Impact of distributed generation on the electric protection system

Abstract

This document provides a study of the impact of distributed generation (particularly Solar and wind energy) on the electric protection system. Due to energy poverty, most countries globally have been opened up to use of DG such as wind and solar powered generators, South Africa being one of them. There has been a prediction of the exhaustion of fossil fuels in the past decades, leaving economies with the need to find sustainable energy options. The contribution of fossil fuels to greenhouse gases has also been a global concern. This has increased the use of DG for sustainable energy systems as well as to curb the level of carbon emissions. While DG may increase energy sustainability, they have various impacts on the electric grid. It is uncertain how DG may affect the protection system of the power grid henceforth the thesis analyses the impact of DG on the electric protection. A comprehensive literature review is carried out on distributed generation and electrical protection. DigSilent PowerFactory software is used to simulate a network pre-and post-connection of the DG according to the South African grid code requirements to reflect the power flow and fault levels. Furthermore, the software is used to populate protection devices for the system. The results include a DigSilent network diagram with simulation results, fault levels pre-and post-connection of the distributed generators and protection coordination of the Distance and Overcurrent Relays.