WIND TURBINE CONTROL SYSTEMS

Wind Turbine Control Systems

Table of Contents

Introduction3

Types of Turbines3

Overview and Objectives4

Statement of Work5

Major Objectives6

Literature Review Of Wind Turbine Control System7

Yaw Control System Of Wind Turbine7

Pitch Control Of Wind Turbine10

Critical Review On Wind Turbine Control Systems12

Transient Simulations13

Mathematical Calculation For Modelling A Simulink Block Of Yaw And Pitch Control System15

Modelling Tools And Methods17

System Model17

Literature Model17

Dynamic Systems Model18

Model Interactions18

Conclusion23

References25

Wind Turbine Control Systems

Introduction

Advancements in simulation technology continue to provide benefits to engineers in the field of wind power engineering. Wind power engineers now have the ability to simulate all aspects of the wind turbine; from detailed structural models of the blades that determine stresses and strains, to highly accurate aerodynamic models of the rotor that reflect its response to the local wind field. In addition to providing detailed predictions of component/system level performance, advanced optimization software can be used to guide engineers towards more suitable solutions to their design challenges.

Types of Turbines

Figure 1.2: Power Curves of Example Wind Turbines (Santoso and Le, 2007, p 2452).

The curves shown in Figure 1.2 address the classifications of wind turbines, showing a fixed speed and a variable speed wind turbines power curve. The difference between the two wind turbines is quite easily stated in that variable speed wind turbines are controlled to change speed while fixed speed turbines are controlled to a finite speed (Ofualagba and Ubeku, 2000,pp. 1-8).

For the wind turbine being developed, the rotor speed will be dependent on the optimization of the rotor efficiency, which is accomplished through generator torque control. The major difference between the two is that the variable speed wind turbine can capture more energy than the fixed speed wind turbine. Along with being more aerodynamically efficient variable speed turbines are fitted with a more complex electrical system which is capable of system dampening and limiting voltage sags to the grid through power smoothing. The drawback to variable speed systems is that they are expensive and require complex control strategies. There is a benefit to fixed speed wind turbines in that they are simple, robust and inexpensive but electrically and aerodynamically inefficient (Ofualagba and Ubeku, 2000, pp. 1-8).

Overview and Objectives

The objective of this thesis is twofold. The primary objective is to develop and validate a numerical simulation model of a wind turbine system. The model will be developed from existing work available in the literature. The model will then be verified and validated against published work. The mechanical transmission components will be modeled in detail. The electrical component will be simplified by capturing the essence of motor/generator principles.

Power electronics will be treated as static power conversion. The second objective of this thesis will be a study of existing control issues, in particular control methods applied below and above rated wind speeds. Existing control approaches given in (Boukhezzar and Siguerdidjane , 2005,pp. 3456- 3461) will be surveyed and implemented. Simulation results will provide insight into the performance of these methods under variable wind speed. This survey will highlight the advantages and disadvantages of control ...