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1	Design, Implementation, and Analysis for an Improved Multiple Inverter Microgrid System Chen, Chien-Liang 17 March 2011 (has links) Distributed generation (DG) is getting more and more popular due to the environmentally-friendly feature, the new generation unit developments, and the ability to operate in a remote area. By clustering the paralleled DGs, storage system and loads, a microgrid (MG) can offer a power system with increased reliability, flexibility, cost effectiveness, and energy efficient feature. Popular energy sources like photovoltaic modules (PV), wind turbines, and fuel cells require the power-electronic interface as the bridge to connect to the utility grid for usable transmission. The inverter-based microgrid system, however, suffers more challenges than traditional rotational power system. Those challenges, including much less over current capability, the nature of the intermittent renewable energy sources, a wide-band dynamic of generation units, and a large grid impedance variation, call for more careful system hardware and control designs to ensure a reliable system operation. Major design interests are found in (i) precision power flow control, (ii) proper current sharing, (iii) smooth transition between grid-tie and islanding modes, and (iv) stability analysis. This dissertation will cover a complete design and implementation of an experimental microgrid with paralleled power conditioning systems operating in the gridtie mode, islanding mode, and mode transfers. A universal inverter is proposed with the LCL filter to operate in both grid-tie and standalone mode without any hardware modification. Next, controllers of individual inverters running in basic microgrid modes will be discussed to ensure high quality output characteristics. The admittance compensation will also be proposed to avoid reverse power flow during the grid-tie connection transient. Combining previous designed single inverters, a CAN-bus multiinverter microgrid system will be established. The current sharing with the proposed frequency-decoupled transmission will be implemented to extend the transmission distance. Next, smooth mode transfer procedures between grid-tie mode and islanding mode will be suggested based on the circuit principles to minimize the excessive electrical stresses. Finally, the state-space analysis of the proposed multi-inverter microgrid system will be conducted to investigate the stability under system variations and optimize the system performance. Experimental and simulation results show that the designed universal inverter can provide stable outputs in different basic microgrid operation modes. With the proposed current sharing scheme, the output current is equally shared among paralleled inverters without a noticeable circulating current. Both the simulation and experimental results of mode transfer show that the multi-inverter based microgrid system is able to switch between grid-tie and islanding modes smoothly to guarantee an uninterrupted power supply to the critical loads. Based on eigenvalue analysis, the study of stability analysis also shows the agreement of the design, simulation and test results which further verifies the reliability of the designed multi-inverter microgrid system. / Ph. D. Microgrid mode transfer grid-tie mode islanding mode stability
2	GIS-based Episode Reconstruction Using GPS Data for Activity Analysis and Route Choice Modeling / GIS-based Episode Reconstruction Using GPS Data Dalumpines, Ron 26 September 2014 (has links) Most transportation problems arise from individual travel decisions. In response, transportation researchers had been studying individual travel behavior – a growing trend that requires activity data at individual level. Global positioning systems (GPS) and geographical information systems (GIS) have been used to capture and process individual activity data, from determining activity locations to mapping routes to these locations. Potential applications of GPS data seem limitless but our tools and methods to make these data usable lags behind. In response to this need, this dissertation presents a GIS-based toolkit to automatically extract activity episodes from GPS data and derive information related to these episodes from additional data (e.g., road network, land use). The major emphasis of this dissertation is the development of a toolkit for extracting information associated with movements of individuals from GPS data. To be effective, the toolkit has been developed around three design principles: transferability, modularity, and scalability. Two substantive chapters focus on selected components of the toolkit (map-matching, mode detection); another for the entire toolkit. Final substantive chapter demonstrates the toolkit’s potential by comparing route choice models of work and shop trips using inputs generated by the toolkit. There are several tools and methods that capitalize on GPS data, developed within different problem domains. This dissertation contributes to that repository of tools and methods by presenting a suite of tools that can extract all possible information that can be derived from GPS data. Unlike existing tools cited in the transportation literature, the toolkit has been designed to be complete (covers preprocessing up to extracting route attributes), and can work with GPS data alone or in combination with additional data. Moreover, this dissertation contributes to our understanding of route choice decisions for work and shop trips by looking into the combined effects of route attributes and individual characteristics. / Dissertation / Doctor of Philosophy (PhD) GPS time use diary episode extraction multinomial logit travel behavior mode detection episode reconstruction GIS map-matching route choice path size logit potential path area scale estimation Python ArcGIS activity analysis trip reconstruction smartphone global positioning system geographic information system toolkit work trip shop trip potential activity location land use activity episode travel episode stop episode transferability scalability modularity scripting big data travel survey respondent burden preprocessing multipath error tracking purpose detection segmentation data filter data smoothing fuzzy logic neural network decision tree rule-based algorithm trajectory point road network network dataset gateway shortest path horizontal dilution of precision HDOP commonality factor mode transfer point Halifax Nova Scotia Space-Time Activity Research variance inflation factor shapefile comma-separated values traveling salesman problem data mining branch-and-bound algorithm pedestrian network alternative route observed route route efficiency route attributes distance time heading bearing duration acceleration latitude longitude coordinate overlay analysis intersect shopping module data logger walk likelihood ratio test classification table path generation kappa statistic degrees data collection transportation research automate framework ArcToolbox spatio-temporal navigation positioning trace path spatial data topology horizontal accuracy SPSS Stata spatial resolution temporal resolution household survey trip reporting proximity analysis DMTI Desktop Mapping Technologies Inc. road intersection route overlap left turn right turn location analysis time geography spatial statistics buffer analysis cycling bus transit public transportation GEOIDE AGILE data need raw data urban canyon endpoint data cleaning elevation satellite outliers automatic processing nearest node classifier classification method short trip multi-point

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Design, Implementation, and Analysis for an Improved Multiple Inverter Microgrid System

GIS-based Episode Reconstruction Using GPS Data for Activity Analysis and Route Choice Modeling / GIS-based Episode Reconstruction Using GPS Data