With the increase in complexity of modern electricity grids, the implementation of state-estimators has become a vital aspect of stability and contingency analyses for stable and secure power system operation. Transmission line reactance is an important component in the computation of state-estimators. Two models utilizing real-time synchrophasor data and ERCOT load information are proposed to compute Thevenin equivalent reactance. This thesis presents the results of implementing these methods to estimate the equivalent reactance of a transmission network between The University of Texas at Austin and The University of Texas, PanAm. / text

A phasor-only estimator carries with it intrinsic improvements over its SCADA analogue with respect to performance and reliability. However, insuring the quality of the data stream which leaves the linear estimator is crucial to establishing it as the front end of an EMS system and network applications which employ synchrophasor data. This can be accomplished using a two-fold solution: the pre-processing of phasor data before it arrives at the linear estimator and the by developing a synchrophasor-only dynamic state estimator as a mechanism for bad data detection and identification. In order to realize these algorithms, this dissertation develops a computationally simple model of the dynamics of the power system which fits neatly into the existing linear state estimation formulation. The algorithms are then tested on field data from PMUs installed on the Dominion Virginia Power EHV network. / Ph. D.

Synchrophasor technology is widely available embedded in modern power grid protection, metering, and recording devices. Utilizing synchrophasor measurements, a novel algorithm is proposed for fault location in multi-terminal transmission lines. In order to implement real-time synchrophasor applications, a software platform called “PhasorEye” was developed in this research. PhasorEye facilitates collecting synchrophasor data stream, visualization of decoded data, and implementation of synchrophasor applications as analysis tools. A laboratory setup involving a RTDS real-time digital simulator and a synchrophasor communication network was assembled to demonstrate and validate the use of the software and the proposed new fault location technique. Tests revealed several challenges in practical application of synchrophasor data for fault location and showed that the proposed fault location algorithm can accurately identify the faulted line segment and fault location. Additionally, several other synchrophasor applications developed by other University of Manitoba researchers were implemented and integrated into the software. / February 2017

Recently, there has been an increase in the deployment of Phasor Measurement Units (PMUs) which has enabled real time, wide area monitoring of power systems. PMUs can synchronously measure operating parameters across the grid at typically 30 samples per second, compared to 1 sample per 2-5 seconds of a conventional Supervisory Control And Data Acquisition (SCADA) system. Such an explosion of data in power systems has provided an opportunity to make electrical grids more reliable. Additionally, it has brought a challenge to extract information from the massive amount of data. In this research, several data mining algorithms are used to extract information from synchrophasor data for improving situational awareness of power systems. The extracted information can be used for event detection, for reducing the dimension of data without losing information, and also to use it as heuristic to process future measurements. The methods proposed in this research work can be broadly classified into two parts: a) stream mining and b) dimension reduction. Stream mining algorithms provide solution utilizing state-of-the-art data stream mining algorithms such as Hoeffding Trees (HT). HT algorithm builds a decision tree by scanning the incoming data stream only once. The tree itself holds sufficient statistics in its leaves to grow the tree and also to make classification decisions of incoming data. Instead of using a large number of samples, which leads to a tree too large to accommodate in memory, the number of samples that are needed to split at each node is determined using Hoeffding bound (HB). HB keeps the size of the decision tree within bounds while also maintaining accuracies statistically competitive to traditional decision trees. Dimension reduction algorithms reduce dimension of the synchrophasor data by extracting maximum information from a huge data set without losing information. In this dissertation, both online and offline dimension reduction algorithms have been studied. The online dimension reduction uses an unsupervised method using principal components of the time series data. The offline method optimizes unique mutual information between the state of the power system and synchrophasor measurements. It optimizes the criteria by reducing redundant information while maximizing relevant information.

Microgrids form small-scale power grids with distributed energy resources such as wind generators, photovoltaic panels, fuel cells, energy storage systems, and controllable loads. The characteristics of a microgrid include bi-directional power flows, flexible modes of operation, as well as variable short circuit currents. Due to the weak injection of fault current and short period nature, the connection of microgrids to the distribution systems or sub-transmission systems creates serious challenges to existing over-current based protection systems. The protection of microgrids is gaining substantial attentions in recent years because of large-scale deployment of microgrids and its impacts to existing electricity infrastructures. New protection methodologies and solutions applicable for microgrids are studied and presented in this dissertation. To effectively protect the microgrids, three areas of study are conducted based on the latest technologies in the protection systems, computing platforms, and communication networks. Firstly, the Point of Interconnection protection using distance protection with residual voltage compensation method for an ungrounded microgrid network is presented. This study resolves the challenging issues of detecting single-phase-to-ground fault at the interconnection line of microgrid. It can correctly identify the fault, properly measure the fault location, and timely isolate the fault without jeopardizing the stability of downstream microgrid system and/or causing dangerous overvoltage and arcing conditions. Secondly, the distribution substation busbar protection using the synchrophasor data is studied to realize fast and reliable bus differential protection. Comparing with other busbar protection schemes, this method has the advantages of low cost, easy configuration, fast expansion, and no circuit limitation. Lastly, an adaptive protection solution for distribution feeders with microgrids is developed and tested using RTDS. This study focuses on providing a framework for microgrid over-current coordination to improve the reliability and dependability of the protected network. Overall, the research studies presented in this dissertation will provide the power industries with new insights and methodologies on microgrid protection. Together with other protection functions, the proposed methods can provide effective microgrid protection against dangerous faults, reduce arcing condition, increase the possibility of seamless islanding, and consequently improve the reliability and resilience of microgrids.

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

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

For decades, power engineers have used simulations to predict grid stability and voltage phase angles. Only recently have equipment been available to actually measure phase angle at points hundreds of miles away. A few of these systems are presently operating in the US by electric grids including the Electric Reliability Council of Texas (ERCOT) and California Independent System Operator (ISO). However, the systems are in their infancy and are far from being used to improve grid reliability. This thesis describes the only independent synchronized phasor network that exists in the US. Thanks to Schweitzer Engineering Laboratories (SEL), we are streaming in points from three locations plus the University of Texas at Austin (UT Austin) as of January 2009. This thesis will describe this network and grid analysis done this far. / text

The development of an experimental synchrophasors network and application of synchrophasors for real-time transmission line parameter monitoring are presented in this thesis. In the laboratory setup, a power system is simulated in a RTDS real-time digital simulator, and the simulated voltages and currents are input to hardware phasor measurement units (PMUs) through the analog outputs of the simulator. Time synchronizing signals for the PMU devices are supplied from a common GPS clock. The real time data collected from PMUs are sent to a phasor data concentrator (PDC) through Ethernet using the TCP/IP protocol. A real-time transmission line parameter monitoring application program that uses the synchrophasor data provided by the PDC is implemented and validated. The experimental synchrophasor network developed in this thesis is expected to be used in research on synchrophasor applications as well as in graduate and undergraduate teaching.

The development of an experimental synchrophasors network and application of synchrophasors for real-time transmission line parameter monitoring are presented in this thesis. In the laboratory setup, a power system is simulated in a RTDS real-time digital simulator, and the simulated voltages and currents are input to hardware phasor measurement units (PMUs) through the analog outputs of the simulator. Time synchronizing signals for the PMU devices are supplied from a common GPS clock. The real time data collected from PMUs are sent to a phasor data concentrator (PDC) through Ethernet using the TCP/IP protocol. A real-time transmission line parameter monitoring application program that uses the synchrophasor data provided by the PDC is implemented and validated. The experimental synchrophasor network developed in this thesis is expected to be used in research on synchrophasor applications as well as in graduate and undergraduate teaching.