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Stability Improvement of LCL-Based Fuel Cell Power Quality Enhancement System Utilizing Phase Compensation of Current Regulator
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Majid Hosseinpour *1   , Rasoul Akbari1 , Mahdi Shahparasti2 |
1- Department of Electrical Engineering, University of Mohaghegh Ardabili, Ardabil, Iran, & Department of Electrical Engineering, University of Mohaghegh Ardabili, Ardabil, Iran,
2- School of Technology and Innovations, University of Vaasa, Vaasa, Finland & School of Technology and Innovations, University of Vaasa, Vaasa, Finland |
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Abstract: (296 Views) |
Grid-connected inverters are key devices for transferring power from distributed generation systems and renewable energy sources to the grid. To suppress current harmonics and enhance the quality of the injected power, various filters are employed, among which the LCL filter is widely used. However, due to the inherent resonance of the LCL filter, the variable impedance of weak grids can introduce disturbances at the inverter output, ultimately leading to system instability. The objective of this paper is to improve the power quality of a fuel-cell-based grid-connected system employing an LCL filter, using a control strategy based on grid-current feedback and active damping of the capacitor current. In this study, a grid-connected fuel cell power-conditioning system with an LCL filter is analyzed. The stable and passive behavior of the system is evaluated while considering the influence of current regulator phase delay. Furthermore, the design procedure and simulation results of the system under study are presented in detail.
The system under study is composed of an inverter is employed to connect the fuel cell to the grid. To eliminate the dominant harmonics at the inverter output, an LCL filter is implemented. The inverter control strategy incorporates grid-current feedback and active damping of the capacitor current. The filter parameters L1, C, and L2 correspond to the inverter-side inductor, filter capacitor, and grid-side inductor of the LCL filter, respectively. The grid impedance, which includes the transmission lines, transformer, and power factor correction capacitor, is modeled by an equivalent parallel Lg-Cg circuit. Since the output voltage of the fuel cell is insufficient for direct grid connection, a DC–DC converter is employed to step up the voltage level. Considering the characteristics of the fuel cell, this converter must operate with a continuous input current with very low ripple.In the current control loop, the grid current iL2 is regulated to be sinusoidal and synchronized with the point of common coupling (PCC) voltage. The PCC voltage (vPCC) is measured through a phase-locked loop (PLL) to ensure synchronization, where θ represents the detected grid voltage angle. This angle θ, combined with the reference current amplitude I∗, is used to generate the current reference (iref). The error signal between iL2 and iref is processed by the current regulator Gi. To damp the resonance of the LCL filter, the capacitor current feedback (iC) is fed back with a damping factor kd. Finally, the outputs of the current regulator Gi and the active damping term are combined to generate the modulation signal vM. Using digital pulse-width modulation (PWM), the corresponding gate signals for the power switches are produced. The proportional–resonant current regulator is denoted by Gi.To validate the accuracy of the theoretical analysis and the feasibility of the proposed control strategy, the required simulations have been carried out. The output power of the grid-connected fuel cell power-conditioning system is considered to be approximately 8.5 kW. In the first stage, the fuel cell voltage is boosted by means of a DC–DC boost converter. Subsequently, the DC-link voltage is injected into the grid through a grid-connected inverter equipped with an LCL filter. The inverter control strategy is based on grid-current regulation combined with active damping of the capacitor current. Moreover, to compensate for the phase delay in the control system, a phase-delay compensator is employed to enhance the quality of the injected power. To demonstrate the dynamic behavior of the studied system, the fuel cell input fuel flow is varied dynamically, so that the accuracy and effectiveness of the control strategy in injecting power proportional to the fuel cell’s generated power can be evaluated. Under full fuel flow, the system produces approximately 5.8 kW. When the fuel flow is reduced by 20%, the output power decreases to about 4.65 kW. Once the fuel flow is increased again, the generated power returns to its nominal value with appropriate dynamic performance.
