In this study, a new transformerless wind energy conversion system to integrate high-power multi-phase permanent magnet wind generators to medium-voltage local grids is presented. The proposed converter topology consists of multi-half-bridge modules with a high ac–direct current (dc) boosting capability. Each phase of an open winding multi-phase generator is connected to the ac side of a half-bridge module, whereas the dc sides of the half-bridge modules are connected in series forming the high-voltage dc-link output. The proposed architecture facilitates the employment of semiconductor switches with a relatively low-voltage rating, which equals the dc-link voltage divided by the number of generator phases. A detailed analysis of the proposed architecture along with the required closed-loop control is presented. The proposed architecture is simulated under different operating conditions using a typical 2 MW system, while the experimental validation is carried out using a low-scale prototype converter.

References

1. 1)
  - 3. El-Refaie, , Ayman, M.: ‘Fractional-slot concentrated-windings synchronous permanent magnet machines: opportunities and challenges’, IEEE Trans. Ind. Electron., 2010, 57, (1), pp. 107–121 (doi: 10.1109/TIE.2009.2030211).
2. 2)
  - 17. Wang, M., Hu, Y., Zhao, W., et al: ‘Application of modular multilevel converter in medium voltage high power permanent magnet synchronous generator wind energy conversion systems’, IET Renew. Power Gener., 2016, 10, (6), pp. 824–833 (doi: 10.1049/iet-rpg.2015.0444).
3. 3)
  - 14. Ng, C., Parker, M., Ran, L., et al: ‘A multi- level modular converter for a large, light weight wind turbine generator’, IEEE Trans. Power Electron., 2008, 23, (3), pp. 1062–1074 (doi: 10.1109/TPEL.2008.921191).
4. 4)
  - 21. Gonzalez-Prieto, I., Duran, M.J., Barrero, F., et al: ‘Impact of post-fault flux adaptation on six-phase induction motor drives with parallel converters’, IEEE Trans. Power Electron., 2017, 32, (1), pp. 515–528 (doi: 10.1109/TPEL.2016.2533719).
5. 5)
  - 15. Liao, Y.H., Chen, H.C., Cheng, H.C., et al: ‘A novel control strategy of circulating currents in paralleled single-phase boost converters with different power sharing for microgrid applications’, IEEE Trans. Ind. Appl., 2014, 50, (2), pp. 1304–1312 (doi: 10.1109/TIA.2013.2289995).
6. 6)
  - 30. Ebrahimi, M., Ali Khajehoddin, S.: ‘A simple DQ current controller for single-phase grid-connected inverters’. 2015 IEEE Applied Power Electronics Conf. and Exposition (APEC), 2015, pp. 2840–2845.
7. 7)
  - 26. Li, R., Xu, D.: ‘Parallel operation of full power converters in permanent-magnet direct-drive wind power generation system’, IEEE Trans. Ind. Electron., 2013, 60, (4), pp. 1619–1629 (doi: 10.1109/TIE.2011.2148684).
8. 8)
  - 31. Elserougi, A., Massoud, A.M., Abdel-Khalik, A.S., et al: ‘A grid-connected HVDC shunt tap based on series-input parallel-output DC–AC multi-module 2-level voltage source converters’. 2015 IEEE Eighth GCC Conf. and Exhibition (GCCCE), 2015, pp. 1–5.
9. 9)
  - 19. Gonzalez, I., Dura, J., Che, H.S., et al: ‘Fault-tolerant efficient control of six-phase induction generators in wind energy conversion systems with series–parallel machine-side converters’. Seventh IET Int. Conf. on Power Electronics, Machines and Drives (PEMD 2014), Manchester, 2014, pp. 1–6.
10. 10)
  - 6. Ge, B., Lu, X., Yu, X., et al: ‘Multiphase-leg coupling current balancer for parallel operation of multiple MW power modules’, IEEE Trans Ind. Electron., 2014, 61, (3), pp. 1147–1157 (doi: 10.1109/TIE.2013.2258307).
11. 11)
  - 27. Williamson, A.C., Spooner, E., Thompson, L.: ‘Large modular PM generators’. IEE Colloq. New Topologies Permanent Magnet Mach. (Digest No: 1997/090), 1997, pp. 1–6.
12. 12)
  - 14. Ge, B., Peng, F.Z.: ‘Current balancer-based grid-connected parallel inverters for high power wind-power system’, Int. Trans. Electr. Energy Syst., 2014, 24, pp. 108–124 (doi: 10.1002/etep.1754).
13. 13)
  - 13. Ko, Y.J., Lee, K.B., Lee, D.C., Kim, J.M.: ‘Fault diagnosis of three-parallel voltage-source converter for a high-power wind turbine’, IET Power Electron., 2012, 5, (7), pp. 1058–1067 (doi: 10.1049/iet-pel.2011.0109).
14. 14)
  - 8. Yaramasu, V., Bin, W.: ‘Predictive control of a three-level boost converter and an NPC inverter for high-power PMSG-based medium voltage wind energy conversion systems’, IEEE Trans. Power Electron., 2014, 29, (10), pp. 5308–5322 (doi: 10.1109/TPEL.2013.2292068).
15. 15)
