Approach to low-cost prevention of DC injection in transformerless grid connected inverters

With the growing popularity of distributed generation, there are concerns over the effects that distributed generators may have on power quality. One highly important aspect often overlooked when considering power quality is DC current and the effects that it may have on distribution components. This study considers the problems associated with DC current injection into the electricity distribution network from transformerless grid connected inverters. A new method of preventing differential mode DC injection from transformerless inverters is proposed which eliminates the need for a bulky and costly isolation transformer. This technique is experimentally validated and its benefits regarding DC injection reduction are shown.

[1]  Andres Barrado,et al.  DC current injection into the network from PV inverters of <5 kW for low-voltage small grid-connected PV systems , 2007 .

[2]  Vassilios G. Agelidis,et al.  A cascaded inverter for transformerless single-phase grid-connected photovoltaic systems , 1999 .

[3]  Edward D. Spooner,et al.  Review of international standards for grid connected photovoltaic systems , 2001 .

[4]  C.M. Johnson,et al.  Auto-Calibrating DC Link Current Sensing Technique for Transformerless, Grid Connected, H-Bridge Inverter Systems , 2006, IEEE Transactions on Power Electronics.

[5]  Tzung-Lin Lee,et al.  A transformerless interface converter for a distributed generation system , 2008, 2008 13th International Power Electronics and Motion Control Conference.

[6]  P. J. Aylott.  Stray current is for life-not just for Christmas. Stray current corrosion management strategies for DC traction systems , 1999 .

[7]  Pablo Sanchis,et al.  High-Efficiency Transformerless Single-phase Photovoltaic Inverter , 2006, 2006 12th International Power Electronics and Motion Control Conference.

[8]  Roberto González,et al.  Transformerless Single-Phase Multilevel-Based Photovoltaic Inverter , 2008, IEEE Transactions on Industrial Electronics.

[9]  T.G. Habetler,et al.  An on-line stator winding resistance estimation technique for temperature monitoring of line-connected induction machines , 2001, Conference Record of the 2001 IEEE Industry Applications Conference. 36th IAS Annual Meeting (Cat. No.01CH37248).

[10]  Pablo Sanchis,et al.  Ground currents in single-phase transformerless photovoltaic systems , 2007 .

[11]  K. W. Lim,et al.  Evaluation of an EMF injection scheme for a permanent magnet brushless DC drive , 1992, [1992] Proceedings of the IEEE International Symposium on Industrial Electronics.