MATLAB Symbolic Computation for the Steady State Modeling of Symmetrically Loaded Self Excited Induction Generator

This paper presents the use of MATLAB symbolic computation technique to model and simulate self-excited induction generator. In this technique, the computer itself carries out both the tedious job of deriving the complex coefficients of the polynomial equations and solving them. Hence, the modeling and programming become very simple yet versatile. Good agreement between the results obtained from the conventional method and that obtained using symbolic computation validates the effectiveness of this new technique

Modified alternator for low wind applications: rat trap generator

Paper presented to the 3rd Annual Symposium on Graduate Research and Scholarly Projects (GRASP) held at the Hughes Metropolitan Complex, Wichita State University, April 27, 2007.Research completed at the Department of Electrical and Computer Engineering, College of EngineeringModified tractor alternator was designed and constructed to suit a 300 W low speed high altitude wind turbine. The tractor alternator did not produce the required power output design speed of the turbine. A modification was thus required and this paper describes the redesign and construction techniques. The analysis is focused on the design aspects, topologies, modeling, and testing of the alternator. The final results were still not up to expectation, but nevertheless, some promising results were obtained and some of them are discussed

Effects of heavy metal pollution on pigmented macrophages in kidney of Vardar chub (Squalius vardarensis Karaman)

Freshwater pollution with heavy metals may influence the immune system of fish, leading to impairment of their health or even to increase of their mortality. The fish kidney is one of the first fish organs to be affected by water contamination. Amounts of kidney macrophages (MACs), which are involved in fish immune response, as well as the qualitative and quantitative changes in the pigmented MACs in fish kidney, are used as biomarkers of pollution. Therefore, in this study we have evaluated relative and total volumes of trunk kidney pigmented MACs, and analyzed the pigments accumulated within them, in Vardar chub (Squalius vardarensis Karaman) sampled from two mining impacted rivers, Kriva and Zletovska, highly contaminated with heavy metals, and from one reference river, Bregalnica, in spring and autumn of 2012. We have observed that main pigments found in kidney MACs of Vardar chub were melanin and lipofuscin/ceroid, as well as that relative volumes of MACs ranged from 0.56-1.68%. Moreover, the results showed that relative volumes of pigmented MACs were higher in metal contaminated rivers, especially in autumn season in the Zletovska River, concurrently with extremely high metal exposure. In addition, condition factors and kidney somatic indices were found significantly lower in the Zletovska River in both seasons, autumn and spring, possibly also as a consequence of high water pollution. Our data confirm that increase in relative volumes of pigmented MACs may serve as warning sign of potential heavy metal pollution in aquatic environment

Wider renewable energy issues for Nepal

The principle of renewable energy for a near bankrupt and developing country like Nepal is well accepted, but its success in filling the needs and aspirations of the development workers and the country is low. The reasons for this include culture, poverty, language, lack of land titles, ancient rights, inadequate education, civil war, civil strife, hunger, greed, business practices, retaliation, infrastructure, bureaucracy and corruption. Examples of how these effects operate are given, together with some possible short term solutions. Possible long term solutions are discussed and the likely ramifications on the society as a whole. Trigger factors are identified which may effect a complete collapse of the intended outcomes, whether via the collapse of the projects, or collapse of the complete society. Given a complete collapse of the renewable energy project or society, a range of possible least worst (or best) outcomes are presented

Sustainable renewable energy development of a remote community in Nepal

This paper describes the process used in the development of two villages in the remote Humla region of Nepal. The process includes both reducing the deforestation and improving the living standard and health of the local people. Specifically, it implements pit latrines, smokeless stoves and electric lighting. The lighting is powered by either pico hydro systems or by solar photovoltaic systems

Investigation of Wind Data Resolution for Small Wind Turbine Performance Study

Small wind turbine sites, in general, use a 0.5Hz sampling interval and a 10-minute averaging interval for a feasibility study or turbine testing.  Studies have established that the calculated performance variation of small wind turbines when averaging at large time intervals.  The performance variation is larger for sites with high wind variability. However, these studies are often based on low sampling frequency and high averaging intervals.  In the present study, wind speed data has been measured at a high sampling frequency of 20Hz with an ultrasonic sensor.  A dynamic model of a 50W Rutland wind turbine is used to analyse the simulated performance using wind speed data at a range of sampling intervals and some averaging intervals.  The wind turbine and the anemometer are installed in a residential area of high wind variability.  The energy is calculated and compared directly using the wind turbine model and using the IEC recommended method of bins.  The direct method results show that the rise in instantaneous sampling intervals up to 20 seconds has an insignificant effect on the energy output.  Whereas, for 2-seconds sampled wind data averaged over 10-minutes, energy overestimates of 19% is observed.  However, where only 10-minute interval averaged wind data are available, there is a significant underestimate in energy by 45%.  The energy calculated using the method of bins overestimates the energy by 19% for high resolution wind data and underestimates by 22% for 10-minute average data

Investigation of Wind Data Resolution for Small Wind Turbine Performance Study

&#x0D; Small wind turbine sites, in general, use a 0.5Hz sampling interval and a 10-minute averaging interval for a feasibility study or turbine testing.  Studies have established that the calculated performance variation of small wind turbines when averaging at large time intervals.  The performance variation is larger for sites with high wind variability. However, these studies are often based on low sampling frequency and high averaging intervals. &#x0D; &#x0D; &#x0D; In the present study, wind speed data has been measured at a high sampling frequency of 20Hz with an ultrasonic sensor.  A dynamic model of a 50W Rutland wind turbine is used to analyse the simulated performance using wind speed data at a range of sampling intervals and some averaging intervals.  The wind turbine and the anemometer are installed in a residential area of high wind variability. &#x0D; &#x0D; &#x0D; The energy is calculated and compared directly using the wind turbine model and using the IEC recommended method of bins.  The direct method results show that the rise in instantaneous sampling intervals up to 20 seconds has an insignificant effect on the energy output.  Whereas, for 2-seconds sampled wind data averaged over 10-minutes, energy overestimates of 19% is observed.  However, where only 10-minute interval averaged wind data are available, there is a significant underestimate in energy by 45%.  The energy calculated using the method of bins overestimates the energy by 19% for high resolution wind data and underestimates by 22% for 10-minute average data.&#x0D; </jats:p