distant and electrically-near PMU sites. When monitored over an event, these yield statistical parameters sufficient for detecting event occurrences. This clustering scheme can be utilized to significantly decrease computation time and allocation of resources while maintaining optimal system observability.
Results from the statistical methods are presented for a select few case studies for both data and power system event detection. In addition, determination of cluster size and content is discussed in detail. Lastly, the viability of monitoring pertinent statistical parameters over various clustering schemes is demonstrated.
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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/.
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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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Pal, Anamitra. "PMU-Based Applications for Improved Monitoring and Protection of Power Systems." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/51093.
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Monitoring and protection of power systems is a task that has manifold objectives. Amongst others, it involves performing data mining, optimizing available resources, assessing system stresses, and doing data conditioning. The role of PMUs in fulfilling these four objectives forms the basis of this dissertation. Classification and regression tree (CART) built using phasor data has been extensively used in power systems. The splits in CART are based on a single attribute or a combination of variables chosen by CART itself rather than the user. But as PMU data consists of complex numbers, both the attributes, should be considered simultaneously for making critical decisions. An algorithm is proposed here that expresses high dimensional, multivariate data as a single attribute in order to successfully perform splits in CART.
In order to reap maximum benefits from placement of PMUs in the power grid, their locations must be selected judiciously. A gradual PMU placement scheme is developed here that ensures observability as well as protects critical parts of the system. In order to circumvent the computational burden of the optimization, this scheme is combined with a topology-based system partitioning technique to make it applicable to virtually any sized system.
A power system is a dynamic being, and its health needs to be monitored at all times. Two metrics are proposed here to monitor stress of a power system in real-time. Angle difference between buses located across the network and voltage sensitivity of buses lying in the middle are found to accurately reflect the static and dynamic stress of the system. The results indicate that by setting appropriate alerts/alarm limits based on these two metrics, a more secure power system operation can be realized.
A PMU-only linear state estimator is intrinsically superior to its predecessors with respect to performance and reliability. However, ensuring quality of the data stream that leaves this estimator is crucial. A methodology for performing synchrophasor data conditioning and validation that fits neatly into the existing linear state estimation formulation is developed here. The results indicate that the proposed methodology provides a computationally simple, elegant solution to the synchrophasor data quality problem.Ph. D.
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Larsson, Bertil. "Tidssynkroniserade mätningar i vattenkraftstationer." Thesis, Uppsala University, Signals and Systems Group, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-125902.
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Vattenfall and Svenska Kraftnät perform start-up tests, where hydropower generators are used to power up the electrical grid in case of a blackout. To monitor the electrical grid, Phasor Measurement Units (PMU) are used. Each PMU is individually equipped with a GPS-receiver to precisely timestamp the data relative to the official time UTC. During the test, it is also of interest to timestamp the measurement signals from individual hydropower generators to later compare with PMU-data, and thus study the power grids impact on the generator.
The aim is to work out an appropriate method to make these measurements and to build a data acquisition system, capable of timestamp data relative to UTC, from a generator in one of Vattenfalls hydroelectric power stations. The problem is that the generator is located in an underground station which hampers the reception of GPS-signals and wiring should be avoided if possible.
Time synchronization has been solved by using Vattenfalls network, which is synchronized by the network protocol NTP. The network includes the concerned hydropower stations and thus can wiring from the surface be avoided. The maximum error for the server in the specific hydroelectric power station is bounded within [-4.62, 3.18] ms relative to UTC. The conclusion is that Vattenfalls NTP-network meets the requirements to distribute time. A platform from National Instruments, programmed with the graphical language LabVIEW, has been used for data acquisition. The platform is programmed to synchronize its internal clock to a NTP-server, timestamp the input signals and save the data on the internal hard drive.
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Tuku, Woldu. "Distributed state estimation using phasor measurement units (PMUs)for a system snapshot." Kansas State University, 2012. http://hdl.handle.net/2097/14129.
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Master of ScienceDepartment of Electrical and Computer Engineering
Noel N. Schulz
As the size of electric power systems are increasing, the techniques to protect, monitor and control them are becoming more sophisticated. Government, utilities and various organizations are striving to have a more reliable power grid. Various research projects are working to minimize risks on the grid. One of the goals of this research is to discuss a robust and accurate state estimation (SE) of the power grid. Utilities are encouraging teams to change the conventional way of state estimation to real time state estimation. Currently most of the utilities use traditional centralized SE algorithms for transmission systems. Although the traditional methods have been enhanced with advancement in technologies, including PMUs, most of these advances have remained localized with individual utility state estimation. There is an opportunity to establish a coordinated SE approach integration using PMU data across a system, including multiple utilities and this is using Distributed State Estimation (DSE). This coordination will minimize cascading effects on the power system. DSE could be one of the best options to minimize the required communication time and to provide accurate data to the operators. This project will introduce DSE techniques with the help of PMU data for a system snapshot. The proposed DSE algorithm will split the traditional central state estimation into multiple local state estimations and show how to reduce calculation time compared with centralized state estimation. Additionally these techniques can be implemented in micro-grid or islanded system.
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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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Deo, Samarth. "Synchronized Phasor Measurement Units : Implementation of PMU Algorithm on HVDC Control Platform." Thesis, KTH, Industriella informations- och styrsystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-138551.
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Power Systems most often operate in the margins of stability limits. With power grids becoming even more automated now, Phasor Measurement Units (PMU’s) and Phasor Data Concentrators (PDC’s) become essential for real-time control of the system. Since PMU’s are time synchronized, the phasors can be compared at the substations, studied for any faults and analyzed at the same time. These PMU’s report the measured magnitude, phasor angle of voltages and currents in real synchronized time in different locations. One good way to measure these quantities is to use the Discrete Fourier Transform (DFT) and analyze the signal as a digital signal. However with transients and noise present in the input signal, DFT might not be the best approach for measurement and/or protection. With the IEEE C37.118 (Standard for Synchrophasor for Power Systems) 2011 version emphasizing on the importance of the two classes of PMU’s- P-class for Protection and M-class for Measurement; every vendor now has to label their products with one of these classes. There is a high precision required for P-class PMU’s whereas a good reporting rate for M-class. Recently The North-American Synchrophasor Initiative (NASPI) and Western Electricity Coordinating Council (WECC) also gave filtering specifications and frequency response of an industry compliant PMU. This thesis discusses the various frequency estimation algorithms, which are compliant with the NASPI/WECC standards. Further such an algorithm is implemented on ABB proprietary hardware and tested against dynamic tests.
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Richter, Marc [Verfasser], and Zbigniew A. [Akademischer Betreuer] Styczynski. "PMU-basierte Zustandsabschätzung in Smart Distribution / Marc Richter. Betreuer: Zbigniew A. Styczynski." Magdeburg : Universitätsbibliothek, 2016. http://d-nb.info/1107181496/34.
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Ahmed, Sheikh. "PMU based PSS and SVC fuzzy controller design for angular stability analysis." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20547.
