+publisher:"University of Texas – Austin" +contributor:("Arapostathis, Aristotle")

University of Texas – Austin

1. Yoon, Ji Hoon. Demand side load control in residential buildings with HVAC controller for demand response.

Degree: PhD, Electrical and Computer Engineering, 2015, University of Texas – Austin

► Demand Response (DR) is a key factor to increase the efficiency of the power grid and has the potential to facilitate supply-demand balance. Demand side… (more)

▼ Demand Response (DR) is a key factor to increase the efficiency of the power grid and has the potential to facilitate supply-demand balance. Demand side load control can contribute to reduce electricity consumption through DR programs. Especially, Heating, Ventilating and Air Conditioning (HVAC) load is one of the major contributors to peak loads. In the United States, HVAC systems are the largest consumers of electrical energy and a major contributor to peak demand. In this research, the Dynamic Demand Response Controller (DDRC) is proposed to reduce peak load as well as saves electricity cost while maintaining reasonable thermal comfort by controlling HVAC system. To reduce both peak load and energy cost, DDRC controls the set-point temperature in a thermostat depending on real-time price of electricity. Residential buildings are modeled with various internal loads using building energy modeling tools. The weather data in different climate zones are used to demonstrate that DDRC decreases peak loads and brings economic benefit in various locations. In addition, two different types of electricity wholesale markets are used to generate DR signals. To assess the performance of DDRC, the control algorithms are improved to consider the characteristics of building envelopes and HVAC equipment. Also, DDRC is designed to be deployed in various areas with different electricity wholesale markets. The indoor thermal comfort on temperature and humidity are considered based on ASHRAE standard 55. Finally, DDRC is developed to a hardware using embedded system. The hardware of DDRC is based on Advanced RISC Microcontroller (ARM) processor and senses both indoor and outdoor environment with Internet connection capability for DR. In addition, user friendly Graphic User Interface (GUI) is generated to control DDRC. Advisors/Committee Members: Baldick, Ross (advisor), Novoselac, Atila (advisor), Arapostathis, Aristotle (committee member), Liedl, Petra G (committee member), Kwasinski, Alexis (committee member).

Subjects/Keywords: Smart grid; Demand response; Real-time price; HVAC; Thermostat

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APA (6^th Edition):

Yoon, J. H. (2015). Demand side load control in residential buildings with HVAC controller for demand response. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/46552

Chicago Manual of Style (16^th Edition):

Yoon, Ji Hoon. “Demand side load control in residential buildings with HVAC controller for demand response.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/46552.

MLA Handbook (7^th Edition):

Yoon, Ji Hoon. “Demand side load control in residential buildings with HVAC controller for demand response.” 2015. Web. 12 Apr 2021.

Vancouver:

Yoon JH. Demand side load control in residential buildings with HVAC controller for demand response. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/46552.

Council of Science Editors:

Yoon JH. Demand side load control in residential buildings with HVAC controller for demand response. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/46552

University of Texas – Austin

2. -6644-4235. Using fast-responding resources to control frequency in a power system.

Degree: PhD, Electrical and Computer Engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/72764

► Frequency control is one of the major concerns of power system operators. Frequency varies as the result of a supply-demand mismatch. Due to possible destructive… (more)

▼ Frequency control is one of the major concerns of power system operators. Frequency varies as the result of a supply-demand mismatch. Due to possible destructive outcomes of large frequency variations, several mechanisms are in operation to keep supply and demand in balance. Increasing penetration of non-dispatchable intermittent generation resources may increase power supply volatility, which makes frequency control more challenging. Emerging utility-scale storage technologies with reasonable cost have participated in electricity markets in recent years. Because of fast-ramping capabilities of these resources, one of their attractive applications is providing frequency regulation service. However, the amount of energy they can produce or consume is limited due to their restricted storage capabilities. Thus, in spite of their fast response to a deployment signal, their duration of response is bounded. In this thesis, we focus on using fast-responding resources to control frequency in power systems. In this research, the ﬁrst question is if the participation of these resources in the regulation market have any adverse eﬀect on the frequency control performance of the system. If the answer is yes, the next question is what is the best strategy to not only prevent the negative consequences but also improve the beneﬁts of using fast-responding resources for frequency control. For this research, the system of Electric Reliability Council of Texas (ERCOT) is selected. All power system studies related to frequency control require an appropriate dynamic model. In this dissertation, a simpliﬁed model is constructed, which represents the ERCOT system frequency response during a short period of time after a contingency. The model is validated and tuned against system frequency measured by Phasor Measurement Units. Especially in situations of not having information about system individual units, this simpliﬁed model is highly advantageous. However, to study system frequency during normal conditions, a more comprehensive model is essential. Thus, we develop ERCOT Frequency Modeling and Analysis Tool (EFMAT), which has the required level of details and accuracy to simulate system frequency. All proposed approaches of modeling and parameter tuning in this research are also applicable to other power systems. In order to answer our research questions, we start with investigation of ERCOT Fast-Responding Regulation Service (FRRS). For selected historic days, conventional regulation providers are replaced by a storage system providing FRRS. For various capacities of the storage system, frequency is simulated using EFMAT and a system frequency control performance index is calculated. Comparing calculated index of diﬀerent simulations can reveal the eﬀect of FRRS capacity on the system performance. The simulations are repeated for several FRRS deployment strategies similar to the strategies of other North America power markets along with our proposed modiﬁcations. Three diﬀerent storage systems are assumed in the simulations: one with… Advisors/Committee Members: Baldick, Ross (advisor), Santoso, Surya (committee member), Arapostathis, Aristotle (committee member), Bickel, Eric (committee member), Adib, Parviz (committee member).

Subjects/Keywords: Frequency control; Fast-responding resources; Storage system; Frequency regulation service; Power system

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APA (6^th Edition):

-6644-4235. (2016). Using fast-responding resources to control frequency in a power system. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/72764

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Chicago Manual of Style (16^th Edition):

-6644-4235. “Using fast-responding resources to control frequency in a power system.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/72764.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-6644-4235. “Using fast-responding resources to control frequency in a power system.” 2016. Web. 12 Apr 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-6644-4235. Using fast-responding resources to control frequency in a power system. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/72764.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-6644-4235. Using fast-responding resources to control frequency in a power system. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/72764

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

3. -0200-4008. Market strategies for wind power producers considering joint volume-price risks.

Degree: PhD, Electrical and computer engineering, 2018, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/8101

► This dissertation studies the strategies of wind power producers (WPPs) who participate in a two-settlement market composed of a day-ahead (DA) market and a real-time… (more)

▼ This dissertation studies the strategies of wind power producers (WPPs) who participate in a two-settlement market composed of a day-ahead (DA) market and a real-time (RT) market. When the WPPs sell energy to the DA markets, they become exposed to RT market risks from uncertain generation output and highly volatile RT market prices. This joint volume-price risk causes a risk-averse firm to choose to sell less energy than the expected generation, which discourages the WPP from fully enjoying the benefits of participating in forward electricity markets. Moreover, since the joint volume-price risk usually has a negative correlation, failing to consider the correlation will reduce the wind power producer's profit. We first present a comprehensive discussion of the effect of the wind-price correlation on offer strategies of wind power producers. The process of building an advanced offer curve that considers the joint information of wind power and RT prices are suggested. We also explore the sensitivity of the expected profit, value at risk (VaR), and conditional value at risk (CVaR) for the advanced offer curves to the variation in the probabilistic parameters of wind power and RT price. We find that the offer curve that considers wind-price correlation results in a small improvement in expected profit, but a meaningful reduction in risks. The benefits of the advanced offer curves increase as the correlation becomes more negative or the variance of wind power and prices increase. Second, we explore a risk-hedging strategy for WPPs that is applicable to general U.S electricity markets. This dissertation proposes a financial instrument referred to as a risk exchange that enables the wind power producers to trade random net payments from uncertain prices and generation outputs, after the DA market is cleared. A negotiation for the risk exchange is modeled by a bargaining game based on a conflict of interest in determining the amounts of the risk exchange. Both Nash and Rubinstein's bargaining game models are addressed to analyze the risk exchange bargaining game. Numerical examples demonstrate that the risk exchange is able to reduce RT market risks successfully and encourages the wind power producers to sell more energy to the DA market. Lastly, we focus on how the different time resolutions of RT and DA markets affects the profits and offer decisions of WPPs. Considering the difference in the time resolutions allows the WPPs to assess their expected profit more accurately. It also enables the WPPs to build an offer curve that is more profitable. To this end, however, a WPP must forecast wind power and RT price at the time resolution of the RT market which is finer than the one hour used in the DA market, possibly entailing an increase in forecasting error variance and overfitting issue. Inappropriate forecasting may lead to a wrong profit assessment and offer decisions. Advisors/Committee Members: Baldick, Ross (advisor), Arapostathis, Aristotle (committee member), Santoso, Surya (committee member), Hasenbein, John (committee member), Nikolova, Evdokia (committee member).

Subjects/Keywords: Electricity markets; Wind power; Risk hedging; Offer strategy; Bargaining game

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APA (6^th Edition):

-0200-4008. (2018). Market strategies for wind power producers considering joint volume-price risks. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/8101

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-0200-4008. “Market strategies for wind power producers considering joint volume-price risks.” 2018. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://dx.doi.org/10.26153/tsw/8101.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-0200-4008. “Market strategies for wind power producers considering joint volume-price risks.” 2018. Web. 12 Apr 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-0200-4008. Market strategies for wind power producers considering joint volume-price risks. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2018. [cited 2021 Apr 12]. Available from: http://dx.doi.org/10.26153/tsw/8101.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-0200-4008. Market strategies for wind power producers considering joint volume-price risks. [Doctoral Dissertation]. University of Texas – Austin; 2018. Available from: http://dx.doi.org/10.26153/tsw/8101

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

4. -6209-4423. Wind power forecasting and its applications to the power system.

