<p>Power generation using wind turbines is a highly researched control field.</p><p>Many control designs have been proposed based on continuous-time models</p><p>like PI-control, or state observers with state feedback but without special</p><p>regard to robustness to model uncertainties. The aim of this thesis was to</p><p>design a robust digital controller for a wind turbine.</p><p>The design was based on a discrete-time model in the polynomial framework</p><p>that was derived from a continuous-time state-space model based on</p><p>data from a real plant. A digital controller was then designed by interactive</p><p>pole placement to satisfy bounds on sensitivity functions.</p><p>As a result the controller eliminates steady state errors after a step</p><p>response, gives sufficient damping by using dynamical feedback, tolerates</p><p>changes in the dynamics to account for non linear effects, and avoids feedback</p><p>of high frequency un modeled dynamics.</p>

It is preferable that control and bearing condition monitoring are integrated, as the condition of the system should influence control actions. As wind turbines mainly work in remote areas, it becomes necessary to develop a wireless platform for the control system. A fuzzy system with self-tuning mechanism was developed. The input speed error and speed change were selected to control the shaft speed, while the kurtosis and peak-to-peak values were used as another set of inputs to monitor the bearing conditions. To enhance effectiveness, wait-and-see (WAS) logic was used as the pre-processing step for the raw vibration signal. The system was implemented on the LabVIEW platform. Experiments have shown that the system can effectively adjust motor rotating speed in response to bearing conditions. For future studies, more advanced fault detection methods can be integrated with proper tuning mechanisms to enrich the performance and function of the controller.

The project contains a force analysis of the vertical axis wind turbine Lucia's supporting arms and a measuring device to experimentally measure the forces is made. The forces between the supporting arms and the tower are calculated theoretically and then simulated by a computere. A measuring devise is then designed to measure the forces experimentally. The forces acting on the attachment between the supporting arms and the tower is primarily the centripetal force, gravitational force and the aerodynamic forces on the rotor wings. The maximum forces were theoretically calculated and is 13.38 kN along the x-axis, -0.25 kN along the y-axis and then 0.5 kN along the z-axis. The axis are acording to a rotational reference system where the x-axis runs along the supporting arm and the y-axis runs along the axis of rotation. The maximum torque that occurs is 0.53 kNm along the y-axis and 1.29 kNm along the z-axis. The size of the forces have been confirmed with a deviation of up to 1.8 % in the simulation using SolidWorks 2010. For the experimental measurements a measuring device has been developed which consists of S-load cells with wave indicator and transmitter, an attachment for the measuring equipment and distanceplates to stabilize the rotor. S-load cells, wave indicator and transmitter were ordered and drawings for the attachment of the measuring equipment and spacer plates was done. The eigenfrequencies and the stress have been investigated for the parts. The eigenfrequencies for the wind turbine was estimated to decline up to 13 % when the measuring device was mounted and the lowest Factor of Safety was 1.67. Before the attachment of the measuring device and the spacer plates can be ordered the attachment of the supporting arms, how the loadcells should be attached to the device and the safety margins need to be examined.

