Synchronized phasor measurements during dynamics tend to be affected by prevailing system frequency. Some major blackouts in power systems are indeed featured with very large frequency disturbance. Quantitative study done in this dissertation shows that small frequency disturbance may lead to measurement errors, and large frequency disturbance may lead to wrong measurements as well as catastrophic results if applied in system protection and control. The purpose of this dissertation is to bring up this issue, point to some possible solutions and application examples. A synchronized frequency measurement method, which has better dynamic performance, is proposed in this dissertation. Based on this accurate synchronized frequency, a phasor compensation algorithm is proposed to correct the errors due to frequency disturbance in legacy PMUs or as alternative frequency tracking algorithm in new PMUs. Phasor positioning and unbalance issues are also investigated in this dissertation. With these improved synchronized measurements, wide area protection and control can be achieved with higher reliability. As an application example, traditional preset out-of-step protection could be replaced by the adaptive out-of-step protection using wide area measurements. Real-time swing curve and real-time EEAC based adaptive out-of-step protection schemes are developed respectively in this dissertation. Numerical Simulations are performed for validation of the proposed concepts. / Ph. D.

Wide-area disturbances are power outages occurring over large geographical regions that dramatically affect the power system reliability, causing interruptions of the electric supply to residential, commercial, and industrial users. Historically, wide-area disturbances have greatly affected societies. Virginia Tech directed a research project related to the causes of the major disturbances in electric power systems. Research results showed that the role of the power system's protection schemes in the wide-area disturbances is critical. Incorrect operations of power system's protection schemes have contributed to a spread of the disturbances. This research defined hidden failures of protection schemes and showed that these kinds of failures have contributed in the degradation of 70-80 percent of the wide-area disturbances. During a wide-area disturbance analysis, it was found that hidden failures in protection schemes caused the disconnection of power system elements in an incorrect and undesirable manner contributing to the disturbance degradation. This dissertation presents a methodology to assess and rank the effects of unwanted disconnections caused by hidden failures based on Regions of Vulnerability and index of severity in the protection schemes. The developed methodology for the evaluation of the Region of Vulnerability found that the indicator that most accurately reflects the relationship of the Region of Vulnerability with the single line diagram is kilometers. For the representation of the Region of Vulnerability in the power system, we found segments in the transmission line in which the occurrence of faults do make the relay to operate, producing the unwanted disconnection caused by hidden failure. The results in the test system show that the infeed currents restrain the Region of Vulnerability from spreading along power system elements. Finally the methodology to compute the index of severity is developed. The index of severity has the objective of ranking the protection schemes, considers the dynamics of the protection schemes, and evaluates the overall disturbance consequence under the static and dynamic perspectives. / Ph. D.

Wide-area measurement systems (WAMS) enable the monitoring of overall bulk power systems and provide critical information for understanding and responding to power system disturbances and cascading failures. The North American Frequency Monitoring Network (FNET) takes GPS-synchronized wide-area measurements in a low-cost, easily deployable manner at the 120 V distribution level, which presents more opportunities to study power system dynamics. This work explores the topics of power system disturbance analysis and detection by utilizing the wide-area measurements obtained in the distribution networks. In this work, statistical analysis is conducted based on the major disturbances in the North American Interconnections detected by the FNET situation awareness system between 2006 and 2008. Typical frequency patterns of the generation and load loss events are analyzed for the three North American power Interconnections: the Eastern Interconnection (EI), the Western Electricity Coordinating Council (WECC), and the Electric Reliability Council of Texas (ERCOT). The linear relationship between frequency deviation and frequency change rate during generation/loss mismatch events is verified by the measurements in the three Interconnections. The relationship between the generation/load mismatch and system frequency is also examined based on confirmed generation loss events in the EI system. And a power mismatch estimator is developed to improve the current disturbance detection program. Various types of power system disturbances are examined based on frequency, voltage and phase angle to obtain the event signatures in the measurements. To better understand the propagation of disturbances in the power system, an automated visualization tool is developed that can generate frequency and angle replays of disturbances, as well as image snapshots. This visualization tool correlates the wide-area measurements with geographical information by displaying the measurements over a geographical map. This work makes an attempt to investigate the visualization of the angle profile in the wide-area power system to improve situation awareness. This work explores the viability of relying primarily on distribution-level measurements to detect and identify line outages, a topic not yet addressed in previous works. Line outage sensitivity at different voltage levels in the Tennessee Valley Authority (TVA) system is examined to analyze the visibility of disturbances from the point of view of wide-area measurements. The sensor placement strategy is proposed for better observability of the line trip disturbances. The characteristics of line outages are studied extensively with simulations and real measurements. Line trip detection algorithms are proposed that employs the information in frequency and phase angle measurements. In spite of the limited FDR coverage and confirmed training cases, an identification algorithm is developed which uses the information in the real measurements as well as the simulation cases to determine the tripped line. / Ph. D.

