Early wind turbine main control system

The focus of is coordinated control of wind farms over three control levels: central control, wind farm control, and individual turbine control. Under-load tap changing transformers and convectional mechanical switched capacitors are used to implement the control strategies, which can be implemented on both fixed- and variable-speed turbines.

Two major systems for controlling a wind turbine. Change orientation of the blades to change the aerodynamic forces. With a power electronics converter, have control over generator torque. To maximize power output, want constant optimal tip speed ratio. As wind speed increases, rotor speed increases.

Figure 4: Schematic of a wind turbine closed-loop control system. One of the approaches to control aerodynamic torque. { This ultimately comes by controlling the rotor L=D. Stall-regulated rotors are designed with section shapes and mean angles of attack to cause the rotor to stall at higher wind speeds, beginning at rated power wind speeds.

Pitch controlled WTs have an active control system which varies the pitch angle of the turbine blades to decrease torque and rotational speed in WTs. This type of control is usually employed in high wind speeds only where high rotational speeds and aerodynamic torques can damage the equipment.

As mentioned earlier, depending on wind speed, there are two control regimes. In the below rated wind speed region, the pitch angle is fixed at 0 and the generator torque is controlled to maintain max-Cp operation in the face of turbulence.

Control of variable-speed wind turbines: Standard and adaptive techniques for maximizing energy capture. IEEE Control Systems Magazine, 26(3):70–81, June 2006. K. Stol and M. J. Balas. Periodic disturbance accommodating control for speed regulation of wind turbines. In Proc. AIAA/ASME Wind Energy Symp., pages 310–320, Reno, NV, 2002.