Vindkraften expanderar allt mer i Sverige och årsproduktionen ökade till 6,1 TWh år 2011, vilket är en ökning med 74 % jämfört med 2010. De nya vindkraftverken som sätts upp idag är oftast av effektstorlekarna 2 000 – 3 000 kW. De som restes tidigare är omkring 200 – 600 kW. I Sverige finns det många vindkraftverk som har varit i drift under en längre tid, och det är flera som passerat sin tekniska livslängd på 20 år. De första vindkraftverken som man reste står ofta på platser med väldigt goda vindförhållanden och har väldigt låga effekter, om man jämför med dagens vindkraftverk. Det börjar därför bli högaktuellt att demontera äldre befintliga verk och resa nya. Detta kallas för vindkraftens generationsskifte, kanske mer känt som repowering. Tyskland, Danmark och Nederländerna är länder som redan har bytt ut stora delar av sina vindkraftsflottor. Danmark är världsledande inom repowering och har bytt ut omkring två tredjedelar av sina äldre verk. I många av de projekt som genomförts har en dubblering och ibland till och med en fyrdubblering av energinmängden skett! Genom att resa nya verk blir det oftast färre verk på platsen, samtidigt som mer energi levereras. På så sätt utnyttjas platsen på ett bättre sätt, vindkraftselen blir billigare. Det blir samtidigt enklare att uppnå politiska riktlinjer med mål inom förnybar energi och många anser att landskapsbilden förbättras. Detta examensarbete genomfördes i syfte att undersöka möjligheterna och lönsamheten för generationsskiften i Hallands län. För att veta vart de olika vindkraftverken är placerade i Halland genomfördes en kartläggning och identifiering initialt. När verken var kartlagda gjordes projekteringar av nya parker. Det visade sig vara ont om plats att resa de nya verken, eftersom de är högre än de gamla och kräver längre avstånd till bostäder. Därför genomfördes inte enbart projektering av parker där befintliga vindkraftverk står utan även på helt nya områden som idag inte har någon vindkraft. I varje projekt utfördes ekonomiska beräkningar som grundar sig på energiberäkningarna från projekteringen i vindatlasprogrammet WindPRO. Arbetet har också behandlat hur och om ersättning till ägare av befintliga verk och markägare kan ske, samt vad alternativen är för de befintliga vindkraftverken vid ett generationsskifte. Projektgruppen har varit i kontakt med vindkraftsägare och ställt frågor om hur de ställer sig till ett generationsskifte. Det främsta resultatet som projektgruppen kommit fram till är att generationsskiften absolut har goda möjligheter till att bli lönsamma. Det kan dock bli problematiskt att få plats med nya vindkraftverk på områden där gamla verk står. Det beror på kommunens regler om avstånd till närboende, och att ett visst antal verk måste resas vid nybyggnation. Ändras dessa regler för generationsskiften, blir möjligheterna väldigt goda. Vad det gäller efterhandsvärde på de gamla verken är slutsatsen, att det går att göra en bra affär genom att sälja sitt verk. Vid skrotning däremot blir intäkterna från försäljning av metallerna för små för att täcka demonteringskostnaden. Generellt sett har vindkraftsägarna en positiv syn till ett generationsskifte. / The installations of wind turbines are expanding rapidly each day in Sweden and 2011 wind energy generated 6,1 TWh. This is an increase with 74 % compared to 2010. The modern wind turbine that becomes integrated in the Swedish electricity grid at the moment often has a power capacity of 2000-3000 kW. Many of those wind turbines which are already integrated in the grid soon need to be replaced. These turbines often have a power capacity of 200-600 kW. Many of these old turbines have been generating electricity for almost 20 year, which is the technical lifetime for a wind turbine. These old turbines are also often located on sites with great energy levels. This makes it interesting to investigate the possibilities and if there is a profit in repowering. Repowering is when you dismantle old turbines and replace them with new ones. Germany, Denmark and the Netherlands are countries in Europe, which have already been doing repowering for some time. Denmark is the country where most repowering has been done. They have exchanged two thirds of their old turbines. In most of the projects which has been done, the energy level has been doubled and in some cases even quadrupled! When the modern larger turbines replace the old smaller ones, fewer turbines are raised on the site although the energy level increases. While doing repowering the sites are used in a better way, it makes the electricity prices cheaper, the political ambitions in renewable energy are easier reached and many people also claim, that the landscape is improved. This bachelor´s thesis has the objective to investigate the possibilities and the profit for future repowering projects in county of Halland, Sweden. To find out where the wind turbines are located in the county, mapping and identification where done. When the mapping was done, projections of new parks where created. It turned out that these old turbines often where located on a very limited area, which makes it hard to establish new larger turbines. This is because they need larger distance to the nearest residences. Because of this, projections also where done on other locations. In every project economical calculations were made, which are based on the energy results from the projections, which were made in WindPRO. The thesis has investigated how and if the owner of the old wind turbines and the land holder can be compensated when repowering. Researching and brainstorming on different scenarios for what will happen to the old turbines has also been done. We have had contact with owners of wind turbines to find out, what their opinion are about repowering. The prime conclusion from this bachelor thesis is that repowering has good possibilities to be profitable. There might be some problems to project new wind turbines on the same site where the old turbines where located, if the municipality don’t change the distance demands to residences and the demand that a group of wind turbines must be raised. If these demands are changed, the future for repowering looks very promising. Another conclusion where that there might be good profit in selling the used wind turbine, but to sell the used material of a wind turbine to recycling is not profitable. Profit from selling the turbine material to recycling does not cover the cost for dismantling it. Owners of the wind turbines have in general a positive attitude to repowering.

With the number of wind power units (WPUs) on the rise worldwide, it is inevitable that some of these would be exposed to natural disasters like tsunamis and it will become a necessity to consider their effects in the design process of WPUs. This study initially attempts to quantify the forces acting on an existing WPU due to a tsunami bore impact. Surge and bore heights of 2m, 5m and 10m are used to compute the forces using the commercially available full 3D Navier Stokes equation solver FLOW3D. The applicability of FLOW3D to solve these types of problems is examined by comparing results obtained from the numerical simulations to those determined by small scale laboratory experiments. The simulated tsunami forces on the WPU are input into a simplified numerical structural model of the WPU to determine its dynamic response. The tsunami force is also used to obtain base excitation which when applied on the WPU would be equivalent dynamically to the tsunami forces acting on it. This base excitation is useful to obtain the response of the WPU experimentally, the setup for which is available at University of California, San Diego's (UCSD) Large High Performance Outdoor Shake Table (LHPOST). The facility allows full scale experimental setup capable of subjecting a 65kW Nordtank wind turbine to random base excitations. A stress analysis of turbine tower cross section is performed in order to assess the structural integrity of the WPU. It has been determined that the WPU is unsafe for bore/surge heights above 5 m. It has also been postulated that the structural responses could be considerable in case of the taller multi megawatt wind power units of present day.