  - 4. Zhang, X., Chen, J., Ma, Y., et al: ‘Bandwidth expansion method for circulating current control in parallel three-phase PWM converter connection system’, IEEE Trans. Power Electron., 2014, 29, (12), pp. 6847–6856 (doi: 10.1109/TPEL.2014.2311046).
16. 16)
  - 22. Gonzalez-Prieto, I., Duran, M.J., Che, H.S., et al: ‘Fault-tolerant operation of six-phase energy conversion systems with parallel machine-side converters’, IEEE Trans. Power Electron., 2016, 31, (4), pp. 3068–3079 (doi: 10.1109/TPEL.2015.2455595).
17. 17)
  - 15. Parker, M., Ng, C., Ran, L., et al: ‘Power control of direct drive wind turbine with simpliﬁed conversion stage transformerless grid interface’. Proc. 41st Int. UPEC, Newcastle upon Tyne, UK, September 2006, vol. 1, pp. 65–68.
18. 18)
  - 23. Duran, M.J., Prieto, I.G., Bermudez, M., et al: ‘Optimal fault-tolerant control of six-phase induction motor drives with parallel converters’, IEEE Trans. Ind. Electron., 2016, 63, (1), pp. 629–640 (doi: 10.1109/TIE.2015.2461516).
19. 19)
  - 2. Gjerde, S.S., Olsen, P.K., Ljøkelsøy, K., et al: ‘Control and fault handling in a modular series-connected converter for a transformerless 100 kV low-weight offshore wind turbine’, IEEE Trans. Ind. Appl., 2014, 50, (2), pp. 1094–1105 (doi: 10.1109/TIA.2013.2272032).
20. 20)
  - 26. Potgieter, J., Kamper, M.: ‘Torque and voltage quality in design optimization of low-cost non-overlap single layer winding permanent magnet wind generator’, IEEE Trans. Ind. Electron., 2012, 59, (5), pp. 2147–2156 (doi: 10.1109/TIE.2011.2159955).
21. 21)
  - 29. Wu, B., Yongqiang, L., Zargari, N., et al: ‘Power conversion and control of wind energy systems’ (IEEE Press, John Wiley, 2011).
22. 22)
  - 24. Asplund, G.: ‘Tapping power from a HVDC transmission system’. US Patent US2010/0091527A1, April 2010.
23. 23)
  - 28. Jia, S., Qu, R., Li, J., et al: ‘Study of direct-drive permanent-magnet synchronous generators with solid rotor back iron and different windings’, IEEE Trans. Ind. Appl., 2016, 52, (2), pp. 1369–1379.
24. 24)
  - 7. Gohil, G., Maheshwari, R., Bede, L., et al: ‘Modified discontinuous PWM for size reduction of the circulating current filter in parallel interleaved converters’, IEEE Trans. Power Electron., 2015, 30, (7), pp. 3457–3470 (doi: 10.1109/TPEL.2014.2339392).
25. 25)
  - 12. Hu, Y., Zeng, R., Cao, W., et al: ‘Design of a modular, high step-up ratio DC–DC converter for HVDC applications integrating offshore wind power’, IEEE Trans. Ind. Electron., 2016, 63, (4), pp. 2190–2202 (doi: 10.1109/TIE.2015.2510975).
26. 26)
  - 16. Carmeli, M.S., Castelli-Dezza, F., Marchegiani, G., et al: ‘Design and analysis of a medium voltage DC wind farm with a transformer-less wind turbine generator’. 2010 XIX Int. Conf. on Electrical Machines (ICEM), Rome, 2010, pp. 1–6.
27. 27)
  - 7. Chunkag, V., Kanthaphayao, Y., Kamnarn, U.: ‘Distributed control system for a parallel-connected AC/DC converters’, IET Power Electron., 2013, 6, (33), pp. 446–456 (doi: 10.1049/iet-pel.2012.0390).
28. 28)
  - 33. Jacobson, B., Karlsson, P., Asplund, G., et al: ‘VSC-HVDC transmission with cascaded two-level converters’. Presented at the CIGRE Session, Paris, France, 2010.
29. 29)
  - 32. Jovcic, D., Ahmed, K.: ‘High voltage direct current transmission: converters, systems and DC grids’ (John Wiley, 2015), p. 193.
30. 30)
  - 1. Yaramasu, V., Wu, B., Sen, P.C., et al: ‘High-power wind energy conversion systems: state-of-the-art and emerging technologies’, Proc. IEEE, 2015, 103, (5), pp. 740–788 (doi: 10.1109/JPROC.2014.2378692).
31. 31)
  - 20. Yuan, X., Li, Y., Chai, J.: ‘A transformerless modular permanent magnet wind generator system with minimum generator coils’. 2010 25th Annual IEEE Applied Power Electronics Conf. and Exposition (APEC), Palm Springs, CA, 2010, pp. 2104–2110.
32. 32)
  - 11. Lyu, J., Zhang, J., Cai, X., et al: ‘Circulating current control strategy for parallel full-scale wind power converters’, IET Power Electron., 2016, 9, (4), pp. 639–647 (doi: 10.1049/iet-pel.2014.0926).
33. 33)
  - 13. Gandomkar, A., Parastar, A., Seok, J.K.: ‘High-power multilevel step-up DC/DC converter for offshore wind energy systems’, IEEE Trans. Ind. Electron., 2016, 63, (12), pp. 7574–7585 (doi: 10.1109/TIE.2016.2594050).

Series-connected multi-half-bridge modules converter for integrating multi-megawatt wind multi-phase permanent magnet synchronous generator with dc grid

References

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