access icon free Improved control algorithm for grid-connected cascaded H-bridge photovoltaic inverters under asymmetric operating conditions

Here, a single-stage cascaded H-bridge (CHB) inverter is presented for grid-connected photovoltaic (PV) systems. The CHB inverter has separate DC links and allows individual control of PV arrays. The conversion efficiency is high and the harmonic generation is lower than conventional PV inverters. Although the CHB inverter is a good candidate for injection of solar power into grid, its control issues have not been completely solved. One of the main challenges in the CHB inverter is the harmonic generation when the connected PV arrays to the H-bridge cells have different amounts of insolation. This study deals with the asymmetrical operating conditions of PV arrays (or H-bridge cells) in the CHB inverter and presents an analytical equation for determination of cells’ modulation indices based on PV arrays data. Then, a control loop is added to the tracking algorithm of conventional control systems to determine whether an H-bridge cell is in the linear modulation or not. In the case of overmodulation, the corresponding DC link voltage is increased by the controller to bring it back to the linear region. The validity of new method is confirmed by simulations and experiments on a seven-level 1.7 kW CHB inverter.

Inspec keywords: power generation control; photovoltaic power systems; insulation; harmonic generation; solar cell arrays; solar power stations; invertors; power system harmonics; modulation; power grids

Other keywords: power 1.7 kW; linear modulation; insulation; asymmetric operating condition; overmodulation; PV array system; DC link voltage; H-bridge cell; tracking algorithm; improved control algorithm; grid connected cascaded H-bridge photovoltaic inverter; PV inverter; solar power injection; single-stage CHB inverter; harmonic generation

Subjects: DC-AC power convertors (invertors); Control of electric power systems; Solar cells and arrays; Power system control; Power supply quality and harmonics; Insulation and insulating coatings; Solar power stations and photovoltaic power systems

