Nonlinear control schemes for extremum power seeking and torsional vibration mitigation in variable speed wind turbine systems

Doctor of PhilosophyDepartment of Electrical and Computer EngineeringDon GruenbacherWarren WhiteThis dissertation presents nonlinear control schemes to improve the productivity and lifespan of doubly fed induction generator (DFIG)-based and permanent magnet generator (PMG)-based variable speed wind turbines. To improve the productivity, a nonlinear adaptive control scheme is developed to maximize power capture. This controller consists of three feedback loops. The first loop controls electrical torque of the generator in order to cancel the nonlinear term of the turbine equation of motion using the feedback linearization concept. The nonlinearity cancelation requires a real-time estimation of aerodynamic torque. This is achieved through a second loop which estimates the ratio of the wind turbine power capture versus the available wind power. A third loop utilizes this estimate to identify the shaft speed at which the wind turbine operates at a greater power output. Contrary to existing techniques in literature, this innovative technique does not require any prior knowledge of the optimum tip speed ratio. The presented technique does not need a dither or perturbation signal to track the optimum shaft speed at the maximum power capture. These features make this technique superior to existing methods. Furthermore, the lifespan of variable speed wind turbines is improved by reducing stress on the wind turbine drivetrain. This is achieved via developing a novel vibration mitigation technique using sliding-mode control theory. The technique measures only generator speed as the input signal and then passes it through a high-pass filter in order to extract the speed variations. The filtered signal and its integral are then passed through identical band-pass filters centered at the dominant natural frequency of the drivetrain. These two signals formulate a sliding surface and consequently a control law to damp the drivetrain torsional stress oscillations caused by electrical and mechanical disturbances. This technique provides a robust mitigation approach compared with existing techniques. These control schemes are verified through holistic models of DFIG- and PMG-based wind turbines. Except for wind turbine aerodynamics, for which an existing simulator is used, the developed models of all components including DFIG, PMG, converters, multi-mass drivetrain, and power line are presented in this dissertation

Adaptive Control of Surge Impedance for Electric Motors in Motor Drive Systems

This article studies the possibility of controlling the surge impedance of the electric motor in motor drives. The existing solution to suppress (or eliminate) the reflected wave impact on the motor insulation run by a Si-IGBT or SiC-MOSFET-based drive is to use either a sinewave filter or dv/dt filter. The alternative solution suggested in this article is to implement a high-bandwidth electronic circuit at the end of the cable or at the motor terminals to match the surge impedance of the cable and motor. The high-frequency voltage ringing due to the reflected waves in motor drives is around 1 MHz, depending on the cable parameters and the length of the cable. In the proposed method, the electronic circuit can quickly detect the dv/dt rise and fall edges and adjust the electronic circuit equivalent impedance when pulses arrive the motor terminals. Thus, the cable and motor surge impedances can be matched over a short time to prevent reflected waves. As a result, the leakage currents passing through the ball bearing and overvoltage stress on the motor insulation can be suppressed significantly

E-Mobility -- Advancements and Challenges

Mobile platforms cover a broad range of applications from small portable electric devices, drones, and robots to electric transportation, which influence the quality of modern life. The end-to-end energy systems of these platforms are moving toward more electrification. Despite their wide range of power ratings and diverse applications, the electrification of these systems shares several technical requirements. Electrified mobile energy systems have minimal or no access to the power grid, and thus, to achieve long operating time, ultrafast charging or charging during motion as well as advanced battery technologies are needed. Mobile platforms are space-, shape-, and weight-constrained, and therefore, their onboard energy technologies such as the power electronic converters and magnetic components must be compact and lightweight. These systems should also demonstrate improved efficiency and cost-effectiveness compared to traditional designs. This paper discusses some technical challenges that the industry currently faces moving toward more electrification of energy conversion systems in mobile platforms, herein referred to as E-Mobility, and reviews the recent advancements reported in literature

Co-infection of Phlebotomus papatasi (Diptera: Psychodidae) gut bacteria with Leishmania major exacerbates the pathological responses of BALB/c mice

Clinical features and severity of the leishmaniasis is extremely intricate and depend on several factors, especially sand fly-derived products. Bacteria in the sand fly’s gut are a perpetual companion of Leishmania parasites. However, consequences of the concomitance of these bacteria and Leishmania parasite outside the midgut environment have not been investigated in the infection process. Herein, a needle infection model was designed to mimic transmission by sand flies, to examine differences in the onset and progression of L. major infection initiated by inoculation with “low” or “high” doses of Enterobacter cloacae and Bacillus subtilis bacteria. The results showed an alteration in the local expression of pro- and anti-inflammatory cytokines in mice receiving different inoculations of bacteria. Simultaneous injection of two bacteria with Leishmania parasites in the low-dose group caused greater thickness of ear pinna and enhanced tissue chronic inflammatory cells, as well as resulted in multifold increase in the expression of IL-4 and IL-1β and a decrease in the iNOS expression, without changing the L. major burden. Despite advances in scientific breakthroughs, scant survey has investigated the interaction between micro and macro levels of organization of leishmaniasis that ranges from the cellular to macro ecosystem levels, giving rise to the spread and persistence of the disease in a region. Our findings provide new insight into using the potential of the vector-derived microbiota in modulating the vertebrate immune system for the benefit of the host or recommend the use of appropriate antibiotics along with antileishmanial medicines