The existing 3-stage research turbine at Turbomachinery Performance and Flow Research Laboratory (TPFL) facility, Texas A & M University (TAMU) was replaced with a newly designed and manufactured 2-stage turbine in accordance with the design requirements as per DooSan, DHI. This new design of turbine consisted of bowed stator and rotor blades to study the effect on reduction of secondary ow losses and thus improvement in turbine efficiency if any. The new design also incorporated labyrinth seals on both inner and outer shrouds. Extensive Inter-stage and Performance experiments were carried out on this new turbine. Inter-stage measurements were accomplished by traversing three 5-hole probes radially and circumferentially, using the existing probe traverse system in TPFL. Performance tests were conducted for varying pressure ratio, at fixed rotational speed and for varying rotational speed with fixed pressure ratio and the efficiency was plotted against u/c_0. Each condition was tested and measured two to three times to check for reproducibility of the data. The results from inter-stage experiments show that the rotor row loss coefficient is about four times higher than the stator row loss coefficient. This high rotor loss coefficient reduces the total to static efficiency. From the performance tests, the maximum total-to-static efficiency observed was 85.2 percent located at around u/c_0 = 0.75. This relatively low efficiency is in consonance with the inter-stage results (high rotor loss coefficient).

It takes 3~5 years to finish a power plaint project including location, reliability, environment evaluating, investigation, etc. In addition, it is difficulty to get a right place and hinder by the environment protection. So, it is an important class on boosting the existing power generation capacity. It was used to enhance power generation capacity by increasing the combustion chamber temperature in traditional way. However, it not only increases the exhaust temperature of gas turbine, but also increase the compressor ration. However, it is more difficulty on the design of gas turbine. And then we consider the other way in this thesis by reducing inlet air temperature of compressor to increase the density and flow of air and the power generation capacity. The result is magic that the power generation capacity enhance 10% ~20%. The analysis of Combustion Turbine Inlet Air Cooling System by Absorption refrigerant system(CTIAC-ABS) describe in chapter 2 including fundamental of a gas turbine, the absorption refrigerant chiller, the inlet cooling coil and cogeneration system. It lets us know how to select the style of cogeneration and specification of an absorption refrigerant chiller. It is important to consider the mass condensate water in the air side of inlet cooling coil. The author suggest to use the analysis method of wet-coil developed by Threlkeld(1970). The CTIAC system could be used to the Gas Turbine System, Gas Turbine with HRSG System and Combined System. Because of there is not high pressure steam, we can use the fired-gas absorption refrigerant system as the source of chiller on the CTIAC-ABS system. There is the high pressure steam of Gas Turbine with HRSG System and Combined System. So we can divided the high pressure steam into two part, one to process and the other could be used as the heat source of absorption refrigerant chiller There are two advantages of using CTIAC-ABS on cogeneration power plaint. 1.The new purpose of mass high pressure steam could be used in cogeneration power plaint in Taiwan. 2.Reduction operational cost of CTIAC-ABS The author finished the sensibility of power generation capacity with the analysis of practical operative data, classification of gas turbine and the power plaint Simulation program (GateCycle). When the compressor inlet temperature decrease from 30OC to 10OC, the results are : air flow rate increase 6.3%, fuel flow rate increase 5.95%, exhaust air temperature decrease 1.7% and exhaust air flow rate increase 6.3%, net power output increase 12.2%, heat rat decrease 3.7% and thermal efficiency upward 1.32%.Then, the author got a simulative equation of power capacity. The typical gas turbines operate at full-load condition, 52.25% of annual hours, in 1998 in Taiwan. Gas turbines were almost full load on daytime and half-load or closed at night. If we apply the CTIAC-ABS system on TPC's combined power plant, it can operate at 8:00~18:00 on daytime and shutdown at night. If there is high pressure steam in the cogeneration with HRSG, the CTIAC-ABS system can operate at the time that the cogeneration power plant is operative. How to decide the capacity of absorption refrigerant chiller? The author decided the maximum capacity of absorption refrigerant chiller operating at 31OC , 80%RH of weather condition that limit by 2.5% ***. The author forecasts the lowest compressor inlet air temperature will be 10OC. The steam double-effect CTIAC-ABS system could make the compressor inlet air temperature decrease from 30OC to 10 OC and enhances the heat rate 3.8%, the thermal efficiency 1.2%. The fired-direct CTIAC-ABS system also enhances the heat rate 5% and the thermal efficiency 1.5%. The results are close to the simulation of GateCycle program. So, the author compared the result of simulation with real data that the optimumal operative point of the CTIAC-ABS system is 10OC.

