بهبود پایداری گذرای مبدل متصل به شبکه هنگام افت ولتاژ شدید با تکنیک امپدانس مجازی
محورهای موضوعی : مهندسی برق و کامپیوترامید عبدلی 1 , مهدی قلی‌پور 2 , رحمت‌الله هوشمند 3
1 - دانشگاه اصفهان
2 - دانشگاه اصفهان
3 - دانشگاه اصفهان
کلید واژه: امپدانس مجازی, PLL, مبدل متصل به شبکه, پایداری گذرا, افت ولتاژ,
چکیده مقاله :
با افزایش نفوذ منابع تولید پراکنده مبتنی بر اینورتر، دستورالعمل‌های شبکه خواستار عدم قطع این مبدل‌ها از شبکه هنگام رخداد خطا می‌باشند. این مبدل‌ها همچنین می‌بایست با تزریق توان راکتیو به رفع خطا کمک کنند. از آنجایی که شبکه‌های برق سلفی خالص نبوده و دارای مقاومت اهمی نیز هستند، این شبکه‌ها هنگام رخداد خطا با مشکل ناپایداری مبدل روبه‌رو می‌شوند. مبدل‌ها که جهت سنکرون‌ماندن با شبکه از حلقه قفل فاز (PLL) استفاده می‌کنند، هنگام رخداد خطای افت ولتاژ سنگین، دیگر قادر به حفظ پایداری با شبکه نیستند. در نتیجه این مبدل‌ها قادر به گذر از خطا نبوده و می‌بایست از شبکه جدا شوند. این مقاله با ارائه روشی جدید مبتنی بر امپدانس مجازی در هنگام رخداد افت ولتاژ سنگین، پایداری سنکرون با شبکه برق را حفظ می‌کند. این روش نیاز به تخمین تقریبی امپدانس شبکه دارد و مبدل را مجازاً با نقطه‌ای که اتصال قوی‌تری دارد سنکرون می‌کند. با استفاده از روش پیشنهادی در هنگام افت ولتاژ، مبدل به شبکه متصل مانده و می‌تواند به شبکه توان راکتیو تزریق کند. نتایج شبیه‌سازی با استفاده از نرم‌افزار Matlab درستی روش پیشنهادی برای بهبود پایداری گذرای مبدل را نشان می‌دهد.
With the rise in the penetration of inverter based distributed energy sources, grid codes say that converters should not be disconnected during the fault. These sources should also help the grid by reactive power injection. Power system grids are resistive inductive and the converter may be unstable during the fault. Converters use phase locked loop (PLL) to synchronize with the grid. PLL is not able to be stable during severe voltage drop, so converters cannot ride through the fault and should be disconnected. In this paper a novel method based on virtual impedance is proposed to maintain the synchronization during severe voltage drop. This method needs grid impedance estimation and virtually connects the converter to a point that has a stronger connection. By this novel method, during voltage drop, the converter stays connected to the grid and injects reactive power. Simulation results in MATLAB verify the ability of proposed method in improving the transient stability of converter.
[1] I. Series, Microgrids and Active Distribution Networks, the Institution of Engineering and Technology, 2009.
[2] R. Teodorescu, M. Liserre, and P. Rodriguez, Grid Converters for Photovoltaic and Wind Power Systems, John Wiley & Sons, 2011.
[3] C. Y. Tang, Y. T. Chen, and Y. M. Chen, "PV power system with multi-mode operation and low-voltage ride-through capability," IEEE Trans. on Industrial Electronics, vol. 62, no. 12, pp. 7524-7533, Dec. 2015.
[4] E. Afshari, et al., "Control strategy for three-phase grid-connected PV inverters enabling current limitation under unbalanced faults," IEEE Trans. on Industrial Electronics, vol. 64, no. 11, pp. 8908-8918, Nov. 2017.
[5] L. Djilali, E. N. Sanchez, F. Ornelas-Tellez, A. Avalos, and M. Belkheiri, "Improving microgrid low-voltage ride-through capacity using neural control," IEEE Systems J., vol. 14, no. 2, pp. 2825-2836, Jun. 2019.
[6] A. Mojallal and S. Lotfifard, "Enhancement of grid connected PV arrays fault ride through and post fault recovery performance," IEEE Trans. on Smart Grid, vol. 10, no. 1, pp. 546-555, Jan. 2017.
[7] D. Eltigani and S. Masri, "Challenges of integrating renewable energy sources to smart grids: a review," Renewable and Sustainable Energy Reviews, vol. 52, pp. 770-780, Dec. 2015.
[8] H. Tian, F. Gao, C. Ma, G. He, and G. Li, "A review of low voltage ride-through techniques for photovoltaic generation systems," in Proc. IEEE Energy Conversion Congress and Exposition, ECCE’14, pp. 1566-1572, Pittsburgh, PA, USA, 14-18 Sept. 2014.