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Master of ScienceDepartment of Electrical and Computer Engineering
Shelli Starrett
Variability in power systems is increasing due to pushing the system to limits for economic purposes, the inclusion of new energy sources like wind turbines and photovoltaic, and the introduction of new types of loads such as electric vehicle chargers. In this new environment, system monitoring and control must keep pace to insure system stability and reliability on a wide area scale. Phasor measurement unit technology implementation is growing and can be used to provide input signals to new types of control. Fuzzy logic based power system stabilizer (PSS) controllers have also been shown effective in various studies. This thesis considers several choices of input signals, composed assuming phasor measurement availability, for fuzzy logic-based controllers. The purpose of the controller is to damp power systems’ low frequency oscillations. Nonlinear transient simulation results for a 4-machine two-area system and 50 machine system are used to compare the effects of input choice and controller type on damping of system oscillations. Reactive power in the system affects voltage, which in turn affects system damping and dynamic stability. System stability and damping can be enhanced by deploying SVC controllers properly. Different types of power system variables play critical role to damp power swings using SVC controller. A fuzzy logic based static var compensator (SVC) was used near a generator to damp these electromechanical oscillations using different PMU-acquired inputs. The goal was again improve dynamic stability and damping performance of the system at local and global level. Nonlinear simulations were run to compare the damping performance of different inputs on the 50 machine system.
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Wang, Hao. "Two-Stage Fault Location Detection Using PMU Voltage Measurements in Transmission Networks." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/54565.
Full textAbstract:
Fault location detection plays a crucial role in power transmission network, especially on security, stabilization and economic aspects. Accurate fault location detection in transmission network helps to speed up the restoration time, therefore, reduce the outage time and improve the system reliability [1]. With the development of Wide Area Measurement System (WAMS) and Phasor Measurement Unit (PMU), various fault location algorithms have been proposed.
The purpose of this work is to determine, modify and test the most appropriate fault location method which can be implemented with a PMU only linear state estimator. The thesis reviews several proposed fault location methods, such as, one-terminal [2], multi-terminal [3]-[11] and travelling wavelets methods [12]-[13]. A Two-stage fault location algorithm using PMU voltage measurements proposed by Q. Jiang [14] is identified as the best option for adaption to operate with a linear state estimator. The algorithm is discussed in details and several case studies are made to evaluate its effectiveness. The algorithm is shown to be easy to implement and adapt for operation with a linear state estimator. It only requires a limited number of PMU measurements, which makes it more practical than other existing methods. The algorithm is adapted and successfully tested on a real linear state estimator monitored high voltage transmission network.Master of Science
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Guo, Yuanjun. "Advanced statistical process control methods for PMU-based loss-of-mains detection." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.695361.
Full textAbstract:
High penetration levels of distributed renewable generation has brought considerable issues and challenges to the operation and control of power systems for countries and regions where there are abundant, but geographically distributed, renewable energy resources. One of such challenging issue is the Loss-of-mains (LOM) and islanding detection. This thesis aims at developing a variety of monitoring methods to tackle this problem. Principal Component Analysis (PCA) method is a linear method which assumes that data follows a normal Gaussian distribution. Therefore, for a Gaussian distributed frequency variable, a PCA model can be calculated with corresponding confidence limits, which is then used for detecting abnormal transients and identifying the islanding sites occurring in the UK utility network. In order to monitor the dynamic characteristics of power systems, a dynamic PCA (DPCA) approach is proposed by incorporating time lags at the modelling stage, thus the auto- and cross-correlations can be extracted. Moreover, power system processes are time-varying, thus a recursive PCA (RPCA) monitoring scheme is also proposed as a reliable extension of PCA to achieve adaptive updating of training data and confidence limits. A novel radial basis function neural network (RBFNN) model-based PCA method is then proposed to monitor non-Gaussian variables in power systems, combing with the newly developed Teaching-Learning-Based-Optimisation (TLBO) method to tune the non linear parameters of RBF neurons. This research has shown that statistical process control methods such as PCA and its extensions can be successfully applied to power system loss-of-mains detection, so that large volumes of PMU data can be efficiently processed and an adequate monitoring model can be built for a given confidence limit. They further provide a wide-area view and early accurate warning of the network for system operators, with the length of time to identify faults and the risks of damaging connected equipment being reduced.
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Zhou, Ming. "Advanced System Monitoring with Phasor Measurements." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27813.
Full textAbstract:
Phasor Measurement Units (PMUs) are widely acknowledged as one of the most promising developments in the field of real-time monitoring of power systems. By aligning the time stamps of voltage and current phasor measurements that are consistent with Coordinated Universal Time (UTC), a coherent picture of the power system state can be achieved through either direct measurements or simple linear calculations. With the growing number of PMUs planned for installation in the near future, both utilities and research institutions are looking for the best solutions to the placement of units as well as to the applications that make the most of phasor measurements.
This dissertation explores a method for optimal PMU placement as well as two applications of synchronized phasor measurements in state estimation. The pre-processing PMU placement method prepares the system data for placement optimization and reduces the size of the optimization problem. It is adaptive to most of the optimal placement methods and can save a large amount of computational effort. Depth of un-observability is one of the criteria to allow the most benefit out of a staged placement of the units. PMUs installed in the system provide synchronized phasor measurements that are highly beneficial to power system state estimations. Two related applications are proposed in the dissertation. First, a post-processing inclusion of phasor measurements in state estimators is introduced. This method avoids the revision of the existing estimators and is able to realize similar results as mixing phasor data with traditional SCADA with a linear afterwards step. The second application is a method to calibrate instrument transformers remotely using phasor measurements. Several scans of phasor measurements are used to accomplish estimating system states in conjunction with complex instrument transformer correction factors. Numerical simulation results are provided for evaluation of the calibration performance with respect to the number of scans and load conditions.
Conducting theoretical and numerical analysis, the methods and algorithms developed in this dissertation are aimed to strategically place PMUs and to incorporate phasor measurements into state estimators effectively and extensively for better system state monitoring. Simulation results show that the proposed placement method facilitates approaching the exact optimal placement while keep the computational effort low. Simulation also shows that the use of phasor measurement with the proposed instrument transformer correction factors and proposed state estimation enhancement largely improves the quality of state estimations.Ph. D.
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Sukhavasi, Vijay Krishna. "Steady State Testing and Analysis of a Phasor Measurement Unit." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/46328.
Full textAbstract:
Phasor Measurement Units (PMUs) have been instrumental in building a reliable and robust Power System. Recent blackouts have increased the importance of PMUs and PMUs from various manufacturers are being installed in the in large quantities in the North American Grid. The interoperability and accuracy of these PMUs is important to obtain full benefit of the wide area monitoring systems. With the large number of installed PMUs it has become necessary to validate their performance and understand the limitations of each model. A test system was built by NIST in cooperation with NASPI to test for compliance to the existing IEEE C37.118 standard. This thesis presents the development of a Steady State Test System at Virginia Tech based on the NIST Steady State Testing system. The various issues that were faced during the process of development are discussed and the methodology implemented for solving these problems is described. This thesis also presents the additional benefits derived from the results obtained when different PMUs were tested using the Virginia Tech PMU Steady State Test System.Master of Science
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Palizban, Atefeh. "Wide-area monitoring and control utilizing PMU measurements for a system protection scheme." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52888.
Full textAbstract:
The ever increasing complexity of the electrical grid has made it difficult to predict and anticipate contingencies. This is mainly due to the advent of deregulated electricity markets, aging transmission infrastructure and the growing penetration of renewable resources. The wave of blackouts in recent years has made utilities much more aware of the need for power system wide monitoring and control. One of the fundamental requirements to achieve that goal is to have common measurement reference. A few technology enablers have emerged which have led to development of a new kind of measurement paradigm; Phasor Measurement Units, or PMUs.
