Earthing Systems and Earth Fault Protection in Power System Distribution Network

Narayan, Sanjay (2019) Earthing Systems and Earth Fault Protection in Power System Distribution Network. [USQ Project]

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Abstract

Ergon Energy and Energex Limited are both subsidiary companies of Energy Queensland and have the responsibility to provide safe and affordable electricity to customers in Queensland. In maintaining a safe distribution power network, earthing and power system protection plays a vital role. This research project performs analysis on different earthing systems and various forms of earth fault protection utilised in distribution power network to improve the detection of high impedance earth faults.

Earth faults are not only by far the most frequent of all faults, but the fault currents may be limited in magnitude by the neutral earthing impedance, or by the earth contact resistance which makes detection challenging for conventional protection schemes. Currently, normal earth fault protection together with sensitive earth fault protection has been employed in both distribution networks to detect and clear earth faults. There have been incidences where earth fault detection has been extremely challenging as fault values drop significantly and the protective device does not have sensitivity to detect and isolate the faulty equipment.

In Energy Queensland’s distribution power network, the neutral of supply transformers at zone substations are either solidly or impedance earth in order to provide a path for earth fault current to flow and allow subsequent operation of protective device. As part of this research project, analysis was carried out on the different forms of earthing systems currently utilised and its implications on earth fault protection. Earth faults were simulated on 11kV feeder model in DigSilent Power Factory Software package. Test cases were developed for earth fault scenarios and the results for each of the different simulated scenarios were recorded and have been discussed in results discussion.

This research project led to the identification of alternate earthing systems and improved earth fault detection capabilities in protective devices. Rapid Earth Fault Current Limiters as an alternate form of earthing / earth fault protection has been identified as part of this research study which may be utilised in Energy Queensland’s distribution power network to enhance earth fault detection capabilities. Rapid Earth Fault Current Limiters performance in-terms of detection of current and speed of operation in comparison to existing traditional earth fault protection schemes and protection relay. Further work is required however in carrying out a detail feasibility study in the application of Rapid Earth Fault Current Limiters in energy Queensland’s network.


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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Engineering (Honours)(Power)
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Mechanical and Electrical Engineering (1 Jul 2013 -)
Faculty/School / Institute/Centre: Current - Faculty of Health, Engineering and Sciences - School of Mechanical and Electrical Engineering (1 Jul 2013 -)
Supervisors: Hewitt, Andrew; Quinton, Matthew
Date Deposited: 16 Aug 2021 05:05
Last Modified: 16 Aug 2021 05:05
URI: http://eprints.usq.edu.au/id/eprint/43125

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