A higher rated power will give you more energy, but you also need the wind to blow at a good speed for lots of time. For example, if a turbine runs for 1 hour at 1000W, it will generate 1000 watt-hours of energy. The units of power are watts, and units of energy watt-hours. Your electricity bill is based on how much energy you use: if you look at the bill you will be charged per kWh (short for kilowatt-hour) you use. However all this relates to power, not energy. Schematic Power Curve for a 1kW Wind Turbine This is 11 mph or 9.7 knots.Ĭommercial wind turbines have different power curves depending on whether they’re designed to operate at lower or higher wind speeds. At the lower end, a minimum wind speed of about 5 m/s is often considered necessary for a wind turbine to be viable. This shows that wind turbines have a wide operating window for stronger winds. A shut-down wind speed of 25 m/s is 56 mph or 48.6 knots. To put these speeds in perspective, maximum power is at about 11 m/s which is 24.6 mph or 21 knots. Typically shut-down speeds are about 25 m/s. The power then stays fairly constant with increasing wind speed until the turbine is shut down for safety reasons. The power increases with wind speed up to it’s rated power, which is at a defined wind speed (wind turbine specifications will state the rated power and the wind speed for the rated power). You’ll note that the power doesn’t start increasing at zero wind speed: each turbine has a ‘cut-in’ wind speed at which it starts to produce power.
The curve below shows an example ‘power curve’ for a wind turbine rated at 1000W. Thus the rated power of a wind turbine is the power that the turbine will produce at a particular wind speed. The power output is fairly obviously dependent on how much wind is blowing. However, the turbine will not produce this rated power all the time. To model the lower rigid body in SubDyn, you can use rigid links between nodes of the cables, again, adding lumped masses/inertias as needed to get the overall mass, center of mass, and inertia of the lower rigid body are as you want.The most basic specification for a wind turbine is a power rating.Ī residential wind turbine might be rated at 5kW, and much bigger wind farm turbines might be rated at several MWs each. You can add lumped (concentrated) masses/inertias at the node endpoints of the beams to ensure that the overall mass, center of mass, and inertia of the upper rigid body are as you want. As such, I'd recommend using quite stiff beam elements. To model the upper rigid body in SubDyn, ideally you'd place rigid links between the interface node and the nodes connecting the cables, but there is a bug in SubDyn that was recently found regarding this functionality, as reported recently on the OpenFAST issues page. for all platform mass, center of mass, and inertia properties in ElastoDyn, except PtfmYIner, which you should set equal to the rotational inertia of the undeflected tower about its centerline, at least when YawDOF = True, as discussed in other forum topics). So, you can set PtfmRefzt = PtfmCMzt = PtfmMass = 0 (etc. In that case, the 6 platform DOFs should be enabled in ElastoDyn, but the mass, center of mass, and inertia of the upper rigid body needs to be modeled in SubDyn. It probably makes sense to model the entire floating substructure (upper and lower rigid bodies and cables) in the same module (SubDyn).