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| Keywords: Grid-connected inverter, Fuel cell, Active damping, Phase compensator |
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Full-Text [PDF 875 kb]
(14 Downloads)
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Type of Study: Research |
Received: 2024/10/3 | Accepted: 2025/08/8 | Published: 2025/08/10
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1. حسینپور مجید، ثابت فر تورج. سیستم بهساز توان فتوولتاییک متصل به شبکه با فیلتر LCL مبتنی بر استراتژی کنترل فیدبک جریان سمت اینورتر و جریان سمت شبکه. نشریه کیفیت و بهرهوری صنعت برق ایران. ۱۴۰۲; ۱۲ (۲): ۳۹-۵۶. 2. Akhavan, A., Mohammadi, H.R., Vasquez, J.C. and Guerrero, J.M., 2020. Passivity-based design of plug-and-play current-controlled grid-connected inverters. IEEE Transactions on Power Electronics, 35(2), pp.2135-2150. [ DOI:10.1109/TPEL.2019.2920843] 3. Ali, R., Heydari‐doostabad, H., Sajedi, S. and O'Donnell, T., 2024. Improved design of passive damping for single phase grid‐connected LCL filtered inverter considering impedance stability. IET Power Electronics, 17(4), pp.511-523. [ DOI:10.1049/pel2.12666] 4. Awal, M.A., Della Flora, L. and Husain, I., 2022. Observer based generalized active damping for voltage source converters with LCL filters. IEEE Transactions on Power Electronics, 37(1), pp.125-136. [ DOI:10.1109/TPEL.2021.3093504] 5. Awal, M.A., Yu, H., Husain, I., Yu, W. and Lukic, S.M., 2020. Selective harmonic current rejection for virtual oscillator controlled grid-forming voltage source converters. IEEE Transactions on Power Electronics, 35(8), pp.8805-8818. [ DOI:10.1109/TPEL.2020.2965880] 6. Awal, M.A., Yu, W. and Husain, I., 2020. Passivity-based predictive-resonant current control for resonance damping in LCL-equipped VSCs. IEEE Transactions on Industry Applications, 56(2), pp.1702-1713. [ DOI:10.1109/TIA.2019.2959594] 7. Awal, M.A., Yu, H., Della Flora, L., Yu, W., Lukic, S. and Husain, I., 2019, September. Observer based admittance shaping for resonance damping in voltage source converters with LCL filter. In 2019 IEEE Energy Conversion Congress and Exposition (ECCE) (pp. 4455-4462). IEEE. [ DOI:10.1109/ECCE.2019.8913194] 8. Awal, M.A., Yu, W. and Husain, I., 2019. Passivity-based predictive-resonant current control for resonance damping in LCL-equipped VSCs. IEEE Transactions on Industry Applications, 56(2), pp.1702-1713. [ DOI:10.1109/TIA.2019.2959594] 9. Bai, H., Wang, X. and Blaabjerg, F., 2017. Passivity enhancement in renewable energy source based power plant with paralleled grid-connected VSIs. IEEE Transactions on Industry Applications, 53(4), pp.3793-3802. [ DOI:10.1109/TIA.2017.2685363] 10. Ben Hamad, K., Luta, D.N. and Raji, A.K., 2021. A grid-tied fuel cell multilevel inverter with low harmonic distortions. Energies, 14(3), p.688. [ DOI:10.3390/en14030688] 11. Chen, W., Zhang, Y., Tu, Y., Guan, Y., Shen, K. and Liu, J., 2023. Unified active damping strategy based on generalized virtual impedance in LCL-type grid-connected inverter. IEEE Transactions on Industrial Electronics, 70(8), pp.8129-8139. [ DOI:10.1109/TIE.2022.3232647] 12. Elkayam, M. and Kuperman, A., 2019. Optimized design of multiresonant AC current regulators for single-phase grid-connected photovoltaic inverters. IEEE Journal of Photovoltaics, 9(6), pp.1815-1818. [ DOI:10.1109/JPHOTOV.2019.2937386] 13. Fang, T., Shen, S., Zhang, L., Jin, Y. and Huang, C., 2021. Capacitor current feedback with phase-lead compensator to eliminate resonant frequency forbidden region for LCL-type grid-connected inverter in weak grid. IEEE Journal of Emerging and Selected Topics in Power Electronics, 9(5), pp.5581-5596. [ DOI:10.1109/JESTPE.2021.3059024] 14. Hosseinpour, M., Sabetfar, T. and Shahparasti, M., 2024. Grid‐tied