Backup Relay for 66kV Hub Substation Protection in the High Voltage Distribution Network

Chandigere, Tarisai (2018) Backup Relay for 66kV Hub Substation Protection in the High Voltage Distribution Network. [USQ Project]


This paper is addressing the bus zone protection as an integral part of providing continuity, security and safety of power supply. Bus zone protection shortfalls not addressed during engineering design and commissioning can be detrimental to the supply of power. Redundancy of bus differential schemes with different operating characteristics will be implemented with no addition to the primary infrastructure.

This paper will therefore look at:
• Understanding the concepts applied by relay elements to make a trip decision.
• The impact of settings on security and sensitivity.
• Testing the operating characteristics.

The project is vital in mitigating the material risks associated with lack of redundancy. The material risks are monetary losses and safety risks which could result in injury or loss of life and plant. Current numerical relays have backup protection schemes built within the relay which in this case would be directional overcurrent, but this falls short in that a failure of the relay will lead in loss of both protection schemes. Utilising relays from different manufacturers implies that the strength in one relay covers the weakness of the other relay.

The selection of quantitative methods gives required values for protection settings. Relevant applicable information was gathered through literature review of texts, manuals and research papers. CITECT, a SCADA software was used to get the loading and electrical parameters of the bus zone. These values were then used to perform calculations to determine protection settings for the new relay. As shown in Figure 1 the two relays have different operating characteristics. Simulation of different fault conditions is going to be conducted using the OEM software.

Applicable standards and cost of relay failure have been determined and collated into an opportunity framework. It has been ascertained that no primary equipment will be added. The challenge will be in designing redundancy to meet Australian Standards without changing the backbone infrastructure. After project completion a viable backup protection scheme for the bus zone should be available.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Mechanical and Electrical Engineering (1 Jul 2013 - 31 Dec 2021)
Supervisors: Wen, Paul
Qualification: Bachelor of Engineering (Honours) (Electrical and Electronics)
Date Deposited: 15 Sep 2021 06:00
Last Modified: 27 Jun 2023 04:31
Uncontrolled Keywords: Bus Zone; Differential Relay; Backup Protection; Low Impedance

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