Leakage Current Mitigation in On-Grid Photovoltaic Systems Using a Flexible Multi-Level Inverter Topology

Caíque C. A. de Carvalho; Paulo R. D. R. da Silva; José M. Araújo; José A. Pomilio

doi:10.18618/REP.e202527

Authors

Caíque C. A. de Carvalho Universidade Estadual de Campinas (UNICAMP) https://orcid.org/0009-0005-1865-9350
Paulo R. D. R. da Silva Universidade Estadual de Campinas (UNICAMP) https://orcid.org/0000-0003-4585-9807
José M. Araújo Instituto Federal da Bahia https://orcid.org/0000-0002-4170-7067
José A. Pomilio Universidade Estadual de Campinas (UNICAMP) https://orcid.org/0000-0001-5457-4438

DOI:

https://doi.org/10.18618/REP.e202527

Keywords:

Leakage current, Common mode voltage, Multi-level PWM, Photovoltaic inverters

Abstract

Leakage current is an issue that often causes problems in transformerless grid-connected PV inverters, such as electromagnetic interference, which is conducted or radiated and derates the quality of power injected into the grid. It can also lead to electrical safety problems, impair the performance of other equipment nearby, and thus make the generation system unavailable. Therefore, mitigation procedures for the leakage current in transformerless grid-connected PV inverters are essential to ensure system efficiency and safety. In this sense, a new single-phase grid-connected transformerless inverter topology was proposed using modulation switching techniques to keep the leakage current at acceptable standard levels. With the proposed topology, by monitoring the leakage current rms value, the inverter can be driven in a three- or five-level pattern for the main switches, thereby keeping the leakage current at a satisfactory level. The topology was implemented in a versatile hardware-in-loop Typhoon-HIL to emulate a digital twin of the complete system, with the control loops and switching generation embedded in a family Texas Instruments F28335 DSP. The results obtained for total harmonic distortion and energy conversion efficiency were then compared with other consolidated topologies, and the leakage current was proved to be effectively modified when the inverter is switched in three- or five-level modes.

Downloads

Download data is not yet available.

Author Biographies

Caíque C. A. de Carvalho, Universidade Estadual de Campinas (UNICAMP)

Born on February 27, 1994, in Salvador, Bahia, Brazil, he is a PhD candidate in Electrical Engineering at UNICAMP. He holds a Master's degree in Electrical Engineering from the Federal University of Bahia - UFBA (2021), with a focus on power systems, and a Bachelor's degree in Electrical Engineering from UNIJORGE (2017), where he developed the "Smart Meter" project aimed at efficient energy consumption management. His research interests encompass power electronics, photovoltaic systems, fast charging stations, energy conversion systems, and electric vehicles.

Paulo R. D. R. da Silva, Universidade Estadual de Campinas (UNICAMP)

Born on June 24, 1996, in Itapetinga, Bahia, Brazil, Master's degree from UNICAMP (2022) in Electrical Energy with an emphasis on power systems and a degree in Electrical Engineering from the Federal University of Roraima - UFRR (2019) with an emphasis on power systems. Link with the Embedded Systems and Power Electronics Group - GSEEP. Working in the areas of Power Systems and advanced notions in Computer Science and Programming Languages.

José M. Araújo, Instituto Federal da Bahia

Born on April 12, 1973, in Serrinha, Bahia, Brazil, Ph.D. degree from Federal University of Bahia -UFBA (2011) in Electrical Engineering with an emphasis on control systems theory, Master's degree from Federal University of Espírito Santo - UFES (2003) in Electrical Engineering with an emphasis on electrical drives and a degree in Education - Electricity Teaching from the State University of Bahia - UNEB (1996). Senior member of the Instituto of Electrical and Electronic Engineers (IEEE). Link with the Signals and Systems Research Group - GPSS. Working in the areas of Control Systems Theory, Power Electronics, and Electrical Drives.

