The problem of monitoring an electric power system by placing as few measurement devices in the system as possible is closely related to the well known vertex covering and dominating set problems in graph theory. A set S of vertices is defined to be a power dominating set of a graphs if every vertex and every edge in the system is monitored by the set S (following a set of rules for power system monitoring). The minimum cardinality of a power dominating set of a graph is its power domination number. In this thesis, we investigate the power domination number of a block graph.

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

The Phasor Measurement Unit provides clear data for ease of grid visibility. A major component of the device is the Global Positioning System (GPS) for time synchronization across the board. However, this device has become more susceptible to cyber-attacks such as spoofing. This paper constructs an opensource testbed for the playback of PMU data and testing of cyberattacks on PMUs. Using a local GPS device to simulate what is done in the PMU, MATLAB for data conversion, and Linux operating system running on Ubuntu, the simulator can be constructed. The spoofing attack is done by adding a phase shift of the incoming data to simulate that the data is coming from a different time stamp and shifts between the original. Finally, it is all brought together by viewing the output in an open source Phasor Data Concentrator (PDC) to validate the process. / Master of Science / To monitor the bulk electrical grid, devices used to calculate at what level the grid is at and what point in time as well. These devices that are called Phasor Measurement Units and send this data to the control center for engineers to process and make decisions. Within each device is a Global Positioning System (GPS) to tell which device is sending data and at what time. The GPS device is what is susceptible to be entered by malicious individuals. To better prepare and prevent this, a testbed would be a good solution to test if the preventative measure works. However, the best of the best costs too much money, so the next best solution is an open source test bed that could be implemented anyway. The work in this paper constructs an opensource testbed and simulates a full GPS spoofing attack.

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

This thesis is based around the use of energy harvesting in systems, specifically for a Bluetooth Low Energy (BLE) mesh testbed. This BLE mesh is located in a well lit lab and is currently powered by mains electricity. Systems such as the BLE mesh are considered Internet of Things (IoT). The market for these systems is rapidly expanding and in turn so is the energy use. Many systems are powered by battery, and the need to replace a battery with an energy harvesting system has arisen. This thesis will explore the possibilities to power a node in this mesh and introduce a level of intelligence to allow the system to better predict available energy to harvest. The lab the BLE mesh is in is characterised for potential energy sources. Light is chosen to be an exceptional power source, from here a lux metre is created from a photovoltaic (PV) cell. This PV cell would function as both the power for the system and provide a method to measure the current light intensity. This would help add a layer of intelligence to the system to allow future systems to better understand how much energy is available. This idea can be implemented in other harvesters as well. / Denna avhandling är baserad på användningen av energiskördning i ett system, specifikt i en Bluetooth Low Energy (BLE)-mesh. Denna BLE-mesh befinner sig i ett väl upplyst labb och är för närvarande strömdrivet genom huvudström. System som BLE-mesh anses vara en del av Internet of Things (IoT). Marknaden för dessa system expanderar snabbt och därmed ökar också energiförbrukningen. Många system är batteridrivna och det har uppstått ett växande behov av att ersätta batteriet med ett energiskördsystem. Denna avhandling kommer att utforska möjligheterna att strömförsörja en nod i denna mesh och införa en intelligensnivå för att förbättra systemets möjlighet att förutspå energi som är tillgänglig för att skördas. Labbet där BLE-meshen befinner sig karakteriseras för potentiella energikällor. Ljus valdes som en exceptionell kraftkälla, och därifrån skapas en luxmeter från en fotovoltaisk (PV) cell. Denna PV-cell ska fungera både som strömkälla för systemet och utgöra en metod för att mäta nuvarande ljusintensitet. Detta skulle bidra till att lägga till ett skikt av intelligens i systemet för att göra det möjligt för framtida system att bättre förutspå tillgänglig skördbar energi. Denna idé kan även implementeras i andra energiskördsystem.

Master of Science / Department 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.

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.

Ingeniero Civil Eléctrico / En 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.

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.

The operation and control of the power system in an efficient way is important in order to keep the system secure, reliable and economical. With advancements in smart grid, several new algorithms have been developed for improved operation and control. These algorithms need to be extensively tested and validated in real time before applying to the real electric power grid. This work focuses on the development of a real time test bed for testing and validating power system control algorithms, hardware devices and cyber security vulnerability. The test bed developed utilizes several hardware components including relays, phasor measurement units, phasor data concentrator, programmable logic controllers and several software tools. Current work also integrates historian for power system monitoring and data archiving. Finally, two different power system test cases are simulated to demonstrate the applications of developed test bed. The developed test bed can also be used for power system education.