Scholarship & Research
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Item Resilience assessment of active distribution networks(Montana State University - Bozeman, College of Engineering, 2021) Miller, Ryan Jared Alexander; Chairperson, Graduate Committee: Maryam BahramipanahPower system resilience focuses on a system's ability to prepare for and recover from events which would severely degrade its performance. With severe weather events and regional disasters such as hurricanes, polar vortex cold, and wildfires increasing in frequency and intensity in recent years, work toward simulation and quantification techniques of power system resilience is more necessary than ever. To generate a realistic model, this work produces a geographic topography to geographically lay out and test power system. Furthermore, different extreme events such as flooding, hurricanes, wildfires, and tornadoes are modeled, and the proposed technique evaluates their impacts on the power system degradation and resilience. The availability of recovery resources and several stochastic recovery dynamics that modify the system's depth of degradation and recovery profile during repair time are studied in this work. Multiple resilience metrics are proposed to aid in analyzing the system's recovery performance. The performance of this proposed technique is then evaluated for a flood of intermediate intensity which causes component failures and system outages within the grid. System recovery resources are varied by adjusting the number of crews who can simultaneously repair the system. Resilience indices are evaluated, and it is shown that with increasing availability of repair crews and recovery resources, the system resilience improves. The proposed strategy can be applied to an arbitrary test system with ease. Different strategies such as energy storage management and repair prioritization can be modified in future works to test potential improvements or optimizations for a given test system under the occurrence of a specific extreme event.Item A radiation tolerant computer mission to the International Space Station(Montana State University - Bozeman, College of Engineering, 2017) Julien, Connor Russell; Chairperson, Graduate Committee: Brock LaMeresThe harmful effects of radiation on electronics used in space poses a difficult problem for the aerospace industry. Memory corruption and other faults caused by the harsh radiation environment are difficult to mitigate. The following Masters of Science thesis describes the design and testing of a radiation tolerant, low-cost computer system to meet the increasing demand of fault tolerant space computing. The computer is implemented on a modern Field Programmable Gate Array (FPGA), which enables a novel fault mitigation strategy to be deployed on a commercial part, thus reducing the cost of the system. Using modern processing nodes as small as 28nm, FPGAs can provide increased computational performance and power efficiency. Common mitigation techniques like triple modular redundancy and memory scrubbing are expanded by utilizing partial reconfiguration on the FPGA and by introducing extra spare processors. Our computer system has been in development at Montana State University for the past 10 years and has undergone a series of technology demonstrations to increase its technical readiness level. These include high energy particle bombardment at the Texas A&M Radiation Effects Facility, 8 high altitude balloon flights to 30km, and two sounding rocket flights to altitudes greater than 120km. This computer is currently being demonstrated onboard the International Space Station and will be the payload for two stand-alone small satellite missions in low Earth orbit in 2018. This Masters of Science thesis presents improvements to the system by moving the design to a new, low power FPGA with a new processor synchronization method. This thesis will present the design, testing, and characterization of the computer system along with conveying data collected by the experiment on the International Space Station.Item Reliability analysis of radiation induced fault mitigation strategies in field programmable gate arrays(Montana State University - Bozeman, College of Engineering, 2014) Hogan, Justin Allan; Chairperson, Graduate Committee: Brock LaMeresThis dissertation presents the results of engineering design and analysis of a radiation tolerant, static random-access-memory-based field programmable gate array reconfigurable computer system for use in space flight applications. A custom satellite platform was designed and developed at Montana State University. This platform facilitates research into radiation tolerant computer architectures that enable the use of commercial off-the-shelf components in harsh radiation environments. The computer architectures are implemented on a Xilinx Virtex-6 field programmable gate array, the configuration of which is controlled by a Xilinx Spartan-6 field programmable gate array. These architectures build upon traditional triple modular redundancy techniques through the addition of spare processing resources. The logic fabric is partitioned into discrete, reconfigurable tiles with three tiles active in triple modular redundancy and remaining tiles maintained as spares. A voter circuit identifies design-level faults triggering rapid switch to a spare tile. Blind or readback scrubbing prevents the accumulation of configuration memory faults. The design and results from a variety of integrated system tests are presented as well as a reliability analysis of the radiation effects mitigation strategy used in the system. The research questions addressed by this dissertation are: 1) Does the inclusion of spare circuitry increase system reliability? 