Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
권호 표지
DOI QR코드

DOI QR Code

Enhanced robustness with damping interval widening strategy of LCL-type converter under weak grid condition

  • Wang, Qi (College of Electrical and Power Engineering, Taiyuan University of Technology) ;
  • Qin, Wenping (College of Electrical and Power Engineering, Taiyuan University of Technology) ;
  • Wang, Lei (College of Electrical and Power Engineering, Taiyuan University of Technology) ;
  • Han, Xiaoqing (College of Electrical and Power Engineering, Taiyuan University of Technology) ;
  • Wang, Peng (College of Electrical and Power Engineering, Taiyuan University of Technology)
  • Received : 2019.04.20
  • Accepted : 2019.10.11
  • Published : 2020.03.20
⟨ Previous Next ⟩

Abstract

Active damping methods are widely adopted to present a damping effect on the resonance phenomenon without the power loss of LCL-type converters connected to a grid. However, extra sensors are used to implement the damping strategy. In this paper, a sensorless damping strategy where only the grid current is sampled has been proposed. Furthermore, the inner relationship between the tradition capacitor current feedback strategy and the proposed strategy has been clarified. Considering the digital delay and a weak grid, a robust method that uses unit delay feedback to mitigate the phase lag and to widen the effective damping interval has been developed. With this simple measure, stability is enhanced during the Nyquist frequency and robustness is improved when the LCL parameters vary and grid impedance exists. Finally, simulation and experimental results are presented to verify the feasibility and engineering significance of the proposed strategy.

Keywords

Acknowledgement

This work was supported by Shanxi Province Science and Technology Major Project (20181102028), National Key R&D Program of China (2018YFB0904700), National Natural Science Foundation for Youth of China (51807130), Natural Science Foundation of Shanxi Province (201701D121134) National Natural Science Foundation of China (U1610121).

References

  1. Xiaoqiang, L., et al.: Wide damping region for LCL-type grid-connected inverter with an improved capacitor-current-feedback method. IEEE Trans. Power Electron 30(9), 5247-5259 (2015) https://doi.org/10.1109/TPEL.2014.2364897
  2. Dongsheng, Y., Ruan, X., Wu, H.: Impedance shaping of the grid-connected inverter with LCL filter to improve its adaptability to the weak grid condition. IEEE Trans. Power Electron 29(11), 5795-5805 (2014) https://doi.org/10.1109/TPEL.2014.2300235
  3. Xiaoqiang, L., et al.: Capacitor-voltage feedforward with full delay compensation to improve weak grids adaptability of LCL-filtered grid-connected converters for distributed generation systems. IEEE Trans. Power Electron 33(1), 749-764 (2018) https://doi.org/10.1109/TPEL.2017.2665483
  4. Yi, T., et al.: Exploring inherent damping characteristic of LCL-filters for three-phase grid-connected voltage source inverters. IEEE Trans. Power Electron. 27(3), 1433-1443 (2012) https://doi.org/10.1109/TPEL.2011.2162342
  5. Shuitao, Y., et al.: A robust control scheme for grid-connected voltage-source inverters. IEEE Trans. Ind. Electron. 58(1), 202-212 (2011) https://doi.org/10.1109/TIE.2010.2045998
  6. Chen, X., Zhang, Y., Wang, S., et al.: Impedance-phased dynamic control method for grid-connected inverters in a weak grid. IEEE Trans. Power Electron. 32(1), 274-283 (2017) https://doi.org/10.1109/TPEL.2016.2533563
  7. Guoqiao, S., et al.: A new feedback method for PR current control of LCL-filter-based grid-connected inverter. IEEE Trans. Ind. Electron. 57(6), 2033-2041 (2010) https://doi.org/10.1109/TIE.2010.2040552
  8. Xu, J., Xie, S., Qian, Q., et al.: Adaptive feedforward algorithm without grid impedance estimation for inverters to suppress grid current instabilities and harmonics due to grid impedance and grid voltage distortion. IEEE Trans. Ind. Electron. 64(9), 7574-7578 (2017) https://doi.org/10.1109/TIE.2017.2711523
  9. Zhou, X., Zhou, L., Chen, Y., et al.: Robust grid-current-feedback resonance suppression method for LCL-type grid-connected inverter connected to weak grid. IEEE J. Emerg. Sel. Topics Power Electron. 6(4), 2126-2137 (2018). https://doi.org/10.1109/jestpe.2018.2805823
  10. Han, Y., Li, Z., Yang, P., et al.: Analysis and design of improved weighted average current control strategy for LCL-type grid-connected inverters. IEEE Trans. Energy Convers. 32(3), 941-952 (2017) https://doi.org/10.1109/TEC.2017.2669031
  11. Xu, J., Xie, S., Tang, T.: Active damping-based control for grid-connected LCL-filtered inverter with injected grid current feedback only. IEEE Trans. Ind. Electron. 61(9), 4746-4758 (2014) https://doi.org/10.1109/TIE.2013.2290771
  12. Tang, Y., Loh, P.C., Wang, P., et al.: Generalized design of high performance shunt active power filter with output LCL filter. IEEE Trans. Ind. Electron. 59(3), 1443-1452 (2012) https://doi.org/10.1109/TIE.2011.2167117
  13. Parker, S.G., Mcgrath, B.P., Holmes, D.G.: Regions of active damping control for LCL filters. IEEE Trans. Ind. Appl. 50(1), 424-432 (2014) https://doi.org/10.1109/TIA.2013.2266892
  14. Wang, J., Yan, J.D., Jiang, L., et al.: Delay-dependent stability of single-loop controlled grid-connected inverters with LCL filters. IEEE Trans. Power Electron. 31(1), 743-757 (2016) https://doi.org/10.1109/TPEL.2015.2401612
  15. Yang, D., Ruan, X., Wu, H.: Impedance shaping of the grid-connected inverter with LCL filter to improve its adaptability to the weak grid condition. IEEE Trans. Power Electron. 29(11), 5795-5805 (2014) https://doi.org/10.1109/TPEL.2014.2300235
  16. Wang, X., Blaabjerg, F., Loh, P.C.: Grid-current-feedback active damping for LCL resonance in grid-connected voltage source converters. IEEE Trans. Power Electron. 31(1), 213-223 (2016) https://doi.org/10.1109/TPEL.2015.2411851
  17. Hanif, M., Khadkikar, V., Xiao, W., et al.: Two degrees of freedom active damping technique for, LCL filter-based grid connected PV systems. IEEE Trans. Ind. Electron. 61(6), 2795-2803 (2014) https://doi.org/10.1109/TIE.2013.2274416
  18. Bao, C., Ruan, X., Wang, X., et al.: Step-by-step controller design for LCL-type grid-connected inverter with capacitor-current-feedback active-damping. IEEE Trans. Power Electron. 29(3), 1239-1253 (2014) https://doi.org/10.1109/TPEL.2013.2262378
  19. Dick, C.P., Richter, S., Rosekeit, M., et al.: Active damping of LCL resonance with minimum sensor effort by means of a digital infinite impulse response filter. In: European Conference on Power Electronics and Applications, Aalborg, pp. 1-8 (2007)
  20. Chen, Y., Xie, Z., Zhou, L., et al.: Optimized design method for grid-current-feedback active damping to improve dynamic characteristic of LCL-type grid-connected inverter. Int. J. Electr. Power Energy Syst. 100(9), 19-28 (2018) https://doi.org/10.1016/j.ijepes.2018.01.055
  21. Krishnan, R., Kazmierkowski, M.P., Blaabjerg, F., et al.: Control in power electronics: selected problems. Control Power Electron. 25(4), 146-148 (2002)