Leakage current reduction in a Three-phase Transformerless photovoltaic inverter using the single-vector and double-vector model predictive control systems along with improved THD and switching Frequency

Document Type : Original Article

Authors

1 Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

2 Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran,

Abstract

Nowadays the demand for photovoltaic (PV) systems has greatly increased due to their various advantages. In many applications for the purposes of reducing losses, increasing the efficiency and having the lower size and weight the transformer has been removed from the grid connected PV systems. In such situations, due to the absence of the galvanic isolation, the common mode voltage becomes unstable leading to flow of leakage current through the parasitic capacitor. The leakage current increases losses, deteriorates the quality of injected currents, causes the electromagnetic interference and finally presents personal safety problems.
Therefore, it should be reduced to statutory limits which is defined by the VDE0126-1-1 standard. In the present paper attemps have been made to do so, using the single-vecror and double-vector model predictive control (MPCs) systems. In this approach, without using any extra hardware not only the leakage current is reduced, but the switching frequency and the THD index are also simultaneously minimized. The simulation results confirm the superior performance of the proposed method over other valuable methods.

Keywords

References

[1]      E. Gubia, P. Sanchis, A. Ursua, J. Lopez, and L. Marroyo, "Ground currents in single‐phase transformerless photovoltaic systems," Progress in photovoltaics: research and applications, vol. 15, 2007
[2]      H. Xiao and S. Xie, “An optimized transformerless photovoltaic grid connected inverter,” IEEE Transactions on Industrial Electronics, vol. 58, no. 5, 2011
[3]      D. Meneses, F. Blaabjerg, O, Garcia, and J. A. Cobos, "Review and Comparison of Step-Up Transformerless Topologies for Photovoltaic AC-Module Application," IEEE Transactions on Power Electronics, vol. 28, Iss. 6, 2013
[4]      Y. Bae and R. Y. Kim, “Suppression of common-mode voltage using a multicentral photovoltaic inverter topology with synchronized PWM,” IEEE Transactions on Industrial Electronics, vol. 61, Iss. 9, 2014.
[5]      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 Transactions on Power Electronics, vol. 27, Iss. 2, 2012.
 [6]  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 Transactions on Industrial Electronics, vol. 59, Iss. 1, 2012.
[7]      Automatic disconnection device between a generator and the public low-voltage grid, DIN VDE V 0126-1-1, 2006
[8]       T. Kerekes, R. Teodorescu, M. Liserre, C. Klumpner, and M. Sumner, “Evaluation  of Three-Phase Transformerless Photovoltaic Inverter Topologies” IEEE Transactions on Power Electronics, Vol. 24 No.9,  2009.
[9]      G. Oriti, A. L. Julian, and T. A. Lipo, “A new space vector modulation strategy for common mode reduction,” in Proc. IEEE PESC 1997, Vol.2, 1997.
[10]      E. Ün, and A. M. Hava, “A near-state PWM method with reduced switching losses and reduced common-mode voltage for three-phase voltage source inverters,” IEEE Transactions on Industry Applications, vol. 45, No.2, 2009.
[11]      M. Cacciato, A. Consoli, G. Scarccella, and A. Testa, “Reduction of common-mode currents in PWM inverter motor drives,” IEEE Transactions on Industry Applications, Vol. 35, No. 2, 1999.
[12]       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 Transactions on Industrial Electronics,Vol.57,Iss. 4, 2010.
[13]      T. K. S. Freddy, N. A. Rahim, H. W. P. Hew and H. S. Che, “Modulation Techniques to Reduce Leakage Current in Three-Phase Transformerless H7 Photovoltaic Inverter,” IEEE Transactions on Industrial Electronics, Vol. 62, Iss. 1, 2015