2) How do single-points-of-failure affect system reliability? and 3) Does migrating single-points-of-failure to an older technology node (technology partitioning) offer an improvement in reliability?Item Battery state-of-health assessment using a near real-time impedance measurement technique under no-load and load conditions(Montana State University - Bozeman, College of Engineering, 2011) Christophersen, Jon Petter; Chairperson, Graduate Committee: M. Hashem NehrirThe reliability of battery technologies has become a critical issue as the United States seeks to reduce its dependence on foreign oil. One of the significant limitations of in-situ battery health and reliability assessments, however, has been the inability to rapidly acquire information on power capability during aging. The Idaho National Laboratory has been collaborating with Montana Tech of the University of Montana and Qualtech Systems, Incorporated, on the development of a Smart Battery Status Monitor. This in-situ device will track changes in battery performance parameters to estimate its state-of-health and remaining useful life. A key component of this onboard monitoring system will be rapid, in-situ impedance measurements from which the available power can be estimated. A novel measurement technique, known as Harmonic Compensated Synchronous Detection, has been developed to acquire a wideband impedance spectrum based on an input sum-of-sines signal that contains frequencies separated by octave harmonics and has a duration of only one period of the lowest frequency. For this research, studies were conducted with high-power lithium-ion cells to examine the effectiveness and long-term impact of in-situ Harmonic Compensated Synchronous Detection measurements. Cells were cycled using standardized methods with periodic interruptions for reference performance tests to gauge degradation. The results demonstrated that in-situ impedance measurements were benign and could be successfully implemented under both no-load and load conditions. The acquired impedance spectra under no-load conditions were highly correlated to the independently determined pulse resistance growth and power fade. Similarly, the impedance measurements under load successfully reflected changes in cycle-life pulse resistance at elevated test temperatures. However, both the simulated and measured results were corrupted by transient effects and, for the under-load spectra, a bias voltage error. These errors mostly influenced the impedance at low frequencies, while the mid-frequency charge transfer resistance was generally retained regardless of current level. It was further demonstrated that these corrupting influences could be minimized with additional periods of the lowest frequency. Therefore, the data from these studies demonstrate that Harmonic Compensated Synchronous Detection is a viable in-situ impedance measurement technique that could be implemented as part of the overall Smart Battery Status Monitor.Item Controller design for PSS and FACTS devices to enhance damping of low-frequency power oscillations in power systems(Montana State University - Bozeman, College of Engineering, 2006) You, Ruhua; Chairperson, Graduate Committee: Hashem Nehrir.Low frequency electromechanical oscillations are inevitable characteristics of power systems and they greatly affect the transmission line transfer capability and power system stability. PSS and FACTS devices can help the damping of power system oscillations. The objective of this dissertation is to design an advanced PSS and propose a systematic approach for damping controller design for FACTS devices. Intelligent control strategy which combines the knowledge of system identification, fuzzy logic control, and the neural networks are applied to the PSS design. A fuzzy logic based PSS is developed and tuned by neural network strategy. The proposed PSS improved the damping of power system oscillations over a conventional PSS. But the same control strategy is not satisfactory for the FACTS damping controller design, mainly because of the different location and role of FACTS devices in power system oscillations compared to PSS. A systematic approach is proposed to design damping controllers for FACTS devices. The problem is considered from a control point of view and treated as a feedback control problem. A low order plant transfer function is obtained by PRONY method; proper control input is selected and a damping controller is designed combining the eigenvalue sensitivity analysis and the root locus method. A gain varying strategy is proposed to change the controller gain according to the transmission line loading condition for better damping effect. This approach is successfully applied in damping controller design for SVC, TCSC, and UPFC. Simulation results demonstrate good damping effects of these controllers Another work accomplished in this dissertation is the modeling of UPFC, a voltage-sourced converter-based FACTS device who simultaneously control bus voltage and power flows on transmission lines. The UPFC brings quite a few challenges to power system simulation and study including power flow calculations, modeling of converter control and UPFC dynamics, interfacing UPFC with the power system for transient simulation program development and physical and operating constraint modeling. The proposed model accurately represented the behavior of UPFC in quasi-steady state and well demonstrated the unique capability of the UPFC to control both the load flow and the bus voltage rapidly and independently.