A global view of power system's frequency opens up a new window to the "world" of large system's dynamics. With the aid of global positioning system (GPS), measurements from different locations can be time-synchronized; therefore, a system-wide observation and analysis would be possible. As part of the U.S. nation-wide power frequency monitoring network project (FNET), the first part of the study focuses on utilizing system simulation as a tool to assess the frequency measurement accuracy needed to observe frequency oscillations from events such as remote generation drops in three U.S. power systems. Electromechanical wave propagation phenomena during system disturbances, such as generation trip, load rejection and line opening, have been observed and discussed. Further uniform system models are developed to investigate the detailed behaviors of wave propagation. Visualization tool is developed to help to view frequency behavior simulations. Frequency replay from simulation data provides some insights of how these frequency electromechanical waves propagate when major events occur. The speeds of electromechanical wave propagation in different areas of the U.S. systems, as well as the uniform models were estimated and their characteristics were discussed. Theoretical derivation between the generator's mechanical powers and bus frequencies is provided and the delayed frequency response is illustrated. Field-measured frequency data from FNET are also examined. Outlier removal and wavelet-based denoising signal processing techniques are applied to filter out spikes and noises from measured frequency data. System's frequency statistics of three major U.S. power grids are investigated. Comparison between the data from phasor measurement unit (PMU) at a high voltage substation and from FNET taken from 110 V outlets at distribution level illustrates the close tracking between the two. Several generator trip events in the Eastern Interconnection System and the Western Electricity Coordinating Council system are recorded and the frequency patterns are analyzed. Our trigger program can detect noticeable frequency drop or rise and sample results are shown in a 13 month period. In addition to transient states' observation, the quasi-steady-state, such as oscillations, can also be observed by FNET. Several potential applications of FNET in the areas of monitoring & analysis, system control, model validation, and others are discussed. Some applications of FNET are still beyond our imagination. / Ph. D.

Since the deregulation of power systems was started in 1989 in the UK, many countries have been motivated to undergo deregulation. The United State started deregulation in the energy sector in California back in 1996. Since that time many other states have also started the deregulation procedures in different utilities. Most of the deregulation market in the United States now is in the wholesale market area, however, the retail market is still undergoing changes. Deregulation has many impacts on power system network operation and control. The number of power transactions among the utilities has increased and many Independent Power Producers (IPPs) now have a rich market for competition especially in the green power market. The Federal Energy Regulatory Commission (FERC) called upon utilities to develop the Regional Transmission Organization (RTO). The RTO is a step toward the national transmission grid. RTO is an independent entity that will operate the transmission system in a large region. The main goal of forming RTOs is to increase the operation efficiency of the power network under the impact of the deregulated market. The objective of this work is to study Internet based Wide Area Information Sharing (WAIS) applications in the deregulated power system. The study is the first step toward building a national transmission grid picture using information sharing among utilities. Two main topics are covered as applications for the WAIS in the deregulated power system, state estimation and Total Transfer Capability (TTC) calculations. As a first step for building this national transmission grid picture, WAIS and the level of information sharing of the state estimation calculations have been discussed. WAIS impacts to the TTC calculations are also covered. A new technique to update the TTC using on line measurements based on WAIS created by sharing state estimation is presented. / Ph. D.

