Development, Modeling, and Applications of PMUs

Integration of digital devices such as phasor measurement units (PMUs) at substations have been on the rise to provide efficiency, flexibility, reliability and economic benefits in power system operation and control. However, these devices may also bring additional challenges caused by inherent cyber vulnerabilities and bad data problems that in turn lead to the malfunction of these devices.% or incorrect decisions by the operator.These vulnerabilities can lead to system instability, inefficient, and power outages. The research work in this dissertation suggests possible solutions to these problems using the following approaches: improving phasor measurement quality, validating PMU performance, and decentralizing monitoring and control applications. Most commercial PMUs are designed with a Discrete Fourier Transform-based algorithm that can generate attenuated phasors with errors during dynamic system conditions. As a solution to this problem, the Wavelet Transform (WT)-based phasor estimation has been proposed for better accuracy during dynamic conditions. The developed WT-PMU has two different mother functions specifically designed for noisy and harmonics environment. A switching algorithm has also been developed to select the most suitable phasor estimation based on the system operating conditions. The developed PMU has been tested using a testbed in the lab following IEEE test suite specifications; the testbed is extended for remote testing using Erkios, a data delivery and management platform.The second part of the research presented in this dissertation relates to PMU-based model validation. Offline simulation tools are commonly used to simulate large power systems. There are mismatches between field measurements from PMUs and offline simulation results even if accurate power system models are used because of the internal features of PMUs. A PMU emulator for power system dynamic simulators has been developed to compensate the phasors of the dynamic simulator to match the response from PMUs. Finally, a decentralized voltage stability application using a distributed computing platform has been developed. The Laplacian-based Thevenin parameter estimation has been developed to mitigate errors in commonly used Thevenin-based voltage stability indices using PMUs. Simulation results indicate superior performance of adaptive PMU, PMU emulator, and Laplacian-based voltage stability, as well as satisfactory performance of the decentralized implementation of the voltage stability

Exploring Risk and Protective Factors for Cyberbullying and Their Interplay: Evidence from a Sample of South Korean College Students

This study explored risk and protective factors for cyberbullying perpetration and examined whether they independently and interactively predicted cyberbullying perpetration. Based on key propositions of micro-level theories of crime and delinquency, we adopted two risk factors, cyberbullying victimization and association with cyberbullying peers, and two protective factors, morality and self-control. Using a sample of South Korean college students (N = 244; 112 women (45.9%), 132 men (54.1%); Mean (age) = 22), we found that the two risk factors were positively associated with cyberbullying perpetration, while only one of the two protective factors, which is morality, had a negative relationship with cyberbullying perpetration. In addition, the two protective factors partially buffered the effects of both risk factors on cyberbullying perpetration. The implications and limitations of these findings were also discussed

Automated Cybersecurity Tester for IEC61850-Based Digital Substations

Power substations are the crucial nodes of an interconnected grid, serving as the points where power is transferred from the transmission/distribution grids to the loads. However, interconnected cyberphysical systems and communication-based operations at substations lead to many cybersecurity vulnerabilities. Therefore, more sophisticated cybersecurity vulnerability analyses and threat modeling are required during productization phases, and system hardening is mandatory for the commercialization of products. This paper shows the design and methods to test the cybersecurity of multicast messages for digital substations. The proposed vulnerability assessment methods are based on the semantics of IEC61850 Generic Object Oriented Substation Event (GOOSE) and Sampled Value (SV), and cybersecurity features from IEC62351-6. Different case scenarios for cyberattacks are considered to check the vulnerabilities of the device under test (DUT) based on the IEC62351-6 standard. In order to discover security vulnerabilities in a digital substation, the proposed cybersecurity tester will generate malicious packets that compromise the regular functionality. The results show that the proposed cybersecurity testing module is able to detect potential vulnerabilities in multicast messages and the authentication methods (e.g., message authentication code) of multicast communications. Both commercial and simulated devices are used for the case studies

The Dynamics of Intra-Family Relationships During Incarceration and the Implications for Children of Incarcerated Parents

The current study examines effects of changes in intra-family relationships after parental incarceration on internalizing behaviors of the children of incarcerated parents. Using data from a sample of 249 incarcerated parents with minor children in South Korea, the present study found that perceived degradation of family relationships among inmate parents, their non-incarcerated spouses, and children was a significant risk factor of internalizing behaviors of children of incarcerated parents. The current study also found that inmate parents who had more frequent family contact were more likely to perceive improvements of all forms of intra-family relationships during incarceration. The implications of these findings are discussed

Automated Cybersecurity Tester for IEC61850-Based Digital Substations

Power substations are the crucial nodes of an interconnected grid, serving as the points where power is transferred from the transmission/distribution grids to the loads. However, interconnected cyberphysical systems and communication-based operations at substations lead to many cybersecurity vulnerabilities. Therefore, more sophisticated cybersecurity vulnerability analyses and threat modeling are required during productization phases, and system hardening is mandatory for the commercialization of products. This paper shows the design and methods to test the cybersecurity of multicast messages for digital substations. The proposed vulnerability assessment methods are based on the semantics of IEC61850 Generic Object Oriented Substation Event (GOOSE) and Sampled Value (SV), and cybersecurity features from IEC62351-6. Different case scenarios for cyberattacks are considered to check the vulnerabilities of the device under test (DUT) based on the IEC62351-6 standard. In order to discover security vulnerabilities in a digital substation, the proposed cybersecurity tester will generate malicious packets that compromise the regular functionality. The results show that the proposed cybersecurity testing module is able to detect potential vulnerabilities in multicast messages and the authentication methods (e.g., message authentication code) of multicast communications. Both commercial and simulated devices are used for the case studies

OpenCL Performance Evaluation on Modern Multicore CPUs

Utilizing heterogeneous platforms for computation has become a general trend, making the portability issue important. OpenCL (Open Computing Language) serves this purpose by enabling portable execution on heterogeneous architectures. However, unpredictable performance variation on different platforms has become a burden for programmers who write OpenCL applications. This is especially true for conventional multicore CPUs, since the performance of general OpenCL applications on CPUs lags behind the performance of their counterparts written in the conventional parallel programming model for CPUs. In this paper, we evaluate the performance of OpenCL applications on out-of-order multicore CPUs from the architectural perspective. We evaluate OpenCL applications on various aspects, including API overhead, scheduling overhead, instruction-level parallelism, address space, data location, data locality, and vectorization, comparing OpenCL to conventional parallel programming models for CPUs. Our evaluation indicates unique performance characteristics of OpenCL applications and also provides insight into the optimization metrics for better performance on CPUs

Synthesis, structure, and ligand exchange of a copper(II)-based molecular helix with 2,6-pyridinedicarboxylates

<div><p>An one-dimensional (1-D) metal–organic polymer, [Cu₂(PDA)₂(DMF)₂]_n (PDA = 2,6-pyridinedicarboxylate, DMF = dimethylformamide), was synthesized by reaction of copper(II) nitrate hemi(pentahydrate) and 2,6-pyridinedicarboxylic acid in DMF. The complex shows a molecular helix structure consisting of five-coordinate Cu(II) building blocks with distorted square pyramidal geometry. Tridentate chelating PDA, DMF, and an oxygen from the carboxylate of the adjacent Cu(II) building unit are coordinated to the copper(II) center. The weakly coordinated DMF groups in [Cu₂(PDA)₂(DMF)₂]_n easily exchange with a pyridine to generate a pyridine-coordinated non-helical 1-D metal–organic polymer with six-coordinate pseudooctahedral Cu(II) units.</p></div