In this lecture, we're going to hear about wind turbine terminologiy and components that you are going to use in this course. It's an introduction where you afterwards should be able to list the main components of the commercial horizontal-axis wind turbine. And you should be able to list the main degrees of freedom that such a turbine has. The main component of the turbine is the rotor that generates the aerodynamic torque from the wind. It's the nacelle that converts the torque into electrical power up here. It's the tower that holds the nacelle and the rotor blades up in the wind, and also provides access to the nacelle for maintenance. And it's the foundation that holds the whole turbine in place and into the wind. The main degrees of freedom of wind turbine is the azimuth, the rotation off the rotor we call the azimuth. And normally it's calculated from vertical distance, the azimuth angle. We have the yaw, which is the degree of freedom that is used to turn the nacelle into the wind and the whole rotor. Then we have the pitch angle, which is rotations of the blades about it's lengthwise axis, typical due to a controller action. If we look at the rotor it consists of the blades, the hub, the spinner, and the pitch bearing, and also the pitch system, which is inside the hub. Here we see a picture of a hub and a spinner. You can see the hub behind the spinner in here, the metal part, and outside typical glass fiber plastic hub. And then we have the blades here on the ground. In this case, for these blades the pitch bearing, the bearing which turns the blades about their lengthwise axis is part of the blade and not of the hub. Typically, it would be part of the hub. And here we see how the whole rotor is lifted up to the turbine we have here at the DTU campus, Risoe. If we look at the nacelle it consists of the drivetrain that converts the air dynamic torque that goes in through the hub, through the main shaft, or also called the low speed shaft. It is hold by the main bearing and a gearbox where there's also a bearing, and it translate the speed of the low speed shaft into a high speed shaft that goes into the generator. On the high speed shaft we have also the mechanical break for breaking the turbine at stand still. And all this is mounted on the bed plate which forms the entire nacelle. And this bed plate can then also turn in the all direction on the tower top using a yaw drives. The generator is connected to the converter, typically we have a variable speed turbine, which a converter can convert the speed of the generator into the grid frequency. And this is then through some transformation into the grid. The tower, the typical tower you see is a tubular tower made of steel. But it could also be a lattice tower or even a combination, like a tripod tower, where you have larger structures than you have in lattice tower. Then we have the foundation typically on shore, it's a gravitational foundation where the gravity is holding the whole thing, and it's made out of concrete. Here you see where we are pouring the foundation for the research turbine at the Risoe Campus, DTU, and here we see how the towers are mounted on this foundation. When we go offshore, there are different kinds of foundations, and this is a large research area where we can have a monopile where we have, similar to the tower tubular steel structure that is hammered into the ground. We can have had a tripod, which can also be hammered into the ground, the feet of the tripod. Or it could also have a pocket foundation, where there is a big steel structure that is sucked into the ground. We can have the jacket. Or we can also have floating devices like semi-submersible. Structure with mooring lines or a spar buoy, where it's more like a buoy also mounted with mooring lines to the ground. So we come to the summary. The main components of a horizontal-axis wind turbine is the rotor blade, the nacelle, and the tower, and it's foundation. And inside the nacelle we have the drivetrain with the main bearing, the gearbox, the brake and the generator, and some power electronics that converts the power produced in the generator to the grid side through some transformers. The main degrees of freedom is the azimuth rotation of the rotor, which is the one generating the power. The yaw rotation of the nacelle which makes sure that we can turn the turbine into the wind. And then we have the pitch rotation of the blades, about the length with axis which we use for controlling the aerodynamic torque on the rotor.