Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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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 Wide-area control strategies for improving transient stability in a multi-machine power systems(Montana State University - Bozeman, College of Engineering, 2020) Ojetola, Samuel Toluwanimi; Chairperson, Graduate Committee: Todd Kaiser and Josh WoldTransient stability is the ability of synchronous machines in an interconnected power system to remain in synchronism after been subjected to a large disturbance. Transient instability is one of the less probable but severe events that a power system encounter in its daily operations. Historically, it has been the dominant stability problem in power systems and has been the focus of much of the power industry's attention. Traditionally, when a generator or group of generators begin to lose synchronism with the rest of the system, they are tripped or islanded from the network to maintain transient stability and to prevent or limit cascaded outages. However, with the increase in the penetration of inverter-based generation, tripping schemes may become difficult to apply because of wide distribution of generation and loss of system inertia. This research presents control strategies that improves the transient stability of a power system without having to trip generators. This is achieved by modulating the active power absorbed or injected by distributed energy storage devices. These devices are located at the high voltage bus of several generators in a synchronous power system and are independently controlled. The strategy is based upon local and center-of-inertia frequency estimated in real time from wide-area measurements. It is shown that by absorbing or injecting real-power into a power system to remove as much kinetic energy gained during a disturbance as quickly as possible before it is converted to potential energy, synchronism can be maintained. The performance of the control strategy is evaluated on several multi-machine power system models. The result shows that this control strategy significantly improves the transient stability of power systems.Item An electrical power system implementing fixed power point tracking with temperature compensation(Montana State University - Bozeman, College of Engineering, 2017) Zack, Kevin William; Chairperson, Graduate Committee: Brock LaMeresFor the past decade Montana State University (MSU) researchers have been developing a Radiation Tolerant Computing System (RTCS) to support the National Aeronautics and Space Administrations (NASA) technology road map for space technology. The next iteration of this effort is a free flying CubeSat being developed in the Electrical and Computer Engineering Department named RadSat-g. This thesis addresses the Electrical Power System (EPS) of the satellite avionics in support of RTCS for RadSat-g. One of the main problems that CubeSat developers face is the small amount of solar power generated due to available space for solar cell placement on the small frame of a CubeSat. Charging the battery from the solar panels generally employ one of two types of energy transfer methods, direct energy transfer and power point tracking. Direct energy transfer's disadvantage is the strings of solar cells need to be tuned to the battery and as such has the potential to leave valuable space on the solar panel unused. Power point tracking has the advantage of the ability to utilize variable string lengths, this allows each solar panel to have the maximum number of cells and therefore exploit the maximum available power. In terms of CubeSat power availability, the RTCS has a substantial power requirement, so power point tracking is required for the satellite to be power positive. To accommodate this requirement, a new EPS needed to be researched, designed and built. This new EPS, named Phoenix v2.3 EPS, meets the needs of the RadSat-g mission while leveraging components with flight heritage from past MSU Space Science Engineering and Laboratory missions.Item Applications of fuzzy logic control for damping power system oscillations(Montana State University - Bozeman, College of Engineering, 2000) Lu, JieItem 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.Item A new islanding detection technique for distributed generation(Montana State University - Bozeman, College of Engineering, 2006) Menon, Vivek Viswanathan; Chairperson, Graduate Committee: M. Hashem NehrirThe phenomenon of unintentional islanding, which occurs when a distributed generator (DG) continues to feed power into the grid when power flow from the central utility source has been interrupted, can result in serious injury to the linemen who are trying to fix the line. Several strategies have been proposed in the past to avoid such an occurrence. Of the existing islanding detection propositions two schemes one of which is an active technique (the positive feedback technique) and the other one a passive technique (the VU and THD technique) are found by the author to be very effective but not without drawbacks. The principles of these strategies are combined to obtain a new hybrid islanding detection technique for synchronously rotating DGs. Simulation results show that the proposed hybrid technique is more effective than each of the above schemes. Simulation results are given for two testbeds to verify the advantages of the proposed hybrid islanding detection technique.