HVDC is usually used to link two AC power systems with same or different system frequencies. Nevertheless, even the two AC power systems linked have the same rated system frequency, the actual frequencies of the two AC systems may be different from time to time due to different load conditions. As a result, asynchronous operation occurs to the HVDC system, which leads to a lot of harmonics to be induced. The frequencies of the main harmonic are within several to several tens Hz (i.e. sub-harmonics), which coincide with the turbine resonant frequency range. Therefore, it has the potential of producing the sub-synchronous resonance phenomena. Usually, the sub-synchronous resonance arising from the excitation by the sub-harmonics currents persists only a very short period of time, thereby the induced fatigue loss would not so serious. However, due to the cumulating characteristics, the fatigue loss may reach the dangerous degree if the shafts and blades are persistently subjected to such resonance excitations. According to such a situation, the fatigue life expenditure of the turbine shafts and blades are evaluated in the thesis. It is anticipated that the potential danger of the turbine-generators in conjunction with the operations of HVDC system can be found.

A computational study of three-dimensional turbulent flow and heat transfer was performed in four types of rotating channels. The first type is a rotating rectangular channel with V-shaped ribs. The channel aspect ratio (AR) is 4:1, the rib height-to-hydraulic diameter ratio (e/Dh) is 0.078 and the rib pitch-to-height ratio (P/e) is 10. The rotation number and inlet coolant-to-wall density ratio were varied from 0.0 to 0.28 and from 0.122 to 0.40, respectively, while the Reynolds number was varied from 10,000 to 500,000. Three channel orientations (90 degrees, -135 degrees, and 135 degrees from the rotation direction) were also investigated. The second type is a rotating rectangular channel with staggered arrays of pinfins. The channel aspect ratio (AR) is 4:1, the pin length-to-diameter ratio is 2.0, and the pin spacing-to-diameter ratio is 2.0 in both the stream-wise and span-wise directions. The rotation number and inlet coolant-to-wall density ratio varied from 0.0 to 0.28 and from 0.122 to 0.20, respectively, while the Reynolds number varied from 10,000 to 100,000. For the rotating cases, the rectangular channel was oriented at 150 degrees with respect to the plane of rotation. In the rotating two-pass rectangular channel with 45-degree rib turbulators, three channels with different aspect ratios (AR=1:1; AR=1:2; AR=1:4) were investigated. Detailed predictions of mean velocity, mean temperature, and Nusselt number for two Reynolds numbers (Re=10,000 and Re=100,000) were carried out. The rib height is fixed as constant and the rib-pitch-to-height ratio (P/e) is 10, but the rib height-to-hydraulic diameter ratios (e/Dh) are 0.125, 0.094, and 0.078, for AR=1:1, AR=1:2, and AR=1:4 channels, respectively. The channel orientations are set as 90 degrees, the rotation number and inlet coolant-to-wall density ratio varied from 0.0 to 0.28 and from 0.13 to 0.40, respectively. The last type is the rotating two-pass smooth channel with three aspect ratios (AR=1:1; AR=1:2; AR=1:4). Detailed predictions of mean velocity, mean temperature and Nusselt number for two Reynolds numbers (Re=10,000 and Re=100,000) were carried out. The rotation number and inlet coolant-to-wall density ratio varied from 0.0 to 0.28 and from 0.13 to 0.40, respectively. A multi-block Reynolds-averaged Navier-Stokes (RANS) method was employed in conjunction with a near-wall second-moment turbulence closure.

This research will use a vibrating U-tube which will cause the water around the tube sway in but will manage the helix leaf blade water turbine which (1998) will develop using Gorlov (Gorlov Helical Turbine). It will also study and discuss electricity generating technology. The vertical motion created external force under the U-tube and about the water will cause the fluid to vibrate and lead the tube cause the domestic water turbine to rotate thus generating electricity. In this article discovers the best size for a generating system and the power rate using the Taguchi method and manufactures the U-tube generating system model and the predecessor gauges the data to make the confirmation, the experimental result discovered the Taguchi method and the actual gauging data best tallies the size. The test results show that in the tube, the fluid oscillation frequency and the blade area rate can affect the structure of the system as well as the true power rate while the external force cycle resonance frequency scope generates electricity.