The aim of the study was to show whether or not there exists, and if so, to understand, a common creativity, vision and imagination of the members of Småland’s Entrepreneurial Academy’s organisation. The method used for this research is the fictive narrative collage , which consists of the collection of fictive stories. The author has also made her own additions to the method. A composer composes songs to the narratives, two artists illustrate the narratives. The research is carried out on the total population within Småland’s Entrepreneurial Academy which consists of 10 permanent members of the organisation. The theory focuses on different areas, such as creativity, vision and imagination as well as on the entrepreneur and the organisation. The latter two to provide the research with a foundation for the whole. Analyses were carried out and interpreted by the author, coupled to the theory, but also with a starting point in the interpretations that the composer and artists made in their contributions. Theatrical metaphors are used to draw parallels and to make further clarifications in the interpretation and the texts. The results show that vision, imagination and creativity do exist and common characteristics have been able to be identified, such as the creativity of the entrepreneur and his or her desire to go his or her own way, to not enter into conflict with his or her own role. In the vision, there are common trains of thought, where a balance in life/existence is the most central. If imagination is allowed completely free flight, the research group will allow anarchy to reign.

Since large scale unscheduled tripping of wind power generation could lead to power system stability problem. Thus network interconnection regulations become more rigid when the wind power penetration reaches a non-neglible portion of the total power generation. This thesis presents a comparison of five different low voltage ride through (LVRT) capability enhancement technologies, i.e., additional rotor resistance, DC bus chopper, crowbar on rotor, the combination of above schemes, and grid voltage support by controlling grid side converter. System simulations are performed under Digsilent environment with model and control blocks provided by the package. Additional models are developed to implement the LVRT enhancement schemes studied. A Doubly-Fed Induction Generator (DFIG) with pitch control is used to simulate different system fault scenarios with different voltage sag magnitude and duration time. Simulation results indicate that different enhancement schemes provide various levels in relieving DC bus overvoltage, rotor winding overcurrent, and overspeed problems, and the method combines all tested schemes seems to provide the best result.

Demand is emerging for offshore wind power plant (WPP) that often has favorable capacity factor and high capacity value as compared with onshore wind farms. There are many challenges regarding power losses, economics, protection system and reliability of the wind farm. Collection system design decisions play an essential role to efficient operation of the WPP. Wind generators also have to be able to cope with grid disturbances. Low voltage ride-through (LVRT) capability of wind turbines requires generator units remain in operation for severe voltage drops during ¡@grid system faults, and be able to withstand depressed voltage for a few seconds in a recovery period. Technical requirements set out in grid codes for off shore wind farm normally relate to different connection points. A rigor LVRT requirement would increase the overall investment costs of the wind farm. In most offshore wind farm projects, radial collector systems connecting a number of wind turbines and terminated at the offshore platform have served well the requirements for an economical design. However, due to the lack of redundancy, its reliability is poor. To improve the reliability of the collector system, the inclusion of a cable section that interconnects the remote ends of two adjacent radial feeders has been proposed. The transmission system of a wind farm takes the power generated and sends it to shore. Medium voltage AC transmission is the simplest one, just gathering the cables from the collector system and taking them together until they reach the point of common coupling (PCC).Through wind farm dynamic simulations by using DIgSIENT package, this thesis demonstrates that the ride through capability which occur at the particular wind parks with different collector system topology are greater than those which the wind turbines are capable of riding through, i.e., LVRT curves of different wind farm collection system designs of an offshore WPP and a single wind generator are different. This can be exploited to reduce the cost in complying with LVRT requirement of offshore WPP.

Electric motors are used widely in industrial manufacturing plants. Bearing faults, insulation faults, and rotor faults are the major causes of electric motor failures. Based on the line current analysis, this dissertation mainly deals with the low cost incipient fault detection of inverter-fed driven motors. Basically, low order inverter harmonics contributions to fault diagnosis, a motor drive embedded condition monitoring method, analysis of motor fault signatures in noisy line current, and a few specific applications of proposed methods are studied in detail. First, the effects of inverter harmonics on motor current fault signatures are analyzed in detail. The introduced fault signatures due to harmonics provide additional information about the motor faults and enhance the reliability of fault decisions. It is theoretically and experimentally shown that the extended fault signatures caused by the inverter harmonics are similar and comparable to those generated by the fundamental harmonic on the line current. In the next chapter, the reference frame theory is proposed as a powerful toolbox to find the exact magnitude and phase quantities of specific fault signatures in real time. The faulty motors are experimentally tested both offline, using data acquisition system, and online, employing the TMS320F2812 DSP to prove the effectiveness of the proposed tool. In addition to reference frame theory, another digital signal processor (DSP)-based phasesensitive motor fault signature detection is presented in the following chapter. This method has a powerful line current noise suppression capability while detecting the fault signatures. It is experimentally shown that the proposed method can determine the normalized magnitude and phase information of the fault signatures even in the presence of significant noise. Finally, a signal processing based fault diagnosis scheme for on-board diagnosis of rotor asymmetry at start-up and idle mode is presented. It is quite challenging to obtain these regular test conditions for long enough time during daily vehicle operations. In addition, automobile vibrations cause a non-uniform air-gap motor operation which directly affects the inductances of electric motor and results quite noisy current spectrum. The proposed method overcomes the challenges like aforementioned ones simply by testing the rotor asymmetry at zero speed.