Degree: PhD, Electrical & Computer Engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/31412

► The goal of research in this dissertation is to bring more wind resources into the power grid by mitigating the uncertainty of the current wind… (more)

▼ The goal of research in this dissertation is to bring more wind resources into the power grid by mitigating the uncertainty of the current wind power, by developing a new algorithm to respond to the fluctuation of the future wind power, and by building additional transmission lines to bring more wind resources from a remote area to the load center. First, in order to overcome the wind power uncertainty, the probabilistic and ensemble wind power forecasting is proposed to increase the forecasting accuracy and to deliver the probability density function of the uncertainty. Accurate wind power forecasting reduces the amounts and cost of ancillary services (AS). As the mismatch between the bid and actual amount of delivered energy decreases, the imbalance between supply and demand also decreases. If the forecasting ahead is increased up to 24 hours, accurate wind power forecasting can also help wind farm owners bid the exact amount of wind power in the day ahead (DA) market. Furthermore, wind power owners can use the parametric probabilistic density of error distributions for hedging the price risk and building a better offer curve. Second, a novel algorithm to generate many wind power scenarios as a function of installed capacity of wind power is proposed based on an analysis of the power spectral density of wind power. Scenarios can be used to simulate the power system to estimate the required amount of AS to respond to the fluctuation of future wind power as the installed capacity of wind power increases. Scenarios have statistical characteristics of the future wind power that are regressed as a function of the installed capacity of wind power from the statistical characteristics of the current wind power. This algorithm can generate many possible scenarios to simulate the power system in many different situations. Third, optimal transmission expansion by simulating the power system with the multiple load and wind power scenarios in different locations is planned to prepare the preliminary result to bring more wind resources in remote areas to the load center in Texas. In this process, the geographical smoothing effects of wind power and the stochastic correlation structure between the load and wind power are considered. Furthermore, the generalized dynamic factor model (GDFM) is used to synthesize load and wind power scenarios to keep their correlation structure. The premise of the GDFM is that a few factors can drive the correlated movements of load and wind power simultaneously, so the scenario generation process is parsimonious. Advisors/Committee Members: Baldick, Ross (advisor), Santoso, Surya (committee member), Arapostathis, Aristotle (committee member), Webber, Michael (committee member), Morton, David (committee member).

Subjects/Keywords: Wind power forecasting; Generalized dynamic factor model; Power spectral density

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APA (6^th Edition):

-6209-4423. (2015). Wind power forecasting and its applications to the power system. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31412

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-6209-4423. “Wind power forecasting and its applications to the power system.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/31412.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-6209-4423. “Wind power forecasting and its applications to the power system.” 2015. Web. 12 Apr 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-6209-4423. Wind power forecasting and its applications to the power system. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/31412.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-6209-4423. Wind power forecasting and its applications to the power system. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31412

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

5. Yang, Sungpil. Robustness properties of quaternion-based attitude control systems.

Degree: PhD, Aerospace Engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/38095

► Both stabilizing and tracking solutions of the rigid-body attitude control problem, using various attitude representations, are now well understood. Based on the sensor availability, numerous… (more)

▼ Both stabilizing and tracking solutions of the rigid-body attitude control problem, using various attitude representations, are now well understood. Based on the sensor availability, numerous full-state feedback or gyro-free output feedback controllers have been proposed and studied. In the dissertation, we revisit classical proportional-derivative (PD) type attitude controllers when the system is subject to uncertainties like time-delay in the feedback loop, measurement errors, external disturbance torques and modeling uncertainties. We not only analyze existing PD-type controllers while considering various types of uncertainties, but also design tracking controllers robust to the system parameter uncertainties. We adopt the quaternion representation for the attitude kinematics so that we can avoid the geometric singularities coming with minimal 3-dimensional parameter representations. For stability and robustness analysis of the PD-type controllers, we do not rely on the linear system framework in which the original dynamics are considered as the sum of the nominal linear part and the nonlinear perturbation part. Instead, another approach is suggested as suitable for the quaternion kinematic representation so that results are not restricted to a neighborhood of the origin. We first deal with one of the common Lyapunov functions used for quaternion-based attitude control problem. Then, through the strictification process, a new Lyapunov function is constructed which can be analyzed based on the standard Lyapunov stability analysis method. As a result, we establish sufficient conditions for locally stability or boundedness of the system subject to aforementioned uncertainties for both PD full-state feedback and PD-like gyro-free output feedback controllers. When our scope is narrowed to the system parameter uncertainties, we propose adaptive controllers that track predefined reference trajectories and estimate the unknown inertial parameters. Specifically, we apply a dynamic scaling-based Immersion and Invariance method for the first time to the attitude tracking problem. We also provide a way to control and estimate the upper bound of a dynamic scaling factor which has not yet been seen in the literature. Advisors/Committee Members: Akella, Maruthi Ram, 1972- (advisor), Bakolas, Efstathios (committee member), Arapostathis, Aristotle (committee member), Acikmese, Behcet (committee member), Mazenc, Frederic (committee member).

Subjects/Keywords: Attitude control; Quaternion kinematics; Robustness; Adaptive control; Uncertainties; Delay; Disturbances

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APA (6^th Edition):

Yang, S. (2016). Robustness properties of quaternion-based attitude control systems. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/38095

Chicago Manual of Style (16^th Edition):

Yang, Sungpil. “Robustness properties of quaternion-based attitude control systems.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/38095.

MLA Handbook (7^th Edition):

Yang, Sungpil. “Robustness properties of quaternion-based attitude control systems.” 2016. Web. 12 Apr 2021.

Vancouver:

Yang S. Robustness properties of quaternion-based attitude control systems. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/38095.

Council of Science Editors:

Yang S. Robustness properties of quaternion-based attitude control systems. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/38095

University of Texas – Austin

6. DeAngelis, David. Encouraging expert participation in online communities.

Degree: PhD, Electrical and Computer Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-08-4161

► In concept, online communities allow people to access the wide range of knowledge and abilities of a heterogeneous group of users. In reality, current implementations… (more)

▼ In concept, online communities allow people to access the wide range of knowledge and abilities of a heterogeneous group of users. In reality, current implementations of various online communities suffer from a lack of participation by the most qualified users. The participation of qualified users, or experts, is crucial to the social welfare and widespread adoption of such systems. This research proposes techniques for identifying the most valuable contributors to several classes of online communities, including question and answer (QA) forums and other content-oriented social networks. Once these target users are identified, content recommendation and novel quantitative incentives can be used to encourage their participation. This research represents an in-depth investigation into QA systems, while the major findings are widely applicable to online communities in general. An algorithm for recommending content in a QA forum is introduced which can route questions to the most appropriate responders. This increases the efficiency of the system and reduces the time investment of an expert responder by eliminating the need to search for potential questions to answer. This recommender is analyzed using real data captured from Yahoo! Answers. Additionally, an incentive mechanism for QA systems based on a novel class of incentives is developed. This mechanism relies on systemic rewards, or rewards that have tangible value within the framework of the online community. This research shows that human users have a strong preference for reciprocal systemic rewards over traditional rewards, and a simulation of a QA system based on an incentive that utilizes these reciprocal rewards outperforms a leading incentive mechanism according to expert participation. An architecture is developed for a QA system built upon content recommendation and this novel incentive mechanism. This research shows that it is possible to identify the most valuable contributors to an online community and motivate their participation through a novel incentive mechanism based on meaningful rewards. Advisors/Committee Members: Barber, K. Suzanne (advisor), Perry, Dewayne E. (committee member), Arapostathis, Aristotle (committee member), Julien, Christine (committee member), Francisco-Revilla, Luis (committee member).

Subjects/Keywords: Social networks; Trust in multi-agent systems; User modeling; Question and answer systems; Online communities

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APA (6^th Edition):

DeAngelis, D. (2011). Encouraging expert participation in online communities. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-08-4161

Chicago Manual of Style (16^th Edition):

DeAngelis, David. “Encouraging expert participation in online communities.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2011-08-4161.

MLA Handbook (7^th Edition):

DeAngelis, David. “Encouraging expert participation in online communities.” 2011. Web. 12 Apr 2021.

Vancouver:

DeAngelis D. Encouraging expert participation in online communities. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4161.