PMUs bear high potential for wide-area system monitoring and control as well for conducting advanced engineering analysis. PMUs can provide time-synchronized high-resolution estimates of voltage and currents (both phase amplitude and angle) as well as frequency and rate of change of frequency. Such measurements, alternatively called synchrophasors, can provide visibility of a power system distributed over a wide geographical area and can be utilized in a multitude of applications including real-time monitoring, advanced power system protection, and advanced control schemes.
In this thesis, a new special protection scheme (SPS) is proposed based on synchronized measurements provided by PMUs. An existing remedial action scheme (RAS) protecting for contingencies impacting the tie-line interconnecting the Alcan system to B.C. Hydro, using conventional relays is studied, and a new scheme based on time-synchronized, and high-resolution voltage angle measurements from PMU’s in a Wide-are monitoring system (WAMs) is proposed . In this new scheme, the angles of the buses at large power plants in both systems are examined and used to calculate various criteria based on region center of angle and the kinetic energy function to implement RAS.
The results of a number of time domain simulations demonstrate that the proposed scheme can lead to faster operation of the SPS and decreased amount of generation and load shedding in the Alcan system. The achieved speed and efficiency of the proposed scheme in comparison to the existing installed scheme further highlight the opportunity in utilizing PMU measurements in online applications for power system protection and monitoring.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Brogan, Paul Vincent. "PMU based multi-objective optimisation function for wide-area monitoring protection and control." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705648.
Full textAbstract:
This thesis describes and computationally tests a method of using PMU data to generate an optimisation metric that accurately reflects the desirability of a given power system's operating conditions. The optimisation function takes into consideration the voltage profile across the network, reactive power flow, transmission losses and line loading. The optimisation function was investigated as a wide-area control variable for on load tap changing transformers and switched shunt capacitors. Networks whose control assets were optimised with this wide-area optimisation metric were found to be able to handle a greater load and distributed generation before acceptable operating conditions were infringed. The wide-area controlled networks, that were modelled in PSSE, were also found to have a consistently higher efficiency, a better voltage profile and to be more resilient against voltage instability. The initial testing of the optimisation method assumed complete observation of the network in question. The investigation continues to demonstrate how a regression method could be used to extrapolate the global optimisation metric from a limited number of PMU placements on the system. A parsimonious multivariate linear regression method is developed that suggests the best PMU placements and quantifies the degree of error that might result from the reduced visibility. The optimisation function is intended as a method of reducing a profusion of PMU data down to a single simple metric. The optimisation metric can be quickly interpreted by a network operator, its variation used to inform the operation of assets or the desirability of specific asset operation. The metric could easily be transported over legacy SCADA systems, given its small size and the lack of reliance on a reporting rate. The intention of this work is facilitate a power system that can operate more efficiently, handle more distributed generation and provide a better service.
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Costa, Federica. "Real-time PMU monitoring of an IEEE 5-Bus Network implemented on OPAL system." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21405/.
Full textAbstract:
This thesis studies the state-of-the-art of phasor measurement units (PMUs) as well as their metrological requirements stated in the IEEE C37.118.1 and C37.118.2 Standards for guaranteeing correct measurement performances. Communication systems among PMUs and their possible applicability in the field of power quality (PQ) assessment are also investigated.
This preliminary study is followed by an analysis of the working principle of real-time (RT) simulators and the importance of hardware-in-the-loop (HIL) implementation, examining the possible case studies specific for PMUs, including compliance tests which are one of the most important parts.
The core of the thesis is focused on the implementation of a PMU model in the IEEE 5-bus network in Simulink and in the validation of the results using OPAL RT-4510 as a real-time simulator.
An initial check allows one to get an idea about the goodness of the results in Simulink, comparing the PMU data with respect to the load-flow steady-state information. In this part, accuracy indices are also calculated for both voltage and current synchrophasors.
The following part consists in the implementation of the same code in OPAL-RT 4510 simulator, after which an initial analysis is carried out in a qualitative way in order to get a sense of the goodness of the outcomes.
Finally, the confirmation of the results is based on an examination of the attained voltage and current synchrophasors and accuracy indices coming from Simulink models and from OPAL system, using a Matlab script.
This work also proposes suggestions for an upcoming operation of PMUs in a more complex system as the Digital Twin (DT) in order to improve the performances of the already-existing protection devices of the distribution system operator (DSO) for a future enhancement of power systems reliability.
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Guo, Tingyan. "On-line identification of power system dynamic signature using PMU measurements and data mining." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/online-identification-of-power-system-dynamic-signature-using-pmu-measurements-and-data-mining(989938d4-c236-48a7-a653-17326937f5b4).html.
Full textAbstract:
This thesis develops a robust methodology for on-line identification of power system dynamic signature based on incoming system responses from Phasor Measurement Units (PMUs) in Wide Area Measurement Systems (WAMS). Data mining techniques are used in the methodology to convert real-time monitoring data into transient stability information and the pattern of system dynamic behaviour in the event of instability. The future power system may operate closer to its stability limit in order to improve its efficiency and economic value. The changing types and patterns of load and generation are resulting in highly variable operating conditions. Corrective control and stabilisation is becoming a potentially viable option to enable safer system operation. In the meantime, the number of WAMS projects and PMUs is rising, which will significantly improve the system situational awareness. The combination of all these factors means that it is of vital importance to exploit a new and efficient Transient Stability Assessment (TSA) tool in order to use real-time PMU data to support decisions for corrective control actions. Data mining has been studied as the innovative solution and considered as promising. This work contributes to a number of areas of power systems stability research, specifically around the data driven approach for real-time emergency mode TSA. A review of past research on on-line TSA using PMU measurements and data mining is completed, from which the Decision Tree (DT) method is found to be the most suitable. This method is implemented on the test network. A DT model is trained and the sensitivity of its prediction accuracy is assessed according to a list of network uncertainties. Results showed that DT is a useful tool for on-line TSA for corrective control approach. Following the implementation, a generic probabilistic framework for the assessment of the prediction accuracy of data mining models is developed. This framework is independent of the data mining technique. It performs an exhaustive search of possible contingencies in the testing process and weighs the accuracies according to the realistic probability distribution of uncertain system factors, and provides the system operators with the confidence level of the decisions made under emergency conditions. After that, since the TSA for corrective control usually focuses on transient stability status without dealing with the generator grouping in the event of instability, a two-stage methodology is proposed to address this gap and to identify power system dynamic signature. In this methodology, traditional binary classification is used to identify transient stability in the first stage; Hierarchical Clustering is used to pre-define patterns of unstable dynamic behaviour; and different multiclass classification techniques are investigated to identify the patterns in the second stage. Finally, the effects of practical issues related to WAMS on the data mining methodologies are investigated. Five categories of issues are discussed, including measurement error, communication noise, wide area signal delays, missing measurements, and a limited number of PMUs.
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Fransson, Benjamin. "Effektivare övervakning i distributionsnät." Thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-276064.
