This chapter discusses the control systems for ocean, wind and wave energy. A general study on wind turbine control suggests that a variable-speed turbine, requiring torque and speed control, can absorb 2.3% more energy than a fixed-speed counterpart, where the speed is fixed by the electrical grid frequency. In the case of wave energy, the numbers are more dramatic. A study on latching control, which is a relatively simple implementation of the more ideal complex-conjugate control, suggests that energy capture can increase by as much as afactor of 2 with control in irregular waves and by up to a factor of 4 in regular waves.

Chapter Contents:

• 8.1 Overview of control scheme
• 8.1.1 Introduction
• 8.1.2 What is control?
• 8.1.3 Control systems for ocean energy
• 8.1.4 Conclusions
• 8.2 Implications of control schemes for electrical system design in tidal energy converters
• 8.2.1 General control strategy for tidal current energy extraction
• 8.2.2 Fixed-speed variable-pitch tidal turbine
• 8.2.3 Variable-speed fixed-pitch turbine
• 8.2.4 Tidal turbine control
• 8.3 Implications of control schemes for electrical system design in wave energy converters
• 8.3.1 Introduction
• 8.3.2 Relationship between control schemes and the WEC electrical system
• 8.3.3 Impact of efficiency on power extraction
• 8.3.4 Discussion
• 8.4 References

Inspec keywords: nonlinear control systems; wave power generation; power generation control; robust control; tidal power stations; wind turbines; torque control; three-term control; angular velocity control; optimal control

Other keywords: variable speed turbine; nonlinear control; wave energy; control systems; complex-conjugate control; wind energy; speed control; optimal control; latching control; ocean energy; torque control; robust control; wind turbine control

Subjects: Stability in control theory; Optimal control; Wave power; Mechanical variables control; Control of electric power systems; Tidal power stations and plants; Nonlinear control systems; Wind power plants; Velocity, acceleration and rotation control