Master of Science / Department 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.

Master of Science / Department of Electrical and Computer Engineering / William Kuhn / From 2004 to 2008, Kansas State University's Electrical and Computer Engineering (ECE) department, along with the NASA Jet Propulsion Laboratory and Peregrine Semiconductor, researched design techniques for producing a low-power, 400 MHz micro-transceiver suitable for future use on Mars scout missions. In 2012, Dr. Kuhn's Digital Radio Hardware Design class, ECE765, adapted the K-State circuit designs from this research project to investigate the possibility of producing a 2.4 GHz micro-transceiver in Peregrine Semiconductor’s newer 0.25 [mu]m Silicon on Sapphire process. This report expands upon the work completed in the Digital Radio Hardware Design (ECE765) course. The schematics and layout of the subsections of the receiver portion of the micro-transceiver chip, consisting of a transmit/receive switch, low-noise amplifier, mixer, intermediate-frequency amplifiers, and an analog-to-digital converter are described. Circuits designed to date require a total of 15 mW to operate. This report is intended as a guide for future students who will take over this project, make modifications, adapt the transmit portion of the micro-transceiver from previous work, and finish layout before fabrication of a full 2.4 GHz prototype chip.

Master of Science / Department of Electrical and Computer Engineering / Behrooz Mirafzal / In this thesis, a modified version of the phasor pulse width modulation (PPWM) switching method for use in a single-stage three-phase boost inverter is presented. Because of the required narrow pulses in the PPWM method and limitations in controller resolution, e.g. dSPACE, the desired switching pattern for a boost inverter requires a costly processor. A low resolution processor can cause pulse dropping which results in some asymmetric conditions in output waveforms of the boost inverter and therefore, an increase in the THD of the output waveform. In order to solve this problem, a new switching pattern is developed which guarantees symmetric conditions in the switching pattern by discretizing the switching pattern in every switching cycle. This switching pattern has been applied to a boost inverter model developed by SimPowerSystems toolbox of MATLAB/Simulink. The model has been simulated in a wide range of input DC voltage and load. Moreover, a laboratory-scaled three-phase boost inverter has been designed, built, and tested using an identical switching pattern in the same input voltage and load range. Both simulation and experimental results confirm the effectiveness of the new switching pattern.

Master of Science / Department of Electrical and Computer Engineering / Behrooz Mirafzal / Increasing energy demand, rising oil prices, and environmental concerns have forced attention to alternative energy sources that are environmentally friendly and independent of fossil fuels. Renewable energy sources (RES) have become an attractive alternative to the traditional energy sources for electric power generation. However, one of the main challenges of RES adaption arises when connecting RES to the electric grid. Voltage source inverters (VSIs), typically, connect RES to the electric grid. Similar to any engineering system, detailed dynamic models of the VSIs are needed for design and analysis purposes. However, due to the non-linearity of VSIs, development of dynamic models that can accurately describe their behavior is a complex task. In this thesis, a detailed averaged-state-space model of the two-level three-phase space vector pulse width modulation VSI and its companion LCL filter is derived. Because VSIs can operate under stand-alone and grid-tied modes, two models were derived for each case. In the derived models, the VSI modulation index m and phase angle ϕ are initially considered constant. In practice, however, these parameters are considered the main control parameters. To model these parameters as control inputs, small-signal models of the VSI under stand-alone and grid-tied modes were derived. To verify the accuracy of the developed large-signal and small-signal models, Matlab/Simulink simulations were carried out. The simulation results were compared against the models results. Moreover, the models were verified through lab experiments. The developed models can be used as design and analysis tools. In addition, the developed models can be used as fast and efficient simulation tools for system studies, when the modeling of switching transients is not needed. Nowadays, the number of VSIs connected to the electric grid is growing exponentially. The amount of time and computation needed to simulate VSIs using simulation software packages can be significantly decreased by the use of the developed models.

