A Robust Photovoltaic Power Conditioning System Connected to Weak Grid Through Virtual Impedance Shaping
Document Type : Original Article
Authors
1 Department of Electrical Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
2 School of Technology and Innovations, University of Vaasa, Vaasa, Finland
10.22059/jser.2024.369348.1364
Abstract
Grid-connected inverters are crucial in transmitting power from distributed production systems and renewable sources to the grid. However, these inverters often generate current harmonics due to high-frequency switching and DC link ripple. To address these issues, various filters, including the LCL filter, are employed. This paper focuses on improving the power quality of grid-connected photovoltaic arrays using LCL filters, primarily through a current sensor and virtual impedance shaping. The paper divides the output impedance of the photovoltaic array power optimization system into an active and passive part. It neutralizes the active component by introducing a series of virtual impedances and counteracts its adverse effects with parallel virtual impedance. The design process for both series and parallel virtual impedance is elaborated, and the system's sensitivity is thoroughly analyzed. To validate the proposed approach, extensive simulations have been carried out using MATLAB software. The simulations demonstrate the robust and precise performance of the control system in effectively injecting the maximum power generated by the photovoltaic array into the grid. Additionally, they showcase the high-quality current being injected into the grid and the system's capacity to maintain stability, even in a weak network environment.
Keywords
[1] Hosseinpour, M., Dastgiri, A. and Shahparasti, M., 2024. Design and Analysis of a Power Quality Improvement System for Photovoltaic Generation Based on LCL-Type Grid Connected Inverter. International Journal of Engineering, 37(2), pp.252-267. https://doi.org/10.5829/ije.2024.37.02b.04
[2] He, Y., Wang, X., Ruan, X., Pan, D. and Qin, K., 2020. 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, 36(2), pp.2373-2383. https://doi.org/10.1109/TPEL.2020.3008160
[3] He, Y., Wang, X., Pan, D., Ruan, X. and Su, G., 2021. An ignored culprit of harmonic oscillation in LCL-type grid-connected inverter: Resonant pole cancelation. IEEE Transactions on Power Electronics, 36(12), pp.14282-14294. https://doi.org/10.1109/TPEL.2021.3084810
[4] Zhang, H., Ruan, X., Lin, Z., Wu, L., Ding, Y. and Guo, Y., 2021. Capacitor voltage full feedback scheme for LCL-type grid-connected inverter to suppress current distortion due to grid voltage harmonics. IEEE Transactions on Power Electronics, 36(3), pp.2996-3006. https://doi.org/10.1109/TPEL.2020.3014338
[5] Zou, C., Liu, B., Duan, S. and Li, R., 2014. Influence of delay on system stability and delay optimization of grid-connected inverters with LCL filter. IEEE Transactions on Industrial Informatics, 10(3), pp.1775-1784. https://doi.org/10.1109/TII.2014.2324492
[6] 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. https://doi.org/10.1109/TPEL.2016.2565598
[7] 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. https://doi.org/10.22111/ieco.2020.32122.1221
[8] Zhou, L., Chen, Y., Luo, A., Guerrero, J.M., Zhou, X., Chen, Z. and Wu, W., 2016. Robust two degrees‐of‐freedom single‐current control strategy for LCL‐type grid‐connected DG system under grid‐frequency fluctuation and grid‐impedance variation. IET Power Electronics, 9(14), pp.2682-2691. https://doi.org/10.1049/iet-pel.2016.0120
[9] Wu, W., Peng, L., Qi, Y., Liu, Q., Huang, Z., Dong, F., Chen, M. and Wang, B., 2017, October. An improved active damping method with grid-side current feedback to maximize damping ratio for LCL-type grid-connected inverter. In 2017 IEEE Energy Conversion Congress and Exposition (ECCE) (pp. 5607-5611). IEEE. https://doi.org/10.1109/ECCE.2017.8096933
