The aim of this thesis study is to design a hybrid energy system comprised of wind turbines, diesel generators and batteries to provide electricity for an off - grid rural community in Kenya. Wind Measurements collected over six years from 12 locations in Kenya have been studied and one site selected for this project due to its wind potential, geographical location and socio-economic potential. The energy system is designed to cater for the electricity demand of 500 households, one school, one medical clinic and an irrigation system. The system will support up to 3000 people. The Hybrid Optimization Model for Electric Renewables (HOMER) is the software tool that has been used to simulate the hybrid system and analyze its results. The optimization has been carried out and presented according to cost of electricity and sensitivity graphs have been used demonstrate the optimization based on diesel price and wind turbine hub height.

Thesis (M.App.Sc.) - Carleton University, 2007. / Includes bibliographical references (p. 194-202). Also available in electronic format on the Internet.

Thesis (M.S.)--University of Wisconsin--Madison, 1996. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 143-162).

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 140-147).

Thesis (M.E.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (leaves 139-141). Also available via the World Wide Web.

abstract: As electric powered unmanned aerial vehicles enter a new age of commercial viability, market opportunities in the small UAV sector are expanding. Extending UAV flight time through a combination of fuel cell and battery technologies enhance the scope of potential applications. A brief survey of UAV history provides context and examples of modern day UAVs powered by fuel cells are given. Conventional hybrid power system management employs DC-to-DC converters to control the power split between battery and fuel cell. In this study, a transistor replaces the DC-to-DC converter which lowers weight and cost. Simulation models of a lithium ion battery and a proton exchange membrane fuel cell are developed and integrated into a UAV power system model. Flight simulations demonstrate the operation of the transistor-based power management scheme and quantify the amount of hydrogen consumed by a 5.5 kg fixed wing UAV during a six hour flight. Battery power assists the fuel cell during high throttle periods but may also augment fuel cell power during cruise flight. Simulations demonstrate a 60 liter reduction in hydrogen consumption when battery power assists the fuel cell during cruise flight. Over the full duration of the flight, averaged efficiency of the power system exceeds 98%. For scenarios where inflight battery recharge is desirable, a constant current battery charger is integrated into the UAV power system. Simulation of inflight battery recharge is performed. Design of UAV hybrid power systems must consider power system weight against potential flight time. Data from the flight simulations are used to identify a simple formula that predicts flight time as a function of energy stored onboard the modeled UAV. A small selection of commercially available batteries, fuel cells, and compressed air storage tanks are listed to characterize the weight of possible systems. The formula is then used in conjunction with the weight data to generate a graph of power system weight versus potential flight times. Combinations of the listed batteries, fuel cells, and storage tanks are plotted on the graph to evaluate various hybrid power system configurations. / Dissertation/Thesis / Masters Thesis Engineering 2016

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2014 / The research in this thesis deals with the application of Model Based Systems Engineering (MBSE) practices in the modelling of power systems. More particularly, we have presented the modelling hybrid photovoltaic wind integrated in an electrical distribution network using SysML (System Modelling Language) which is a modelling language in support of MBSE. MBSE refers to a formalised practice of systems development through the application of modelling principles, methods, languages and tools to the entire lifecycle of a system. Generally speaking, the modelling of power systems is performed using software such as Matlab Simulink, DigSilent, PowerWorld etc. These software programs allow modelling of a system considering only a specific viewpoint, depending on the objective that is to be assessed. The advantage of the SysML over the above mentioned modelling languages lies from the fact that SysML includes different viewpoints of a system. These views are known as the Four Pillars of SysML. Pillar One refers to the requirements of a system and includes all the functional and non-functional requirements. Pillar Two deals with the structure representation of a system by considering all its subsystems and their different connections. Pillar Three considers the behaviour of a system and includes its activities, sequences and different states. The last Pillar includes the detailed characteristics, physical laws and constraints on the system. The main objectives of this research are the development of models which will include: the system’s requirements; the system’s structure representation in term of different entities involved and the relationship between them; the system’s behaviours in terms of activities in different cases considered and transitions from one state to another as well as the interaction between the system and all the stakeholders. Keywords: Model Based Systems Engineering (MBSE), System Modelling Language (SysML), Renewable Energy systems, Hybrid power systems, photovoltaic systems, wind power systems.