The growth of embedded generation and portable electrical installations has led to an increased demand for low cost, flexible and reliable generator systems for military and commercial applications. An interior permanent magnet (IPM) machine has high power density due to its reluctance torque and magnetic torque components so it can produce a large constant power-speed range. However, an IPM machine needs demagnetizing current at high-speed during the flux-weakening region and thus develops an inverter shutdown problem in an uncontrolled generator mode operation. In order to overcome the disadvantages of the IPM machine, the permanent magnet assisted synchronous reluctance generator (PMa-SynRG) can be a good solution for low cost, high efficiency reliable generator systems. A PMa-SynRG can produce a high efficiency drive by utilizing the proper amount of magnet and reluctance torque. This work proposes a PMa-SynRG with two flux barriers and permanent magnets embedded in the second layer of the rotor. A neodymium magnet (NdFeB) was used as permanent magnets in the rotor to prevent demagnetization. Finding the minimum amount of magnet is one of the goals of the optimization process. The objectives of this work are to build an optimal design for the 3kW generator and an advanced power electronics converter for the PMa-SynRG drive system. In order to find the optimized 3kW machine, a Lumped Parameter Model (LPM) was used to achieve fast computation, and Differential Evolution Strategy (DES) was used to embed the LPM in an efficient numerical optimization routine to identify optimum designs. Finite Element Analysis (FEA) was used for test performance of optimum designs. On the basis of differences between LPM and FEA, model predictions were used to fine tune the LPM model. For new optimum design converges, numerical optimizations and iterations were performed to produce LPM and FEA predictions. For the drive system, the thyristor based, current-fed drive is much simpler and has lower power losses compared to the pulse width modulation (PWM) drive. Eliminating the requirement for self-controlled switches is a distinct advantage for lower cost. Another feature of the developed current-fed drive is its inherent capability to provide generating action by making the PMa-SynRG operates as a generator, rectifying the phase voltages by means of the three-phase rectifier and feeding the power into the load. These features make the current-fed drive a good candidate for driving any type of synchronous generators including the proposed PMa-SynRG.

The use of high power converters has increased tremendously. Increased demand for transportation, housing and industrial needs means that more number of power converters interact with the utility power grid. These converters are non-linear and they draw harmonic currents, significantly affecting power quality. To reduce harmonics, filters, power factor correction circuits and capacitor banks are required. And the development of hybrid technologies and renewable energy power stations trigger a demand for power converters with bi-directional capabilities. The objective of this thesis is to develop a high power quality, bi-directional AC-DC power converter that is a solution to the aforementioned problems. This thesis studies an existing topology for a high power AC-DC power conversion with transformer isolation. The topology consists of an uncontrolled rectifier followed by a DC-DC converter to produce a set voltage output. A design example of the topology is simulated using the PSIM software package (version 6). Critical performance characteristics such as power factor and total harmonic distortion are analyzed. Following that study a new topology is proposed, which is an improvement over the older design, with reduced power conversion stages. The new topology has a fully controlled current source Pulse Width Modulation (PWM) rectifier at the front end to replace the uncontrolled rectifier and DC-DC combination. This topology has multiquadrant operational capabilities and the controller employs Selective Harmonic Elimination techniques to produce the programmed PWM switching functions for the rectifier. A design example of the converter and the digital controller are simulated in PSIM environment. The converter input current THD (Total Harmonic Distortion) and input power factor are within IEEE 519 and DoE standards. The converter is simulated in both first and fourth quadrant operations. A side-by-side comparison of the two topologies is done with respect to design and performance features such as power factor, THD, filter size, etc. The new topology converter provides performance superior to that of the older topology. Finally the thesis explores possible applications for the converter in power supplies, renewable energy and hybrid technologies.

With the widespread use of doubly-fed induction generators (DFIG) in wind energy conversion systems, condition monitoring is being given importance. Non-intrusive techniques like motor current signature analysis (MCSA), which involves looking for specific frequency components in the current spectrum, are preferred over analysis of magnetic field, temperature, vibrations or acoustic noise which require additional sensors. The major difficulty in MCSA is isolation of the fault, as multiple faults produce similar signatures. Moreover, closed-loop control makes diagnostics more complicated due to inherent compensation by the controller. This thesis presents a method to diagnose static and dynamic air gap eccentricities in doubly-fed induction generators operated for closed-loop stator power control by using a modified control technique to enable detection and isolation of this fault from electrical unbalances in the stator and rotor and load torque oscillations that produce similar effects. The effectiveness of the proposed control is verified using simulations and preliminary experiments performed on a healthy machine.

