Optimal operation control of hybrid renewable energy systems

Thesis (D. Tech. (Electrical Engineering)) -- Central University of Technology, Free State, 2014For a sustainable and clean electricity production in isolated rural areas, renewable energies appear to be the most suitable and usable supply options. Apart from all being renewable and sustainable, each of the renewable energy sources has its specific characteristics and advantages that make it well suited for specific applications and locations. Solar photovoltaic and wind turbines are well established and are currently the mostly used renewable energy sources for electricity generation in small-scale rural applications. However, for areas in which adequate water resources are available, micro-hydro is the best supply option compared to other renewable resources in terms of cost of energy produced. Apart from being capital-cost-intensive, the other main disadvantages of the renewable energy technologies are their resource-dependent output powers and their strong reliance on weather and climatic conditions. Therefore, they cannot continuously match the fluctuating load energy requirements each and every time. Standalone diesel generators, on the other hand, have low initial capital costs and can generate electricity on demand, but their operation and maintenance costs are very high, especially when they run at partial loads. In order for the renewable sources to respond reliably to the load energy requirements, they can be combined in a hybrid energy system with back-up diesel generator and energy storage systems. The most important feature of such a hybrid system is to generate energy at any time by optimally using all available energy sources. The fact that the renewable resources available at a given site are a function of the season of the year implies that the fraction of the energy provided to the load is not constant. This means that for hybrid systems comprising diesel generator, renewable sources and battery storage in their architecture, the renewable energy fraction and the energy storage capacity are projected to have a significant impact on the diesel generator fuel consumption, depending on the complex interaction between the daily variation of renewable resources and the non-linear load demand. V This was the context on which this research was based, aiming to develop a tool to minimize the daily operation costs of standalone hybrid systems. However, the complexity of this problem is of an extremely high mathematical degree due to the non-linearity of the load demand as well as the non-linearity of the renewable resources profiles. Unlike the algorithms already developed, the objective was to develop a tool that could minimize the diesel generator control variables while maximizing the hydro, wind, solar and battery control variables resulting in saving fuel and operation costs. An innovative and powerful optimization model was then developed capable of efficiently dealing with these types of problems. The hybrid system optimal operation control model has been simulated using fmincon interior-point in MATLAB. Using realistic and actual data for several case studies, the developed model has been successfully used to analyse the complex interaction between the daily non-linear load, the non-linear renewable resources as well as the battery dynamic, and their impact on the hybrid system’s daily operation cost minimization. The model developed, as well as the solver and algorithm used in this work, have low computational requirements for achieving results within a reasonable time, therefore this can be seen as a faster and more accurate optimization tool

Design and control of a hybrid power system for a remote telecommunication facility in Nigeria

The proliferation of mobile base transceiver station sites in Nigeria comes with a growing need to address those sites' source of power. Sustainability and mitigating harmful environmental impact caused by the diesel-only method of power generation is of great concern. This thesis examines the design, optimal sizing, and control of a Hybrid Power system to replace the current diesel-only option on the site. An outdoor base station site in Agbaja, a rural settlement in Kogi State, Nigeria is used as a case study. HOMER pro is used to size the system based on the measured load and available renewable resources. The PV/Diesel/Battery configuration resulted in the least Net Present Cost (NPC), Cost of Energy (COE), and unmet energy. The system is sized as DC for better performance and elimination of multiple energy conversion experienced in the AC system. A comparison between this proposed system and the current system shows a reduction in operating expenditure (OPEX) by 75% with zero unmet energy. Each component of the system is designed and simulated in a MATLAB/Simulink environment and connected to form the whole system. The transient behaviour of the system is studied under varying solar irradiation to ascertain the stability of the power supplied to the sensitive telecommunication load. The result shows a stable power output to the load at rated voltage of 48 V. Also, a low-cost open source Internet of Things (IoT)- based Supervisory Control and Data Acquisition (SCADA) system using ESP32 and Arduino IoT Cloud for monitoring and control of the system using a widget-based dashboard is also presented. Current, voltage, temperature, and humidity sensors are programmed to measure relevant parameters of interest, and the measured Data is processed and parsed to the Arduino IoT Cloud via a Wi-Fi network communication channel. A mobile application is also deployed to aid remote monitoring and control as well. LEDs are used to implement a high temperature and low voltage control logic. The prototype used to demonstrate this only cost $88.34 USD

ReSCon '10, Research Student Conference: Book of Abstracts

The third SED Research Student Conference (ReSCon2010) was hosted over three days, 21-23 June 2010, in the Hamilton Centre at Brunel University. The conference consisted of oral and poster presentations, which showcased the high quality and diversity of the research being conducted within the School of Engineering and Design. The abstracts and presentations were the result of ongoing research by postgraduate research students from the School. The conference is held annually, and ReSCon plays a key role in contributing to research and innovations within the School