Full textAbstract:
SCADA is the primary system for control and monitoring of distribution grids. As the expectations on how the grid must operate changes with the increased use of renewable energy sources, it also requires new methods of monitoring. Phasor Measurement Units (PMU) measures the phase angle and amplitude synchronously with GPS. A collaboration between U.C Berkeley and Power Standard Lab researches the possibilities of implementing synchrophasors in distribution grids. These devices are called micro-PMU and will provide similar services available for transmission grids, though adapted for lower voltage levels. Synchrophasors are useful in the development of a smarter distribution network, which consequently makes them interesting for the Swedish electricity market. Martin Gahr, a student at Berkeley / ETH, has developed a method to determine the topology of a distribution grid using micro-PMU's. The method compares calculated values from SCADA with values from micro-PMU's. The smallest difference between the two readings clarifies the topology. In this thesis the method is used to study an existing distribution grid in central parts of a medium-sized Swedish city. The method gives a satisfactory result when it is implemented on the mashed parts of the distribution grid. There are also indications that micro-PMU's must not be placed at every node to provide a reliable result. Although the method seems to be working on mashed parts of a Swedish distribution grid, it is not particulary interesting to implement the method in reality.
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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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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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Wang, Chen. "Renewable Energy Integrated Power System Stability Assessment with Validated System Model Based on PMU Measurements." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/101015.
Full textAbstract:
Renewable energy is playing an increasingly significant role in power system operation and stability assessment with its numerous penetration expansion. This is not only brought by its uncertain power output and inverter-based equipment structures but also its operation characteristics like Low Voltage Ride Through (LVRT). It is thus necessary to take these characteristics into consideration and further to find more adaptive schemes to implement them for more effective analysis and safer power system operation. All the aforementioned is based on the accurate identification of the system fundamental information. In this dissertation, a systematic approach is proposed to find the valid system model by estimating the transmission line parameters in the system with PMU measurements. The system transient stability assessment is conducted based on this validated model. The constrained stability region is estimated with Lyapunov functions family based method in the center of angles reference frame considering renewables LVRT as operation limits. In order to integrate the LVRT constraints, a polytopic inner approximation mechanism is introduced to linearize and organize the transformed constraints in state space, which brings much scalability to the whole process. From the voltage stability perspective, an approach to adaptively adjust LVRT settings of the renewable energy sources in the system is formulated to guarantee the system load margin and thus the voltage security. A voltage prediction method is introduced for critical renewable energy sources identification. Estimation methods based on interpolation and sensitivities are developed and conducted for saving computation effort brought by continuation power flows. Multiple test cases are studied utilizing the proposed approaches and results are demonstrated.Doctor of Philosophy
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Qwaka, Prince Siphiwo. "The role of policy management units with particular reference to the PMU in the South African Parliament." Thesis, University of the Western Cape, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1215_1328706690.
Full textAbstract:
This study seeks to understand and examine the role of public policy units with a specific focus on the South African National Parliament Policy Management Unit (PMU). The problem being investigated is that of a lack of constructive support and debate in understanding the role and functions of policy management units. Thus, the scope of the study is limited to policy management units with the South African Parliament PMU as a special reference. The primary objective of this study is to investigate the role of policy management units, with particular reference to the PMU in the South African Parliament. The secondary objectives will then be to provide a theoretical perspective of the role and functions of policy management units
and to develop a case of the PMU in Parliament for further analysis and examination. Examples of existing policy units and the support they have with parliaments will be produced, assessed, and explored.
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Ekechukwu, Chinedum. "Improving Low Voltage Ride-Through Requirements (LVRT) Based on Hybrid PMU, Conventional Measurements in Wind Power Systems." Thesis, Karlstads universitet, Avdelningen för fysik och elektroteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-31449.
Full textAbstract:
Previously, conventional state estimation techniques have been used for state estimation in power systems. These conventional methods are based on steady state models. As a result of this, power system dynamics during disturbances or transient conditions are not adequately captured. This makes it challenging for operators in control centers to perform visual tracking of the system, proper fault diagnosis and even take adequate preemtive control measures to ensure system stability during voltage dips. Another challenge is that power systems are nonlinear in nature. There are multiple power components in operation at any given time making the system highly dynamic in nature. Consequently, the need to study and implement better dynamic estimation tools that capture system dynamics during disturbances and transient conditions is necessary. For this thesis work, we present the Unscented Kalman Filter (UKF) which integrates Unscented Transformation (UT) to Kalman Filtering. Our algorithm takes as input the output of a synchronous machine modeled in MATLAB/Simulink as well as data from a PMU device assumed to be installed at the terminal bus of the synchronous machine, and estimate the dynamic states of the system using a Kalman Filter. We have presented a detailed and analytical study of our proposed algorithm in estimating two dynamic states of the synchronous machine, rotor angle and rotor speed. Our study and result shows that our proposed methodology has better efficiency when compared to the results of the Extended Kalman Filter (EKF) algorithm in estimating dynamic states of a power system. Our results are presented and analyzed on the basis of how accurately the algorithm estimates the system states following various simulated transient and small-signal disturbances.
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Goodwin, Leigh. "The Pentecostal Missionary Union (PMU) : a case study exploring the missiological roots of early British Pentecostalism (1909-1925)." Thesis, University of Chester, 2013. http://hdl.handle.net/10034/314921.
Full textAbstract:
The Pentecostal Missionary Union (PMU) commenced in 1909 as a non-sectarian Pentecostal faith mission with many similarities to the China Inland Mission (CIM), influenced by the links of its President, Cecil Polhill, as one of the illustrious Cambridge Seven missionaries. In 1924 it amalgamated into the newly formed British Assemblies of God (AOG), with a full merger in 1925. This thesis reconstructs the historical narrative of the PMU examining its theology and praxis. This thesis is not a descriptive biographical narrative of the PMU’s leaders and missionaries but a historiography exploring the PMU’s development in its original context based on information provided by primary sources. Other than one 1995 Masters dissertation, no research has been conducted specifically on the PMU. This research seeks to recover the lost voice of early British non-sectarian Pentecostal missiology marginalized by Protestant mission historiography and overlooked by Pentecostal historiographers focused on American or later periods of Pentecostalism. Pentecostal historiographies have interpreted the twentieth century global revival movement largely through the ‘latter rain’ motif as an eschatologically providential event, discontinuous with previous ecclesiastical history. Pentecostal mission historiography is still developmental, especially in the employment of an historical roots methodology as opposed to traditional providential approaches. This thesis argues that early British Pentecostalism, before the Great War, originated as a non-sectarian mission movement strongly linked to antecedent faith mission roots, demonstrating the necessity for Pentecostals to engage with broader research methodologies that challenge traditional perceptions of the emergence and development of Pentecostalism. The Great War was interpreted with an apocalyptic lens that increasingly shifted Pentecostal eschatological emphasis away from missional urgency towards speculative application of Biblical prophecy with early twentieth century events. The severing of the PMU from its faith mission roots during the Great War, through CIM policy averse to Pentecostalism, reinforced Pentecostal perceptions of eschatological discontinuity and the need of a distinctive denominational identity in the uncertainty of the inter-war period. The lifespan of the world’s first modern Pentecostal missionary organisation was relatively short but it encompassed three specific periods of British history: prior to the Great War, the Great War years and the inter-War years This thesis utilises these three distinct periods to provide a progressive narrative highlighting the challenges within the PMU’s developmental history from non-sectarian faith mission to denominational mission department. The missiological emphasis of early Pentecostalism, as exemplified by the PMU, provides an understanding of the Pentecostal global phenomena a century later. Early 20th century Pentecostal revivals occurring in various places could have resulted in Pentecostalism remaining a localised sect but its significance grew through its emphasis on missiological urgency with pneumatological empowerment. Contemporary British and global Pentecostalism cannot be explained without historiographical reference to its earliest missiological roots including the PMU.
