Research on earthing schemes in LV microgrids

For the access of green distributed generation(DG), LV microgrid is an important direction of development nowadays. Because the LV microgirds are in direct contact with users, so how to design its earthing scheme is the first thing to think about in order to guarantee personal safety and reliable operation of the equipments. Earthing schemes of LV mircrogrids are studied in the paper and how it works properly is presented. The principles of neutral earthing modes of microgrid is given according to standard IEC60364 and DGs neutral earthing mode is discussed under different operation modes. How the traditional protection modes of TN and TT are used in LV microgrids is studied. Considering the dispersion and variety of DGs and energy storage devices, combined earthing mode of TN and TT is proposed as a reasonable way for microgrids.