Master of Science / Department of Electrical and Computer Engineering / Karen Garrett / Bala Natarajan / Caterina Scoglio / In this thesis, we propose a statistical model to predict disease dispersal in dynamic networks. We model the process of disease spreading using discrete time Markov chain. In this case, the vector of probability of infection is the state vector and every element of the state vector is a continuous variable between zero and one. In discrete time Markov chains, state probability vectors in each time step depends on state probability vector in the previous time step and one step transition probability matrix. The transition probability matrix can be time variant or time invariant. If this matrix’s elements are functions of elements of vector state probability in previous step, the corresponding Markov chain is non linear dynamical system. However, if those elements are independent of vector state probability, the corresponding Markov chain is a linear dynamical system. We especially focus on the dispersal of soybean rust. In our problem, we have a network of US counties and we aim at predicting that which counties are more likely to get infected by soybean rust during a year based on observations of soybean rust up to that time as well as corresponding observations to previous years. Other data such as soybean and kudzu densities in each county, daily wind data, and distance between counties helps us to build the model. The rapid growth in the number of Internet users in recent years has led malware generators to exploit this potential to attack computer users around the word. Internet users are frequent targets of malicious software every day. The ability of malware to exploit the infrastructures of networks for propagation determines how detrimental they can be to the network’s security. Malicious software can make large outbreaks if they are able to exploit the structure of the Internet and interactions between users to propagate. Epidemics typically start with some initial infected nodes. Infected nodes can cause their healthy neighbors to become infected with some probability. With time and in some cases with external intervention, infected nodes can be cured and go back to a healthy state. The study of epidemic dispersals on networks aims at explaining how epidemics evolve and spread in networks. One of the most interesting questions regarding an epidemic spread in a network is whether the epidemic dies out or results in a massive outbreak. Epidemic threshold is a parameter that addresses this question by considering both the network topology and epidemic strength.

Master of Science / Department of Electrical and Computer Engineering / Noel Schulz / New applications are continuously emerging in the ever-changing field of power systems in the United States and throughout the world, consequently causing new pressures on grid performance. Because power system protection is a fundamental aspect of the system, their operation must be addressed when a system is under high stress or when a high demand of energy is required. An extreme example is the transmission protection of a system because it transports large amounts of power. Transmission lines in a power system are frequently exposed to faults and generally protected by distance relays. If a faulted segment of transmission lines is not cleared in a short period of time, the system becomes unstable. The basic function of distance protection is to detect faults in buses, transmission lines, or substations and isolate them based on voltage and current measurements. Power system protection has previously focused on matching automation and control technologies to system performance needs. This report focuses on project activities that run simulations to determine settings for a protective relay for pilot overreaching transfer tripping and then test the settings using hardware equipment for various scenarios. The first set of scenarios consists of five faults in the system; two faults are in the protected line, and the remaining faults are outside the protective line. The second set of scenarios consists of instrument transformer failures in which the current transformer (CT) of one relay fails to operate while the other relay is fully operational. The second scenario consists of a failure of the voltage transformer (VT) of one relay while the other relay remains fully operational. Finally, the third and fourth scenarios consist of the failure of both CTs and VTs for each relay.

Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn / This thesis elaborates on the theory and art of the design of two key RF radio hardware subsystems: analog Frequency Dividers and Low Noise Amplifiers (LNAs). Specifically, the design and analysis of two Injection Locked Frequency Dividers (ILFDs), one Regenerative Frequency Divider (RFD), and two different LNAs are documented. In addition to deriving equations for various performance metrics and topology-specific optimization criterion, measurement data and software simulations are presented to quantify several parameters of interest. Also, a study of the design of LNAs is discussed, based on three “regimes:” impedance matching, transconductance-boosting, and active noise cancelling (ANC). For the ILFDs, a study of injection-locked synchronization and phase noise reduction is offered, based on previous works. As the need for low power, high frequency radio devices continues to be driven by the mobile phone industry, Frequency Dividers that are used as prescalars in phase locked loop frequency synthesizers (PLLs) must too become capable of operation at higher frequencies while consuming little power. Not only should they be low power devices, but a wide “Locking Range” (LR) is also desired. The LR is the bandwidth of signals that a Frequency Divider is capable of dividing. As such, this thesis documents the design and analysis of two ILFDs: a Tail-ILFD and a Quench-ILFD. Both of these ILFDs are implemented on the same oscillator circuit, which consumes 2.28 mW, nominally. Measurements of the Tail and Quench-ILFDs’ LRs are plotted, including one representing the Quench-ILFD operating at “very low” power. Also, an RFD is detailed in this thesis, which consumes 410 μW. This thesis documents Locking Ranges for the Tail and Quench-ILFDs of 12% and 3.7% of 6.4 GHz respectively, during nominal operation. In “very low” power mode, the Quench-ILFD has a LR of 4.8% while consuming 219.6 μW of power. For the RFD, simulations report a LR of 16.7% while consuming 410 μW. Recently in 2011, a wideband LNA topology by Nozahi et al., which employs Partial Noise Cancelling (PNC) of the thermal noise generated by active devices, was presented and claimed to achieve a minimum and maximum NF of 1.4 dB and 1.7 dB (from 100 MHz to 2.3 GHz), while consuming 18 mW from a 1.8 V supply. This thesis details the theory, design, and simulation results of a narrowband version of this PNC LNA. In order to compare the largesignal performance of this narrowband LNA to that of a well-known implementation, an LNA employing inductive source-degeneration (referred to as a “S-L LNA”) is designed and analyzed through simulation. The PNC LNA operates at a frequency of 2.3 GHz while the S-L LNA operates at 2.8 GHz. Simulations report a NF of 1.76 dB for the PNC LNA and 2.3 dB for the SL LNA, at their respective operating frequencies. Both LNAs consume roughly 15 mW of quiescent power from a 1.8 V supply. Lastly, a case for the suspected design and layout faults, which caused fabricated versions of the RFD and two LNAs documented in this thesis to fail, is presented. First, measurements of the two LNAs are shown, which display the input impedance of the S-L LNA and the s₂₁ responses for both. Then, general layout concerns are addressed, followed by topology-specific circuit design flaws.