This study focuses on the molasses based complex medium design for benzaldehyde lyase production by recombinant E. coli BL21 and development of a feeding strategy based on the designed complex medium. For this purpose, firstly, the effects of molasses were investigated in laboratory scale bioreactors. As E. coli BL21 was not able to utilize sucrose, molasses was pretreated and hydrolyzed to fructose and glucose. Thereafter, effect of pretreated molasses concentration was investigated in the range of 16 to 56 kg m-3 by batch-bioreactor experiments / and the highest cell concentration and benzaldehyde lyase activity were obtained as CX=5.3 kg m-3 and A=1617 U cm-3, respectively, in the medium containing 7.5 kg m-3 glucose and 7.5 kg m-3 fructose. Then, different feeding strategies were developed to produce efficient cells with high concentration and BAL activity. In the first strategy, after 10 hours of batch-cultivation with molasses based medium having 7.5 kg m-3 glucose and 7.5 kg m-3 fructose concentration, based on the airflow rate, pretreated molasses was fed to the system. When air flow rate decreased considerably, fed was given to the system that results in increase in glucose and fructose concentration in the medium to 2.5 kg m-3. At the end of the process, the highest cell concentration obtained was CX=7.4 kg m-3. The maximum activity was reached at 20th hour as A=2360 U cm-3. On the other hand, as air flow variation only demonstrated the absence of glucose not fructose, a second strategy, based on the detection of the fructose and glucose concentrations during the process, was applied. In this strategy when glucose and fructose were depleted, fed was given to the system that results in increase in glucose and fructose concentration in the medium to 2.5 kg m-3 / and the highest BAL activity was obtained as 2370 U cm-3 at t= 26 h where the cell concentration was 7.5 kg m-3. At the last strategy, when glucose and fructose were depleted, fed was given to the system that results in increase in CGlucose=1.5 kg m-3 and CFructose=1.5 kg m-3 in the production medium to decrease the accumulation of acetic acid. By this strategy highest cell concentration was obtained as 8.04 kg m-3 at t=24 h and the highest BAL activity was 2315 U cm-3. These strategies could be accepted having the same BAL activity with little distinctions. However, cell concentration of the last one was higher than others and also the lowest amount of carbon source was used. Thus, last one could be chosen as the most favorable strategy.

In this study, the aim was to investigate the effects of exponential feeding strategy on benzaldehyde lyase (BAL) production by recombinant Escherichia coli BL21. For this purpose, the effects of medium components were investigated to optimize the initial medium composition of the fed-batch fermentations. For the batch bioreactor operations, the highest cell concentration and BAL activity were achieved in a media containing 30 g L-1 pretreated molasses, and 5 g L-1 (NH4)2HPO4 as 5.07 g L-1, and 1611 U ml-1 at t=8 h, respectively. Thereafter, in order to increase the cell growth and BAL production while avoiding acetate accumulation, fed-batch bioreactor operations were conducted with exponential feeding at different specific growth rates namely, 0.1 h-1 (mu-0.1), 0.15 h-1 (mu-0.15), and 0.2 h-1 (mu-0.2), and a combined exponential and constant feeding (mu-0.2+) strategy. In the experiments, 9 hours of batch-wise operation with the optimized production medium was followed by a fed-batch operation phase using the pre-determined exponential feeding profiles and for mu-0.2+ operation after 10 hours of exponential feeding as mu-0.2, where the feed rate was kept constant at 21.6 g h-1. Additionally, the plasmid stability was investigated using the feeding method of mu-0.2+ operation with antibiotics in the feed solution, and it was observed that the plasmid was stable. Among the three exponential feeding conditions, the highest cell concentration and BAL activity were determined in

The study in this thesis focuses on the DTV antennas for mobile applications. By using the novel techniques in the proposed antenna, the narrow-band problem and the radiation pattern of the conventional DTV antenna can be improved. In the first design, the antenna comprises two radiating arms. By adjusting the open gap between the ends of the two radiating arms, large impedance bandwidth can be obtained for DTV signal reception. In the second design, by integrating a coupling portion into the dipole antenna, the full-wavelength resonant mode can be excited successfully and combined with the half-wavelength mode to form a wide operating band. Finally, in the third design, a U-shaped feeding gap is embedded within the V-shaped antenna to excite the full-wavelength resonant mode. Additionally, the dipole antenna can radiate comparable E£X and E£c components, resulting in no nulls in the total-power radiation patterns in the horizontal and vertical planes.