# Power coefficient Cp of wind turbines

The power coefficient of wind turbine (ratio between useful mechanical power and the total wind power) varies when the tip-speed ratio varies. I know also that we tend to keep constant the power coefficient in tip-speed values of 8-10 (on average, considering a 3 blades turbine) wherein we reach the maximum power and later we tend to decrease Cp when the wind power becomes too high in order to keep constant the power (pitch control for example). My question is: how we keep constant the power coefficient Cp for tip-speed ratio of 8-10? Is this done with converters? And is this done with a MPPT algorithm? (MPPT is the maximum power point tracking). If yes, is it possible to keep constant Cp also with pitch control or active stall?

• What does this mean: tip-speed values of 8-10 and, what does this variant mean: tip-speed ratio of 8-10 – Andy aka Mar 15 at 9:45
• What do you think pitch control does, since you mention it? – Solar Mike Mar 15 at 9:52
• Do you think frequency control might be more important? Since the whole point is to inject power into the grid... – Solar Mike Mar 15 at 10:10
• Once the max generator output has been reached and the wind speed continues to increase, what controls the blade speed? – Solar Mike Mar 15 at 11:29
• Have you worked on a wind turbine? Ever climbed a tower? Actually measured single or 3 phase voltages in one? The power factor? If the generator can’t keep the blades within their speed range, then the brakes are put on and the rotor rotated out of the wind to reduce the stress loading. Well worth finding out how small, medium and large ones work and their differences. Some manufacturers have done clever things, check out Vestas for example. – Solar Mike Mar 15 at 12:22