Design and Analysis of a Power Quality Improvement System for Photovoltaic Generation Based on LCL-Type Grid Connected Inverter

Document Type : Original Article


1 Department of Electrical and Computer Engineering, University of Mohaghegh Ardabili, Ardabil, Iran

2 School of Technology and Innovations, University of Vaasa, Vaasa, Finland


Grid-connected inverters are considered vital elements for effectively connecting renewable energy sources and distributed generation system applications. Ripple-induced current harmonics in DC link and high switching frequency are the disadvantages of grid-connected inverters that are reduced by LCL filters. However, the intrinsic resonance in the LCL filter leads to instability of the power transmission system. As a result, suitable damping is essential for removing resonance in the LCL filters. The contribution of this paper is to improve the quality of injectable power of LCL filter-based grid-connected photovoltaic array. For this contribution, the stability of the grid-connected inverter has been investigated using active damping method, and maximum power point tracking (MPPT) for the PV array has been performed. The capacitor voltage feedforward active damping method considering computational delay is presented in this paper. By using the inverter-side current feedback beside this method, the proposed control maintains the system's low-frequency specifications independent of the grid impedance changes. It provides high harmonic rejection capability without additional compensators. Also, the number of sensors is decreased due to the alternative measurement of the capacitor voltage instead of the grid voltage for the phase lock loop (PLL). Meanwhile, maximum power point tracking is implemented using the incremental conductance (IC) technique in the boost converter. In addition, a simple and suitable computational method for designing LCL filter parameters is presented, and the system’s sensitivity is analyzed. Finally, the simulation has been implemented in MATLAB software that indicates the accurate performance of the control system in injecting the maximum power of the photovoltaic array into the grid and the highly desirable quality of the injectable current to the grid.

Graphical Abstract

Design and Analysis of a Power Quality Improvement System for Photovoltaic Generation Based on LCL-Type Grid Connected Inverter


