Earthing System Design, Modelling and Evaluation of a Typical PV Plant of 1kV or Larger

Abstract

The work in this thesis presents a detailed study into the behaviour of an earthing system associated with a grid connected solar photovoltaic plant. A computer simulation model is developed and used for conducting experiments to investigate how a solar plant earthing system reacts to variations in plant con guration and other conditions associated with the plant. Also in eld measurements were conducted on an existing soar plant earthing system to verify the accuracy of the developed model. The key ndings of the study have shown that solar plants with an isolated or resonant earthed neutral point are in all practical cases safe under the worst possible fault scenarios. Also larger plants are inherently more safe than smaller plants. Furthermore the e ect on the earthing system of the length of the MV cables connecting the plant to the grid, the short circuit power of the grid and the phase angle of the grid have been investigated with the results showing minimal impact on the behaviour of the earthing system.