OMICRON Magazine

Magazine | Issue 2 2020 Traveling wave protection relays and fault locators have significant advantages when it comes to the tripping speed and precision of fault location in transmission lines. They improve both safety and system stability, while effectively protecting assets from damage. One of the challenges of using this new technology is that the existing solutions for testing are time-consuming, complex and incomplete. Our CMC TWX1 accessory of- fers you a field-tested, user-friendly and highly precise solution for testing traveling wave protection relays. Protecting assets at the speed of light Even though it’s been almost 90 years since traveling waves were first described, using them in protection technology for tripping and fault location hasn’t been feasible until recently. Traveling waves are of great interest to those in the asset protection field, because they propagate around the speed of light, and they’re the first fault indicators to arrive in the protection system. The latest protection relays and fault locators operate in the time domain. By detecting and time stamping the traveling waves that arrive in each terminal and employing peer to peer communication, these devices are able to make tripping decisions and fault location calculations with unprecedented speed and precision. The arrival time of a traveling wave is not useful unless it is measured with nanosecond precision, therefore a testing solution that is going to be viable needs to have a similar level of accuracy. In order to test these traveling wave relays under real world conditions and put them through their paces, Salt River Project, an agency from the state of Arizona that serves as an electrical utility for the Phoenix metropolitan area, started a pilot project and partnered with OMICRON for testing. Site selection and preparation The site for the pilot trial was chosen based on two requirements. First, it needed to have a high level of probability for all of the operations that would take place during the trial period and second, a direct fiber connection (which is necessary for differential protection relays working in the time domain) had to be available. In order to deploy and evaluate the new technology Salt River Project selected the 8.49 mile (13.66 km) overhead 69 kV sub-transmission line between the Dinosaur and Micromill One substations southeast of Phoenix, AZ. Aside from an existing optical ground wire (OPWG), the line experiences persistent wild- life activity and the lack of surrounding structures increases its exposure to seasonal thunderstorms. The traveling wave relays are installed in parallel with standard phasor protection, which allows them Traveling waves are of great interest to those in the asset protection field, because they propagate around the speed of light, and they’re the first fault indicators to arrive in the protection system. Anthony J Sivesind, Senior Principal Engineer, Salt River Project 7