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Mishra, Chetan. "Optimal Substation Coverage for Phasor Measurement Unit Installations." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/78056.
Full textAbstract:
The PMU has been found to carry great deal of value for applications in the wide area monitoring of power systems. Historically, deployment of these devices has been limited by the prohibitive cost of the device itself. Therefore, the objective of the conventional optimal PMU placement problem is to find the minimum number devices, which if carefully placed throughout the network, either maximize observability or completely observe subject to different constraints. Now due to improved technology and digital relays serving a dual use as relay & PMU, the cost of the PMU device itself is not the largest portion of the deployment cost, but rather the substation installation. In a recently completed large-scale deployment of PMUs on the EHV network, Virginia Electric & Power Company (VEPCO) has found this to be so. The assumption then becomes that if construction work is done in a substation, enough PMU devices will be placed such that everything at that substation is measured. This thesis presents a technique proposed to minimize the number of substation installations thus indirectly minimizing the synchrophasor deployment costs. Also presented is a brief history of the PMU and its applications along with the conventional Optimal PMU placement problem and the scope for expanding this work.Master of Science
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Atkins, David Wayne. "Placing monitoring devices in electric power networks modeled by block graphs." [Johnson City, Tenn. : East Tennessee State University], 2003. http://etd-submit.etsu.edu/etd/theses/available/etd-0713103-210119/unrestricted/AtkinsD080503f.pdf.
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Thesis (M.S.)--East Tennessee State University, 2003.Title from electronic submission form. ETSU ETD database URN: etd-0713103-210119. Includes bibliographical references. Also available via Internet at the UMI web site.
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da, Silva Melo Dácio. "Aplicação de sincrofasores para aferição de parâmetros elétricos de linhas de transmissão." Universidade Federal de Pernambuco, 2008. https://repositorio.ufpe.br/handle/123456789/5210.
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Previous issue date: 2008Companhia Hidro Elétrica do São Francisco
Este trabalho apresenta uma metodologia que permite medir os parâmetros elétricos de linha, baseado na oscilografia dos registradores digitais de perturbação, e em seguida permite avaliar a precisão da metodologia desenvolvida em relação aos métodos de cálculo convencionalmente utilizados. A partir da metodologia proposta, foram desenvolvidas rotinas computacionais, utilizando-se o software MATLAB, que possibilitam aferir os parâmetros das linhas de transmissão, tendo como entrada de dados os registros de oscilografia dos registradores digitais de perturbação, desde que estes possuam suas medições e conversões analógico-digitais sincronizadas através de sistema de posicionamento global. A validação da metodologia utilizada e das rotinas computacionais desenvolvidas foi realizada através de simulações preliminares no software ATP. A partir de tais simulações, foi possível a geração de registros de oscilografia em dois terminais de uma linha de transmissão utilizada como teste. De posse desses registros, foram utilizadas rotinas computacionais desenvolvidas no MATLAB para aferição dos parâmetros. Em testes realizados em laboratório, foi validada a possibilidade de obtenção de fasores com erros inferiores a 0,1 graus elétricos em seus argumentos. Tal precisão representa a condição necessária para se obter os parâmetros elétricos de uma linha de transmissão com um erro inferior a três por cento. Como estudos de caso em campo, foram realizadas aferições dos parâmetros elétricos da LT da CHESF Messias-Recife II, de 500 kV.
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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.
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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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Vijayarengan, Manoaj Srikumar. "Coordinated operations of distributed wind generation in a distribution system using PMUs." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/15039.
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Master of ScienceDepartment of Electrical and Computer Engineering
Noel N. Schulz
Wind energy is becoming one of the most widely implemented forms of renewable energy worldwide. Traditionally, wind has been considered a non-dispatchable source of energy due to the uncertainty of wind speed and hence the variable availability of wind power. Advances in technology allow the consideration of the impact of distributed wind turbines and farms on distribution systems. It is possible to combine the clean energy attributes of wind with the quickly dispatchable nature of a storage facility in order to provide the maximum amount of locally available power economically to the loads present on the distribution feeder. However, a monitoring and control system needs to be provided that is capable of detecting the changes associated with the distribution feeder load and also the variable generation output from the wind farms. This task can be accomplished using a Phasor Measurement Unit (PMU) which has very high sampling rates and hence can measure very rapid and dynamic changes in power levels associated with distribution feeder load and wind generation. The data which is obtained from these PMUs can be used to calculate the amount of distributed generation and storage that can be dispatched locally at the distribution feeder, thus resulting in a reduction in the peak load levels associated with the distribution feeder as seen by the substation monitoring system. Simulations will work to balance load requirements, wind generation output, and distributed storage providing a stable system utilizing maximum renewable resources. The standard IEEE 37-node distribution test feeder is used in the study. Probabilistic models are implemented for distribution feeder load, and the models are analyzed through simulations. Four different combinations of charging and discharging methods have been investigated. Two analytically different algorithms have been used for wind and battery dispatch, one based on forecasted load information and the other based on historical measurements obtained from PMUs. The strategies being investigated can also be used to implement other important applications such as distribution system state estimation, protection and instability prediction.
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Zhu, Kun. "Data Quality in Wide-Area Monitoring and Control Systems : PMU Data Latency, Completness, and Design of Wide-Area Damping Systems." Doctoral thesis, KTH, Industriella informations- och styrsystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-129078.
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The strain on modern electrical power system operation has led to an ever increasing utilization of new Information Communication Technology (ICT) systems to enhance the reliability and efficiency of grid operation. Among these proposals, Phasor Measurement Unit (PMU)-based Wide-Area Monitoring and Control (WAMC) systems have been recognized as one of the enablers of “Smart Grid”, particularly at the transmission level, due to their capability to improve the real-time situational awareness of the grid. These systems differ from the conventional Supervisory Control And Data Acquisition (SCADA) systems in that they provide globally synchronized measurements at high resolutions. On the other hand, the WAMC systems also impose several stringent requirements on the underlying ICT systems, including performance, security, and availability, etc. As a result, the functionality of the WAMC applications is heavily, but not exclusively, dependent on the capabilities of the underlying ICT systems. This tight coupling makes it difficult to fully exploit the benefits of the synchrophasor technology without the proper design and configuration of ICT systems to support the WAMC applications. The strain on modern electrical power system operation has led to an ever increasing utilization of new Information Communication Technology (ICT) systems to enhance the reliability and efficiency of grid operation. Among these proposals, Phasor Measurement Unit (PMU)-based Wide-Area Monitoring and Control (WAMC) systems have been recognized as one of the enablers of “Smart Grid”, particularly at the transmission level, due to their capability to improve the real-time situational awareness of the grid. These systems differ from the conventional Supervisory Control And Data Acquisition (SCADA) systems in that they provide globally synchronized measurements at high resolutions. On the other hand, the WAMC systems also impose several stringent requirements on the underlying ICT systems, including performance, security, and availability, etc. As a result, the functionality of the WAMC applications is heavily, but not exclusively, dependent on the capabilities of the underlying ICT systems. This tight coupling makes it difficult to fully exploit the benefits of the synchrophasor technology without the proper design and configuration of ICT systems to support the WAMC applications. In response to the above challenges, this thesis addresses the dependence of WAMC applications on the underlying ICT systems. Specifically, two of the WAMC system data quality attributes, latency and completeness, are examined together with their effects on a typical WAMC application, PMU-based wide-area damping systems. The outcomes of this research include quantified results in the form of PMU communication delays and data frame losses, and probability distributions that can model the PMU communication delays. Moreover, design requirements are determined for the wide-area damping systems, and three different delay-robust designs for this WAMC application are validated based on the above results. Finally, a virtual PMU is developed to perform power system and communication network co-simulations. The results reported by this thesis offer a prospect for better predictions of the performance of the supporting ICT systems in terms of PMU data latency and completeness. These results can be further used to design and optimize the WAMC applications and their underlying ICT systems in an integrated manner. This thesis also contributes a systematic approach to design the wide-area damping system considering the PMU data latency and completeness. Finally, the developed virtual PMU, as part of a co-simulation platform, provides a means to investigate the dependence of WAMC applications on the capabilities of the underlying ICT systems in a cost-efficient manner.QC 20131015
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Jones, Kevin David. "Three-Phase Linear State Estimation with Phasor Measurements." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/32119.