Council of Science Editors:

DeAngelis D. Encouraging expert participation in online communities. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4161

University of Texas – Austin

7. Onwuchekwa, Chimaobi Nwachukwu. Analysis and control of power converters with instantaneous constant-power loads.

Degree: PhD, Electrical and Computer Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-08-4002

► This dissertation examines the effects of instantaneous constant-power loads (CPLs) on power converters. These CPLs are prevalent in distributed power architectures and are also present… (more)

▼ This dissertation examines the effects of instantaneous constant-power loads (CPLs) on power converters. These CPLs are prevalent in distributed power architectures and are also present in certain motor-drive applications. CPLs introduce a destabilizing nonlinear effect on power converters through an inverse voltage term that leads to significant oscillations in the main bus voltage or to its collapse. Boundary control is studied in order to stabilize dc-dc converters with instantaneous CPLs. The three basic topologies are studied: buck, boost, and buck-boost. Converter dynamics are analyzed in both switching states and the various operating regions of switch interaction with a first-order switching surface are identified. The analysis reveals important characteristics of CPLs. For non-minimum phase converters, in order to avoid issues related with the fact that the closed-loop state-dependent switching function is undefined on the switching surface, reflective mode solutions to both converter systems are defined in the sense of Filippov. Sufficient conditions for large-signal stability of the closed loop converter operating points are established. It is shown that first-order switching surfaces with negative slopes achieve large-signal stability, while positive slopes lead to instability. In particular, for the boost converter it is illustrated via simulations and experiments that positive slopes may lead to another closed-loop limit cycle. It is also shown that instability as well as system-stalling, which is termed the invariant-set problem, may still occur in reflective mode. However, a hysteresis band that contains the designed boundary may be used to prevent system-stalling, and also allow for a practical implementation of the controller by avoiding chattering. Regulation is also achieved. The dynamic behavior of single-phase full-wave uncontrolled rectifiers with instantaneous CPLs is also explored. Stable operation is shown to be dependent on initial condition and circuit parameters, which must fall within reasonable ranges that validate a CPL model. A necessary condition for stable operation of the rectifier system is thus derived. Furthermore, input and output characteristics of the rectifier with a CPL are investigated, and comparisons are made with the resistive case. A more complete model for the rectifier system that incorporates line-voltage distortion is also utilized to study the rectifier system. Simulations and experimental results are included for verification. Advisors/Committee Members: Kwasinski, Alexis (advisor), Grady, William M. (committee member), Driga, Mircea (committee member), Arapostathis, Aristotle (committee member), Akella, Maruthi (committee member).

Subjects/Keywords: Boundary control; Constant-power loads; Distributed power; Nonlinear system

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APA (6^th Edition):

Onwuchekwa, C. N. (2011). Analysis and control of power converters with instantaneous constant-power loads. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-08-4002

Chicago Manual of Style (16^th Edition):

Onwuchekwa, Chimaobi Nwachukwu. “Analysis and control of power converters with instantaneous constant-power loads.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2011-08-4002.

MLA Handbook (7^th Edition):

Onwuchekwa, Chimaobi Nwachukwu. “Analysis and control of power converters with instantaneous constant-power loads.” 2011. Web. 12 Apr 2021.

Vancouver:

Onwuchekwa CN. Analysis and control of power converters with instantaneous constant-power loads. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4002.

Council of Science Editors:

Onwuchekwa CN. Analysis and control of power converters with instantaneous constant-power loads. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-08-4002

University of Texas – Austin

8. -4449-4172. On spatial birth-death and matching processes, and Poisson shot-noise fields.

Degree: PhD, Mathematics, 2019, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/2894

► In this dissertation we deal with certain spatial stochastic processes that are closely related to Spatial birth-death (SBD) processes. These processes are stochastic processes that… (more)

Subjects/Keywords: Spatial birth-death processes; Stochastic geometry; Large deviations of point processes

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APA (6^th Edition):

-4449-4172. (2019). On spatial birth-death and matching processes, and Poisson shot-noise fields. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/2894

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Chicago Manual of Style (16^th Edition):

-4449-4172. “On spatial birth-death and matching processes, and Poisson shot-noise fields.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://dx.doi.org/10.26153/tsw/2894.

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Author name may be incomplete

MLA Handbook (7^th Edition):

-4449-4172. “On spatial birth-death and matching processes, and Poisson shot-noise fields.” 2019. Web. 12 Apr 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-4449-4172. On spatial birth-death and matching processes, and Poisson shot-noise fields. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Apr 12]. Available from: http://dx.doi.org/10.26153/tsw/2894.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-4449-4172. On spatial birth-death and matching processes, and Poisson shot-noise fields. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/2894

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

University of Texas – Austin

9. -3517-1144. Energy storage sizing for low-inertia microgrids, and lessons learned from a potential microgrid.

Degree: PhD, Electrical and Computer engineering, 2016, University of Texas – Austin

URL: http://hdl.handle.net/2152/40268

► The coordinated control of multiple distributed generators in a microgrid and the preservation of adequate system inertia in real-time operations are some of the principal… (more)

▼ The coordinated control of multiple distributed generators in a microgrid and the preservation of adequate system inertia in real-time operations are some of the principal technical challenges for stable microgrid operation. One issue in particular pertains to grid-tied inverters, which, as mandated by present standards, are only permitted to operate at unity power factor, thereby requiring the microgrid’s synchronous generators to operate at a low power factor. This behavior accordingly introduces ramifications by limiting the generator’s active power output, which would compromise frequency and voltage stability margins. Consideration is also given to the effect of line impedances, since interconnecting microgrid lines can be described by a variety of X/R ratios that affect the control and flow of active and reactive power. Moreover, the absence of a stiff grid presents control challenges for grid-tied inverters due to the inverters’ tendency to regulate the voltage at the point of common coupling. These same inverters also jeopardize microgrid stability due to their low equivalent inertia as traditional forms of generation (i.e., spinning sources) become displaced by inertia-less inverters. Because of this low microgrid inertia, fluctuations in the output power of renewable energy sources or changes in local load levels may lead to power quality or frequency/voltage stability concerns. Therefore, energy storage sizing is investigated in this dissertation, as it is closely related to the stability analysis of microgrids. Furthermore, an existing residential community (in Austin, TX) described by a moderate penetration of photovoltaic sources and electric vehicle charging is considered, and the implications of said community being retrofitted to a microgrid are examined. Advisors/Committee Members: Baldick, Ross (advisor), Kwasinski, Alexis (advisor), Arapostathis, Aristotle (committee member), Hallock, Gary (committee member), Uriarte, Fabian (committee member).

Subjects/Keywords: Microgrid; Stability; Frequency; Voltage; Energy storage

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APA (6^th Edition):

-3517-1144. (2016). Energy storage sizing for low-inertia microgrids, and lessons learned from a potential microgrid. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/40268

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Chicago Manual of Style (16^th Edition):

-3517-1144. “Energy storage sizing for low-inertia microgrids, and lessons learned from a potential microgrid.” 2016. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/40268.

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MLA Handbook (7^th Edition):

-3517-1144. “Energy storage sizing for low-inertia microgrids, and lessons learned from a potential microgrid.” 2016. Web. 12 Apr 2021.

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Author name may be incomplete

Vancouver:

-3517-1144. Energy storage sizing for low-inertia microgrids, and lessons learned from a potential microgrid. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2016. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/40268.

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Author name may be incomplete

Council of Science Editors:

-3517-1144. Energy storage sizing for low-inertia microgrids, and lessons learned from a potential microgrid. [Doctoral Dissertation]. University of Texas – Austin; 2016. Available from: http://hdl.handle.net/2152/40268

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University of Texas – Austin

10. -7683-5336. Data analytics applications to fault locations and overcurrent protection devices.

Degree: PhD, Electrical and Computer Engineering, 2019, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/3062

► Power quality (PQ) monitors installed in transmission and distribution systems record disturbance events occurring in the system, such as root mean square (RMS) variations and… (more)

▼ Power quality (PQ) monitors installed in transmission and distribution systems record disturbance events occurring in the system, such as root mean square (RMS) variations and transients caused by short-circuit faults, transformer energizing, or capacitor switching around the clock, resulting in a large amount of data. Although the collected data contain valuable information about the system, they are often merely stored without any further analysis. Analysis of these data presents opportunities for improving the performance of power systems as well as for monitoring the health of the grid as a whole. The general objective of this proposal is to develop algorithms that make use of three phase voltage and current measurements recorded from the power quality monitors. Specifically, algorithms are developed for the analysis of (1) short circuit faults with their locations (fault analytics) and (2) overcurrent protection devices installed in the system (device analytics). The fault analytics module is used to identify fault events among other power quality events and estimates the location to the fault occurring in the system. The proposed method uses variable window size in calculating phasors and estimates a single fault location that is more accurate than the multiple locations estimated by the conventional approach using Fourier and cosine filters. The device analytics module aims to evaluate the overcurrent protection devices operating to isolate short-circuit faults from the system. This module identifies recloser and fuse operations and estimates the empirical inverse time-current characteristics of the devices. The results of the device analytics are used to evaluate device opening intervals and coordination and to further narrow down fault location because faults are located downstream from the clearing device. Finally, the dissertation presents a data analytics framework and an open power quality disturbance event schema. The schema is developed to promote the sharing of data recording PQ disturbance events and the metadata providing descriptive and quantitative analysis of the events. Advisors/Committee Members: Santoso, Surya (advisor), Baldick, Ross (committee member), Hallock, Gary (committee member), Arapostathis, Aristotle (committee member), Karadkar, Unmil (committee member).

Subjects/Keywords: Fault location; Power system faults; Power system measurements; Power system reliability; Power system protection; Power quality; Intelligent systems

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APA (6^th Edition):

-7683-5336. (2019). Data analytics applications to fault locations and overcurrent protection devices. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/3062

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Chicago Manual of Style (16^th Edition):

-7683-5336. “Data analytics applications to fault locations and overcurrent protection devices.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://dx.doi.org/10.26153/tsw/3062.

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Author name may be incomplete

MLA Handbook (7^th Edition):

-7683-5336. “Data analytics applications to fault locations and overcurrent protection devices.” 2019. Web. 12 Apr 2021.

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Author name may be incomplete

Vancouver:

-7683-5336. Data analytics applications to fault locations and overcurrent protection devices. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Apr 12]. Available from: http://dx.doi.org/10.26153/tsw/3062.