José A. Pomilio, Universidade Estadual de Campinas (UNICAMP)

was born in Jundiaí, Brazil, in 1960. He received his B.S., M.S., and Ph.D. in electrical engineering from the University of Campinas, Campinas, Brazil, in 1983, 1986, and 1991, respectively. From 1988 to 1991, he was the Head of the Power Electronics Group, Brazilian Synchrotron Light Laboratory. He was a visiting professor at the University of Padova in 1993 and 2015 and at the Third University of Rome in 2003 in Italy. He is a Professor at the School of Electrical and Computer Engineering, University of Campinas, where he has been teaching since 1984. His main interests are power electronics and power quality. Dr. Pomilio was the President of the Brazilian Power Electronics Society in 2000–2002 and a member of the Administrative Committee of the IEEE Power Electronics Society in 1997–2002.

References

J. Twidell, Renewable Energy Resources (4th ed), Routledge, 2021. DOI: https://doi.org/10.4324/9780429452161

J. R. Sim˜oes-Moreira, A. Hernandez Neto, A. C. d. Amaral, A. Nakano, C. R. d. F. Pacheco, D. S. Sowmy, D. Perecin, D. C. Zachariadis, E. Ioshimoto, E. S. Yamada, et al., “Energias renov´áveis, geração distribuída e eficiência energ´ética”, Energias renováveis, geração distribuída e eficiência energética, p. 393, 2021.

J. Jana, H. Saha, K. Das Bhattacharya, “A review of inverter topologies for single-phase grid-connected photovoltaic systems”, Renewable and Sustainable Energy Reviews, vol. 72, pp. 1256–1270, 2017. DOI: https://doi.org/10.1016/j.rser.2016.10.049

D. Yergin, O Novo Mapa: Energia, Clima e o Conflito entre Nações, Bookman Editora, 2023.

S. Nema, R. K. Nema, G. Agnihotri, “Inverter topologies and control structure in photovoltaic applications: A review”, Journal of Renewable and Sustainable Energy, vol. 3, no. 1, p. 012701, 01 2011. DOI: https://doi.org/10.1063/1.3505096

D. Kolantla, S. Mikkili, S. R. Pendem, A. A. Desai, “Critical reviewon various inverter topologies for PV system architectures”, IET Renewable Power Generation, vol. 14, no. 17, pp. 3418–3438, 2020. DOI: https://doi.org/10.1049/iet-rpg.2020.0317

L. Hassaine, E. OLias, J. Quintero, V. Salas, “Overview of power inverter topologies and control structures for grid connected photovoltaic systems”, Renewable and Sustainable Energy Reviews, vol. 30, pp. 796–807, 2014. DOI: https://doi.org/10.1016/j.rser.2013.11.005

I. D. Pharne, Y. N. Bhosale, “A review on multilevel inverter topology”, in 2013 International Conference on Power, Energy and Control (ICPEC), pp. 700–703, 2013. DOI: https://doi.org/10.1109/ICPEC.2013.6527746

V. Agelidis, D. Baker, W. Lawrance, C. Nayar, “A multilevel PWM inverter topology for photovoltaic applications”, in ISIE ’97 Proceeding of the IEEE International Symposium on Industrial Electronics, vol. 2, pp. 589–594 vol.2, 1997. DOI: https://doi.org/10.1109/ISIE.1997.649027

C. C. A. De Carvalho, P. R. D. R. Da Silva, J. A. Pomilio, J. M. Ara´ujo, “Leakage Current Mitigation in Transformerless Grid-Connected PV Inverters Through Level Modulation Switching”, in 2023 IEEE 8th Southern Power Electronics Conference (SPEC), pp. 1–7, IEEE, 2023. DOI: https://doi.org/10.1109/SPEC56436.2023.10407919

T. Kerekes, Analysis and modeling of transformerless photovoltaic inverter systems, Institut for Energiteknik, Aalborg Universitet, 2009.

Y. R. Kafle, G. E. Town, X. Guochun, S. Gautam, “Performance comparison of single-phase transformerless PV inverter systems”, in 2017 IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 3589–3593, 2017. DOI: https://doi.org/10.1109/APEC.2017.7931213

S. Yu, J. Wang, X. Zhang, F. Li, “Complete parasitic capacitance model of photovoltaic panel considering the rain water”, Chinese Journal of Electrical Engineering, vol. 3, no. 3, pp. 77–84, 2017.