[14]      R. Rahimi, B. Farhangi, S. Farhangi, “New Topology to Reduce Leakage Current in ThreePhase Transformerless Grid-Connected Photovoltaic Inverters,” Power Electronics and Drive Systems Technologies Conference (PEDSTC), 2016 7th
[15]      G. Vazquez, T. Kerekes, J. Rocabert, P. Rodríguez, R. Teodorescu, and D. Aguilar, "A photovoltaic three-phase topology to reduce common mode voltage,” 2010 IEEE International Symposium on Industrial Electronics, 2010.
[16]      L. June-Seok and L. Kyo-Beum, "New Modulation Techniques for a   Leakage Current Reduction and a Neutral-Point Voltage Balance in Transformerless Photovoltaic Systems Using a Three-Level Inverter, ” IEEE Transactions on Power Electronics, Vol. 29, No.4, 2014
[17]      F. Bradaschia, M. C. Cavalcanti, P. E. P. Ferraz, F. A. S. Neves, E. C. dos Santos, and J. H. G. M. da Silva, "Modulation for Three-Phase Transformerless Z-Source Inverter to Reduce Leakage Currents in Photovoltaic Systems,” IEEE Transactions on Industrial Electronics, Vol.58, Iss.12, 2011.
[18]      L. Zhou, F. Gao, G. Shen, T. Xu, W. Wang “Low Leakage Current Transformerless Three-Phase Photovoltaic Inverter,” 2016 IEEE Energy Conversion Congress and Exposition (ECCE), 2016
[19]       X. Guo, “Three-Phase CH7 Inverter with A New Space Vector Modulation to Reduce Leakage Current for Transformerless Photovoltaic Systems,”  IEEE Journal of Emerging and Selected Topics in Power Electronics Vol. 5, Issue: 2, 2017 
[20]      X. Gue, R. He, X. Sun, J. Gurrero “Leakage Current Elimination of Four- Leg Inverter for Transformerless Three-Phase PV Systems,” IEEE Transactions on Power Electronics Vol. 31, Iss. 3, 2016.
[21]      N. Noroozi, M. yaghubi, M. zolghadri; "A modulation method for leakage current reduction in a three-phase grid-tie quasi-Z-source ";IEEE Transactions on Industrial Electronics, 4 september 2018.
[22]      محمدرضا علیزاده پهلوانی، حمید ابراهیمی و حامد حیدری دوست آباد، " طراحی مشاهده‌گر نوین جریان خروجی UPS در سیستم کنترل پیش‌بین براساس مدل فضای حالت"، مجله مهندسی برق دانشگاه تبریز، جلد 47، شماره 4، زمستان 96.
[23]      محسن دارابیان و ابوالفضل جلیلوند " کنترل پیش‌بین با روی‌کرد میرایی نوسانات سیستم قدرت در حضور مزارع بادی با استفاده از سیستم ذخیره‌ساز انرژی ابرخازنی و SSSC" مجله مهندسی برق دانشگاه تبریز، جلد 46، شماره 2، تابستان 95.
[24]      M. Calais, and V. Agelidis; "Multilevel converters for single-phase grid connected photovoltaic systems, an overview"; in IEEE - International Symposium on Industrial Electronics, 7-10 Jul. 1998.
[25]      J. Rodr´ıguez, J. Pontt, C. Silva et al. “Predictive current control of a voltage source inverter”, IEEE Transactions on Industrial Electronics, vol. 54, no. 1, February 2007.
[26]      P. Cortes, J. Rodriguez, C. Silva, and A. Flores, “Delay compensation in model predictive current control of a three-phase inverter,” IEEE Trans. Ind. Electron., vol. 59, no. 2, Feb. 2012.
[27]      S.Kwak, S. Mun, “ Model predictive control methods to reduce common-mode voltage for three-phase voltage source inverters” IEEE Transactions on Power Electronics, Vol.30, No. 9, 2015
[28]      J. Baek, S. Kwak, T. Kim, “A Generalized Predictive Current Control Method based on Two Vectors for Three-Phase Voltage Source Inverters,” 2015 17th European Conference on Power Electronics and Applications (EPE'15 ECCE-Europe), 2015
[29]      S. Kwak, S. E. Kim, J. C.Park. “Predictive Current Control Methods with Reduced Current Errors and Ripples for Single-Phase Voltage Source Inverters,” IEEE Transactions on Industrial Informatics, Vol. 11, Iss. 5, October 2015.
[30]      J. Baek, S.E. Kim. “Predictive Control Method for Load Current of Single-Phase Voltage Source Inverters,” 2015 IEEE Applied Power Electronics Conference and Exposition (APEC), 2015.
TABRIZ JOURNAL OF ELECTRICAL ENGINEERING
Volume 50, Issue 4 - Serial Number 94
March 2021
Pages 1819-1832

Files

Share

How to cite

Statistics