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Given the ability of the Phasor Measurement Unit (PMU) to directly measure the system state and the increasing implementation of PMUs across the electric power industry, a natural expansion of state estimation techniques would be one that employed the exclusive use of PMU data. Dominion Virginia Power and the Department of Energy (DOE) are sponsoring a research project which aims to implement a three phase linear tracking state estimator on Dominionâ s 500kV network that would use only PMU measurements to compute the system state. This thesis represents a portion of the work completed during the initial phase of the research project. This includes the initial development and testing of two applications: the three phase linear state estimator and the topology processor. Also presented is a brief history of state estimation and PMUs, traditional state estimation techniques and techniques with mixed phasor data, a development of the linear state estimation algorithms and a discussion of the future work associate with this research project.Master of Science
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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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Khan, Muhammad Ayaz. "State Estimation and Voltage Phasor Measurements in Distribution Networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Find full textAbstract:
The thesis faces the problem of the use of phasor measurement units (PMU) for the state estimation in distribution networks, and in particular the problem of a suitable phasor estimation in different buses of a distribution network in absence of proper time synchronization with the universal time reference. In particular, an approach recently proposed by Mingotti et al. to obtain an equivalent synchronization, starting from asynchronous measurement has been presented and tested. This method assumes the availability of a distributed measurement system where each remote unit is a power meter. The algorithm implemented in Matlab by Mingotti et al. has been studied and tested by a comparison with the load flow results provided by the Electromagnetic Transient Program (EMTP-RV). The algorithm adopts two different methods for voltage phasor estimation, the first calculate the phasors as a linear combination of measured voltages, the second makes use of the longitudinal equivalent impedances of the network branches. In order to tune the load flow calculation environment, different case studies have been analyzed, and in particular the European Medium Voltage distribution test network and the European Low voltage distribution test network proposed by CIGRE Task Force C6.04.02. During the analysis, for each bus, voltages, currents and phase displacements are calculated and compared with the benchmark results reported in the Cigré brochure. A four-buses network has been considered to test both methods of the above mentioned algorithm. The obtained results are very close to the one provided by EMTP. The accuracy of the algorithm appears to get worse in case of lightly loaded network, a behaviour that is justified by the small phase displacements that the voltages show in these condition. The studied equivalent synchronization procedure can be usefully implemented to achieve a widespread monitoring of a power network at affordable cost.
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Wu, Zhongyu. "Synchronized Phasor Measurement Units Applications in Three-phase Power System." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51660.
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Phasor Measurement Units (PMUs) are widely acknowledged as one of the most significant developments in the field of real-time monitoring of power system. By aligning time stamps of voltage and current phasor measurements, which are consistent with Coordinated Universal Time (UTC), a coherent picture of the power system state can be achieved through either direct measurements or simple linear calculations. With the growing number of PMUs installed or planned to be installed in the near future, both utilities and research institutions are looking for novel applications of synchrophasor measurements from these widely installed PMUs. In this dissertation, the author proposes two new PMUs measurements applications: three-phase instrument transformer calibration, and three-phase line parameter calculation with instrument transformers.
First application is to calibrate instrument transformers. Instrument transformers are the main sensors used in power systems. They provide isolation between high voltage level of primary side and metering level of the secondary side. All the monitoring and measuring systems obtain input signals from the secondary side of instrument transformers. That means when instrument transformers are not accurate, all the measurements used in power system are inaccurate. The most important job of this dissertation is to explore a method to automatically calibrate all the instrument transformers in the power system based on real-time synchrophasor measurements.
The regular instrument transformer calibration method requires the instrument transformer to be out of service (offline) and calibrated by technicians manually. However, the error of instrument transformer changes when environment changes, and connected burden. Therefore, utilities are supposed to periodically calibrate instrument transformers at least once a year. The high labor and economic costs make traditional instrument transformer calibration method become one of the urgent problems in power industry. In this dissertation we introduce a novel, low cost and easy method to calibrate three-phase instrument transformers. This method only requires one three-phase voltage transformer at one bus calibrated in advance. All other instrument transformers can be calibrated by this method as often as twice a day, based on the synchrophasor measurements under different load scenarios.
Second application is to calculate line parameters during calibrating instrument transformers. The line parameters, line impedance and line shunt admittance, as needed by utilities are generated by the computer method. The computer method is based on parameters, such as the diameter, length, material characteristics, the distance among transmission line, the distance to ground and so on. The formulas to calculate line parameters have been improved and re-modeled from time to time in order to increase the accuracy. However, in this case, the line parameters are still inaccurate due to various reasons. The line parameters errors do affect the instrument transformers calibration results (with 5% to 10% error). To solve this problem, we present a new method to calculate line parameters and instrument transformers in the same processing step.
This method to calibrate line parameter and instrument transformers at the same time only needs one pre-calibrated voltage transformer and one pre-calibrated current transformer in power system. With the pre-calibrated instrument transformers, the line parameter as well as the ratio correction factors of all the other instrument transformers can be solved automatically. Simulation results showed the errors between calculated line parameters and the real line parameter, the errors between calibrated ratio correction factors and the real ratio correction factors are of the order of 10e-10 per unit. Therefore, high accuracy line parameters as well as perfectly calibrated instrument transformers can be obtained by this new method. This method can run automatically every day. High accuracy and dynamic line parameters will significantly improve power system models. It will also increase the reliability and speed of the relay system, enhance the accuracy of power system analysis, and benefit all other researches using line parameters. New methods of calculating line parameter and the instrument transformer calibrations will influence the whole power industry significantly.Ph. D.
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Martins, Carlos Henrique Nascimento. "Plataforma de processamento de sinais para aplicações em sistemas de potência." Universidade Federal de Juiz de Fora (UFJF), 2011. https://repositorio.ufjf.br/jspui/handle/ufjf/4100.