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Author name may be incomplete

Council of Science Editors:

-7683-5336. Data analytics applications to fault locations and overcurrent protection devices. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/3062

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Author name may be incomplete

University of Texas – Austin

11. Kim, Jaeweon. Bandwidth and power efficient wireless spectrum sensing networks.

Degree: PhD, Electrical and Computer Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-05-2727

► Opportunistic spectrum reuse is a promising solution to the two main causes of spectrum scarcity: most of the radio frequency (RF) bands are allocated by… (more)

▼ Opportunistic spectrum reuse is a promising solution to the two main causes of spectrum scarcity: most of the radio frequency (RF) bands are allocated by static licensing, and many of them are underutilized. Frequency spectrum can be more efficiently utilized by allowing communication systems to find out unoccupied spectrum and to use it harmlessly to the licensed users. Reliable sensing of these spectral opportunities is perhaps the most essential element of this technology. Despite significant work on spectrum sensing, further performance improvement is needed to approach its full potential. In this dissertation, wireless spectrum sensing networks (WSSNs) are investigated for reliable detection of the primary (licensed) users, that enables efficient spectrum utilization and minimal power consumption in communications. Reliable spectrum sensing is studied in depth in two parts: a single sensor algorithm and then cooperative sensing are proposed based on a spectral covariance sensing (SCS). The first novel contribution uses different statistical correlations of the received signal and noise in the frequency domain. This detector is analyzed theoretically and verified through realistic simulations using actual digital television signals captured in the US. The proposed SCS detector achieves significant improvement over the existing solutions in terms of sensitivity and also robustness to noise uncertainty. Second, SCS is extended to a distributed WSSN architecture to allow cooperation between 2 or more sensors. Theoretical limits of cooperative white space sensing under correlated shadowing are investigated. We analyze the probability of a false alarm when each node in the WSSN detects the white space using the SCS detection and the base station combines individual results to make the final decision. The detection performance compared with that of the cooperative energy detector is improved and fewer sensor nodes are needed to achieve the same sensitivity. Third, we propose a low power source coding and modulation scheme for power efficient communication between the sensor nodes in WSSN. Complete analysis shows that the proposed scheme not only minimizes total power consumption in the network but also improves bit error rate (BER). Advisors/Committee Members: Andrews, Jeffrey G. (advisor), Vishwanath, Sriram (committee member), Arapostathis, Aristotle (committee member), Vikalo, Haris (committee member), Barr, Ronald E. (committee member).

Subjects/Keywords: Spectrum sensing; Cognitive radio; Spectral covariance; Minimum energy; CDMA; Wireless networks

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APA (6^th Edition):

Kim, J. (2011). Bandwidth and power efficient wireless spectrum sensing networks. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-05-2727

Chicago Manual of Style (16^th Edition):

Kim, Jaeweon. “Bandwidth and power efficient wireless spectrum sensing networks.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2011-05-2727.

MLA Handbook (7^th Edition):

Kim, Jaeweon. “Bandwidth and power efficient wireless spectrum sensing networks.” 2011. Web. 12 Apr 2021.

Vancouver:

Kim J. Bandwidth and power efficient wireless spectrum sensing networks. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-2727.

Council of Science Editors:

Kim J. Bandwidth and power efficient wireless spectrum sensing networks. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-05-2727

12. Niu, Yichuan. Quantifying and mitigating wind power variability.

Degree: PhD, Electrical and Computer Engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/32845

► Understanding variability and unpredictability of wind power is essential for improving power system reliability and energy dispatch in transmission and distribution systems. The research presented… (more)

▼ Understanding variability and unpredictability of wind power is essential for improving power system reliability and energy dispatch in transmission and distribution systems. The research presented herein intends to address a major challenge in managing and utilizing wind energy with mitigated fluctuation and intermittency. Caused by the varying wind speed, power variability can be explained as power imbalances. These imbalances create power surplus or deficiency in respect to the desired demand. To ameliorate the aforementioned issue, the fluctuating wind energy needs to be properly quantified, controlled, and re-distributed to the grid. The first major study in this dissertations is to develop accurate wind turbine models and model reductions to generate wind power time-series in a laboratory time-efficient manner. Reliable wind turbine models can also perform power control events and acquire dynamic responses more realistic to a real-world condition. Therefore, a Type 4 direct-drive wind turbine with power electronic converters has been modeled and designed with detailed aerodynamic and electric parameters based on a given generator. Later, using averaging and approximation techniques for power electronic circuits, the order of the original model is lowered to boost the computational efficiency for simulating long-term wind speed data. To quantify the wind power time-series, efforts are made to enhance adaptability and robustness of the original conditional range metric (CRM) algorithm that has been proposed by literatures for quantitatively assessing the power variability within a certain time frame. The improved CRM performs better under scarce and noisy time-series data with a reduced computational complexity. Rather than using a discrete probability model, the improved method implements a continuous gamma distribution with parameters estimated by the maximum likelihood estimators. With the leverage from the aforementioned work, a wind farm level behavior can be revealed by analyzing the data through long-term simulations using individual wind turbine models. Mitigating the power variability by reserved generation sources is attempted and the generation scenarios are generalized using an unsupervised machine learning algorithm regarding power correlations of those individual wind turbines. A systematic blueprint for reducing intra-hour power variations via coordinating a fast- and a slow- response energy storage systems (ESS) has been proposed. Methods for sizing, coordination control, ESS regulation, and power dispatch schemes are illustrated in detail. Applying the real-world data, these methods have been demonstrated desirable for reducing short-term wind power variability to an expected level. Advisors/Committee Members: Santoso, Surya (advisor), Arapostathis, Aristotle (committee member), Baldick, Ross (committee member), Longoria, Raul G. (committee member), Tiwari, Mohit (committee member).

Subjects/Keywords: Wind power variability; Statistics; Conditional range metric; Energy storage system; Wind turbine; Model reduction; Variability mitigation; Probability; Gamma distribution; Bayesian inference

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APA (6^th Edition):

Niu, Y. (2015). Quantifying and mitigating wind power variability. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/32845

Chicago Manual of Style (16^th Edition):

Niu, Yichuan. “Quantifying and mitigating wind power variability.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/32845.

MLA Handbook (7^th Edition):

Niu, Yichuan. “Quantifying and mitigating wind power variability.” 2015. Web. 12 Apr 2021.

Vancouver:

Niu Y. Quantifying and mitigating wind power variability. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/32845.

Council of Science Editors:

Niu Y. Quantifying and mitigating wind power variability. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/32845

University of Texas – Austin

13. -8916-5076. Post-contingency states representation and redispatch for restoration in power systems operation.

Degree: PhD, Electrical and Computer Engineering, 2018, University of Texas – Austin

URL: http://hdl.handle.net/2152/63632

► In this treatise, we will present a dynamic version of the Security Constrained Optimal Power Flow (SCOPF) problem, the "Look Ahead Security Constrained Optimal Power… (more)

▼ In this treatise, we will present a dynamic version of the Security Constrained Optimal Power Flow (SCOPF) problem, the "Look Ahead Security Constrained Optimal Power Flow" (LASCOPF) problem with post-contingency states representation and redispatch scheme for restoration to normal operation, following an outage represented in the mathematical formulation. We will also propose a distributed algorithm to solve the OPF, SCOPF, and LASCOPF problems. The objective of the problem is to minimize the cost of operation, over a number of dispatch intervals and across all contingency scenarios subject to the constraints of the network. It is, therefore, a large optimization problem, requiring an effective distributed solution method. As one of the means to address this challenge, we will be extending the Proximal Message Passing (PMP) algorithmic framework, which is based on another algorithm, called Alternating Direction Method of Multipliers (ADMM) and combine it with the Auxiliary Problem Principle (APP). The resulting algorithm, which we hereafter will call Auxiliary Proximal Message Passing (APMP) is extremely scalable with respect to both network size and the number of scenarios. We implement a look-ahead contingency planning, representing the post-contingency states of the system ahead of time, in a Receding Horizon Control (RHC) or, Model Predictive Control (MPC) type of formulation. One goal of this work is to particularly focus our attention on the trajectories of post-contingency line temperature rise, line MW flow rise, and line current rise and try to limit them through our proposed method. We also investigate how to reduce the computational burden. The reason for paying particular attention to line temperature rise and limiting the same, is the intention of the present scheme to make the most use of the existing transmission capability, without costly transmission upgrades. The means of attaining that goal is to make use of short term thermal overload rating and dynamic thermal limit, and in the event of an actual outage, modifying the dispatch in such a way, that the flows on the remaining lines can be brought back to within allowed values in a given time interval. We demonstrate the effectiveness of our distributed method with a series of numerical simulations based on some simple systems and the IEEE test systems. Finally, we conclude, with a suggestion to some possible future research directions. Advisors/Committee Members: Baldick, Ross (advisor), Santoso, Surya (committee member), Caramanis, Constantine (committee member), Arapostathis, Aristotle (committee member), Hasenbein, John J (committee member).

Subjects/Keywords: Distributed optimization; Convex optimization; Optimal power flow (OPF); Security constrained optimal power flow (SCOPF); Look-ahead security constrained optimal power flow (LASCOPF); Alternating direction method of multipliers (ADMM); Proximal message passing (PMP); Auxiliary problem principle (APP)

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APA (6^th Edition):

-8916-5076. (2018). Post-contingency states representation and redispatch for restoration in power systems operation. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/63632

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Chicago Manual of Style (16^th Edition):

-8916-5076. “Post-contingency states representation and redispatch for restoration in power systems operation.” 2018. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/63632.

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MLA Handbook (7^th Edition):

-8916-5076. “Post-contingency states representation and redispatch for restoration in power systems operation.” 2018. Web. 12 Apr 2021.

