ABB’s new generation RED670, GPS-based, line differential protection IED (Intelligent Electronic Device) has just completed a successful nine-month site trial with National Grid on 400kV substation circuits in North Wales. The extended trial has enabled ABB to demonstrate the RED670’s capabilities in a realistic ‘in-service’ environment, without exposing the power system to undue risk, and it operated perfectly under all conditions, including correct operation following a lightning strike on the overhead line.
Following this successful site trial, ABB is now able to offer the IEC 61850 compliant RED670 as part of its bay solution for substation protection and automation systems based on National Grid's standardised NICAP (National scheme for Integrated Control And Protection) engineering philosophy and specification.
A PROTECTION AND CONTROL PRODUCT
The RED670 is part of ABB’s new generation IED670 series protection and automation products for transmission applications, developed to implement all aspects of the new IEC 61850 standard to ensure open, futureproof and flexible system architectures. It is designed for protection, monitoring and control of overhead lines and cables with up to five line terminals. The RED670’s phase segregated line differential protection enables reliable single/two/three pole tripping and auto-reclosing with synchronising and synchro-check. In addition, the RED670 is capable of handling transformer feeders and generator and transformer blocks.
Andy Osiecki, ABB’s Substation Automation Manager, explains the importance of the site trial, “ABB had, of course, carried out extensive laboratory testing with the RED670. But as far as the customer is concerned there is nothing like real-life experience to show how a system behaves when subjected to the electrical noise and RFI found at a working site. This trial enabled us to install RED670 devices in a threeended 400kV substation circuit between Trawsfyndd, Legacy and Deeside. They were connected alongside the existing protection systems where they were subjected to same working environment and fed the same live input data. The only difference from a fully live installation was that the RED670 devices didn’t perform any actual tripping. Instead, we monitored their outputs to check that they were analysing the data correctly and making the right decisions.”
As well as mimicking the behaviour of the existing site protection systems, the RED670 devices were subjected periodically to additional tests to monitor their stability under abnormal conditions. This involved planned route switching of the communications channels and simulation of the loss of the GPS signal, both individually and simultaneously. There were also times when the devices were subjected to unplanned communications interference, they performed appropriately under these circumstances and then even better when the problem was resolved.
LIGHTNING STRIKE
A stroke of luck with the weather put the RED670 to the ultimate test. Andy Osiecki continues:
“The RED670 devices performed very well under what were relatively normal operating conditions. However, near the end of the test programme there was a lightning strike that created a transient primary fault on the overhead line close to Trawsfyndd. This kind of event makes a lot of different things happen very quickly on a network, especially a large, sudden increase in current. I am pleased to report that the RED670 responded perfectly, providing exactly the right switching response.”
Andy Osiecki concludes: “Now that the RED670 has completed this onerous test programme we are able to utilise the device as part of our NICAP approach to substation protection and automation projects. It will feature on our current 275kV substation project at Stalybridge, as well as new NICAP projects at Greystones, Ratcliffe-on-Soar, Willington and Wilton.”