Farhadi-Kangarlu, M., Mohammadi, F. (2019). Performance Improvement of Single-Phase Transformerless Grid-Connected PV Inverters Regarding Common-Mode Voltage (CMV) and LVRT. Journal of Operation and Automation in Power Engineering, (), -. doi: 10.22098/joape.2006.4366.1344

M. Farhadi-Kangarlu; F. Mohammadi. "Performance Improvement of Single-Phase Transformerless Grid-Connected PV Inverters Regarding Common-Mode Voltage (CMV) and LVRT". Journal of Operation and Automation in Power Engineering, , , 2019, -. doi: 10.22098/joape.2006.4366.1344

Farhadi-Kangarlu, M., Mohammadi, F. (2019). 'Performance Improvement of Single-Phase Transformerless Grid-Connected PV Inverters Regarding Common-Mode Voltage (CMV) and LVRT', Journal of Operation and Automation in Power Engineering, (), pp. -. doi: 10.22098/joape.2006.4366.1344

Farhadi-Kangarlu, M., Mohammadi, F. Performance Improvement of Single-Phase Transformerless Grid-Connected PV Inverters Regarding Common-Mode Voltage (CMV) and LVRT. Journal of Operation and Automation in Power Engineering, 2019; (): -. doi: 10.22098/joape.2006.4366.1344

Performance Improvement of Single-Phase Transformerless Grid-Connected PV Inverters Regarding Common-Mode Voltage (CMV) and LVRT

Articles in Press, Accepted Manuscript , Available Online from 30 January 2019

^{}Faculty of Electrical and Computer Engineering, Urmia University, Urmia, Iran

Abstract

The single-phase transformerless grid-connected photovoltaic (PV) systems, mainly the low-power single-phase systems, require high efficiency, small size, lightweight, and low-cost grid-connected inverters. However, problems such as leakage current, the DC current injection and safety issues are incorporated with transformerless grid-connected PV inverters. Besides, the new standards such as Low-Voltage Ride-Through (LVRT) capability and staying connected to the grid during the fault occurrence should be considered for the next generation of transformerless PV inverters. In this paper, a study is going underway on the LVRT capability and the Common-Mode Voltage (CMV) in a number of most common transformerless grid-connected PV inverters. In fact, by a comprehensive study on all possible switching combinations and the current paths during the freewheeling period of the selected inverters, the proposed control strategy for performance improvement of the PV inverters under the normal and the LVRT conditions is presented. As a matter of fact, a reconfigurable PWM method is proposed, which makes it possible to switch between two PWM methods and hence provide improved performance of the inverters in the LVRT condition. Finally, the results of simulations in the normal and the LVRT operations to verify the theoretical concepts are indicated.

[1] K. O. Kovanen, “Photovoltaics and power distribution,” Renewable Energy Focus, vol. 14, no. 3, pp. 20-21, May/Jun. 2013.

[2] A. Sadeghi Yazdankhah and R. Kazemzadeh, “Power management in a utility connected micro-grid with multiple renewable energy sources,” J. Oper. Autom. Power Eng., vol. 5, no. 1, pp. 1-10, 2017.

[3] J. Carrasco, L. Franquelo, J. Bialasiewicz, E. Galvan, R. Portillo Guisado, M. Prats, J. Leon and N. Moreno-Alfonso,N “Power electronic systems for the grid integration of renewable energy sources: a survey”, IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1002-1016, 2006.

[4] Y. Gu, W. Li, Y. Zhao, B. Yang, C. Li, and X. He, “Transformerless inverter with virtual DC bus concept for cost-effective grid-connected PV power systems,” IEEE Trans. Power Electron., vol. 28, no. 2, pp. 793-805, Feb. 2013.

[5] M. Islam, S. Mekhilef, and M. Hasan, “Single phase transformerless inverter topologies for grid-tied photovoltaic system: A review,” Renewable Sust. Energy Rev., vol. 45, pp. 69-86, 2015.

[6] M. C. Cavalcanti, K. C. de Oliveira, A. M. de Farias, F. A. S. Neves, G. M. S. Azevedo and F. C. Camboim, “Modulation techniques to eliminate leakage currents in transformerless three-phase photovoltaic systems,” IEEE Trans. Ind. Electron., vol. 57, no. 4, pp. 1360-1368, April 2010.

[7] X. Guo and X. Jia, “Hardware-based cascaded topology and modulation strategy with leakage current reduction for transformerless PV systems,” IEEE Trans. Ind. Electron., vol. 63, no. 12, pp. 7823-7832, Dec. 2016.

[8] M. C. Cavalcanti, A. M. Farias, K. C. Oliveira, F. A. S. Neves and J. L. Afonso, “Eliminating leakage currents in neutral point clamped inverters for photovoltaic systems,” IEEE Trans. Ind. Electron., vol. 59, no. 1, pp. 435-443, Jan. 2012.

[9] Teodorescu, Remus, Marco Liserre, and Pedro Rodriguez. “Grid converters for photovoltaic and wind power systems,” John Wiley Sons, vol. 29, 2011.

[10] T. K. S. Freddy, N. A. Rahim, W. P. Hew and H. S. Che, “Comparison and analysis of single-phase transformerless grid-connected PV inverters,” IEEE Trans. Power Electron., vol. 29, no. 10, pp. 5358-5369, Oct. 2014.