Automated CFD Optimization to Maximize Wind Farms Performance and Land Use

In this research, a computational system was designed to analyze and optimize the layout of wind farms under variable operational conditions. At first, a wind turbine computational fluid dynamic (CFD) model was developed covering the near wake. The near wake flow field was validated against near wake velocity data from the MEXICO experiment. The CFD simulation demonstrated that the tip speed ratio and the pitch angle greatly influence the near wake behavior, affecting the velocity deficit and the turbulence intensity profile in this region. The CFD model was extended to cover the far wake, aiming to become a computational tool applicable to propose a solution to the Wind Farm Layout Optimization Problem. The CFD model was then coupled to a MATLAB optimization routine, working in an automated way to find optimized solutions to maximize wind farm land use. The study concludes that it is possible to have a significant improvement on the use of land and output power production by staggering the first row of turbines away from the wake effects. The staggered configuration achieved 10% improvement in the use of land compared with an aligned configuration, both of them working under the same operational conditions. Additionally, control strategies can result in benefits for the wind farm: two cases studies showed improvements within 2.52% and 4.63% in the output power. The last study of this dissertation implemented different inlet velocity profiles to evaluate the impact of vertical wind shear on wake profiles. At the heights analyzed, different velocity inlet profiles did not result in significant changes to the wake of the wind turbine. The velocity deficit remained approximately the same for the three approaches (log law, HRRR and constant inlet) implemented in this work. The vertical wind shear might be more significant at higher altitude and for greater wind turbine diameters. Moreover, a transient model based on LES theory showed that there can be changes in the direction of propagation of the wake when velocity fluctuations are introduced to the model

Aeronautical Engineering: A continuing bibliography with indexes, supplement 110

This bibliography lists 504 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1979

Aeronautical Engineering: A continuing bibliography with indexes, supplement 113, September 1979

This bibliography lists 436 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1979

A cumulative index to Aeronautical Engineering: A continuing bibliography

This bibliography is a cumulated index to the abstracts contained in NASA SP-7037(132) through NASA SP-7037(143) of Aeronautical Engineering: A continuing bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, contract, and report number indexes

Deployment and operational aspects of rural broadband wireless access networks

Broadband speeds, Internet literacy and digital technologies have been steadily evolving over the last decade. Broadband infrastructure has become a key asset in today’s society, enabling innovation, driving economic efficiency and stimulating cultural inclusion. However, populations living in remote and rural communities are unable to take advantage of these trends. Globally, a significant part of the world population is still deprived of basic access to the Internet. Broadband Wireless Access (BWA) networks are regarded as a viable solution for providing Internet access to populations living in rural regions. In recent years, Wireless Internet Service Providers (WISPs) and community organizations around the world proved that rural BWA networks can be an effective strategy and a profitable business. This research began by deploying a BWA network testbed, which also provides Internet access to several remote communities in the harsh environment of the Scottish Highlands and Islands. The experience of deploying and operating this network pointed out three unresolved research challenges that need to be addressed to ease the path towards widespread deployment of rural BWA networks, thereby bridging the rural-urban broadband divide. Below, our research contributions are outlined with respect to these challenges. Firstly, an effective planning paradigm for deploying BWA networks is proposed: incremental planning. Incremental planning allows to anticipate return of investment and to overcome the limited network infrastructure (e.g., backhaul fibre links) in rural areas. I have developed a software tool called IncrEase and underlying network planning algorithms to consider a varied set of operational metrics to guide the operator in identifying the regions that would benefit the most from a network upgrade, automatically suggesting the best long-term strategy to the network administrator. Second, we recognize that rural and community networks present additional issues for network management. As the Internet uplink is often the most expensive part of the operational expenses for such deployments, it is desirable to minimize overhead for network management. Also, unreliable connectivity between the network operation centre and the network being managed can render traditional centralized management approaches ineffective. Finally, the number of skilled personnel available to maintain such networks is limited. I have developed a distributed network management platform called Stix for BWA networks, to make it easy to manage such networks for rural/community deployments and WISPs alike while keeping the network management infrastructure scalable and flexible. Our approach is based on the notions of goal-oriented and in-network management: administrators graphically specify network management activities as workflows, which are run in the network on a distributed set of agents that cooperate in executing those workflows and storing management information. The Stix system was implemented on low-cost and small form-factor embedded boards and shown to have a low memory footprint. Third, the research focus moves to the problem of assessing broadband coverage and quality in a given geographic region. The outcome is BSense, a flexible framework that combines data provided by ISPs with measurements gathered by distributed software agents. The result is a census (presented as maps and tables) of the coverage and quality of broadband connections available in the region of interest. Such information can be exploited by ISPs to drive their growth, and by regulators and policy makers to get the true picture of broadband availability in the region and make informed decisions. In exchange for installing the multi-platform measurement software (that runs in the background) on their computers, users can get statistics about their Internet connection and those in their neighbourhood. Finally, the lessons learned through this research are summarised. The outcome is a set of suggestions about how the deployment and operation of rural BWA networks, including our own testbed, can be made more efficient by using the proper tools. The software systems presented in this thesis have been evaluated in lab settings and in real networks, and are available as open-source software

Aeronautical Engineering: A cumulative index to the 1980 issue

This bibliography is a cumulative index to reports, articles, and other documents introduced into the NASA scientific and technical information system. Abstracts for the entries cited appeared in issues 119 through 130 of Aeronautical Engineering: A Continuing Bibliography (NASA SP-7037). Subject, personal author, corporate author, contract number, and report/accession number indexes are provided

SUSTAINABLE ENERGY HARVESTING TECHNOLOGIES – PAST, PRESENT AND FUTURE

Chapter 8: Energy Harvesting Technologies: Thick-Film Piezoelectric Microgenerato