B. Chen, J.-S. Lai, “A family of single-phase transformerless inverters with asymmetric phase-legs”, in 2015 IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 2200–2205, 2015. DOI: https://doi.org/10.1109/APEC.2015.7104654

Y. P. Siwakoti, F. Blaabjerg, “Common-ground-type transformerless inverters for single-phase solar photovoltaic systems”, IEEE Transactions on Industrial Electronics, vol. 65, no. 3, pp. 2100–2111, 2017.

T. Ahmad, Z. Miao, “Common mode voltage reduction schemes for voltage source converters in an autonomous microgrid”, in 2015 North American Power Symposium (NAPS), pp. 1–5, IEEE, 2015. DOI: https://doi.org/10.1109/NAPS.2015.7335128

H. Abu-Rub, M. Malinowski, K. Al-Haddad, Power electronics for renewable energy systems, transportation and industrial applications, John Wiley & Sons, 2014. DOI: https://doi.org/10.1002/9781118755525

Y. P. Siwakoti, F. Blaabjerg, “Common-ground-type transformerless inverters for single-phase solar photovoltaic systems”, IEEE Transactions on Industrial Electronics, vol. 65, no. 3, pp. 2100–2111, 2018. DOI: https://doi.org/10.1109/TIE.2017.2740821

M. Biswas, S. P. Biswas, M. R. Islam, M. A. Rahman, K. M. Muttaqi, “A new H7 transformer-less single-phase inverter to improve the performance of grid-connected solar photovoltaic systems”, in 2021 IEEE Industry Applications Society Annual Meeting (IAS), pp. 1–6, IEEE, 2021. DOI: https://doi.org/10.1109/IAS48185.2021.9677126

C. C. De Carvalho, G. C. Prym, G. P. De Lima, P. R. Da Silva, M. G. Villalva, J. M. Ara´ujo, “A Novel H7 Transformerless Single-Phase Inverter Topology for Leakage Current Reduction”, in 2022 14th Seminar on Power Electronics and Control (SEPOC), pp. 1–6, IEEE, DOI: https://doi.org/10.1109/SEPOC54972.2022.9976438

O. López, R. Teodorescu, F. Freijedo, J. Doval-Gandoy, “Eliminating ground current in a transformerless photovoltaic application”, 2007 IEEE Power Engineering Society General Meeting, PES, 2007. DOI: https://doi.org/10.1109/PES.2007.385789

S. Araujo, P. Zacharias, B. Sahan, “Novel grid-connected non-isolated converters for photovoltaic systems with grounded generator”, in 2008 IEEE Power Electronics Specialists Conference, pp. 58–65, IEEE, jun 2008. DOI: https://doi.org/10.1109/PESC.2008.4591897

DIN, DIN. VDE V 0126-1-1, Automatic disconnection device between a generator and the public low voltage grid, VDE STANDARTS,

IEC, IEC. 62109-2, Safety of power converters for use in photovoltaic power systems – Part 2: Particular requirements for inverters, IEC STANDARTS, 2011.

G. C. S. Prym, C. C. A. De Carvalho, G. P. De Lima, P. R. D. R. Da Silva, J. M. Ara´ujo, M. G. Villalva, “Topologies Analysis of Transformerless PV Inverters with Leakage Current Reduction”, in 2022 14th Seminar on Power Electronics and Control (SEPOC), pp. 1–6, 2022. DOI: https://doi.org/10.1109/SEPOC54972.2022.9976421

D. VDE, “0126-1-1”, Eigenerzeugungsanlagen am Niederspannungsnetz, 2006.

H. F. Xiao, K. Lan, L. Zhang, “A quasi-unipolar SPWM full-bridge transformerless PV grid-connected inverter with constant common mode voltage”, IEEE Transactions on Power Electronics, vol. 30, no. 6, pp. 3122–3132, 2014. DOI: https://doi.org/10.1109/TPEL.2014.2331367

M. N. H. Khan, M. Forouzesh, Y. P. Siwakoti, L. Li, T. Kerekes, F. Blaabjerg, “Transformerless inverter topologies for single-phase

photovoltaic systems: A comparative review”, IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 8, no. 1, pp. 805–835, 2019.

