This paper deals with a permanent magnet synchronous generator (PMSG) based variable speed autonomous wind energy conversion system (AWECS). Back back connected voltage source converter (VSC) and a voltage source inverter (VSI) with a battery energy storage system (BESS) at the intermediate dc link are used to realize the voltage and frequency controller (VFC). The BESS is used for load leveling and to ensure the reliability of the supply to consumers connected at load bus under change in wind speed. The generator-side converter operated in vector control mode for achieving maximum power point tracking (MPPT) and to achieve unity power factor operation at PMSG terminals. The load-side converter is operated to regulate amplitude of the load voltage and frequency under change in load conditions. The three-phase four wire consumer loads are fed with a non-isolated star-delta transformer connected at the load bus to provide stable neutral terminal. The proposed AWECS is modeled, design and simulated using MATLAB R2007b simulink with its sim power system toolbox and discrete step solver.
- Permanent Magnet Synchronous Generator
- Star-delta Transformer
- Voltage Source Converters
- Maximum Power Point Tracking
- Wind Energy
Fig. 1 Proposed control scheme of VFC for PMSG based AWECS
EXPECTED SIMULATION RESULTS:
Fig. 2 Performance of Controller during fall in wind speed
Fig. 3 Performance of Controller during rise in wind speed
Fig. 4 Performance of Controller at fixed wind speed and balanced/unbalanced non-linear loads
A new configuration of voltage and frequency controller for a permanent magnet synchronous generator based variable speed autonomous wind energy conversion system has been designed modeled and its performance is simulated. The VFC has used two back-back connected VSC’s and BESS at intermediate dc link. The GSC has been controlled in vector controlled to achieve MPPT, unity power factor operation of PMSG. The LSI has been controlled to maintain amplitude of load voltage and its frequency. The VFC has performed the function of a load leveler, a load balancer, and a harmonic eliminator.
 J. F. Gieras and M. Wing, Permanent Magnet Motor Technology – Design and Application, Marcel Dekker Inc., New York, 2002.
 M. Kimura, H. Koharagi, K. Imaie, S. Dodo, H. Arita and K. Tsubouchi, “A permanent magnet synchronous generator with variable speed input for co-generation system,” IEEE Power Engineering Society Winter Meeting, 2001, vol. 3, 28 Jan.-1 Feb. 2001, pp. 1419 – 1424.
 T.F. Chan, L.L. Lai, Yan Lie-Tong, “Performance of a three-phase AC generator with inset NdFeB permanent-magnet rotor,” IEEE Trans. Energy Conversion, vol.19, no.1, pp. 88- 94, March 2004.
 T.F. Chan, W. Wang, L.L. Lai, “Analysis and performance of a permanent-magnet synchronous generator supplying an isolated load,” IET, Electric Power Applications, vol. 4, no. 3, pp.169-176, March 2010.
 K. Amei, Y. Takayasu, T. Ohji and M. Sakui, “A maximum power control of wind generator system using a permanent magnet synchronous generator and a boost chopper circuit,” Proc. of the Power Conversion Conference, PCC Osaka 2002, vol. 3, 2-5 April 2002, pp. 1447 – 1452.