Modeling and PI Control of Spar Offshore Floating Wind Turbine

摘要

Reliable control strategies are necessary for long term operation of offshore wind turbines because they are sited in severe environment. Offshore wind turbines experience environmental loads like wind, wave and current. This paper proposes a stratagem of applying the proportional integral (PI) control algorithm in the blade pitch mechanism of a 5 MW benchmark NREL offshore wind turbine (Jonkman et al., 2009) in a LABVIEW environment. Owing to the irregular wind and waves, the platform will be unstable which in turn affects the overall stability of the turbine. The turbine is assumed to be installed in water depth of 320 m on a spar platform. The spar when subjected to the wave loads, exhibit irregular and chaotic responses. The primary objective is to control the pitch so as to obtain optimum generated power. The control algorithm has to be effective in two regions of operation viz., in controlling power in operational wind speeds and also to keep the wind turbine safe in extreme severe wind conditions. In this process, the control techniques vary the blade pitch angle for generating optimum power production as well as stable closed loop operation. Numerical results and simulations are shown to validate the proposed methodology and to demonstrate its effectiveness.