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Este trabalho tem por objetivo principal apresentar o desenvolvimento de plataformas eletrônicas de processamento de sinais de alto desempenho para monitoramento do sistema elétricos de potência. No trabalho são discutidas arquiteturas de hardware para três aplicações em sistemas de potência: analisador fasorial (Phasor Measurement Unit - PMU), analisador de qualidade de energia elétrica (QEE) e analisador de harmônicos variantes no tempo (AHVT). Além disso são todos os conceitos de eletrônica digital e analógica envolvidos na concepção deste projeto, tomando como base equipamentos de mercado, a literatura pertinente e as normas reguladoras para dispositivos de análise de parâmetros elétricos. No projeto é abordado principalmente a implementação de hardware, que envolve implementação de estruturas de conversão Analógico Digital, filtro anti-aliasing, condicionamento de sinais, processamento e gerenciamento de dados e finalmente meios de comunicação. O hardware foi testado utilizando algoritmos básicos de processamento de sinais sendo apresentado casos reais de monitoramento dos parâmetros do sinal elétrico e uma versão inicial do AHVT.
This work has the aim to present the development of electronic platforms for signal processing for high performance electric power monitoring system. At this work are discussed hardware architectures for three power systems applications: phasor measurement unit (PMU), Power Quality Analyzer (PQ) and Time Varying Harmonic Analyzer (TVHA). Also are explained all features of analog and digital electronics involved in the design of this project, based on commercial devices, the literature and regulatory standards for electrical parameters devices. The project is addressed principally to hardware implementation, which involves implementation of structures such as the Analog to Digital conversion, anti-aliasing filter, signal conditioning, processing and data management and communication. The hardware is tested using basic digital signal algorithms and real cases of parameters monitoring are presented. Furthermore prototype version of the TVHA is presented.
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Ghassempour, Aghamolki Hossein. "Phasor Measurement Unit Data-based States and Parameters Estimation in Power System." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6505.
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The dissertation research investigates estimating of power system static and dynamic states (e.g. rotor angle, rotor speed, mechanical power, voltage magnitude, voltage phase angle, mechanical reference point) as well as identification of synchronous generator parameters. The research has two focuses:
i. Synchronous generator dynamic model states and parameters estimation using real-time PMU data.
ii.Integrate PMU data and conventional measurements to carry out static state estimation.
The first part of the work focuses on Phasor Measurement Unit (PMU) data-based synchronous generator states and parameters estimation. In completed work, PMU data-based synchronous generator model identification is carried out using Unscented Kalman Filter (UKF). The identification not only gives the states and parameters related to a synchronous generator swing dynamics but also gives the states and parameters related to turbine-governor and primary and secondary frequency control. PMU measurements of active power and voltage magnitude, are treated as the inputs to the system while voltage phasor angle, reactive power, and frequency measurements are treated as the outputs. UKF-based estimation can be carried out at real-time. Validation is achieved through event play back to compare the outputs of the simplified simulation model and the PMU measurements, given the same input data. Case studies are conducted not only for measurements collected from a simulation model, but also for a set of real-world PMU data. The research results have been disseminated in one published article.
In the second part of the research, new state estimation algorithm is designed for static state estimation. The algorithm contains a new solving strategy together with simultaneous bad data detection. The primary challenge in state estimation solvers relates to the inherent non-linearity and non-convexity of measurement functions which requires using of Interior Point algorithm with no guarantee for a global optimum solution and higher computational time. Such inherent non-linearity and non-convexity of measurement functions come from the nature of power flow equations in power systems.
The second major challenge in static state estimation relates to the bad data detection algorithm. In traditional algorithms, Largest Normalized Residue Test (LNRT) has been used to identify bad data in static state estimation. Traditional bad data detection algorithm only can be applied to state estimation. Therefore, in a case of finding any bad datum, the SE algorithm have to rerun again with eliminating found bad data. Therefore, new simultaneous and robust algorithm is designed for static state estimation and bad data identification.
In the second part of the research, Second Order Cone Programming (SOCP) is used to improve solving technique for power system state estimator. However, the non-convex feasible constraints in SOCP based estimator forces the use of local solver such as IPM (interior point method) with no guarantee for quality answers. Therefore, cycle based SOCP relaxation is applied to the state estimator and a least square estimation (LSE) based method is implemented to generate positive semi-definite programming (SDP) cuts. With this approach, we are able to strengthen the state estimator (SE) with SOCP relaxation. Since SDP relaxation leads the power flow problem to the solution of higher quality, adding SDP cuts to the SOCP relaxation makes Problem’s feasible region close to the SDP feasible region while saving us from computational difficulty associated with SDP solvers. The improved solver is effective to reduce the feasible region and get rid of unwanted solutions violate cycle constraints. Different Case studies are carried out to demonstrate the effectiveness and robustness of the method.
After introducing the new solving technique, a novel co-optimization algorithm for simultaneous nonlinear state estimation and bad data detection is introduced in this dissertation. ${\ell}_1$-Norm optimization of the sparse residuals is used as a constraint for the state estimation problem to make the co-optimization algorithm possible. Numerical case studies demonstrate more accurate results in SOCP relaxed state estimation, successful implementation of the algorithm for the simultaneous state estimation and bad data detection, and better state estimation recovery against single and multiple Gaussian bad data compare to the traditional LNRT algorithm.
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Singh, Narender. "Feeder Dynamic Rating Application for Active Distribution Networks using Synchrophasors." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187665.
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There is an ever increasing demand of electricity and to meet this demand, installation of new transmission and distribution lines is required. This task requires a significant investment and consent from the respective authorities. An alternative is to utilize maximum capability of the existing lines. Static line ratings are based on a conservative estimate, which means that on most occasions, the actual capacity of lines is much higher than the static line ratings. In order to provide a solution to this problem, this thesis introduces an approach that has been developed to utilize real time weather conditions, conductor sag data and the actual line loading of the conductor from PMU to provide dynamic line ratings for active distribution networks. The application has been developed in LabVIEW environment which provides a user friendly front panel where real-time ampacity can be seen as a waveform while being compared to the actual line loading. The developed application has been tested on the reference grid created for IDE4L project. The ampacity calculation method introduced here makes use of real-time data available through a real-time simulator in SmarTS lab at KTH, Sweden.Det är ett ökande behov av elektricitet och för att möta detta behövet, installation av nya transmission och distributionsledningar behövs. Denna utbyggnad kräver ett stort engagemang och förståelse från ansvariga grupper. Ett alternativ är att utnyttja max-kapaciteten på redan befintliga ledningar. Installerade ledningar har räknats på ett konservativt sätt, vilket innebär att det vid vissa tillfällen går att öka belastingen på på dessa. För att ge en lösning på detta problem, introducerar den här avhandlingen en metod för att använda realtids-väderdata, tabeller för ledningarnas utvidgning och realtids-belastningsdata från PMU för att framställa dynamisk data för aktiva distributions-nätverk. Applikationen har utvecklas i LabVIEW-miljön som har ett användarvänligt GUI, där “Real-time ampacity” kan ses som en vågform medans den jämförs mot den faktiska belastningen på ledningen. Den utvecklade appliktionen har testats på referens-miljön som skapts för IDE4L projektet. “Ampacity calculation metoden” som introduceras här använder sig av realtidsdata som görs tillgänglig igenom en realtids-simulator i SmarTSlab på Kungliga Tekniska Högskolan i Sverige.
