MODELING OF THE WIND TURBINE WITH A PERMANENT MAGNET SYNCHRONOUS GENERATOR

1. MODELING OF THE WIND TURBINE WITH A PERMANENT MAGNET SYNCHRONOUS GENERATOR SINDHU.C.MANOHARAN Edited By Sarath S Nair www.technologyfuturae.com www.technologyfuturae.com

2. CONTENTS • Introduction • How does a wind turbine work • Model of wind turbine with PMSG • Different types of PMSG • Constructional features • Modeling of generator • Voltage and torque equation Permanent Magnet Synchronous Generator • Control schemes of a permanent magnet (PM) generator • AC-DC-AC Power Conversion System • Conclusion www.technologyfuturae.com

3. INTRODUCTION • Wind energy is one of the best technologies available today to provide a sustainable supply to the world development. • In terms of the generators for wind-power application, there are different types of wind turbine are there, fixed-speed wind turbines and variable speed wind turbine • In fixed speed wind turbine, induction generators are used (application in wind farms). But the limitations of such generators are low efficiency and poor power quality • In variable speed wind turbine, doubly fed induction generators and permanent magnetic synchronous generators are used. www.technologyfuturae.com

4. HOW DOES A WIND TURBINE WORK www.technologyfuturae.com

5. MODEL OF WIND TURBINE WITH PMSG • VSC1=machine side power converter • T1=interface transformer • L1=inductance of the transformer • Ug=Output voltage of VSC1 • fg=electric frequency www.technologyfuturae.com

6. DIFFERENT TYPES OF PMSG • Radial flux permanent magnet machine (RFPM) • Axial flux permanent magnet machine (AFPM) • Transverse flux permanent magnet machine (TFPM) www.technologyfuturae.com

7. RFPM machines • The RFPM machine is producing the magnetic flux in the radial direction with PMs which are radial oriented. It is the best choice for direct drive wind turbine • AFPM machines • The AFPM machine is a machine producing magnetic flux in the axial direction with permanent magnets. (application in low speed low power range) • TFPM machines • The transverse flux (TF) principle means that the path of the magnetic flux is perpendicular to the direction of the rotor rotation. www.technologyfuturae.com

8. CONSTRUCTION OF PMSG • Stator is composed by teeth formed by silicon iron sheets • These teeth are fixed by 2 bronze disks in their end. • Skewing is provided to avoid cogging torque www.technologyfuturae.com

9. PRINCIPAL PARTS OF GENERATOR www.technologyfuturae.com

10. PERMANENT MAGNET SYNCHRONOUS GENERATOR • Voltage for a PM generator in the d-q axis synchronous rotational reference frame can be expressed as www.technologyfuturae.com

11. GENERATOR MODEL • The dynamic model of PMSG is derived from two phase synchronous reference frame ,in which q axis is 90 ahead of d axis with respect to the direction of rotation www.technologyfuturae.com

12. l GENERATOR MODEL (cont’d) • The electrical model of PMSG in the synchronous reference frame is • Rs =stator resistance • Ld and Lq=inductance of the generator on d and q axis • Lld and Llq=leakage inductance of generator on d and q axis • We=electrical rotating speed(=Np Wg) www.technologyfuturae.com

13. GENERATOR MODEL (cont’d) • Ld=Lds+ Lqs then equation becomes • We assume Ld=Lq=L then equation becomes www.technologyfuturae.com

14. GENERATOR MODEL (cont’d) • ed=0 • eq=we • Apply in above equation we will get equivalent circuit as www.technologyfuturae.com

15. TORQUE EQUATION • As the inductance of d and q axis are equal the torque can be expressed as follows… • Which shows Torque can be regulated by current through q axis www.technologyfuturae.com

16. CONTROL STRATEGY OF WIND TURBINE • Pitch control strategy • Yaw control www.technologyfuturae.com

17. DESIGN SPECIFICATION OF PMSG • Rated power = 2MW; • Rated wind speed = 12m/s; • Resistance: Ra =.1Ohm; • Inductance: L =0.005H; • Gear ratio: ng =77; • Number of pole pairs: np =2; • Radius of wind turbine rotor: R=41m; • Equivalent inertia: J=8000kg.m2; www.technologyfuturae.com

18. AC-DC-AC POWER CONVERSION SYSTEM • The amplitude and frequency of the output voltage are not constant due to the variable speed and fixed excitation of the permanent magnets. • 3-phase diode rectifier is used for the AC/DC conversion. • The SPWM (sinusoidal pulse width modulated) inverter with filter is adapted for the DC/AC power conversion. • The PIC microcontroller combined with dedicated SA4828 chip is adopted to control of the SPWM inverter for a 20kW direct driven PM generator wind power generation system. www.technologyfuturae.com

19. SUMMARY • The complete model of the variable speed wind turbine with PMSG that is scheduled to connect AC grid is discussed • The design characteristics Constructional features of PMSG is discussed • The control strategy for AC/DC/AC power conversion of the PM generator are also discussed www.technologyfuturae.com

20. REFERENCE [1] E. Muljadi, S. Drouilhet, R. Holz and V. Gevorgian, "Analysis of permanent magnet generator for wind power battery charging,“ IEEE-IAS Annual Meeting, vol.1 , Oct. 1996 ,pp.541-548. [2] A. J. G. Westlake, J. R. Bumby, and E. Spooner, "Damping the power-angle oscillations of a permanent-magnet synchronous generator with particular reference to wind applications," IEE Proc.- Electr. Power Appl, Vol. 143, No. 3, May 1996, pp. 269-280. [3] Ozdemir Gol’ and Bijan Sobhi-Najafabadi, “Use of Impedance Models in Permanent Magnet Synchronous Generator Design” [4] Ming Yin, “Modeling of the Wind Turbine with a Permanent Magnet Synchronous Generator for Integration” [5] Rogel R. Wallace,Thomas A. Lipo, Luis A. Moran,Juan A. Tapia:Design and Construction of a Permanent Magnet Axial Flux Synchronous Generatorin Proc. IEEE PESC’90, San Antonio, TX, USA, vol. 1, pp. 325~332, Jun. 1990. www.technologyfuturae.com

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