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Author name may be incomplete

Vancouver:

-8916-5076. Post-contingency states representation and redispatch for restoration in power systems operation. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2018. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/63632.

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Author name may be incomplete

Council of Science Editors:

-8916-5076. Post-contingency states representation and redispatch for restoration in power systems operation. [Doctoral Dissertation]. University of Texas – Austin; 2018. Available from: http://hdl.handle.net/2152/63632

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14. Duque, Luis Felipe. The double obstacle problem and the two membranes problem.

Degree: PhD, Mathematics, 2018, University of Texas – Austin

URL: http://hdl.handle.net/2152/68152

► In the first part of this dissertation, we study the existence, regularity and the free boundary of the double obstacle problem in different formulations that… (more)

Subjects/Keywords: Differential equations; Free boundary problems; Double membranes problem; Double obstacle problem; Obstacle problem; Regularity

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APA (6^th Edition):

Duque, L. F. (2018). The double obstacle problem and the two membranes problem. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/68152

Chicago Manual of Style (16^th Edition):

Duque, Luis Felipe. “The double obstacle problem and the two membranes problem.” 2018. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/68152.

MLA Handbook (7^th Edition):

Duque, Luis Felipe. “The double obstacle problem and the two membranes problem.” 2018. Web. 12 Apr 2021.

Vancouver:

Duque LF. The double obstacle problem and the two membranes problem. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2018. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/68152.

Council of Science Editors:

Duque LF. The double obstacle problem and the two membranes problem. [Doctoral Dissertation]. University of Texas – Austin; 2018. Available from: http://hdl.handle.net/2152/68152

15. Kai, Moses An. Implementation and lessons learned from the Texas Synchrophasor Network.

Degree: PhD, Electrical and Computer Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/19468

► For decades, power engineers have used simulations to predict grid stability and voltage phase angles. Only recently have equipment been available to actually measure phase… (more)

Subjects/Keywords: Phasor; Synchrophasor network; Synchronized phasor network; Texas network; Phasor measurement unit; Synchrophasor Analysis

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APA (6^th Edition):

Kai, M. A. (2012). Implementation and lessons learned from the Texas Synchrophasor Network. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/19468

Chicago Manual of Style (16^th Edition):

Kai, Moses An. “Implementation and lessons learned from the Texas Synchrophasor Network.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/19468.

MLA Handbook (7^th Edition):

Kai, Moses An. “Implementation and lessons learned from the Texas Synchrophasor Network.” 2012. Web. 12 Apr 2021.

Vancouver:

Kai MA. Implementation and lessons learned from the Texas Synchrophasor Network. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/19468.

Council of Science Editors:

Kai MA. Implementation and lessons learned from the Texas Synchrophasor Network. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/19468

16. Han, David Ching-Wey. Action selection and coordination of autonomous agents for UAV surveillance.

Degree: PhD, Electrical and Computer Engineering, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-12-4486

► Agents, by definition, (1) are situated in an environment upon which their actions affect changes and (2) have some level of autonomy from the control… (more)

Subjects/Keywords: Autonomous agents; Action selection; Commitment; UAV

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APA (6^th Edition):

Han, D. C. (2011). Action selection and coordination of autonomous agents for UAV surveillance. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-12-4486

Chicago Manual of Style (16^th Edition):

Han, David Ching-Wey. “Action selection and coordination of autonomous agents for UAV surveillance.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2011-12-4486.

MLA Handbook (7^th Edition):

Han, David Ching-Wey. “Action selection and coordination of autonomous agents for UAV surveillance.” 2011. Web. 12 Apr 2021.

Vancouver:

Han DC. Action selection and coordination of autonomous agents for UAV surveillance. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4486.

Council of Science Editors:

Han DC. Action selection and coordination of autonomous agents for UAV surveillance. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4486

17. Srinivasan, Mahesh. Hierarchical control of dc microgrids with constant power loads.

Degree: PhD, Electrical and Computer Engineering, 2017, University of Texas – Austin

URL: http://hdl.handle.net/2152/62067

► This dissertation proposes general methodologies for designing hierarchical control schemes for dc microgrids loaded by constant power loads (CPLs). CPLs form a major proportion of… (more)

▼ This dissertation proposes general methodologies for designing hierarchical control schemes for dc microgrids loaded by constant power loads (CPLs). CPLs form a major proportion of the system loads in many microgrids. Without proper control, CPLs present destabilizing effect at the dc microgrid. In addition to stable operation of microgrid, proper current sharing among paralleled sources is essential. The proposed hierarchical control strategy consists of two control levels. The lower level consists of droop-based primary controllers which enables current-sharing among paralleled sources and also damps limit cycle oscillations due to CPLs. The higher level consists of secondary controller which compensates for voltage deviations due to primary controller. This higher level is implemented either as autonomous controllers or as a centralized controller. In the case of autonomous secondary controllers, they operate alongside of primary controllers in each of the paralleled converters. In the case of centralized secondary controller, a remote secondary controller uses a high speed communication link to communicate to local controllers. Interfacing sources with different characteristics and voltage ranges necessitates the use of complex converter topologies. As an initial step towards implementing hierarchical control scheme for such microgrids with CPLs, a linear controller is proposed for dc microgrids with standalone SEPIC, Cuk and Zeta converters. During the first stage of the two stage controller, limit cycle oscillations are damped by inserting a virtual resistance in series with the converter input inductor. During the second stage, an integral controller is added to the first stage to compensate for voltage deviations. For microgrids containing different converter topologies, stability of equilibrium points is examined and stability conditions are derived and explained. Experiments performed on a prototype microgrid are used to verify the proposed control laws. Expanding study on stability of microgrids, the maximum real power load in a dc microgrid bus is traced geometrically. The generalized circle diagram approach used in a conventional power system is modified for this purpose. The different types of buses present in a dc microgrid are described and the locus of operating points is obtained. The proposed method is verified by simulations on an example dc microgrid. Advisors/Committee Members: Baldick, Ross (advisor), Kwasinski, Alexis (committee member), Arapostathis, Aristotle (committee member), Hallock, Gary (committee member), Hebner, Robert (committee member).

Subjects/Keywords: Microgrids; Constant power loads; Power electronic converters; Stability

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APA (6^th Edition):

Srinivasan, M. (2017). Hierarchical control of dc microgrids with constant power loads. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/62067

Chicago Manual of Style (16^th Edition):

Srinivasan, Mahesh. “Hierarchical control of dc microgrids with constant power loads.” 2017. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/62067.

MLA Handbook (7^th Edition):

Srinivasan, Mahesh. “Hierarchical control of dc microgrids with constant power loads.” 2017. Web. 12 Apr 2021.

Vancouver:

Srinivasan M. Hierarchical control of dc microgrids with constant power loads. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2017. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/62067.

Council of Science Editors:

Srinivasan M. Hierarchical control of dc microgrids with constant power loads. [Doctoral Dissertation]. University of Texas – Austin; 2017. Available from: http://hdl.handle.net/2152/62067

18. Kim, Myungchin. Design and operation of modular microgrids.

Degree: PhD, Electrical and Computer engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/31416

► Microgrids are being considered as a solution for implementing more reliable and flexible power systems compared to the conventional power grid. Various factors, such as… (more)

▼ Microgrids are being considered as a solution for implementing more reliable and flexible power systems compared to the conventional power grid. Various factors, such as low system inertia, might make the task of microgrid design and operation to be nontrivial. In order to address the needs for operational flexibility in a simpler manner, this dissertation discusses modular approaches for design and operation of microgrids. This research investigates Active Power Distribution Nodes (APDNs), which is a storage integrated power electronic interface, as an interface block for designing modular microgrids. To perform both voltage/current regulation and energy management of APDNs, two hierarchical control frameworks for APDNs are proposed. The first framework focuses on maintaining the charge level of the embedded energy storage at the highest available level to increase system availability, and the second framework focuses on autonomous power sharing, and storage management. The detailed design process, control performance and stability characteristics are also studied. The performance is also verified by both simulation and experiments. The control approaches enable application of APDNs as a power router realizing distributed energy management. The decentralized configuration also increases modularity and availability of power networks by preventing single point-of-failures. The advantages of using APDNs as a connection interface inside a power network are discussed from an availability perspective by performing a comparison using Markov-based availability models. Furthermore, the operation of APDNs as power buffers is explored and the application of APDNs enabling modular implementation of microgrids is also studied. APDNs enable the system expansion process—i.e. connecting new loads to the original system—to be performed without modifying the configuration of the original system. The analysis results show that a fault-tolerant microgrid with an open architecture can be realized in a modular manner with APDNs. APDNs also enable simplified selectivity planning for system protection. The effect of modular operation on microgrids is also studied by using an inertia index. The index not only provides insights on how system performance is affected by modular operation of modular microgrids, but is also used to develop a simpler operation strategy to mitigate the effect of plug and play operations. Advisors/Committee Members: Baldick, Ross (advisor), Kwasinski, Alexis (advisor), Arapostathis, Aristotle (committee member), Hallock, Gary (committee member), Hebner, Robert (committee member).

Subjects/Keywords: Power control; Energy management; Hiearchical control; Microgrids

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APA (6^th Edition):

Kim, M. (2015). Design and operation of modular microgrids. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31416

Chicago Manual of Style (16^th Edition):

Kim, Myungchin. “Design and operation of modular microgrids.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/31416.

MLA Handbook (7^th Edition):

Kim, Myungchin. “Design and operation of modular microgrids.” 2015. Web. 12 Apr 2021.