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Biswas, Shuchismita. "Power Grid Partitioning and Monitoring Methods for Improving Resilience." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104684.
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This dissertation aims to develop decision-making tools that aid power grid operators in mitigating extreme events. Two distinct areas are focused on: a) improving grid performance after a severe disturbance, and b) enhancing grid monitoring to facilitate timely preventive actions. The first part of the dissertation presents a proactive islanding strategy to split the bulk power transmission system into smaller self-adequate islands in order to arrest the propagation of cascading failures after an event. Heuristic methods are proposed to determine in what sequence should the island boundary lines be disconnected such that there are no operation constraint violations. The idea of optimal partitioning is further extended to the distribution network. A planning problem for determining which parts of the existing distribution grid can be converted to microgrids is formulated. This partitioning formulation addresses safety limits, uncertainties in load and generation, availability of grid-forming units, and topology constraints such as maintaining network radiality. Microgrids help maintain energy supply to critical loads during grid outages, thereby improving resilience. The second part of the dissertation focuses on wide-area monitoring using Phasor Measurement Unit (PMU) data. Strategies for data imputation and prediction exploiting the spatio-temporal correlation in PMU measurements are outlined. A deep-learning-based methodology for identifying the location of temporary power systems faults is also illustrated. As severe weather events become more frequent, and the threats from coordinated cyber intrusions increase, formulating strategies to reduce the impact of such events on the power grid becomes important; and the approaches outlined in this work can find application in this context.Doctor of Philosophy
The modern power grid faces multiple threats, including extreme-weather events, solar storms, and potential cyber-physical attacks. Towards the larger goal of enhancing power systems resilience, this dissertation develops strategies to mitigate the impact of such extreme events. The proposed schemes broadly aim to- a) improve grid performance in the immediate aftermath of a disruptive event, and b) enhance grid monitoring to identify precursors of impending failures. To improve grid performance after a disruption, we propose a proactive islanding strategy for the bulk power grid, aimed at arresting the propagation of cascading failures. For the distribution network, a mixed-integer linear program is formulated for identifying optimal sub-networks with load and distributed generators that may be retrofitted to operate as self-adequate microgrids, if supply from the bulk power systems is lost. To address the question of enhanced monitoring, we develop model-agnostic, computationally efficient recovery algorithms for archived and streamed data from Phasor Measurement Units (PMU) with data drops and additive noise. PMUs are highly precise sensors that provide high-resolution insight into grid dynamics. We also illustrate an application where PMU data is used to identify the location of temporary line faults.
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O'Flynn, Alexander W. "Testing of Phasor Measurement Units (PMUs) for Distribution Network Applications." Thesis, Queensland University of Technology, 2020.
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Enabling islanded operation of power distribution networks will greatly improve the reliability of supply for customers. Measurement devices such as Phasor Measurement Units (PMUs) are required to protect and control the islanded network. PMUs are widely used in transmission network. This thesis examines whether existing PMUs meet the performance requirements to enable islanded distribution network operation.
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Arraño, Vargas Felipe Antonio. "Esquema de detección de inestabilidad para operación en isla eléctrica utilizando sincrofasores." Tesis, Universidad de Chile, 2014. http://www.repositorio.uchile.cl/handle/2250/116369.
Full textAbstract:
Ingeniero Civil EléctricoEn cualquier sistema eléctrico de potencia, sea éste complejo o no, existen perturbaciones o contingencias que pueden causar inestabilidad angular, de frecuencia y/o de tensión. El no poder recuperar el estado de equilibrio inicial se puede traducir en una segregación del sistema en dos o más partes, masivas pérdidas de suministro eléctrico o, lo que es peor aún, un apagón total. En los últimos años los sistemas de medición dinámica han experimentado un importante avance gracias a mediciones sincronizadas, éstas permiten adquirir varias muestras por segundo y proveer información coherente entre los ángulos de las medidas, haciéndolas comparables entre sí. Estas medidas otorgan información suficiente para evitar inestabilidades luego de ocurrida una perturbación, realizando acciones correctivas de protección sistémica tales como desprendimientos de carga, desprendimientos de generación y segregación en islas eléctricas de forma controlada. Considerando que esta tecnología puede ser aplicada en Chile, y particularmente en el sector sur del Sistema Interconectado Central (SIC), este trabajo propone un esquema de detección de inestabilidad para operación en isla eléctrica utilizando mediciones sincrofasoriales, con el objetivo de mantener el suministro eléctrico en la Isla Grande de Chiloé cuando el colapso del sistema es inminente luego de ocurrida una contingencia. El esquema verifica que tanto la diferencia angular, la primera y segunda derivada entre dos puntos del sistema permanezcan en una región estable o controlable. En caso de que alguna variable presente valores fuera de los límites establecidos se determina que el colapso del sistema es posible y que la segregación del sector seleccionado del resto de la red permitiría mantener el suministro eléctrico. Para la construcción de este esquema se simulan, en el software DIgSILENT y con la base del Centro de Despacho Económico de Carga (CDEC) del SIC actualizada a la fecha, tres contingencias reales y seis contingencias extremas para cuatro escenarios de operación. El esquema logra tener una exactitud de 88,9% y una sensibilidad de un 66,7% por otro lado, la operación en isla eléctrica sería posible en solo un escenario de operación, siendo necesaria la implementación de Esquemas de Desconexión de Carga y de Generación para que sea posible en otros dos.
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Lin, Hua. "Communication Infrastructure for the Smart Grid: A Co-Simulation Based Study on Techniques to Improve the Power Transmission System Functions with Efficient Data Networks." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/29248.
Full textAbstract:
The vision of the smart grid is predicated upon pervasive use of modern digital communication techniques in today's power system. As wide area measurements and control techniques are being developed and deployed for a more resilient power system, the role of communication networks is becoming prominent. Advanced communication infrastructure provides much wider system observability and enables globally optimal control schemes. Wide area measurement and monitoring with Phasor Measurement Units (PMUs) or Intelligent Electronic Devices (IED) is a growing trend in this context. However, the large amount of data collected by PMUs or IEDs needs to be transferred over the data network to control centers where real-time state estimation, protection, and control decisions are made. The volume and frequency of such data transfers, and real-time delivery requirements mandate that sufficient bandwidth and proper delay characteristics must be ensured for the correct operations. Power system dynamics get influenced by the underlying communication infrastructure. Therefore, extensive integration of power system and communication infrastructure mandates that the two systems be studied as a single distributed cyber-physical system.
This dissertation proposes a global event-driven co-simulation framework, which is termed as GECO, for interconnected power system and communication network. GECO can be used as a design pattern for hybrid system simulation with continuous/discrete sub-components. An implementation of GECO is achieved by integrating two software packages: PSLF and NS2 into the framework. Besides, this dissertation proposes and studies a set of power system applications which can be only properly evaluated on a co-simulation framework like GECO, namely communication-based distance relay protection, all-PMU state estimation and PMU-based out-of-step protection. All of them take advantage of interplays between the power grid and the communication infrastructure. The GECO experiments described in this dissertation not only show the efficacy of the GECO framework, but also provide experience on how to go about using GECO in smart grid planning activities.Ph. D.