With devastating natural disasters on the rise, technological improvements are needed in the field of search and rescue (SAR). Unmanned aerial vehicles (UAVs) would be ideal for the search function such that manned vehicles can be prioritized to distributing first-aid and ultimately saving lives. One of the major reasons that UAVs are under utilized in SAR is that they lack a long flight endurance which compromises their effectiveness. Dirigibles are well suited for SAR missions since they can hover and maintain lift without consuming energy and can be easily deflated for packaging and transportation. This research focuses on extending flight endurance of small-scale airship UAVs through improvements to the infrastructure design and flight trajectory planning. In the first area, airship design methodologies are reviewed leading to the development and experimental testing two hybrid fuel-electric power plants. The prevailing hybrid power plant design consists of a 4-stroke 14cc gasoline engine in-line with a brushless DC motor/generator and variable pitch propeller. The results show that this design can produce enough mechanical and electrical power to support 72 hours of flight compared to 1-4 hours typical of purely electric designs. A power plant configuration comparison method was also developed to compare its performance and endurance to other power plant configurations that could be used in dirigible UAVs. Overall, the proposed hybrid power plant has a 600% increase in energy density over that of a purely electric configuration. In the second area, a comprehensive multi-objective cost function is developed using spatially variable wind vector fields generated from computational fluid dynamic analysis on digital elevations maps. The cost function is optimized for time, energy and collision avoidance using a wavefront expansion approach to produce feasible trajectories that obey the differential constraints of the airship platform. The simulated trajectories including 1) variable vehicle velocity, 2) variable wind vector field (WVF) data, and 3) high grid resolutions were found to consume 50% less energy on average compared to planned trajectories not considering one of these three characteristics. In its entirety, this research addresses current UAV flight endurance limitations and provides a novel UAV solution to SAR surveillance.

The ever increasing demand for electricity has driven society toward the installation of new generation facilities. Concerns such as high costs associated with installation of new facilities, environmental pollution, higher transmission and distribution losses, depleting fossil fuels has created a lot of interest in exploring the renewable energy sources for generation, particularly near the load sites. Accordingly, emphasis has been put on Wind, and Photovoltaic (PV) energy systems. A study on the operational characteristics of these systems reveals that the power generation is high at certain optimal points and recognizing these optimum points and operating the system accordingly is an interesting and important part of the system design. Further, a hybrid Wind- PV system has higher reliability and generation capability when compared to either source alone, and as a result many such hybrid systems with an additional energy storage backup for increased reliability have been proposed. While the systems with energy storage are reported to have satisfactory performance, the energy storage component is typically found to incur the highest cost, requiring frequent maintenance and hence acts as a deterrent for increasing the renewable energy generation. Particularly, for small grid connected applications like shopping malls, office buildings, etc. any additional power that could not be provided by the hybrid system could be provided by the grid, and in case the power generation is higher it could be sent to the grid. For cases like this, it would be ideal if systems could be developed without energy storage, and maximum possible power could be extracted from the hybrid energy sources. Also, the power quality concerns posed due to the random nature of the power generated from the hybrid system, is an important issue that must be addressed. The conventional control methods used typically require overly sized component ratings, resulting in the degradation of the dynamic performance while adding to the cost of the system. This dissertation addresses these issues by proposing faster maximum power extraction algorithms from the hybrid renewable energy system, and proposes new control architecture for improving the output power quality to the grid.

Government of Sri Lanka has policy target to achieve 100% electrification by end of year 2012. Grid-based electrification is possible up to maximum 95% of the population in Sri Lanka. Balance 5% of the electrification has to be mainly depending on off-grid technologies such as solar PV, wind, biomass and micro hydro.   Use of renewable based off-grid technologies is limited by the seasonal variation of the resource. This barrier could be overcome by coupling renewable based power generation technologies with a diesel generation thereby forming a hybrid power system. Given the comparatively higher investment cost, a hybrid power plant needs to be carefully designed and optimized to generate electricity at competitive prices.   There are some Isolated Islands located in the Jaffna Peninsula (Northern part of Sri Lanka) called Eluvaithivu, Analaithivu, Nainathivu and Delft Islands. These islands are far away from mainland. At present diesel generators are supplying electricity to these islands for limited hours. Electrification rate of these islands are very low due to the Grid limitations. Also cost of electricity generation is very high due to the high diesel price.   The main objective of the present study is “Selection of optimized mix of renewable based power generation technologies to form a mini-grid and to supply reliable, cost effective electricity supply to the people living in Eluvaithivu Island’ and thereby support the 100% electrification target by Govt. of Sri Lanka in 2012.   Data collection, survey has been conducted in the Eluvaithivu Island to find out the status of present system, priority needs, resource data and load data to propose suitable power system for this Island. An extensive analyse was conducted using HOMER software model and the result is presented in the report. Optimum design emerges as a wind-diesel hybrid power system having wind turbines generator, diesel generators, battery bank, converter and a hybrid controller.   The result revealed that the economic viability of the project, in the form of a community owned wind-diesel hybrid power system operated on cost-recovery basis is not feasible. But it is an attractive option for CEB to reduce its long term losses on diesel fuel. In other words, if CEB implement this project, it would be an ideal win-win situation where both the CEB and the island community are benefited.