Master of Science / Department of Electrical and Computer Engineering / Anil Pahwa / This research project builds upon previous work related to intelligent and energy efficient lighting in modern street and outdoor lighting systems. The concept of implementing modern smart grid technologies such as the proposed Street & Outdoor Lighting Intelligent Monitoring System (SOLIMS) is developed. A random sample of photocells from two municipal electric power systems is used to collect data of the actual on/off times of random photocells versus Civil Twilight (sunrise/sunset) times. A business case was developed using the data collected from the observations to support an electric utility company’s implementation of SOLIMS as an alternative to current operations. The goal of the business case is to demonstrate energy and capacity savings, reduced maintenance and operating costs, and lower carbon emissions.

Master of Science / Department of Electrical and Computer Engineering / Balasubramaniam Natarajan / This thesis proposes an automated crack detection and classification algorithm to detect durability cracking (“D”-cracking) in pavement by using image processing and pattern recognition techniques. For the Departments of Transportation across the country, efficient and effective crack detection is vital to maintaining quality roadways. Manual inspection of roadways is tedious and cumbersome. Previous research has focus on distinct transverse and longitudinal cracks. However, “D”-cracking presents a unique challenge since the cracks are fine and have a distinctive shape surrounding the intersection of the transverse and longitudinal joints. This thesis presents an automated crack detection and classification system using several known image processing techniques. The algorithm consists of four sections: 1) lighting correction, 2) subimage processing, 3) postprocessing and 4) classification. Some images contain uneven lighting, which are corrected based on a model of the lighting system. The region of interest is identified by locating the lateral joints. These regions are then divided into overlapping subimages, which are then divided into cracked and noncracked pixels using thresholds on the residual error. Postprocessing includes a row/column sum filter and morphological open operation to reduce noise. Finally, metrics are calculated from the final crack map to classify each section as cracked or noncracked using the Mahalanobis distance from the noncracked distribution.

Master of Science / Department of Electrical and Computer Engineering / Ruth D. Miller / This thesis presents the design of a multilevel D-STATCOM inverter for small to mid-size (10–20 kW) permanent-magnet wind or solar installations. The proposed inverter can actively regulate the reactive power on individual feeder lines at a programmable output while providing the variable output power of the renewable energy source. The aim is to provide utilities with distributive control of VAR compensation and power factor correction on feeder lines. The designed inverter utilizes a 5-level hybrid-clamped multilevel voltage-source converter topology and uses the optimized harmonic stepped waveform technique for harmonic elimination. The topology allows for the separation of active and reactive power control and the ability to operate under any load conditions. Reactive power is controlled by the modulation index and active power is controlled by the phase angle. Simulations and validation of the proposed inverter were carried out using MATLAB/Simulink and SimPowerSystems toolboxes.