PEMFC power conditioning system based on capacitor voltage thorough feedback procedure in a weak and harmonics‐polluted network. Energy Science & Engineering, 12(1), pp.149-167. [ DOI:10.1002/ese3.1624] 15. Hosseinpour, M., Sabetfar, T., Dejamkhooy, A. and Shahparasti, M., 2023. Design and control of LCL-type grid-tied PV power conditioning system based on inverter and grid side currents double feedback. International Journal of Modelling and Simulation, pp.1-21. [ DOI:10.1080/02286203.2023.2204319] 16. Hosseinpour, M., Kholousi, A. and Poulad, A., 2022. A robust controller design procedure for LCL‐type grid‐tied proton exchange membrane fuel cell system in harmonics‐polluted network. Energy Science & Engineering, 10(10), pp.3798-3818. [ DOI:10.1002/ese3.1250] 17. Hosseinpour, M., Asad, M. and Rasekh, N., 2021. 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, 45, pp.843-859. [ DOI:10.1007/s40998-021-00414-z] 18. Huang, M., Wang, X., Loh, P.C. and Blaabjerg, F., 2015. LLCL-filtered grid converter with improved stability and robustness. IEEE Transactions on Power Electronics, 31(5), pp.3958-3967. [ DOI:10.1109/TPEL.2015.2467185] 19. Li, M., Zhang, X., Guo, Z., Wang, J., Wang, Y., Li, F. and Zhao, W., 2020. The control strategy for the grid-connected inverter through impedance reshaping in q-axis and its stability analysis under a weak grid. IEEE Journal of Emerging and Selected Topics in Power Electronics, 9(3), pp.3229-3242. [ DOI:10.1109/JESTPE.2020.3024863] 20. Lin, Z., Ruan, X., Zhang, H. and Wu, L., 2023. A hybrid-frame control based impedance shaping method to extend the effective damping frequency range of the three-phase adaptive active damper. IEEE Transactions on Industrial Electronics, 70(1), pp.509-521. [ DOI:10.1109/TIE.2022.3153802] 21. Liu, L., Xu, J., Ye, J., Zheng, Z. and Shen, A., 2024. Controller parameter optimization of LCL-type grid-connected inverters for passivity margin enhancement. International Journal of Electrical Power & Energy Systems, 159, p.110046. [ DOI:10.1016/j.ijepes.2024.110046] 22. Liu, T., Liu, J., Liu, Z. and Liu, Z., 2020. A study of virtual resistor-based active damping alternatives for LCL resonance in grid-connected voltage source inverters. IEEE Transactions on Power Electronics, 35(1), pp.247-262. [ DOI:10.1109/TPEL.2019.2911163] 23. Qasem, N.A. and Abdulrahman, G.A., 2024. A Recent Comprehensive Review of Fuel Cells: History, Types, and Applications. International Journal of Energy Research, 2024(1), p.7271748. [ DOI:10.1155/2024/7271748] 24. Rasekh, N. and Hosseinpour, M., 2020. Adequate tuning of LCL filter for robust performance of converter side current feedback control of grid connected modified-Y-source inverter. International Journal of Industrial Electronics Control and Optimization, 3(3), pp.365-378. 25. Rasekh, N. and Hosseinpour, M., 2020. LCL filter design and robust converter side current feedback control for grid-connected Proton Exchange Membrane Fuel Cell system. International Journal of Hydrogen Energy, 45(23), pp.13055-13067. [ DOI:10.1016/j.ijhydene.2020.02.227] 26. Rodriguez-Diaz, E., Freijedo, F.D., Guerrero, J.M., Marrero-Sosa, J.A. and Dujic, D., 2019. Input-admittance passivity compliance for grid-connected converters with an LCL filter. IEEE Transactions on Industrial Electronics, 66(2), pp.1089-1097. [ DOI:10.1109/TIE.2018.2835374] 27. Rodriguez-Diaz, E., Freijedo, F.D., Vasquez, J.C. and Guerrero, J.M., 2019. Analysis and comparison of notch filter and capacitor voltage feedforward active damping techniques for LCL grid-connected converters. IEEE Transactions on Power Electronics, 34(4), pp.3958-3972. [ DOI:10.1109/TPEL.2018.2856634] 28. Serrano-Delgado, J., Cobreces, S., Rizo, M. and Bueno, E.J., 2021. Low-order passivity-based robust