Vancouver:

Kim M. Design and operation of modular microgrids. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/31416.

Council of Science Editors:

Kim M. Design and operation of modular microgrids. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31416

19. Vivas, Hernán Agustín. The two membranes problem for fully nonlinear local and nonlocal operators.

Degree: PhD, Mathematics, 2019, University of Texas – Austin

URL: http://dx.doi.org/10.26153/tsw/1481

► We study the Two Membranes Problem for fully nonlinear operators both in the local (second order) and nonlocal setting. The problem arises when studying a… (more)

Subjects/Keywords: Fully nonlinear equations; Nonlocal equations; Free boundary problems

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APA (6^th Edition):

Vivas, H. A. (2019). The two membranes problem for fully nonlinear local and nonlocal operators. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://dx.doi.org/10.26153/tsw/1481

Chicago Manual of Style (16^th Edition):

Vivas, Hernán Agustín. “The two membranes problem for fully nonlinear local and nonlocal operators.” 2019. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://dx.doi.org/10.26153/tsw/1481.

MLA Handbook (7^th Edition):

Vivas, Hernán Agustín. “The two membranes problem for fully nonlinear local and nonlocal operators.” 2019. Web. 12 Apr 2021.

Vancouver:

Vivas HA. The two membranes problem for fully nonlinear local and nonlocal operators. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2019. [cited 2021 Apr 12]. Available from: http://dx.doi.org/10.26153/tsw/1481.

Council of Science Editors:

Vivas HA. The two membranes problem for fully nonlinear local and nonlocal operators. [Doctoral Dissertation]. University of Texas – Austin; 2019. Available from: http://dx.doi.org/10.26153/tsw/1481

20. Kwon, Youngsung. Microgrids for base stations : renewable energy prediction and battery bank management for effective state of charge control.

Degree: PhD, Electrical and Computer engineering, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/39298

► Power consumption of cellular communication infrastructure has been considered as a global issue due to its exceptional growth rate. In order to address the challenges… (more)

▼ Power consumption of cellular communication infrastructure has been considered as a global issue due to its exceptional growth rate. In order to address the challenges posed by the increasing power consumption such as carbon emissions, many studies have been focused on designing green cellular networks where carbon emission can be mitigated by reducing power consumption at base stations. Although the previous studies have a common theme of the power saving strategies at base stations, most studies develop the power saving techniques are restricted to cases where the electricity is supplied from conventional grid instead of renewable energy sources. The use of renewable sources poses two main issues such as large footprint and power output variability due to the variation of the natural phenomena driving the sources. This research thus aims at addressing the cellular networks power consumption issue by considering a cluster of neighboring base station in a microgrid configuration, called sustainable wireless area (SWA) that can not only reduce the carbon emission effectively by being powered from distributed renewable sources, but also overcome the renewable power output variability issue by using local energy storage and renewable power prediction two-days. In this sense, this dissertation investigates a novel approach to realize sustainable power supply in a SWA, which incorporates the design of renewable sources, energy storage, and base station electric architecture, and a power control algorithm for their operation. With the aim of mostly powering base stations from renewable sources, the power control strategies are explored based on the predicted renewable energy and battery bank state of charge (SOC). Finally, the effectiveness of the control strategies is evaluated regarding on SWA resiliency and battery bank lifetime aspects. Advisors/Committee Members: Baldick, Ross (advisor), Kwasinski, Alexis (advisor), Arapostathis, Aristotle (committee member), Yu, Edward (committee member), Hebner, Robert (committee member).

Subjects/Keywords: Microgrids; Battery bank state of charge; Renewable energy; Power consumption

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APA (6^th Edition):

Kwon, Y. (2015). Microgrids for base stations : renewable energy prediction and battery bank management for effective state of charge control. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/39298

Chicago Manual of Style (16^th Edition):

Kwon, Youngsung. “Microgrids for base stations : renewable energy prediction and battery bank management for effective state of charge control.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/39298.

MLA Handbook (7^th Edition):

Kwon, Youngsung. “Microgrids for base stations : renewable energy prediction and battery bank management for effective state of charge control.” 2015. Web. 12 Apr 2021.

Vancouver:

Kwon Y. Microgrids for base stations : renewable energy prediction and battery bank management for effective state of charge control. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/39298.

Council of Science Editors:

Kwon Y. Microgrids for base stations : renewable energy prediction and battery bank management for effective state of charge control. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/39298

21. Davila, Gonzalo, 1982-. Problems in non linear PDE : equilibrium configurations in periodic media and non local diffusion.

Degree: PhD, Mathematics, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2012-08-6117

► We study three different problems in non linear PDE. The first problem relates to finding equilibrium configurations in periodic media, more precisely, given an Area-Dirichlet… (more)

Subjects/Keywords: Non linear equations; Stable configurations; Non local diffusion; Non symmetric; Parabolic; Regularity

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APA (6^th Edition):

Davila, Gonzalo, 1. (2012). Problems in non linear PDE : equilibrium configurations in periodic media and non local diffusion. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-08-6117

Chicago Manual of Style (16^th Edition):

Davila, Gonzalo, 1982-. “Problems in non linear PDE : equilibrium configurations in periodic media and non local diffusion.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2012-08-6117.

MLA Handbook (7^th Edition):

Davila, Gonzalo, 1982-. “Problems in non linear PDE : equilibrium configurations in periodic media and non local diffusion.” 2012. Web. 12 Apr 2021.

Vancouver:

Davila, Gonzalo 1. Problems in non linear PDE : equilibrium configurations in periodic media and non local diffusion. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2012-08-6117.

Council of Science Editors:

Davila, Gonzalo 1. Problems in non linear PDE : equilibrium configurations in periodic media and non local diffusion. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-08-6117

22. Kriventsov, Dennis. A local-nonlocal transmission problem.

Degree: PhD, Mathematics, 2015, University of Texas – Austin

URL: http://hdl.handle.net/2152/31513

► We consider solutions to some elliptic equations which change abruptly across a smooth interface. The main equation of interest, motivated by applications to atmospheric dynamics,… (more)

Subjects/Keywords: Nonlocal; Elliptic

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APA (6^th Edition):

Kriventsov, D. (2015). A local-nonlocal transmission problem. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/31513

Chicago Manual of Style (16^th Edition):

Kriventsov, Dennis. “A local-nonlocal transmission problem.” 2015. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/31513.

MLA Handbook (7^th Edition):

Kriventsov, Dennis. “A local-nonlocal transmission problem.” 2015. Web. 12 Apr 2021.

Vancouver:

Kriventsov D. A local-nonlocal transmission problem. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2015. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/31513.

Council of Science Editors:

Kriventsov D. A local-nonlocal transmission problem. [Doctoral Dissertation]. University of Texas – Austin; 2015. Available from: http://hdl.handle.net/2152/31513

23. Hur, Jin, 1973-. Spatial prediction of wind farm outputs for grid integration using the augmented Kriging-based model.

Degree: PhD, Electrical and Computer Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2012-05-5766

► Wind generating resources have been increasing more rapidly than any other renewable generating resources. Wind power forecasting is an important issue for deploying higher wind… (more)

▼ Wind generating resources have been increasing more rapidly than any other renewable generating resources. Wind power forecasting is an important issue for deploying higher wind power penetrations on power grids. The existing work on power output forecasting for wind farms has focused on the temporal issues. As wind farm outputs depend on natural wind resources that vary over space and time, spatial analysis and modeling is also needed. Predictions about suitability for locating new wind generating resources can be performed using spatial modeling. In this dissertation, we propose a new approach to spatial prediction of wind farm outputs for grid integration based on Kriging techniques. First, we investigate the characteristics of wind farm outputs. Wind power is variable, uncontrollable, and uncertain compared to traditional generating resources. In order to understand the characteristics of wind power outputs, we study the variability of wind farm outputs using correlation analysis. We estimate the Power Spectrum Density (PSD) from empirical data. Following Apt[1], we classify the estimated PSD into four frequency ranges having different slopes. We subsequently focus on phenomena relating to the slope of the estimated PSD at a low frequency range because our spatial prediction is based on the period over daily to monthly timescales. Since most of the energy is in the lower frequency components (the second, third, and fourth slope regions have much lower spectral density than the first), the conclusion is that the dominant issues regarding energy will be captured by the low frequency behavior. Consequently, most of the issues regarding energy (at least at longer timescales) will be captured by the first slope, since relatively little energy is in the other regions. We propose the slope estimation model of new wind farm production. When the existing wind farms are highly correlated and the slope of each wind farm is estimated at a low frequency range, we can predict the slope with low frequency components of a new wind farm through the proposed spatial interpolation techniques. Second, we propose a new approach, based on Kriging techniques, to predict wind farm outputs. We introduce Kriging techniques for spatial prediction, modeling semivariograms for spatial correlation, and mathematical formulation of the Kriging system. The aim of spatial modeling is to calculate a target value of wind production at unmeasured or new locations based on the existing values that have already been measured at locations considering the spatial correlation relationship between measured values. We propose the multivariate spatial approach based on Co-Kriging to consider multiple variables for better prediction. Co-Kriging is a multivariate spatial technique to predict spatially distributed and correlated variables and it adds auxiliary variables to a single variable of interest at unmeasured locations. Third, we develop the Augmented Kriging-based Model, to predict power outputs at unmeasured or new wind… Advisors/Committee Members: Baldick, Ross (advisor), Grady, W. Mack (committee member), Arapostathis, Aristotle (committee member), Santoso, Surya (committee member), Kendrick, David A. (committee member).