Performance Optimization of Industrial Overhead Cranes with Respect to Trajectory and Disturbance Rejection

Many research efforts have been performed for the development of crane control systems and for improving the efficiency and safety of them. Despite the numerous crane control strategies in the literature, very few designs are applicable in practice. In this work a crane control strategy has been established in a manner that can be easily implemented in practice. The main contributions of this work can be summarized into applying feedforward and positive feedback controllers in order to improve the command velocity response and provide a minimum load sway during the load transportation, respectively. Moreover, the positive feedbacks from the load sway angle and its velocity improve the crane control dynamic behavior in the presence of an external disturbance such as wind gust. The robustness and simplicity of this method in conjunction with minimal sensor requirements are other advantages of the presented control strategy in this thesis

First report of filarial nematodes in the genus Onchocerca infecting black flies (Diptera: Simuliidae) in Iran

Abstract Black flies are blood-sucking insects of public health importance, and they are effective vectors of pathogens and parasites, such as filarial nematodes of the genus Onchocerca. Our previous surveys have shown that individuals of Simulium turgaicum are annoying pests of humans and livestock in the Aras River Basin of Iran. In the present study, adult black flies of S. turgaicum were trapped from different ecotopes of five villages in Khoda-Afarin County, Iran. By using a sensitive nested PCR assay and targeting the nuclear 18S rDNA-ITS1 marker, filarial infections were found in 38 (1.89%) of 2005 black flies. Homology exploration of 360 bp of the sequences indicated that the filarial worms are members of the family Onchocercidae, with maximum alignment scores of 93–95%. Phylogenetic analysis showed that two Iranian Onchocerca isolates were clustered in the O. fasciata–O. volvulus lineage and were well separated from other filarial nematodes. Both the entomological evidence (empty abdomen of the specimens) and climatologic data (adequate accumulated degree days for development) suggest that the filarial DNA was probably that of infective larvae of vertebrates. This is the first report of an infection by Onchocerca species in S. turgaicum and the first record of onchocercids in black flies in Iran; however, more research is required to demonstrate transmission of these filarial worms by black flies in nature

Condition Monitoring of Squirrel-Cage Induction Motors Fed by PWM-based Drives Using a Parameter Estimation Approach

Abstract 1- A rotor condition monitoring technique is presented in this paper based on a parameter estimation approach. In this technique, the stator currents, voltages and motor speed are used as the input signals, where the outputs will be the rotor’s inductance, resistance and consequently rotor time constant. This approach is verified by simulation of two different induction motor cases. These simulations are buttressed by experimental data obtained for a 2-hp induction motor in the case of healthy as well as one, three and five rotor bar breakages. In these tests, the induction motor was energized from a PWM-based drive, in order to demonstrate the capability of using this method for rotor condition monitoring purposes

The Iranian blood pressure measurement campaign, 2019: study protocol and preliminary results

Purpose Hypertension is one of the most important risk factors for premature mortality and morbidity in Iran. The objective of the Iranian blood pressure (BP) measurement campaign was to identify individuals with raised blood pressure and providing appropriate care and increase the awareness among the public and policymakers of the importance of tackling hypertension. Methods The campaign was conducted in two phases. The first (communication) phase started on May 17th (International Hypertension Day). The second phase started on June 8th, 2019, and lasted up to July 7th during which, blood pressures were measured. The target population was Iranians aged >= 30 years. Participants voluntarily referred to health houses in rural and health posts and comprehensive health centers in urban areas in the setting of the Primary Health Care network. Additionally, over 13,700 temporary stations were set up in highly visited places in urban areas. Volunteer healthcare staff interviewed the participants, measured their BP, and provided them with lifestyle advice and knowledge of the risks and consequences of high blood pressure. They referred participants to physicians in case their BP was high. Participants immediately received a text message containing the relevant advice based on their measured BP and their past history. Results Blood pressure was measured for a total of 26,678,394 participants in the campaign. A total of 13,722,148 participants (51.4%) were female. The mean age was 46 +/- 14.1 years. Among total participants, 15,012,693 adults (56.3%) with no past history of hypertension had normal BP, 7,959,288 participants had BP in the prehypertension range (29.8%), and finally, 3,706,413 participants (13.9%) had either past medical history of hypertension, used medications, or had high BP measured in the campaign. Conclusion The campaign was feasible with the objective to increase the awareness among the public and policymakers of the importance of tackling hypertension in Iran