current control design for grid-tied VSCs. IEEE Transactions on Power Electronics, 36(10), pp.11886-11899. [ DOI:10.1109/TPEL.2021.3068057] 29. Sun, J., 2011. Impedance-based stability criterion for grid-connected inverters. IEEE Transactions on Power Electronics, 26(11), pp.3075-3078. [ DOI:10.1109/TPEL.2011.2136439] 30. Tariq, A.H., Kazmi, S.A.A., Hassan, M., Ali, S.M. and Anwar, M., 2024. Analysis of fuel cell integration with hybrid microgrid systems for clean energy: A comparative review. International Journal of Hydrogen Energy, 52, pp.1005-1034. [ DOI:10.1016/j.ijhydene.2023.07.238] 31. Wang, X. and Blaabjerg, F., 2019. Harmonic stability in power electronic-based power systems: Concept, modeling, and analysis. IEEE Transactions on Smart Grid, 10(3), pp.2858-2870. [ DOI:10.1109/TSG.2018.2812712] 32. Wang, X., Blaabjerg, F. and Loh, P.C., 2017. Passivity-based stability analysis and damping injection for multiparalleled VSCs with LCL filters. IEEE Transactions on Power Electronics, 32(11), pp.8922-8935. [ DOI:10.1109/TPEL.2017.2651948] 33. Wu, H. and Wang, X., 2020. Virtual-flux-based passivation of current control for grid-connected VSCs. IEEE Transactions on Power Electronics, 35(12), pp.12673-12677. [ DOI:10.1109/TPEL.2020.2997876] 34. Xie, C., Li, K., Zou, J. and Guerrero, J.M., 2020. Passivity-based stabilization of LCL-type grid-connected inverters via a general admittance model. IEEE Transactions on Power Electronics, 35(6), pp.6636-6648. [ DOI:10.1109/TPEL.2019.2955861] 35. Yao, W., Yang, Y., Xu, Y., Blaabjerg, F., Liu, S. and Wilson, G., 2019. Phase reshaping via all-pass filters for robust LCL-filter active damping. IEEE Transactions on Power Electronics, 35(3), pp.3114-3126. [ DOI:10.1109/TPEL.2019.2927272] 36. Yao, W., Yang, Y., Zhang, X., Blaabjerg, F. and Loh, P.C., 2017. Design and analysis of robust active damping for LCL filters using digital notch filters. IEEE Transactions on Power Electronics, 32(3), pp.2360-2375. [ DOI:10.1109/TPEL.2016.2565598] 37. Yang, Z., Shah, C., Chen, T., Teichrib, J. and De Doncker, R.W., 2021. Virtual damping control design of three-phase grid-tied PV inverters for passivity enhancement. IEEE Transactions on Power Electronics, 36(6), pp.6251-6264. [ DOI:10.1109/TPEL.2020.3035417] 38. Yepes, A.G., Vidal, A., Malvar, J., Lopez, O. and Doval-Gandoy, J., 2013. Tuning method aimed at optimized settling time and overshoot for synchronous proportional-integral current control in electric machines. IEEE Transactions on Power Electronics, 29(6), pp.3041-3054. [ DOI:10.1109/TPEL.2013.2276059] 39. Yuan, X., Y. Liu, and R. Bucknall, "A Novel Design of a Solid Oxide Fuel Cell-Based Combined Cooling, Heat and Power Residential System in the UK", IEEE Transactions on Industry Applications, Vol. 57, No. 1, pp. 805-813, 2020. [ DOI:10.1109/TIA.2020.3034073] 40. Yu, H., Awal, M.A., Tu, H., Du, Y., Lukic, S. and Husain, I., 2019, September. Passivity-oriented discrete-time voltage controller design for grid-forming inverters. In 2019 IEEE Energy Conversion Congress and Exposition (ECCE) (pp. 469-475). IEEE. [ DOI:10.1109/ECCE.2019.8912988] 41. Zhang, Z., Wu, W., Shuai, Z., Wang, X., Luo, A., Chung, H.S.H. and Blaabjerg, F., 2019. Principle and robust impedance-based design of grid-tied inverter with LLCL-filter under wide variation of grid-reactance. IEEE Transactions on Power Electronics, 34(5), pp.4362-4374. [ DOI:10.1109/TPEL.2018.2864775] |
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Hosseinpour M, Akbari R, Shahparasti M. Stability Improvement of LCL-Based Fuel Cell Power Quality Enhancement System Utilizing Phase Compensation of Current Regulator. ieijqp 2025; 14 (2) :29-43 URL: http://ieijqp.ir/article-1-1013-en.html
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