The Lagerwey LW wind turbine

The Lagerwey LW-50/750 wind turbine is a 750 kW, variable speed wind turbine with an upwind rotor of 50.5-meter diameter. A picture of this turbine is shown in Fig. A.1. The "LW-50/750" is located near Nieuwe-Tonge (Province of Zuid-Holland, The Netherlands). The rotor consists of 3 blades that can be actively and individually pitched over the full span. The pitch control is used for power control at full load, and to stop the turbine if the safe operating limits are exceeded. The turbine is equipped with a gearless (or direct-drive) synchronous ring-generator, which converts the mechanical power into electrical power at variable frequency. Subsequently, an insulated gate bipolar transistor (IGBT) based frequency converter is used to convert the electrical energy of varying frequency to the utility grid with a fixed 50-Hz frequency. The generator torque will follow an external set-point signal, which is calculated by the control computer. The support structure consists of a 46.165-meter conical tower with a circular cross section, and a foundation. The tower is made of tubular steel.

The Lagerwey LW-50/750 belongs to a new generation of wind turbines which are more flexible than the majority of the turbines currently on the market. It has soft characteristics realized in all subsystems in order to reduce internal stresses, and thereby to make lighter, and hence less costly components possible. The explanation

Wind Turbine Components

Figure A.1: Lagerwey LW-50/750 wind turbine, located near Nieuwe-Tonge (Province of Zuid-Holland, The Netherlands).

for this is that in a stiff system concept the transient air loadings go into the structural components as physical strains, and (sooner or later) induce fatigue damage. In a soft system concept, on the other hand, these air loadings are reacted primarily by the subsystem masses with little strain energy involvement. In other words: the subsystems bend under the transient air loading by which internal stresses will be reduced. Hence, there is low tendency for fatigue failure in a dynamically soft system.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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