A. Salem, K. Sedraoui, “Highly Efficient Transformerless Inverter with Flying-Capacitor Buck–Boost for Single-Phase Grid-Connected PV Systems”, Applied Sciences, vol. 11, no. 22, 2021. DOI: https://doi.org/10.3390/app112210841

M. N. H. Khan, M. Forouzesh, Y. P. Siwakoti, L. Li, T. Kerekes, F. Blaabjerg, “Transformerless Inverter Topologies for Single-Phase Photovoltaic Systems: A Comparative Review”, IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 8, no. 1, pp. 805–835, 2020. DOI: https://doi.org/10.1109/JESTPE.2019.2908672

T. Kerekes, R. Teodorescu, P. Rodr´ıguez, G. V´azquez, E. Aldabas, “A New high-efficiency single-phase transformerless PV inverter topology”, IEEE Transactions on Industrial Electronics, vol. 58, no. 1, pp. 184–191, 2011. DOI: https://doi.org/10.1109/TIE.2009.2024092

Y. Tang, W. Yao, P. C. Loh, F. Blaabjerg, “Highly Reliable Transformerless Photovoltaic Inverters with Leakage Current and Pulsating Power Elimination”, IEEE Transactions on Industrial Electronics, vol. 63, no. 2, pp. 1016–1026, 2016. DOI: https://doi.org/10.1109/TIE.2015.2477802

V. Pires, J. Martins, D. Foito, H. Chen, “A grid connected photovoltaic system with a multilevel inverter and a Le-Blanc transformer”, International Journal of Renewable Rnergy Research, vol. 2, no. 1, pp. 84–91, 2012.

Y. P. Siwakoti, A. Mahajan, D. J. Rogers, F. Blaabjerg, “A novel seven-level active neutral-point-clamped converter with reduced active switching devices and DC-link voltage”, IEEE Transactions on Power Electronics, vol. 34, no. 11, pp. 10492–10508, 2019. DOI: https://doi.org/10.1109/TPEL.2019.2897061

O. Abdel-Rahim, M. Takeuchi, H. Funato, H. Junnosuke, “T-type three-level neutral point clamped inverter with model predictive control for grid connected photovoltaic applications”, in 2016 19th International Conference on Electrical Machines and Systems (ICEMS), pp. 1–5, IEEE, 2016.

S. K. Kuncham, K. Annamalai, N. Subrahmanyam, “A two-stage T-type hybrid five-level transformerless inverter for PV applications”, IEEE Transactions on Power Electronics, vol. 35, no. 9, pp. 9510–9521, 2020. DOI: https://doi.org/10.1109/TPEL.2020.2973340

M. Aly, E. M. Ahmed, M. Shoyama, “Modulation method for improving reliability of multilevel T-type inverter in PV systems”, IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 8, no. 2, pp. 1298–1309, 2019. DOI: https://doi.org/10.1109/JESTPE.2019.2898105

M. Schweizer, J. W. Kolar, “High efficiency drive system with 3-level T-type inverter”, in Proceedings of the 2011 14th European conference on power electronics and applications, pp. 1–10, IEEE, 2011.

N. Q. T. Vo, D.-C. Lee, “Bootstrap power supply for three-level neutral-point-clamped voltage source inverters”, in Proceedings of The 7th International Power Electronics and Motion Control Conference, vol. 2, pp. 1038–1043, IEEE, 2012. DOI: https://doi.org/10.1109/IPEMC.2012.6258948

S. Madichetty, A. Dasgupta, S. Mishra, C. K. Panigrahi, G. Basha, “Application of an advanced repetitive controller to mitigate harmonics in MMC with APOD scheme”, IEEE Transactions on Power Electronics, vol. 31, no. 9, pp. 6112–6121, 2015. DOI: https://doi.org/10.1109/TPEL.2015.2501314

W. Chen, X. Yang, W. Zhang, X. Song, “Leakage Current Calculation for PV Inverter System Based on a Parasitic Capacitor Model”, IEEE Transactions on Power Electronics, vol. 31, no. 12, pp. 8205–8217, 2016. DOI: https://doi.org/10.1109/TPEL.2016.2517740

S. Yu, J. Wang, X. Zhang, F. Li, “Complete parasitic capacitance model of photovoltaic panel considering the rain water”, Chinese Journal of Electrical Engineering, vol. 3, no. 3, pp. 77–84, 2017. DOI: https://doi.org/10.23919/CJEE.2017.8250427