Subjects/Keywords: Spatial prediction; Augmented sequential outage checker; Wind generating resources; Augmented Kriging-based model; Multivariate prediction model; Grid integration

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APA (6^th Edition):

Hur, Jin, 1. (2012). Spatial prediction of wind farm outputs for grid integration using the augmented Kriging-based model. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-05-5766

Chicago Manual of Style (16^th Edition):

Hur, Jin, 1973-. “Spatial prediction of wind farm outputs for grid integration using the augmented Kriging-based model.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2012-05-5766.

MLA Handbook (7^th Edition):

Hur, Jin, 1973-. “Spatial prediction of wind farm outputs for grid integration using the augmented Kriging-based model.” 2012. Web. 12 Apr 2021.

Vancouver:

Hur, Jin 1. Spatial prediction of wind farm outputs for grid integration using the augmented Kriging-based model. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-5766.

Council of Science Editors:

Hur, Jin 1. Spatial prediction of wind farm outputs for grid integration using the augmented Kriging-based model. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-05-5766

24. Chunodkar, Apurva Arvind. Switching observer design, consensus management, and time-delayed control with applications for rigid-body attitude dynamics.

Degree: PhD, Aerospace Engineering, 2012, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2012-12-6725

► This dissertation addresses three diverse research problems pertaining to rigid body attitude stabilization and control. The problems addressed result in theoretical development for the topics… (more)

▼ This dissertation addresses three diverse research problems pertaining to rigid body attitude stabilization and control. The problems addressed result in theoretical development for the topics of cooperative control, delayed feedback, and state estimation, through the formulation of a novel class of switching observers. In the area of consensus management for cooperative control, the problem of designing torque control laws that synchronize the attitude of a team of rigid bodies under constant, unknown communication time delays is addressed. Directed communication graphs are considered, which encompass both leader-follower and leaderless architectures. A feedback linearization result involving the Modified Rodrigues parameter (MRP) representation of attitude kinematics reduces the attitude dynamics equations to double integrator agents and the remainder of the control effort achieves position consensus. New necessary and sufficient delay dependent stability conditions for the system of double integrator agents are presented. This dissertation also considers the problem of stabilizing attitude dynamics with unknown piecewise-constant delayed feedback. The problem is addressed through stability analysis of switched linear time-invariant and nonlinear timedelay systems. In the case of linear systems with switched delay feedback, a new sufficiency condition for average dwell time result is presented using a complete type Lyapunov-Krasovskii (L-K) functional approach. Further, the corresponding switched system with nonlinear perturbations is proven to be exponentially stable inside a well characterized region of attraction for an appropriately chosen average dwell time. Finally, this dissertation provides a new switching angular velocity observer formulation to the classical problem of rigid body attitude tracking in the absence of angular rate measurements. Exponential convergence of the angular velocity state estimation errors is proven independent of control design by using a novel error signal definition through this switching-type observer. The switching ensures C0 continuity for all the estimated states. Further, the maximum number of switches required by the observer is shown to be finite and that zeno-type behavior cannot occur. A “separation property” type result in the absence of actual angular rate measurements is established, wherein a linear and nonlinear controller utilizes angular velocity estimates from the proposed observer to achieve attitude tracking. Advisors/Committee Members: Akella, Maruthi Ram, 1972- (advisor), Acikmese, Behcet (committee member), Bennighof, Jeffrey (committee member), Lightsey, E Glenn (committee member), Arapostathis, Aristotle (committee member), Hull, David G. (committee member).

Subjects/Keywords: Attitude dynamics; Time-delay; Consensus; Observer; Separation property

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APA (6^th Edition):

Chunodkar, A. A. (2012). Switching observer design, consensus management, and time-delayed control with applications for rigid-body attitude dynamics. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2012-12-6725

Chicago Manual of Style (16^th Edition):

Chunodkar, Apurva Arvind. “Switching observer design, consensus management, and time-delayed control with applications for rigid-body attitude dynamics.” 2012. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2012-12-6725.

MLA Handbook (7^th Edition):

Chunodkar, Apurva Arvind. “Switching observer design, consensus management, and time-delayed control with applications for rigid-body attitude dynamics.” 2012. Web. 12 Apr 2021.

Vancouver:

Chunodkar AA. Switching observer design, consensus management, and time-delayed control with applications for rigid-body attitude dynamics. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2012. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2012-12-6725.

Council of Science Editors:

Chunodkar AA. Switching observer design, consensus management, and time-delayed control with applications for rigid-body attitude dynamics. [Doctoral Dissertation]. University of Texas – Austin; 2012. Available from: http://hdl.handle.net/2152/ETD-UT-2012-12-6725

25. Bae, Sung Woo. Sustainable microgrid and electric vehicle charging demand for a smarter grid.

Degree: PhD, Electrical, 2011, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2011-12-4702

► A “smarter grid” is expected to be more flexible and more reliable than traditional electric power grids. Among technologies required for the “smarter grid” deployment,… (more)

▼ A “smarter grid” is expected to be more flexible and more reliable than traditional electric power grids. Among technologies required for the “smarter grid” deployment, this dissertation presents a sustainable microgrid and a spatial and temporal model of plug-in electric vehicle charging demand for the “smarter grid”. First, this dissertation proposes the dynamic modeling technique and operational strategies for a sustainable microgrid primarily powered by wind and solar energy resources. Multiple-input dc-dc converters are used to interface the renewable energy sources to the main dc bus. The intended application for such a microgrid is an area in which there is interest in achieving a sustainable energy solution, such as a telecommunication site or a residential area. Wind energy variations and rapidly changing solar irradiance are considered in order to explore the effect of such environmental variations to the intended microgrid. The proposed microgrid can be operated in an islanded mode in which it can continue to generate power during natural disasters or grid outages, thus improving disaster resiliency of the “smarter grid”. In addition, this dissertation presents the spatial and temporal model of electric vehicle charging demand for a rapid charging station located near a highway exit. Most previous studies have assumed a fixed charging location and fixed charging time during the off-peak hours for anticipating electric vehicle charging demand. Some other studies have based on limited charging scenarios at typical locations instead of a mathematical model. Therefore, from a distribution system perspective, electric vehicle charging demand is still unidentified quantity which may vary by space and time. In this context, this study proposes a mathematical model of electric vehicle charging demand for a rapid charging station. The mathematical model is based on the fluid dynamic traffic model and the M/M/s queueing theory. Firstly, the arrival rate of discharged vehicles at a charging station is predicted by the fluid dynamic model. Then, charging demand is forecasted by the M/M/s queueing theory with the arrival rate of discharged vehicles. The first letter M of M/M/s indicates that discharged vehicles arrive at a charging station with the Poisson distribution. The second letter M denotes that the time to charge each EV is exponentially distributed, and the third letter s means that there are s identical charging pumps at a charging station. This mathematical model of charging demand may allow grid’s distribution planners to anticipate charging demand at a specific charging station. Advisors/Committee Members: Kwasinski, Alexis (advisor), Arapostathis, Aristotle (committee member), Driga, Mircea D. (committee member), Grady, William M. (committee member), Hebner, Robert E. (committee member).

Subjects/Keywords: Sustainable microgrid; Electric vehicle charging demand; Smart grid

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APA (6^th Edition):

Bae, S. W. (2011). Sustainable microgrid and electric vehicle charging demand for a smarter grid. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2011-12-4702

Chicago Manual of Style (16^th Edition):

Bae, Sung Woo. “Sustainable microgrid and electric vehicle charging demand for a smarter grid.” 2011. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2011-12-4702.

MLA Handbook (7^th Edition):

Bae, Sung Woo. “Sustainable microgrid and electric vehicle charging demand for a smarter grid.” 2011. Web. 12 Apr 2021.

Vancouver:

Bae SW. Sustainable microgrid and electric vehicle charging demand for a smarter grid. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2011. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4702.

Council of Science Editors:

Bae SW. Sustainable microgrid and electric vehicle charging demand for a smarter grid. [Doctoral Dissertation]. University of Texas – Austin; 2011. Available from: http://hdl.handle.net/2152/ETD-UT-2011-12-4702

University of Texas – Austin

26. Budalakoti, Suratna. Expertise modeling and recommendation in online question and answer forums.

Degree: MSin Engineering, Electrical and Computer Engineering, 2009, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2009-12-519

► Question and answer (Q&A) forums, as a way for seeking expertise on the Internet, have seen rapid growth in popularity in recent years. The expertise… (more)

Subjects/Keywords: Recommender systems; Recommender engine; Expertise modeling; Online forums

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APA (6^th Edition):

Budalakoti, S. (2009). Expertise modeling and recommendation in online question and answer forums. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2009-12-519

Chicago Manual of Style (16^th Edition):

Budalakoti, Suratna. “Expertise modeling and recommendation in online question and answer forums.” 2009. Masters Thesis, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2009-12-519.

MLA Handbook (7^th Edition):

Budalakoti, Suratna. “Expertise modeling and recommendation in online question and answer forums.” 2009. Web. 12 Apr 2021.

Vancouver:

Budalakoti S. Expertise modeling and recommendation in online question and answer forums. [Internet] [Masters thesis]. University of Texas – Austin; 2009. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2009-12-519.

