1. Sliding Mode Control of Wind Energy Generation Systems Using PMSG and Input-Output Linearization Xiangjun Li, Wei Xu, Xinghuo Yu and Yong Feng RMIT University, Australia

2. Platform Technologies Research Institute 2 Outline  Background.  Introduction to PMSG.  Input-output linearization.  SMC design.  Simulation studies.

3. Platform Technologies Research Institute 3 Background We need the energy supply to be sustainable!!!

4. Platform Technologies Research Institute 4 Background Fig. 1. The future smart grid (http://energyinformative.org/what-is-the-smart-grid/)

5. Platform Technologies Research Institute 5 Background Fig. 2. The installed capacity of wind generation.

6. Platform Technologies Research Institute 6 Background Several factors have made wind power generation cost competitive:  The improvement of aerodynamic efficiency of wind turbine;  The potential market and government incentives;  New control schemes for the variable-speed wind turbine which allow the optimization of wind turbine performance.

7. Platform Technologies Research Institute 7 Background  Constant speed system.  Require sturdy mechanical design;  Require stiff power grid.  Variable speed wind energy generation.  Is able to optimize wind energy absorption;  Smooth power output.

8. Platform Technologies Research Institute 8 PMSG Fig. 3. The rationale and structure of PMSG. Magnetic induction of electric current Force on current carrying lines

9. Platform Technologies Research Institute 9 PMSG Fig. 4. Mechanical configurations.

10. Platform Technologies Research Institute 10 PMSG Fig. 5. Application of PMSG in wind energy generation.

11. Platform Technologies Research Institute 11 PMSG  Permanent magnetic synchronous generator is a type of generator in which the excitation field is generated by permanent magnet;  The mechanical frequency matches the required electrical frequency.  PMSG requires less parts than other generators such as induction generator. Thus, it is more mechanically reliable.  PMSG is widely used in wind energy generation and hydro electricity generation.

12. Platform Technologies Research Institute 12 PMSG  By field orientation control (FOC), it can operate the optimal working point and minimize the losses in generator and power electronic circuit;  The use of a multi pole synchronous generator (large diameter synchronous ring generator) can give direct drive function without a gearbox;  Higher efficiency for no additional power supply for the magnet field excitation;  Higher reliability due to the absence of mechanical components such as slip rings, lighter and therefore higher power to weight ratio.

13. Platform Technologies Research Institute 13 PMSG  The control schemes depend on the accurate generator parameter, which vary with temperature and frequency;  The permanent may increase the price of machine and meet with demagnetization phenomenon;  The power factor of machine cannot be adjusted easily.

14. Platform Technologies Research Institute 14 PMSG Fig. 6. The electrical configuration of the PMSG.

15. Platform Technologies Research Institute 15 Problem Description Fig. 7. Signal flow chart of the system.

16. Platform Technologies Research Institute 16 This page is only for you to keep in mind about the relationships of those signals The arrow means “determined by”

17. Platform Technologies Research Institute 17 Problem Description Wind power intensity Mechanical power of wind turbine Performance coefficient Tip speed ratio Optimal angular frequency

18. Platform Technologies Research Institute 18 Problem Description PMSG model Electrical: Mechanical:

19. Platform Technologies Research Institute 19 Problem Description PWM converter algebraic model DC link algebraic model The grid side model is the symmetrical.

20. Platform Technologies Research Institute 20 Problem Description Voltage of the capacitor Angular velocity of the rotator Machine side current in d-q axisGrid side current in d-q axis

21. Platform Technologies Research Institute 21 Problem Description,

22. Platform Technologies Research Institute 22 PMSG ParameterDescriptionValue Rated generator power2MW Rated generator voltage4kV Number of pole pairs11 Moment of inertia2.525*106kgm2 PM flux166.8Wb Stator d-axis inductance0.367H Stator q-axis inductance0.250H Stator resistance0.08 Filter inductance33mH Filter resistance0.078 Inductance between grid side conv. And grid0.0295H Resistance between grid side conv. And grid0.086 DC link capacitance100

23. Platform Technologies Research Institute 23 Input-Output Linearization

24. Platform Technologies Research Institute 24 Uncertainty Analysis is independent of

25. Platform Technologies Research Institute 25 Uncertainty Analysis

26. Platform Technologies Research Institute 26 SMC Design

27. Platform Technologies Research Institute 27 SMC Design Theorem 1. System (1) can be stabilized by the control laws where if where is the th item of matrix,,, and are positive constants.

28. Platform Technologies Research Institute 28  By choosing the uniform control gain for all subsystems, the coupling between them through uncertainty items can be decoupled.  After the decoupling, the stability of the overall system can be achieved by stabilizing each subsystem.  Here we only carry out the simulation study of the subsystem, which is the angular speed of the rotator. The units of the variables are unified. The angular speed and the angular acceleration are two states depicted in Figure 8 and Figure 9. Simulation Studies:Sub-system

29. Platform Technologies Research Institute 29 Simulation Studies:Sub-system Fig. 8. State trajectory of the closed-loop system.

30. Platform Technologies Research Institute 30 Simulation Studies:Sub-system Fig. 9. System response of the closed-loop system.

31. Platform Technologies Research Institute 31 Conclusion  The structure of the wind energy generation system using PMSG has been introduced.  The system, which is described by mathematical model in state space, has been formulated and linearized by the input-output linearization technique.  Uncertainties are included in the modeling and linearization.  SMC controls have been designed to stabilize the system.  Simulation studies are conducted to verify the results.

32. Platform Technologies Research Institute 32 Thanks for your attention! Questions please.