[10] Rasekh, N., Rahimian, M.M., Hosseinpour, M., Dejamkhooy, A. and Akbarimajd, A., 2019, February. A step by step design procedure of PR controller and capacitor current feedback active damping for a LCL-type grid-tied T-type inverter. In 2019 10th International Power Electronics, Drive Systems and Technologies Conference (PEDSTC) (pp. 612-617). https://doi.org/10.1109/PEDSTC.2019.8697853
[11] Zhu, K., Sun, P., Zhou, L., Du, X. and Luo, Q., 2020. Frequency-division virtual impedance shaping control method for grid-connected inverters in a weak and distorted grid. IEEE Transactions on Power Electronics, 35(8), pp.8116-8129. https://doi.org/10.1109/TPEL.2019.2963345
[12] Xu, J., Xie, S., Zhang, B. and Qian, Q., 2018. Robust grid current control with impedance-phase shaping for LCL-filtered inverters in weak and distorted grid. IEEE Transactions on Power Electronics, 33(12), pp.10240-10250. https://doi.org/10.1109/TPEL.2018.2808604
[13] Chen, X., Zhang, Y., Wang, S., Chen, J. and Gong, C., 2017. Impedance-phased dynamic control method for grid-connected inverters in a weak grid. IEEE Transactions on Power Electronics, 32(1), pp.274-283. https://doi.org/10.1109/TPEL.2016.2533563
[14] 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. https://doi.org/10.1007/s40998-021-00414-z
[15] Hosseinpour, M., Sabetfar, T. and Shahparasti, M., 2023. Grid‐tied PEMFC power conditioning system based on capacitor voltage thorough feedback procedure in a weak and harmonics‐polluted network. Energy Science & Engineering. https://doi.org/10.1002/ese3.1624
[16] 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. https://doi.org/10.1016/j.ijhydene.2020.02.227
[17] Akhavan, A., Vasquez, J.C. and Guerrero, J.M., 2020. A simple method for passivity enhancement of current controlled grid-connected inverters. IEEE Transactions on Power Electronics, 35(8), pp.7735-7741. https://doi.org/10.1109/TPEL.2020.2967239
[18] Xie, C., Li, K., Zou, J. and Guerrero, J.M., 2019. Passivity-based stabilization of LCL-type grid-connected inverters via a general admittance model. IEEE Transactions on Power Electronics, 35(6), pp.6636-6648. https://doi.org/10.1109/TPEL.2019.2955861
[19] Wang, X., He, Y., Pan, D., Zhang, H., Ma, Y. and Ruan, X., 2022. Passivity enhancement for LCL-filtered inverter with grid current control and capacitor current active damping. IEEE Transactions on Power Electronics, 37(4), pp.3801-3812. https://doi.org/10.1109/TPEL.2021.3111677
[20] Wang, C., Wang, X., He, Y., Pan, D., Zhang, H., Ruan, X. and Chen, X., 2023. Passivity-Oriented Impedance Shaping for LCL-Filtered Grid-Connected Inverters. IEEE Transactions on Industrial Electronics, 70(9), pp.9078-9090. https://doi.org/10.1109/TIE.2022.3210573
[21] 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. https://doi.org/10.1109/TPEL.2019.2920843
[22] Zhao, J., Xie, C., Li, K., Zou, J. and Guerrero, J.M., 2022. Passivity-oriented design of LCL-type grid-connected inverters with Luenberger observer-based active damping. IEEE Transactions on Power Electronics, 37(3), pp.2625-2635. https://doi.org/10.1109/TPEL.2021.3109434
[23] Xie, C., Li, K., Zou, J., Liu, D. and Guerrero, J.M., 2020. Passivity-based design of grid-side current-controlled LCL-type grid-connected inverters. IEEE Transactions on Power Electronics, 35(9), pp.9813-9823. https://doi.org/10.1109/TPEL.2020.2971380
[24] 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. https://doi.org/10.1109/TPEL.2020.3035417
[25] 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. https://doi.org/10.1109/TIE.2018.2835374
[26] Hans, F., Schumacher, W., Chou, S.F. and Wang, X., 2019. Passivation of current-controlled grid-connected VSCs using passivity indices. IEEE Transactions on Industrial Electronics, 66(11), pp.8971-8980. https://doi.org/10.1109/TIE.2018.2883261