The power industry is currently in the process of re-inventing itself. The unbundling of the traditional monopolistic structure that gave birth to a deregulated electricity market, the mass tendency towards a greener use of energy, the new emphasis on distributed generation and alternative renewable resources, and new emerging technologies have revolutionized the century old industry. Recent blackouts offer testimonies of the crucial role played by protection relays in a reliable power system. It is argued that embracing the paradigm shift of adaptive protection is a fundamental step towards a reliable power grid. The adaptive philosophy of protection systems acknowledges that relays may change their characteristics in order to tailor their operation to prevailing system conditions. The purpose of this dissertation is to present methodology to implement a security/dependability adaptive protection scheme. It is argued that the likelihood of hidden failures and potential cascading events can be significantly reduced by adjusting the security/dependability balance of protection systems to better suit prevailing system conditions. The proposed methodology is based on Wide Area Measurements (WAMs) obtained with the aid of Phasor Measurement Units (PMUs). A Data Mining algorithm known as Decision Trees is used to classify the power system state and to predict the optimal security/dependability bias of a critical protection scheme. / Ph. D.

The reduced stability margin, at which power systems are being operated these days, has encouraged the power industry to come up with new ideas to guarantee a continuous and reliable operation of the bulk interconnected system. The development of the synchronized Phasor Measurement technology, and its deployment in several locations in the network, has introduced a promising means to protect power systems from undesired conditions. This research effort describes a methodology to handle transient stability in power systems using Wide Area Measurements. A correct identification of transiently stable and unstable power oscillations can be achieved with the use of the Out-of-Step protection technique presented in this document. The development of this idea is explained through the analysis of small power system models, and tested in three different operating conditions of the state of California. The main contribution of this research work, to the Out-of-Step relaying theory, is the identification of multiple unstable swings after a given disturbance. In other words, an Out-of-Step protection scheme that handles a network that behaves as a multi-machine system is presented. / Ph. D.

This study explores the potential of vehicle trajectory data obtained from Wide Area Motion Imagery for modeling and analyzing traffic characteristics. The data in question is collected by PV Labs and also known as persistent wide-area video. This video, in combination with PVLab's integrated Tactical Content Management System's spatiotemporal capability, automatically identifies and captures every vehicle in the video view frame, storing each vehicle with a discrete ID, track ID, and time-stamped location. This unique data capture provides comprehensive vehicle trajectory information. This thesis explores the use of data collected by the PVLab's system for an approximate area of 4 square kilometers area in the CBD area of Hamilton, Canada for use in understanding traffic characteristics. The data was collected for two three-hour continuous periods, one in the morning and one in the evening of the same day. Like any other computer vision algorithm, this data suffers from false detection, no detection, and other inaccuracies caused by faulty image registration. Data filtering requirements to remove noisy trajectories and reduce error is developed and presented. A methodology for extracting microscopic traffic data (gap, relative velocity, acceleration, speed) from the vehicle trajectories is presented in details. This study includes the development of a data model for storing this type of large-scale spatiotemporal data. The proposed data model is a combination of two efficient trajectory data storing techniques, the 3-D schema and the network schema and was developed to store trajectory information along with associated microscopic traffic information. The data model is designed to run fast queries on trajectory information. A 15-minute sample of tracks was validated using manual extraction from imagery frames from the video. Microscopic traffic data is extracted from this trajectory data using customized GIS analysis. Resulting tracks were map-matched to roads and individual lanes to support macro and microscopic traffic characteristic extraction. The final processed dataset includes vehicles and their trajectories for an area of approximately 4-square miles that includes a dense and complex urban network of roads over two continuous three-hour periods. Two subsets of the data were extracted, cleaned, and processed for use in calibrating car-following sub-models used in microscopic simulations. The car-following model is one of the cornerstones of any simulation based traffic analysis. Calibrating and validating these models is essential for enhancing the ability of the model's capability of representing local traffic. Calibration efforts have previously been limited by the availability and accuracy of microscopic traffic data. Even datasets like the NGSIM data are restricted in either time or space. Trajectory data of all vehicles over a wide area during an extended period of time can provide new insight into microscopic models. Persistent wide-area imagery provides a source for this data. This study explores data smoothing required to handle measurement error and to prepare model input for calibration. Three car-following models : the GHR model, the linear Helly model, and the Intelligent Driver model are calibrated using this new data source. Two approaches were taken for calibrating model parameters. First, a least square method is used to estimate the best fit value for the model parameter that minimizes the global error between the observed and predicted values. The calibration results outline the limitation of both the WAMI data source and the models themselves. Existing model structures impose limitations on the parameter values. Models become unstable beyond these parameter values and these values may not be near global optima. Most of the car-following models were developed based upon some kinematic relation between driver reaction and expected stimuli of that response. For this reason, models in their current form are ill-suited for calibration with noisy microscopic data. On the other hand, the limitation of the WAMI data is the inability of obtaining an estimate of the measurement errors. With unknown measurement errors, any model development or calibration becomes questionable irrespective of the data smoothing or filtering technique undertaken. These findings indicate requirements for development of a new generation of car-following model that can accommodate noisy trajectory data for calibration of its parameters. / MS / The decision making process undertaken by transportation agencies for planning, evaluating, and operating transportation facilities relies on analyzing traffic and driver behavior in both aggregated and disaggregated manner. Different computational tools relying on representative models of aggregate traffic flow measures and/or driver behavior are used in the decision support system tools. Field data is used not only as an input for the computational tools but also to develop, calibrate, and validate the models representing a particular aspect of traffic and driver behavior. Different approaches have been undertaken to collect the data required for analyzing traffic and driver behavior. One of the applied approach is to collect trajectory (i.e. position, speed, acceleration) information of vehicles in the analysis zone. However, this data collection approach is often limited to relatively small stretch of a roadway for short duration due to high cost of collection and limitation of technology. As a result, the models developed and calibrated using these data often lack generalization power for different situation. This study explores the potential of a new data source to address the aforementioned limitations. The data used in this study collects the trajectory information for the whole population of vehicles in the study area by collecting wide-area (WAMI) video data. The data is collected by Canada based imaging solution company PV Labs. The collection area is relatively large to cover wide range of roadway types and traffic operation system. A framework has been developed to extract traffic flow measures from the trajectory data. The extracted traffic flow measures are then applied to calibrate the car-following model. The car-following model attempts to mimic the longitudinal movement of real-world drivers following another vehicle in front of them. The calibration results outline the limitations of the WAMI data. Although, this dataset is capable of capturing traffic measures for different driving condition, the lack of information about measurement error imposes limits on the direct application of the data for model calibration. Findings of this study can be applied for refinement of the video data capture technology and subsequent application in modelling traffic characteristics as well as development of new and calibration of existing driver behavior model.

