Hydraulic-pneumatic flywheel configurations for controlling the inertia of a wind turbine rotor.

In this article, a methodology is presented for the design of a hydraulic-pneumatic flywheel integrated in a wind turbine rotor. The flywheel enables wind turbines to contribute to power system inertia and it can be used for mitigating loads on the wind turbine. The methodology is applied to the geometry of an existing blade design of a 5-MW wind turbine, but is valid for any arbitrary rotor blade. Several flywheel configurations are derived causing an increase in rotor inertia of the 5-MW wind turbine by 15%, but differ in the position, dimensions and masses of the hydraulic components. These parameters determine the total mass of the hydraulic-pneumatic flywheel, and hence the impact on the mechanical loads on the wind turbine. As a result, a weight-optimized configuration for a flywheel integrated in a wind turbine rotor is derived. [ABSTRACT FROM AUTHOR]