Council of Science Editors:

Budalakoti S. Expertise modeling and recommendation in online question and answer forums. [Masters Thesis]. University of Texas – Austin; 2009. Available from: http://hdl.handle.net/2152/ETD-UT-2009-12-519

University of Texas – Austin

27. Kassas, Zaher. Optimal [H-2] and [H-infinity] control of extremely large segmented telescopes.

Degree: MSin Engineering, Aerospace Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-08-1618

► Extremely large telescopes (ELTs) are the next generation of ground-based reflecting telescopes of optical wavelengths. ELTs possess an aperture of more than 20 meters and… (more)

Subjects/Keywords: Telescopes; H-2 control; H-infinity control; LQR control method; Real-time control systems

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APA (6^th Edition):

Kassas, Z. (2010). Optimal [H-2] and [H-infinity] control of extremely large segmented telescopes. (Masters Thesis). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-08-1618

Chicago Manual of Style (16^th Edition):

Kassas, Zaher. “Optimal [H-2] and [H-infinity] control of extremely large segmented telescopes.” 2010. Masters Thesis, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2010-08-1618.

MLA Handbook (7^th Edition):

Kassas, Zaher. “Optimal [H-2] and [H-infinity] control of extremely large segmented telescopes.” 2010. Web. 12 Apr 2021.

Vancouver:

Kassas Z. Optimal [H-2] and [H-infinity] control of extremely large segmented telescopes. [Internet] [Masters thesis]. University of Texas – Austin; 2010. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1618.

Council of Science Editors:

Kassas Z. Optimal [H-2] and [H-infinity] control of extremely large segmented telescopes. [Masters Thesis]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1618

University of Texas – Austin

28. Le, Ha Thu. Increasing wind power penetration and voltage stability limits using energy storage systems.

Degree: PhD, Electrical and Computer Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-05-864

► The research is motivated by the need to address two major challenges in wind power integration: how to mitigate wind power fluctuation and how to… (more)

▼ The research is motivated by the need to address two major challenges in wind power integration: how to mitigate wind power fluctuation and how to ensure stability of the farm and host grid. It is envisaged that wind farm power output fluctuation can be reduced by using a specific type of buffer, such as an energy storage system (ESS), to absorb its negative impact. The proposed solution, therefore, employs ESS to solve the problems. The key research findings include a new technique for calculating the desired power output profile, an ESS charge-discharge scheme, a novel direct-calculation (optimization-based) method for determining ESS optimal rating, and an ESS operation scheme for improving wind farm transient stability. Analysis with 14 wind farms and a compressed-air energy storage system (CAES) shows that the charge-discharge scheme and the desired output calculation technique are appropriate for ESS operation. The optimal ESSs for the 14 wind farms perform four or less switching operations daily (73.2%-85.5% of the 365 days) while regulating the farms output variation. On average, the ESSs carry out 2.5 to 3.1 switching operations per day. By using the direct-calculation method, an optimal ESS rating can be found for any wind farm with a high degree of accuracy. The method has a considerable advantage over traditional differential-based methods because it does not require knowledge of the analytical form of the objective function. For ESSs optimal rating, the improvement in wind energy integration is between 1.7% and 8%. In addition, a net increase in grid steady-state voltage stability of 8.3%-18.3% is achieved by 13 of the 14 evaluated ESSs. For improving wind farm transient stability, the proposed ESS operation scheme is effective. It exploits the use of a synchronous-machine-based ESS as a synchronous condenser to dynamically supply a wind farm with reactive power during faults. Analysis with an ESS and a 60-MW wind farm consisting of stall-regulated wind turbines shows that the ESS increases the farm critical clearing time (CCT) by 1 cycle for worst-case bolted three-phase-to-ground faults. For bolted single-phase-to-ground faults, the CCT is improved by 23.1%-52.2%. Advisors/Committee Members: Santoso, Surya (advisor), Arapostathis, Aristotle (committee member), Bishop, Robert (committee member), Driga, Mircea (committee member), Grady, William M. (committee member).

Subjects/Keywords: Charge-discharge scheme; Critical clearing time; Compressed-air energy storage system (CAES); Demand mismatch; DFIG; Direct calculation method; Desired output; ESS unit-sizing; Induction generator; Synchronous-machine based ESS; Stall-regulated wind turbine; Steady-state voltage stability; Synchronous condenser; Transient stability; Wind turbine modeling; Wind farm; Wind power farming

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Le, H. T. (2010). Increasing wind power penetration and voltage stability limits using energy storage systems. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-05-864

Chicago Manual of Style (16^th Edition):

Le, Ha Thu. “Increasing wind power penetration and voltage stability limits using energy storage systems.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2010-05-864.

MLA Handbook (7^th Edition):

Le, Ha Thu. “Increasing wind power penetration and voltage stability limits using energy storage systems.” 2010. Web. 12 Apr 2021.

Vancouver:

Le HT. Increasing wind power penetration and voltage stability limits using energy storage systems. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-864.

Council of Science Editors:

Le HT. Increasing wind power penetration and voltage stability limits using energy storage systems. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-864

University of Texas – Austin

29. Pasupathy, Praveenkumar. Coupled passive resonant circuits as battery-free wireless sensors.

Degree: PhD, Electrical and Computer Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-05-725

► Detection and monitoring of the damage created by the corrosion of the steel reinforcement in concrete structures is a challenging and multidisciplinary problem. Economical monitoring… (more)

Subjects/Keywords: Contact-less; Structural health monitoring; Concrete corrosion; Steel reinforcement; Wireless sensors; Signal strength; Circuit design; Sensors

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Pasupathy, P. (2010). Coupled passive resonant circuits as battery-free wireless sensors. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-05-725

Chicago Manual of Style (16^th Edition):

Pasupathy, Praveenkumar. “Coupled passive resonant circuits as battery-free wireless sensors.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2010-05-725.

MLA Handbook (7^th Edition):

Pasupathy, Praveenkumar. “Coupled passive resonant circuits as battery-free wireless sensors.” 2010. Web. 12 Apr 2021.

Vancouver:

Pasupathy P. Coupled passive resonant circuits as battery-free wireless sensors. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-725.

Council of Science Editors:

Pasupathy P. Coupled passive resonant circuits as battery-free wireless sensors. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-05-725

University of Texas – Austin

30. Sadiq, Bilal. Optimality and robustness in opportunistic scheduler design for wireless networks.

Degree: PhD, Electrical and Computer Engineering, 2010, University of Texas – Austin

URL: http://hdl.handle.net/2152/ETD-UT-2010-08-1548

► We investigate in detail two multiuser opportunistic scheduling problems in centralized wireless systems: the scheduling of "delay-sensitive" flows with packet delay requirements of a few… (more)

▼ We investigate in detail two multiuser opportunistic scheduling problems in centralized wireless systems: the scheduling of "delay-sensitive" flows with packet delay requirements of a few tens to few hundreds of milliseconds over the air interface, and the scheduling of "best-effort" flows with the objective of minimizing mean file transfer delay. Schedulers for delay-sensitive flows are characterized by a fundamental tradeoff between "maximizing total service rate by being opportunistic" and "balancing unequal queues (or delays) across users". In choosing how to realize this tradeoff in schedulers, our key premise is that "robustness" should be a primary design objective alongside performance. Different performance objectives – mean packet delay, the tail of worst user's queue distribution, or that of the overall queue distribution – result in remarkably different scheduling policies. Different design objectives and resulting schedulers are also not equally robust, which is important due to the uncertainty and variability in both the wireless environment and the traffic. The proposed class of schedulers offers low packet delays, less sensitivity to the scheduler parameters and channel characteristics, and a more graceful degradation of service in terms of the fraction of users meeting their delay requirements under transient overloads, when compared with other well-known schedulers. Schedulers for best-effort flows are characterized by a fundamental tradeoff between "maximizing the total service rate" and "prioritizing flows with short residual sizes". We characterize two regimes based on the "degree" of opportunistic gain present in the system. In the first regime – where the opportunistic capacity of the system increases sharply with the number of users – the use of residual flow-size information in scheduling will 'not' result in a significant reduction in flow-level delays. Whereas, in the second regime – where the opportunistic capacity increases slowly with the number of users – using flow-size information alongside channel state information 'may' result in a significant reduction. We then propose a class of schedulers which offers good performance in either regime, in terms of mean file transfer delays as well as probability of blocking for systems that enforce flow admission control. This thesis provides a comprehensive theoretical study of these fundamental tradeoffs for opportunistic schedulers, as well as an exploration of some of the practical ramifications to engineering wireless systems. Advisors/Committee Members: De Veciana, Gustavo (advisor), Andrews, Jeffery G. (committee member), Arapostathis, Aristotle (committee member), Hasenbein, John J. (committee member), Shakkottai, Sanjay (committee member).

Subjects/Keywords: Opportunistic scheduling; Opportunistic scheduler; Wireless systems; Delay-sensitive flows; Best-effort flows

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Sadiq, B. (2010). Optimality and robustness in opportunistic scheduler design for wireless networks. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/ETD-UT-2010-08-1548

Chicago Manual of Style (16^th Edition):

Sadiq, Bilal. “Optimality and robustness in opportunistic scheduler design for wireless networks.” 2010. Doctoral Dissertation, University of Texas – Austin. Accessed April 12, 2021. http://hdl.handle.net/2152/ETD-UT-2010-08-1548.

MLA Handbook (7^th Edition):

Sadiq, Bilal. “Optimality and robustness in opportunistic scheduler design for wireless networks.” 2010. Web. 12 Apr 2021.

Vancouver:

Sadiq B. Optimality and robustness in opportunistic scheduler design for wireless networks. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2010. [cited 2021 Apr 12]. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1548.

Council of Science Editors:

Sadiq B. Optimality and robustness in opportunistic scheduler design for wireless networks. [Doctoral Dissertation]. University of Texas – Austin; 2010. Available from: http://hdl.handle.net/2152/ETD-UT-2010-08-1548

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