Main Subjects

  1. Mobashsher MM, Keypour R, Savaghebi M. Distributed optimal voltage control in islanded microgrids. International Transactions on Electrical Energy Systems. 2021;31(11):e13045. 10.1002/2050-7038.13045
  2. Sagar G, Debela T. Implementation of optimal load balancing strategy for hybrid energy management system in dc/ac microgrid with pv and battery storage. International Journal of Engineering, Transactions A: Basics. 2019;32(10):1437-45. 10.5829/ije.2019.32.10a.13
  3. Manna S, Singh DK, Akella AK, Kotb H, AboRas KM, Zawbaa HM, et al. Design and implementation of a new adaptive MPPT controller for solar PV systems. Energy Reports. 2023;9:1818-29. 10.1016/j.egyr.2022.12.152
  4. Tang C-Y, Wu H-J, Liao C-Y, Wu H-H. An optimal frequency-modulated hybrid MPPT algorithm for the LLC resonant converter in PV power applications. IEEE Transactions on Power Electronics. 2021;37(1):944-54. 10.1109/TPEL.2021.309467
  5. Hooshmand M, Yaghobi H, Jazaeri M. Irradiation and Temperature Estimation with a New Extended Kalman Particle Filter for Maximum Power Point Tracking in Photovoltaic Systems. International Journal of Engineering, Transactions C: Aspects,. 2023;36(6):1099-113. 10.5829/ije.2023.36.06c.08
  6. Zeb K, Khan I, Uddin W, Khan MA, Sathishkumar P, Busarello TDC, et al. A review on recent advances and future trends of transformerless inverter structures for single-phase grid-connected photovoltaic systems. Energies. 2018;11(8):1968. 10.3390/en11081968
  7. Giacomini JC, Michels L, Cavalcanti MC, Rech C. Modified discontinuous PWM strategy for three-phase grid-connected PV inverters with hybrid active–passive damping scheme. IEEE Transactions on Power Electronics. 2019;35(8):8063-73. 10.1109/TPEL.2019.2961648
  8. Bharath GV, Hota A, Agarwal V. A new family of 1-φ five-level transformerless inverters for solar PV applications. IEEE Transactions on Industry Applications. 2019;56(1):561-9. 10.1109/TIA.2019.2943125
  9. Guo X, Yang Y, Wang B, Blaabjerg F. Leakage current reduction of three-phase Z-source three-level four-leg inverter for transformerless PV system. IEEE Transactions on Power Electronics. 2018;34(7):6299-308. 10.1109/TPEL.2018.2873223
  10. Hosseinpour M, Rasekh N. A single-phase grid-tied PV based trans-z-source inverter utilizing LCL filter and grid side current active damping. Journal of Energy Management and Technology. 2019;3(3):67-77. 10.22109/jemt.2019.169380.1150
  11. Aalizadeh F, Hosseinpour M, Dejamkhooy A, Shayeghi H. Two-stage control for small-signal modeling and power conditioning of grid-‎ connected quasi-Z-Source inverter with LCL filter for photovoltaic‎ generation‎. Journal of Operation and Automation in Power Engineering. 2021;9(3):242-55. 10.22098/joape.2021.7674.1546
  12. Wu W, Liu Y, He Y, Chung HS-H, Liserre M, Blaabjerg F. Damping methods for resonances caused by LCL-filter-based current-controlled grid-tied power inverters: An overview. IEEE Transactions on Industrial Electronics. 2017;64(9):7402-13. 10.1109/TIE.2017.2714143
  13. Rasekh N, Hosseinpour M. LCL filter design and robust converter side current feedback control for grid-connected Proton Exchange Membrane Fuel Cell system. International Journal of Hydrogen Energy. 2020;45(23):13055-67. 10.1016/j.ijhydene.2020.02.227
  14. Giacomini JC, Michels L, Pinheiro H, Rech C. Design methodology of a passive damped modified LCL filter for leakage current reduction in grid‐connected transformerless three‐phase PV inverters. IET Renewable Power Generation. 2017;11(14):1769-77. 10.1049/iet-rpg.2017.0256
  15. Dannehl J, Fuchs FW, Thøgersen PB. PI state space current control of grid-connected PWM converters with LCL filters. IEEE transactions on power electronics. 2010;25(9):2320-30. 10.1109/TPEL.2010.2047408
  16. Liu J, Zhou L, Molinas M. Damping region extension for digitally controlled LCL‐type grid‐connected inverter with capacitor‐current feedback. IET Power Electronics. 2018;11(12):1974-82. 10.1049/iet-pel.2018.0039
  17. Rasekh N, Rahimian MM, Hosseinpour M, Dejamkhooy A, Akbarimajd A, editors. A step by step design procedure of PR controller and capacitor current feedback active damping for a LCL-type grid-tied T-type inverter. 2019 10th International Power Electronics, Drive Systems and Technologies Conference (PEDSTC); 2019: IEEE. 10.1109/PEDSTC.2019.8697853
  18. Hosseinpour M, Asad M, Rasekh N. A step-by-step design procedure of a robust control design for grid-connected inverter by LCL filter in a weak and harmonically distorted grid. Iranian Journal of Science and Technology, Transactions of Electrical Engineering. 2021;45:843-59. 10.1007/s40998-021-00414-z
  19. Dragičević T, Zheng C, Rodriguez J, Blaabjerg F. Robust quasi-predictive control of $ LCL $-filtered grid converters. IEEE Transactions on Power Electronics. 2019;35(2):1934-46. 10.1109/TPEL.2019.2916604
  20. Cai Y, He Y, Zhou H, Liu J. Active-damping disturbance-rejection control strategy of LCL grid-connected inverter based on inverter-side-current feedback. IEEE Journal of Emerging and Selected Topics in Power Electronics. 2020;9(6):7183-98. 10.1109/JESTPE.2020.3017678
  21. Guan Y, Wang Y, Xie Y, Liang Y, Lin A, Wang X. The dual-current control strategy of grid-connected inverter with LCL filter. IEEE Transactions on Power Electronics. 2018;34(6):5940-52. 10.1109/TPEL.2018.2869625
  22. Zhou X, Zhou L, Chen Y, Shuai Z, Guerrero JM, Luo A, et al. Robust grid-current-feedback resonance suppression method for LCL-type grid-connected inverter connected to weak grid. IEEE Journal of Emerging and Selected Topics in Power Electronics. 2018;6(4):2126-37. 10.1109/JESTPE.2018.2805823
  23. He Y, Wang X, Ruan X, Pan D, Qin K. Hybrid active damping combining capacitor current feedback and point of common coupling voltage feedforward for LCL-type grid-connected inverter. IEEE Transactions on Power Electronics. 2020;36(2):2373-83. 10.1109/TPEL.2020.3008160
  24. Faiz MT, Khan MM, Jianming X, Ali M, Habib S, Hashmi K, et al. Capacitor voltage damping based on parallel feedforward compensation method for LCL-filter grid-connected inverter. IEEE Transactions on Industry Applications. 2019;56(1):837-49. 10.1109/TIA.2019.2951115
  25. Li X, Fang J, Tang Y, Wu X, Geng Y. Capacitor-voltage feedforward with full delay compensation to improve weak grids adaptability of LCL-filtered grid-connected converters for distributed generation systems. IEEE Transactions on Power Electronics. 2017;33(1):749-64. 10.1109/TPEL.2017.2665483
  26. Zou C, Liu B, Duan S, Li R, editors. A feedfoward scheme to improve system stability in grid-connected inverter with LCL filter. 2013 IEEE Energy Conversion Congress and Exposition; 2013: IEEE. 10.1109/ECCE.2013.6647299
  27. Liu B, Wei Q, Zou C, Duan S. Stability analysis of LCL-type grid-connected inverter under single-loop inverter-side current control with capacitor voltage feedforward. IEEE Transactions on Industrial Informatics. 2017;14(2):691-702. 10.1109/TII.2017.2766890
  28. Figueredo RS, Matakas L. Integrated common and differential mode filter with capacitor-voltage feedforward active damping for single-phase transformerless PV inverters. IEEE Transactions on Power Electronics. 2019;35(7):7058-72. 10.1109/TPEL.2019.2956184
  29. Rodriguez-Diaz E, Freijedo FD, Vasquez JC, Guerrero JM. Analysis and comparison of notch filter and capacitor voltage feedforward active damping techniques for LCL grid-connected converters. IEEE Transactions on Power Electronics. 2018;34(4):3958-72. 10.1109/TPEL.2018.2856634
  30. Said-Romdhane MB, Naouar MW, Slama Belkhodja I, Monmasson E. An improved LCL filter design in order to ensure stability without damping and despite large grid impedance variations. Energies. 2017;10(3):336. 10.3390/en10030336