Community Research and Development Information Service - CORDIS

FP5

MICROGRIDS Report Summary

Project ID: ENK5-CT-2002-00610
Funded under: FP5-EESD
Country: United Kingdom

Safety guidelines

A MicroGrid is subject to the same safety requirements as any other utility electric power system. The earthing system of a MicroGrid must be able to deal with both grid-connected and islanded operation.

An extensive literature review of the earthing systems and practices applied today in Low Voltage (LV) power systems worldwide was carried out. The objective of this work was to determine and describe the state of the art in LV grounding practices in various countries, in order to select the most appropriate earthing system/ combination of systems for a MicroGrid.

The main earthing systems, TN (TN-C, TN-S and TN-C-S), TT and IT have been analyzed, with respect to their performance and effectiveness, as well as to the specific protection and equipment requirements associated with their application.

According to this review, the most suitable earthing systems for a MicroGrid are identified as follows in the order of their suitability.
- TN-C-S
- TT
- IT

As per proposed protection guidelines, the MicroGrid would not lose the source earth at the distribution transformer in any event. Accordingly, the micro-sources do not require to be earthed.

At present, the performance of each of these earthing systems in a MicroGrid is investigated via simulation. UM are using the specialist grounding software tool CDEGS for this purpose while NTUA are using EMTP.

Related information

Reported by

University of Manchester
B9, Ferranti Building, PO Box 88
M60 1QD Manchester
United Kingdom
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