The power grid is interconnected in many ways; so that when disturbances occur in a small region, their effects can be seen across large areas causing major blackouts. In order to isolate the fault, measurements taken at different times throughout the blackout need to be collected and analyzed. With each measurement device having its own time source, time alignment can be a quite tedious and lengthy process. The need for a new time synchronized measurement device has arrived. The Phasor Measurement Units (PMU) is not only GPS time synchronized, but it also takes measurements as voltage and current phasors. PMUs are becoming an integral part in many power system applications from load flow analysis and state estimation to analyzing blackout causes. Phasor Data Concentrators (PDC) collect and process PMU data. As such, it is important that PMU and PDC communication is seamless. PDCs are set up at multiple utilities and power authorities and also need to be able to communicate and send data to one another seamlessly to encompass analysis of large measurement systems. If these devices are not working similarly when processing and sending/receiving data, unnecessary problems may arise. Therefore it is important that there is an expectation as to how they should work. However, what is expected from these devices is not entirely clear. For this reason, standards such as IEEE C37.118.2-2011 [5] have been proposed to help make operation as uniform as possible. Unfortunately, the standards for PDCs are lacking and tend to only set up communication protocols. To help normalize PDCs, these standards need to be expanded to include all PDC operations and give little room for discrepancy as to what a PDC should do in any given situation. Tests have been performed on PDCs not only to see how they match up to current standards but on how they act outside of the standards. / Master of Science

As the world moves further into the 21st century, the electricity demand worldwide continues to rapidly grow. The power systems that supply this growing demand continue to be pushed closer to their limits. When those limits are exceeded, system blackouts occur that have massive societal and economical impact. Power system protection relays make up a piece of these limits and can be important factors in preventing or causing a system blackout. The purpose of this thesis is to present a working implementation of an adaptive protection scheme known as the adaptive voting scheme, used to alter the security/dependability balance of protection schemes. It is argued that as power system conditions change, the ability of protection relays to adjust the security/dependability balance based on those conditions can allow relays to play a part in preventing power system catastrophes. It is shown that the adaptive voting scheme can be implemented on existing protection technology given Wide Area Measurements (WAMs) provided by Phasor Measurement Units (PMUs). The proposed implementation characteristics allow numerous existing protection practices to be used without changing the basic operation of the practices. / Master of Science