The importance of the use of renewable energy sources is obviously. But what the problem confused us, is that renewable energy unlike the fossil fuel have such high energy density which means the renewable generally was dispersed form. In other words, in order to obtain amount of the energy we need, require to exploitation a wider cover area. Therefore, scientists and companies are struggling to find high densely renewable energy as possible, which is high altitude wind energy, have very promising but not developed so much by humans. High altitude wind power is indicating the altitude between 3000 meters and 10000 meters. So far, high altitude wind power is a new renewable energy that basically not development or utilization yet, but which is an abundant reserves. High altitude wind power is a widely distributed renewable clean energy. The characterized of high-altitude wind energy is fast speed, wide distribution, high stability and perennial. Utilize high-altitude wind power can get high stability with low cost of wind power generation, which is one of the notable features for high-altitude wind power, but also is one of the most significant advantages for high-altitude wind energy compared to conventional wind energy. High altitude wind power generation equipment is more compact and flexible, far superior then the traditional fan, which equip with thick blades and the tower must be fixed in the depths of the ocean or in the ground.To development renewable power in a large scale, to face the global climate change, achieve the sustainable development become the inevitable for human development. How to solve the energy shortage problem has become an important question, harness high altitude wind power was becomes the focus of multinational technology.

The electric grid of Gotland is connected to the mainland via a 90 km HVDC Classic bipole of 2 * 130 MW. The HVDC link balances the load and production on the island to maintain the frequency within limits, the load varies between 50 and 180 MW throughout the year. The power production on the island comes mainly from wind power. Today, the installed power is about 170 MW but the wind power production will be further exploited and the plan is to add another 500 MW of wind power capacity to the existing plants. These plants will be connected to a new 130 kV transmission grid which will have a connection to the existing 70 kV grid at a new substation called Stenkumla. Along with the increased wind power production on the island comes the need of increased transmission capacity to the mainland. A VSC HVDC link of 500 MW is planned for this purpose and it will be connected to Stenkumla. As of today, it is not certain whether the two grids will be connected or not. Having connected grids is in the interest of the grid owner Gotlands Energi AB, GEAB since they then could utilize the technology of the new link and thereby ensure stableoperation during faults that today would lead to black out. In this thesis the feasibility of having connected grids was investigated and the study was divided into three main parts. •Reactive power and voltage profiles •Short circuit study •Converter trip study This study shows that under the assumptions made regarding production grid layout and proportion of WTG types there will be no need for adding reactive power compensation equipment. That is provided that demands are set on wind power plant contractors to have their equipment contributing with reactive power compensation, even during no load. A trip of the SvK VSC HVDC converter during full power production causes the most severe stress to the system. The major problem proved to be surviving the first 100 ms after converter trip without loosing angular stability and the most important measure to improve the stability was active power reduction of the wind turbines. The overall conclusion is that it is feasible to have connected grids during normal operation but demands has to be put on wind power plant contractors.

Due to the insecurity of the supply of raw materials needed for neodymium-iron-boron magnets, typically used in permanent magnet generators, the use of ferrite magnets as an alternative was investigated. The investigation was conducted by attempting to redesign a generator that previously used neodymium-iron-boron magnets for use with ferrite magnets. The major part of the redesign was to find an alternate rotor design with an electromagnetic design adapted to the characteristics of the ferrite magnets.It was found that  ferrite magnets can be used to replace neodymium-iron-boron magnets with changes to the electromagnetic design of the rotor. The changes of the electromagnetic design increase the amount of magnetically active material in the rotor and, therefore, require the mechanical design of the rotor to be changed. The new rotor design also requires some changes to the generator support structure. A design for a replacement rotor, using ferrite magnets, along with the required changes to the support structure, is presented.

After enjoying one week in the Swedish Lapland, the idea of providing energy to one of those isolated cabins in the far landscape caught our attention. Nowadays, there still exist many dwellings, usually located in rural isolated sites, which have no easy access or even no possibility to get connected to the distribution and transport electricity grids. This situation may cause some inconvenience to the owners, therefore, the interest in finding new alternatives for supplying electricity. Such a problem requires specific solutions, including the development of electrification programs in those countryside isolated spots. Thus, the present project intends to perform a study which would provide the proper electric system to a summerhouse in the North of Sweden. Regarding the current European environmental politics and considering the rural location of the dwelling of study, the project will focus on various renewable alternatives to reach the above mentioned goal. In fact, Sweden has the greatest share of renewable energies in all European Union countries with a fixed goal of reaching 50% of its total energy production by renewable sources by the year 2020. For the present moment, Sweden already accounts for 9.4 GWh on solar energy production and 3.5 TWh on wind power production by the end of 2010. Therefore, the study will build on these alternatives as they represent two of the most extensively developed renewable possibilities in the country. Thereby, the first objective of the project was to determine a concrete location considering both our initial idea and the possibility of obtaining the wind speed and solar radiation data. A plot located 20 km to the north of Lulea was finally chosen. Then, once having the necessary baseline data comes the sizing of the different alternative: stand alone wind turbine system, stand alone PV system and a hybrid system combining wind power with the support of an electric generator. No option including grid connection is taken into consideration due to the lack of accessibility. Finally, it is performed an economic study of each alternative that would lead to a clear conclusion of which is the most appropriate choice in the study case. Economic criteria will therefore be the most significant factor when choosing the optimum alternative. However, environmental issues would also be taken into account. As no traditional electrification is studied, the economic analysis will not refer to the obtained monetary savings regarding to the grid connected option but will be performed by comparing initial investments. After all, it is concluded that the studied dwelling will be electrified by a hybrid system combining wind power with an electric generator. The system includes a 20 kW wind turbine and a diesel fueled generator with 8 kW power service. The generator will provide the required energy to the house during those days when the wind resource is not capable to cover the demand. Therefore, the lack of electricity supply will be avoided. Regarding investment costs of the chosen alternative, the hybrid system accounts for 20,729€ investment, which corresponds to about 40% the total price of both solar and wind stand alone systems. . Considering environmental criteria, the hybrid system only requires 23 diesel liters to be burned during the six summer months. Therefore, emissions due to combustion are relatively low and not considered as damaging. So, the chosen alternative meets both economical and environmental requirements.