[9] A. Q. Al-Shetwi, M. Z. Sujod, F. Blaabjerg, and Y. Yang, "Fault ride-through control of grid-connected photovoltaic power plants: a review," Solar Energy, vol. 180, pp. 340-350, Mar. 2019.
[10] L. Niu, X. Wang, L. Wu, F. Yan, and M. Xu, "Review of low voltage ride-through technology of doubly-fed induction generator," The J. of Engineering, vol. 2019, no. 16, pp. 3106-3108, Mar. 2019.
[11] O. P. Mahela, N. Gupta, M. Khosravy, and N. Patel, "Comprehensive overview of low voltage ride through methods of grid integrated wind generator," IEEE Access, vol. 7, pp. 99299-99326, 2019.
[12] H. Shin, J. Jung, S. Oh, K. Hur, K. Iba, and B. Lee, "Evaluating the influence of momentary cessation mode in inverter-based distributed generators on power system transient stability," IEEE Trans. on Power Systems, vol. 35, no. 2, pp. 1618-1626, Mar. 2019.
[13] S. Mortazavian and Y. A. R. I. Mohamed, "Dynamic analysis and improved lvrt performance of multiple dg units equipped with grid-support functions under unbalanced faults and weak grid conditions," IEEE Trans. on Power Electronics, vol. 33, no. 10, pp. 9017-9032, Oct. 2017.
[14] X. Wang, J. Yao, J. Pei, P. Sun, H. Zhang, and R. Liu, "Analysis and damping control of small-signal oscillations for VSC connected to weak AC grid during LVRT," IEEE Trans. on Energy Conversion, vol. 34, no. 3, pp. 1667-1676, Sept. 2019.
[15] Z. Yang, R. Ma, S. Cheng, and M. Zhan, "Nonlinear modeling and analysis of grid-connected voltage source converters under voltage dips," IEEE J. of Emerging and Selected Topics in Power Electronics, vol. 8, no. 4, pp. 3281-3292, Dec. 2020.
[16] A. Movahedi, A. H. Niasar, and G. B. Gharehpetian, "LVRT improvement and transient stability enhancement of power systems based on renewable energy resources using the coordination of SSSC and PSSs controllers," IET Renewable Power Generation, vol. 13, no. 11, pp. 1849-1860, Aug. 2019.
[17] D. Pan, X. Wang, F. Liu, and R. Shi, "Transient stability of voltage-source converters with grid-forming control: a design-oriented study," IEEE J. of Emerging and Selected Topics in Power Electronics, vol. 8, no. 2, pp. 1019-1033, Jun. 2019.
[18] D. Pan, X. Wang, F. Liu, and R. Shi, "Transient stability analysis of droop-controlled grid-connected converters with inertia emulating low-pass filters," in Proc. IEEE Energy Conversion Congress and Exposition, ECCE’19, pp. 34-40, Baltimore, MD, USA, 29 Sept.-3 Oct. 2019.
[19] L. Huang, H. Xin, Z. Wang, L. Zhang, K. Wu, and J. Hu, "Transient stability analysis and control design of droop-controlled voltage source converters considering current limitation," IEEE Trans. on Smart Grid, vol. 10, no. 1, pp. 578-591, Jan. 2017.
[20] M. G. Taul, X. Wang, P. Davari, and F. Blaabjerg, "An overview of assessment methods for synchronization stability of grid-connected converters under severe symmetrical grid faults," IEEE Trans. on Power Electronics, vol. 34, no. 10, pp. 9655-9670, Oct. 2019.
[21] X. He, H. Geng, R. Li, and B. C. Pal, "Transient stability analysis and enhancement of renewable energy conversion system during LVRT," IEEE Trans. on Sustainable Energy, vol. 11, no. 3, pp. 1612-1623, Jul. 2020.
[22] J. Pei, et al., "Characteristic analysis and risk assessment for voltage-frequency coupled transient instability of large-scale grid-connected renewable energy plants during LVRT," IEEE Trans. on Industrial Electronics, vol. 67, no. 7, pp. 5515-5530, Jul. 2020.
[23] P. Sun, et al., "Virtual capacitance control for improving dynamic stability of the DFIG-based wind turbines during a symmetrical fault in a weak AC grid," IEEE Trans. on Industrial Electronics, vol. 68, no. 1, pp. 333-346, Jan. 2021.
[24] J. A. Suul, S. D'Arco, P. Rodriguez, and M. Molinas, "Impedance-compensated grid synchronisation for extending the stability range of weak grids with voltage source converters," IET Generation, Transmission & Distribution, vol. 10, no. 6, pp. 1315-1326, Apr. 2016.
[25] B. Weise, "Impact of K-factor and active current reduction during fault-ride-through of generating units connected via voltage-sourced converters on power system stability," IET Renewable Power Generation, vol. 9, no. 1, pp. 25-36, Jan. 2015.