[27] Rasekh, N., Hosseinpour, M., Dejamkhooy, A. and Akbarimajd, A., 2021. Robust power conditioning system based on LCL-type quasi-Y-source inverter for grid connection of photovoltaic arrays. International Journal of Automation and Control, 15(6), pp.692-709. https://doi.org/10.1504/IJAAC.2021.118526
[28] Harnefors, L., Bongiorno, M. and Lundberg, S., 2007. Input-admittance calculation and shaping for controlled voltage-source converters. IEEE transactions on industrial electronics, 54(6), pp.3323-3334. https://doi.org/10.1109/TIE.2007.904022
[29] 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. https://doi.org/10.1080/02286203.2023.2204319
[30] 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. https://doi.org/10.1109/TPEL.2020.2997876
[31] Harnefors, L., Wang, X., Yepes, A.G. and Blaabjerg, F., 2016. Passivity-based stability assessment of grid-connected VSCs—An overview. IEEE Journal of emerging and selected topics in Power Electronics, 4(1), pp.116-125. https://doi.org/10.1109/JESTPE.2015.2490549
[32] 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. https://doi.org/10.1109/TSG.2018.2812712
[33] Ruan, X., Wang, X., Pan, D., Yang, D., Li, W. and Bao, C., 2018. Control techniques for LCL-type grid-connected inverters. Springer Singapore. https://doi.org/10.1007/978-981-10-4277-5
[34] He, Y., Wang, X., Ruan, X., Pan, D., Xu, X. and Liu, F., 2019. Capacitor-current proportional-integral positive feedback active damping for LCL-type grid-connected inverter to achieve high robustness against grid impedance variation. IEEE Transactions on Power Electronics, 34(12), pp.12423-12436. https://doi.org/10.1109/TPEL.2019.2906217
[35] Lu, M., Al-Durra, A., Muyeen, S.M., Leng, S., Loh, P.C. and Blaabjerg, F., 2018. Benchmarking of stability and robustness against grid impedance variation for LCL-filtered grid-interfacing inverters. IEEE Transactions on Power Electronics, 33(10), pp.9033-9046. https://doi.org/10.1109/TPEL.2017.2784685
[36] Harnefors, L., Yepes, A.G., Vidal, A. and Doval-Gandoy, J., 2014. Passivity-based stabilization of resonant current controllers with consideration of time delay. IEEE Transactions on Power Electronics, 29(12), pp.6260-6263. https://doi.org/10.1109/TPEL.2014.2328669
[37] Faiz, M.T., Khan, M.M., Jianming, X., Ali, M., Habib, S., Hashmi, K. and Tang, H., 2020. Capacitor voltage damping based on parallel feedforward compensation method for LCL-filter grid-connected inverter. IEEE Transactions on Industry Applications, 56(1), pp.837-849. https://doi.org/10.1109/TIA.2019.2951115
[38] Bimarta, R. and Kim, K.H., 2020. A robust frequency-adaptive current control of a grid-connected inverter based on LMI-LQR under polytopic uncertainties. IEEE Access, 8, pp.28756-28773. https://doi.org/10.1109/ACCESS.2020.2972028
[39] Padmanaban, S., Priyadarshi, N., Bhaskar, M.S., Holm-Nielsen, J.B., Hossain, E. and Azam, F., 2019. A hybrid photovoltaic-fuel cell for grid integration with jaya-based maximum power point tracking: experimental performance evaluation. IEEE Access, 7, pp.82978-82990. https://doi.org/10.1109/ACCESS.2019.2924264
[40] Kim, Y.J. and Kim, H., 2019. Optimal design of LCL filter in grid‐connected inverters. IET Power Electronics, 12(7), pp.1774-1782. https://doi.org/10.1049/iet-pel.2018.5518
[41] Dragičević, T., Zheng, C., Rodriguez, J. and Blaabjerg, F., 2020. Robust quasi-predictive control of LCL-filtered grid converters. IEEE Transactions on Power Electronics, 35(2), pp.1934-1946. https://doi.org/10.1109/TPEL.2019.2916604
[42] Hosseinpour, M. and Kholousi, A., 2023. Design and Analysis of LCL-type Grid-Connected PV Power Conditioning System Based on Positive Virtual Impedance Capacitor-Current Feedback Active Damping. Journal of Solar Energy Research, 8(2), pp.1497-1515. https://doi.org/10.22059/jser.2023.357089.1286
)