Removal of DC offset current from transformerless PV inverters connected to utility

Paper


Sharma, Ronald. 2005. "Removal of DC offset current from transformerless PV inverters connected to utility." 40th International Universities Power Engineering Conference (UPEC 2005). Cork, Ireland 07 - 09 Sep 2005
Paper/Presentation Title

Removal of DC offset current from transformerless PV inverters connected to utility

Presentation TypePaper
Authors
AuthorSharma, Ronald
Journal or Proceedings TitleProceedings of the 40th International Universities Power Engineering Conference (UPEC 2005)
Number of Pages5
Year2005
ISBN095024404X
Conference/Event40th International Universities Power Engineering Conference (UPEC 2005)
Event Details
40th International Universities Power Engineering Conference (UPEC 2005)
Event Date
07 to end of 09 Sep 2005
Event Location
Cork, Ireland
Abstract

Some electricity supply authorities in Australia allow PV inverters of up to 10 kW output to be directly connected to
their grid network. The benefits of avoiding the use of power transformers in such PV applications are higher
conversion efficiency of the PV system and lower costs. These benefits however, can only be realised if the level of DC offset current injected from such transformerless inverter systems is maintained within the stringent limits governed by Australian Standard AS4777.2. Currently, there is a lack of evidence that the level DC offset current can be economically and efficiently maintained within these legal limits. In this paper, it is shown that irrespective of its source, the DC offset current can be maintained within these limits without sacrificing the overall conversion efficiency of the inverter system. Simulation and experimental results are presented to confirm that this simple, cost effective technique can be used to measure and separate small magnitudes of DC offset currents from large values of AC currents without compromising the dynamic response of the current feedback loop. This new technique can also be used to improve the quality of the power supplied by PV inverters that use power transformers.

KeywordsPV inverters; transformerless; unipolar switched; DC offset current
ANZSRC Field of Research 2020401703. Energy generation, conversion and storage (excl. chemical and electrical)
400805. Electrical energy transmission, networks and systems
Public Notes

© 2005 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Byline AffiliationsDepartment of Electrical, Electronic and Computer Engineering
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