[11] M. Xu, L. Zhang, Y. Xing and L. Feng, “A novel H6-type transformerless inverter for grid-connected photovoltaic application,” Proce. 7th IEEE Conf. Ind. Electron. Appl., Singapore, pp. 58-63, 2012.

[12] B. Ji, J. Wang and J. Zhao, “High-efficiency single-phase transformerless PV h6 inverter with hybrid modulation method,” IEEE Trans. Ind. Electron., vol. 60, no. 5, pp. 2104-2115, May 2013.

[13] W. Yu, J. S. J. Lai, H. Qian and C. Hutchens, “High-efficiency MOSFET inverter with h6-type configuration for photovoltaic non-isolated ac-module applications,” IEEE Trans. Power Electron., vol. 26, no. 4, pp. 1253-1260, April 2011.

[14] R. Gonzalez, J. Lopez, P. Sanchis, E. Gubia, A. Ursua and L. Marroyo, “High-efficiency transformerless single-phase photovoltaic inverter,” Proce. 12th Int. Power Electron. Motion Control Conf., Portoroz, pp. 1895-1900, 2006.

[15] B. Yang, W. Li, Y. Gu, W. Cui, and X. He, “Improved transformerless inverter with common-mode leakage current elimination for a photovoltaic grid-connected power system,” IEEE Trans. Power Electron., vol. 27, no. 2, pp. 752-762, Feb. 2012.

[16] D. Barater, G. Buticchi, E. Lorenzani, and C. Concari, “Active common-mode filter for ground leakage current reduction in grid-connected PV converters operating with arbitrary power factor,” IEEE Trans. Ind. Electron., vol. 61, pp. 3940-3950, 2014.

[17] L. Zhang, K. Sun, L. Feng, H. Wu, and Y. Xing, “A family of neutral point clamped full-bridge topologies for transformerless photovoltaic grid-tied inverters,” IEEE Trans. Power Electron., vol. 28, no. 2, pp. 730-739, Feb. 2013.

[18] J. S. Lee and K. B. Lee, “New modulation techniques for a leakage current reduction and a neutral-point voltage balance in transformerless photovoltaic systems using a three-level inverter,” IEEE Trans. Power Electron., vol. 29, pp. 1720-1732, 2014.

[19] Reference technical rules for connecting users to the active and passive LV distribution companies of electricity, Comitato Elettrotecnico Italiano, Italy, 2011.

[20] T. Neumann and I. Erlich, “Modelling and control of photovoltaic inverter systems with respect to German grid code requirements,” Proce. IEEE Power Energy Soc. Gen. Meeting, San Diego, CA, pp. 1-8, 2012.

[21] H. Kobayashi, “Fault ride through requirements and measures of distributed PV systems in Japan,” Proce. IEEE Power Energy Soc. Gen. Meeting, San Diego, CA, 2012, pp. 1-6, 2012.

[22] Y. Yang, F. Blaabjerg and H. Wang, “Low-voltage ride-through of single-phase transformerless photovoltaic inverters,” IEEE Trans. Ind. Appl., vol. 50, no. 3, pp. 1942-1952, May-June 2014.

[23] B. Chen, B. Gu, L. Zhang, J. -S. Lai, “A novel pulse-width modulation method for reactive power generation on a coolmos and sic-diode-based transformerless inverter”, IEEE Trans. Ind. Electron., vol. 63, no. 3, pp. 1539-1548, Mar. 2016.

[24] T. F. Wu, C. L. Kuo, K. H. Sun and H. C. Hsieh, “Combined unipolar and bipolar PWM for current distortion improvement during power compensation,” in IEEE Trans. Power Electron., vol. 29, no. 4, pp. 1702-1709, April 2014.

[25] M. Farhadi Kangarlu, E. Babaei, and F. Blaabjerg, “A lcl-filtered single-phase multilevel inverter for grid integration of PV systems,” J. Oper. and Autom. Power Eng., vol. 4, no. 1, pp. 54-65, 2016.

[26] M. Farhadi-Kangarlu and F. Mohammadi, "Performance comparison of single-phase transformerless grid-connected PV inverters," Proce. 9th Annual Power Electron. Drives Syst. Technol. Conf., Tehran, Iran, pp. 71-76, 2018.

[27] T. K. S. Freddy, J. H. Lee, H. C. Moon, K. B. Lee and N. A. Rahim, “Modulation technique for single-phase transformerless photovoltaic inverters with reactive power capability,” IEEE Trans. Ind. Electron., vol. 64, no. 9, pp. 6989-6999, Sept. 2017.

[28] Y. Yang, F. Blaabjerg and Z. Zou, “Benchmarking of grid fault modes in single-phase grid-connected photovoltaic systems,” IEEE Trans. Ind. Appl., vol. 49, no. 5, pp. 2167-2176, Sept.-Oct. 2013.

[29] M. Ciobotaru, R. Teodorescu and F. Blaabjerg, “A new single-phase PLL structure based on second order generalized integrator,” Proc. 37th IEEE Power Electron. Spec. Conf., pp. 1-6, 2006.

[30] Y. Yang and F. Blaabjerg, “Low-voltage ride-through capability of a single-stage single-phase photovoltaic system connected to the low-voltage grid,” Int. J. Photoenergy, vol. 2013, Article ID 257487, 9 pages, 2013.

[31] M. Heidari, S. Nejad, and M. Monfared, “A new control method for single-phase grid-connected inverter using instantanseous power theory,” J. Oper. Autom. Power Eng., vol. 5, no. 2, pp. 105-116, 2017.