Every utility would love to have a set of protection standards, because standards can help utility to improve productivity and quality of engineering. After all, power system reliability can be improved with good standards. A set of protection standards include setting templates, drawings, guides, etc. A standard should be foolproof, meanwhile it needs flexibility to accommodate different applications. Modern IED relays can have thousands of settings and programmable logic to support various applications. Because of the complexity of IED relays and the applications, the development of standards is typically an evolving process. It takes years of operation experience and numerous lessons-learned to make a set of good protection standards. ElectraNET, an Australia utility has determined to develop a set of protection standards. Through a few previous projects that RTDS was used to verify protection settings, ElectraNET engineers realized the power of RTDS can help them to achieve the goal within a short period. They believe that the newly developed standards can be examined from all the angles by performing RTDS tests in the lab, without taking the risk of trial-and-error.
Two engineers spent three weeks in UNSW RTDS lab to check the transmission line protection standard package. Part of ElectraNET’s network was modeled on RTDS and a few selected relays were put in the test loop. A few line protection schemes were thoroughly checked by simulating all sorts of faults and operation conditions. RSCAD script and VBA/spreadsheet were used to organize the test cases including the planned ones and the on-the-fly cases. During the tests, not only flaws in the protection scheme and settings were identified, a couple of issues with specific relay design was also found. After this test, ElectraNET engineers gained full confidence with their line protection standards.
The experience of this project may provide some help to utility engineers that wish to develop and verify protection standards using RTDS. The RTDS test experience on other protection applications will also be touched in this presentation as well.
Mark Xue, FlexGrid Technologies; Yang Liu, ElectraNet Pty Ltd.