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Fuzzy Modeling and Control of Wind Power
Published in Zhixiong Zhong, Modeling, Control, Estimation, and Optimization for Microgrids, 2019
In recent years wind energy application, as an economic type of renewable energy, is rapidly growing. With increasing oil price, security threats, and environmental concerns, the portion of wind energy is expected to be 12% of total global energy by 2020. Wind turbine electricity generation depends on wind velocity and structure. The variable speed wind turbine, the most common type of wind conversion system, produces more power than a fixed speed turbine. The wind structure with the permanent magnet synchronous generator (PMSG) is an efficient configuration for variable speed systems. Its advantages include fewer repair requirements, DC excitation and high power-to-weight ratios. To connect the wind structure to the network, a full-scale converter is utilized providing a wide operation range for rotation speed and captured power [1].
Wind-Electric Pumping Systems for Communities
Published in Joseph A. Cotruvo, Gunther F. Craun, Nancy Hearne, Providing Safe Drinking Water in Small Systems, 2019
The foundations of wind-electric pumping technology are the ability of standard 50 or 60 hertz induction motors to be operated at variable speed and a fortunate match between the power needs of a centrifugal pump and the power availability from a wind turbine. A threephase induction motor can be operated at variable speed by changing the frequency of its electrical supply, so long as the voltage is also changed correspondingly. With a variable-speed wind turbine the frequency output from the generator varies with the wind speed as the rotor speeds up or slows down in response to wind gusts. The power available from a wind turbine varies as the cube of the wind speed. Following the Affinity Laws, the power required by a centrifugal pump varies as a cube of its speed. Therefore, if a pump is optimally matched to a wind turbine at one speed or frequency, it is optimally matched at all speeds or frequencies.
Renewable Resource Distributed Generators
Published in H. Lee Willis, Walter G. Scott, Distributed Power Generation, 2018
H. Lee Willis, Walter G. Scott
Thus, a variable-speed wind turbine operates at or near optimum in all wind speeds, while a constant-speed turbine would be optimum at only one speed. Over the course of a year, a variable-speed wind turbine will produce something on the order of 10% to 25% more power than a constant-speed turbine of similar size, or about 3% to 10% more power than a constant-speed turbine of similar cost. The variable-speed wind-turbine equipment – mechanical, electrical, and control – are more expensive than their equivalents in a constant-speed turbine. As a result, constant and variable-speed wind turbines of the same size, e.g., 25 meter diameter, would not have the same cost. A constant-speed turbine, of perhaps 26 - 27 meter diameter, could be built for the same cost as a variable-speed turbine of 25 meters, and with its larger swept area, have the potential to collect more wind energy. However, it would recover net energy optimally at only one speed, versus the variable-speed turbine’s ability to more nearly optimize its power extraction under nearly all conditions. In most locations, over the course of a year, the larger constant-speed unit would fall short of the total energy output of the smaller variable-speed wind turbine.
Wind speed forecasting techniques for maximum power point tracking control in variable speed wind turbine generator
Published in International Journal of Modelling and Simulation, 2019
Fouzia Achouri, Boubekeur Mendil
In the variable speed wind turbine, the maximum power is captured by keeping the tip speed ratio at its optimal value and the rotor speed must be adjusted to track the desired rotation speed.
Power curve modeling for wind turbine systems: a comparison study
Published in International Journal of Ambient Energy, 2021
The increase in energy demands increases the importance of renewable energy sources in meeting this demand both economically and environmentally. Wind energy, which is a renewable energy source, has an important place among energy sources because it is an environmentally friendly and free energy source. Recently, the interest in the usage of wind energy through WTSs has been increasing for electrical energy production owing to rapid depletion of fossil fuel resources and rapid population growth. WTSs can be installed almost anywhere and do not take up too much land area. Additionally, it has the advantage of generating electricity in optimum wind conditions at all times regardless of day and night (Keeley and Ikeda 2017). For this system, there are two types of power generation which are called fixed and variable speed. The first type of WTSs whose speed is fixed has generally operated with stall principle to keep rotor speed at constant. For the second type called variable-speed WTS, the tip-speed ratio is adjusted at its optimal value changing the rotor speed by a pitch control unit so as to operate at maximum rotor efficiency. The variable speed wind turbine has higher output efficiency than fixed speed wind turbines. Also, the wind turbine with variable-speed can adjust the rotational speed to wind speed is the ability that, and can operate in the maximum level in almost every time (Singh 2012). For both types of WTSs, the electrical power output varies depending on the size/structure/type of mechanical and electrical components as well as wind speed. Power losses from these components are classified as aerodynamic, mechanical and electrical losses. The aerodynamic losses consist of wing profile losses, wing-tip losses and vortex losses. It is minimised depending on the lift to drag ratio, the tip-speed ratio and aerodynamic design of wings. The mechanical losses on the output power consist of friction losses on the shaft and the losses in the gearbox, and it is called as transmission losses. These losses are generally minimised by using integrated and direct supported transmission systems. These systems are designed depending on the number-type of shaft bearing and the type of gearbox. The last component is the electrical losses including generator and inverter losses, which are used for converting mechanical energy into electrical energy and adjusting the frequency and voltage level, respectively (Hau 2006).