References

    1. 1)
      • 24. Hussein, K.H., Muta, I., Hoshino, T.,, et al: ‘Maximum photovoltaic power tracking: an algorithm for rapidly changing atmospheric conditions’, IEE Proc. Gener. Transm. Distrib., 1995, 14, (1), pp. 5964.
    2. 2)
      • 19. Liu, L., Li, H., Xue, Y.,, et al: ‘Decoupled active and reactive power control for large scale grid-connected photovoltaic systems using cascaded modular multilevel converters’, IEEE Trans. Power Electron., 2015, 30, (1), pp. 176187.
    3. 3)
      • 10. Kumar, N., Saha, T.K., Dey, J.: ‘Sliding-mode control of PWM dual inverter-based grid-connected PV system: modeling and performance analysis’, IEEE J. Emerg. Sel. Topics Power Electron., 2016, 4, (2), pp. 435444.
    4. 4)
      • 6. Villanueva, E., Correa, P., Rodriguez, J., et al: ‘Control of a single-phase cascaded H-bridge multilevel inverter for grid-connected photovoltaic systems’, IEEE Trans. Ind. Electron., 2009, 56, (11), pp. 43994406.
    5. 5)
      • 13. Cortes, P., Kouro, S., Barrios, F.,, et al: ‘Predictive control of a single-phase cascaded H-bridge photovoltaic energy conversion system’. 7th Int. Power Electronics and Motion Control Conf. (IPEMC), 2012, pp. 14231428.
    6. 6)
      • 7. Cecati, C., Ciancetta, F., Siano, P.: ‘A multilevel inverter for photovoltaic systems with fuzzy logic control’, IEEE Trans. Ind. Electron., 2010, 57, (12), pp. 41154125.
    7. 7)
      • 3. Hajizadeh, M., Fathi, S.H.: ‘Fundamental frequency switching strategy for grid-connected cascaded H-bridge multilevel inverter to mitigate voltage harmonics at the point of common coupling’, IET Power Electron., 2016, 9, (12), pp. 23872393.
    8. 8)
      • 17. Miranbeigi, M., Iman-Eini, H.: ‘Hybrid modulation technique for grid-connected cascaded photovoltaic systems’, IEEE Trans. Ind. Electron., 2016, 63, (12), pp. 78437853.
    9. 9)
      • 2. Bedram, A., Davoudi, A., Balog, R.S.: ‘Control and circuit techniques to mitigate partial shading effects in photovoltaic arrays’, IEEE J. Photovolt., 2012, 2, (4), pp. 532546.
    10. 10)
      • 16. Iman-Eini, H., Amini, M., Farhangi, Sh.: ‘Improving the performance of grid-connected cascaded H-bridge photovoltaic inverters under asymmetric insolation conditions’, Iranian J. Electr. Comput. Eng., in Persian language, 2015, 13, (2), pp. 135142.
    11. 11)
      • 14. Rezaei, M., Iman-Eini, H., Farhangi, S.: ‘Grid-connected photovoltaic system based on a cascaded H-bridge inverter’, J. Power Electron., 2012, 12, (4), pp. 578586.
    12. 12)
      • 11. Farivar, G., Hredzak, B., Agelidis, V.: ‘A dc-side sensorless cascaded H-bridge multilevel converter based photovoltaic system’, IEEE Trans. Ind. Electron., 2016, 63, (7), pp. 42334241.
    13. 13)
      • 20. Bacha, S., Picault, D., Burger, B.,, et al: ‘Photovoltaics in microgrids: an overview of grid integration and energy management aspects’, IEEE Ind. Electron. Mag., 2015, 9, (1), pp. 3346.
    14. 14)
      • 25. Eha, H., Vu, T.K., Kim, J.E.: ‘Design and control of proportional- resonant controller based on photovoltaic power conditioning system’. IEEE Energy Conversion Congress and Exposition, 2009, pp. 21982205.
    15. 15)
      • 4. Kouro, S., Leon, J.I., Vinnikov, D., et al: ‘Grid-connected photovoltaic systems: an overview of recent research and emerging PV converter technology’, IEEE Ind. Electron. Mag., 2015, 9, (1), pp. 4761.
    16. 16)
      • 12. Chavarria, J., Biel, D., Guinjoan, F.,, et al: ‘Energy-balance control of PV cascaded multilevel grid-connected inverters under level-shifted and phase-shifted PWMs’, IEEE Trans. Ind. Electron., 2013, 60, (1), pp. 98111.
    17. 17)
      • 22. Yang, Y., Zhou, K., Blaabjerg, F.: ‘Current harmonics from single-phase grid-connected inverters, examination and suppression’, IEEE J. Emerg. Sel. Topics Power Electron., 2016, 4, (1), pp. 221233.
    18. 18)
      • 8. Kouro, S., Wu, B., Moya, A.,, et al: ‘Control of a cascaded H-bridge multilevel converter for grid connection of photovoltaic systems’. 35th Annual Conf. on Industrial Electronics (IECON ‘09), 2009, pp. 39763982.
    19. 19)
      • 1. Kouro, S., Malinowski, M., Gopakumar, K., et al: ‘Recent advances and industrial applications of multilevel converters’, IEEE Trans. Ind. Electron., 2010, 57, (8), pp. 25532580.
    20. 20)
      • 5. Oliveira, F.M., Oliveira da Silva, S.A., Durand, F.R., et al: ‘Grid-tied photovoltaic system based on PSO MPPT technique with active power line conditioning’, IET Power Electron., 2015, 9, (6), pp. 11801191.
    21. 21)
      • 21. Malinowski, M., Gopakumar, K., Rodriguez, J.,, et al: ‘A survey on cascaded multilevel inverters’, IEEE Trans. Ind. Electron., 2010, 57, (7), pp. 21972206.
    22. 22)
      • 9. Xiao, B., Hang, L., Mei, J.,, et al: ‘Modular cascaded H-bridge multilevel PV inverter with distributed MPPT for grid-connected applications’, IEEE Trans. Ind. Appl., 2015, 51, (2), pp. 17221731.
    23. 23)
      • 15. Eskandari, A., Javadian, V., Iman-Eini, H.,, et al: ‘Stable operation of grid connected cascaded H-bridge inverter under unbalanced insolation conditions’. 3rd Int. Conf. on Electric Power and Energy Conversion Systems, 2013, pp. 16.
    24. 24)
      • 23. Zhou, K., Wang, D.: ‘Relationship between space-vector modulation and three-phase carrier-based PWM: a comprehensive analysis’, IEEE Trans. Ind. Electron., 2002, 49, (1), pp. 186196.
    25. 25)
      • 18. Liu, L., Li, H., Xue, Y.,, et al: ‘Reactive power compensation and optimization strategy for grid-interactive cascaded photovoltaic systems’, IEEE Trans. Power Electron., 2015, 30, (1), pp. 188202.
http://iet.metastore.ingenta.com/content/journals/10.1049/iet-pel.2016.0983
Loading

Related content

content/journals/10.1049/iet-pel.2016.0983
pub_keyword,iet_inspecKeyword,pub_concept
6
6
Loading