Development of an IEEE standard for integrated substation automation communication (P1525): specifications for substation applications and key communication performance drivers

The implementation of IEEE 1525 is focused on the use of MMS/Ethernet for the substation LAN. Given the probabilistic nature of the Ethernet, it is uncertain that even the most lenient clock synch requirement (±0.1 ms) can be met using an Ethernet LAN. If not, a separate timing wire or bus may be required. For the substation LAN, IEEE 1525 defines a number of additional performance requirements that are also application specific. This paper discusses: (1) test and evaluation of communication performance which must be based on a standard model; the requirement is to measure the time from the sending application to the receiving application; (2) high-speed LAN communication for relay-to-relay is the most stressing requirement; and (3) to match the present capabilities of sequence of event recorders which now time tag events to the nearest millisecond, highly accurate time synchronization of all IED clocks (to ±0.1 ms) will be required