The purpose of this work is to develop a maximum power tracking control strategy for variable speed wind turbine systems. Modern wind turbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor speed measurements as control variable inputs. The dependence on the accuracy of the measurement devices makes the controller less reliable. The proposed control scheme is based on the stiff system concept and provides a fast response and a dynamic solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier, a dc/dc boost converter, a current controlled voltage source inverter, and a microcontroller that commands the dc/dc converter to control the generator for maximum power extraction. The microcontroller will also be able to control the current output of the three-phase inverter. In this work, the aerodynamic characteristics of wind turbines and the power conversion system topology are explained. The maximum power tracking control algorithm with a variable step estimator is introduced and the modeling and simulation of the wind turbine generator system using the MATLAB/SIMULINK® software is presented and its results show, at least in principle, that the maximum power tracking algorithm developed is suitable for wind turbine generation systems.

Wind power generations have increased impacts on the electric utility power systems. When the wind power is placed into service in an electric system, it becomes a functioning part of the system, which may require other design changes to the system and special practices to integrate it to the system. The presence of the wind power generation units will directly affect voltage profiles along a feeder by changing the direction and magnitude of active/reactive power flows. A number of coordination issues including safety issue, protection, voltages and frequency control presently require study in order to understand technical limits to the penetration of wind power or distributed generation on a given system. The aim of this thesis is to investigate the impacts of wind generators connected to a distribution system. To take load uncertainty and wind power generation uncertainty due to wind speed variation in the analysis, Monte Carlo simulation technique is used. A number of cases are tested to assess the impacts of wind power generations in various scenarios for the studied network. Test results have shown that the when wind power generators are connected to distribution network, it would not only reduce the probability of occurrence of undervoltage but also decrease the feeder losses. The analytical models proposed in this thesis can provide the utility useful information in placing the wind power generators.

The purpose of this work is to develop a maximum power tracking control strategy for variable speed wind turbine systems. Modern wind turbine control systems are slow, and they depend on the design parameters of the turbine and use wind and/or rotor speed measurements as control variable inputs. The dependence on the accuracy of the measurement devices makes the controller less reliable. The proposed control scheme is based on the stiff system concept and provides a fast response and a dynamic solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier, a dc/dc boost converter, a current controlled voltage source inverter, and a microcontroller that commands the dc/dc converter to control the generator for maximum power extraction. The microcontroller will also be able to control the current output of the three-phase inverter. In this work, the aerodynamic characteristics of wind turbines and the power conversion system topology are explained. The maximum power tracking control algorithm with a variable step estimator is introduced and the modeling and simulation of the wind turbine generator system using the MATLAB/SIMULINK® software is presented and its results show, at least in principle, that the maximum power tracking algorithm developed is suitable for wind turbine generation systems.

Bachelor's thesis. / Format: PDF. Bibl.

The objective of this Thesis is to develop a methodological framework to guide the decision maker in selecting a decommissioning method for offshore wind farms which is supported by the majority of relevant stakeholders. Initially, a literature review has been conducted to find out which methods are available to decommission an off-shore wind farm and which criteria can influence the outcome.Two methods have been found in literature, namely partial and total removal of the foundation. Furthermore, twenty one (21) criteria have been found which could influence the results. These criteria can be divided in four categories which are economical, environmental, social and technical.Subsequently, a methodological framework was developed that included four steps. First, the possible decommissioning methods should be identified. Following on that, information should be collected and stakeholders should be selected. Subsequently, criteria should be selected and as last a multi criteria decision aid method should be used. It is expected that this procedure would lead to a decommissioning method which is supported by most of the stakeholders.To validate the methodological framework, a case study in the Netherlands has been selected. For this case study, four (4) stakeholders were identified and eleven (11) criteria were assessed. The outranking multi-criteria decision aid method PROMETHEE II was selected and results were obtained. Analyzing the results, it was possible to conclude that only one stakeholder preferred the total removal method while the other three stakeholders preferred the partial removal method.

During our study trip to Tanzania we discovered one of the great issues for farmers to be need of running water. So we asked ourselves: How can water from Lake Victoria be transported to the small scale farmer’s household and farm in the most optimized way? During the stay in North West of Tanzania we made field trips to the rural areas in Mara Region in order to understand the farmers who are the potential users. We performed semi structured interviews and observations during the whole field study. We also came to the conclusion that wind is a good source of power which can be used to pump water. The wind comes in from Lake Victoria in the same direction everyday. So therefore we decided to construct a water pumping wind power station for small scale farmers.