LAN Commissioning


The question "Does anyone know if there are guidelines or industry standard for commissioning substation LAN which focuses on Ethernet switches and possibly routers?" was asked on LinkedIn. My response was:

Yang, RFC2544 has a series of tests for benchmarking the performance of interconnect devices like Ethernet switches. The test protocols in there might be a good start for proving network performance. Any 61850-based substation FAT or SAT should be for the system, not just for the IEDs. Without Ethernet you don’t have a substation control/protection system. This testing could be system-level performance-based, making sure the inter-trips and controls work within the required time-frame and reliability. I like component testing, but this is more targeted at type testing or design testing. However, if the substation control functional specification has network performance requirements (latency, throughput etc) then this should be tested at the FAT and SAT too. IEC 61850-4 has the breakdown of what is done and when. FAT and SAT are described in section 7.3.6 and 7.3.7 respectively.

Hi Yang, thanks for the reminder about Y.1564. I had a nagging feeling there was another test spec out there. I haven’t seen Y.1564 used in substations, but that doesn’t mean it shouldn’t be considered. I think there is much the power industry can learn from Telecoms. I think a ping test is a very poor test. Firstly it only tests the IP/Management VLAN and not the others that might be in place. Secondly the performance metrics are coarse (millisec times). A more thorough test would include packet injection and capture to make sure frames are not lost at close to line limits. In addition low priority traffic should be injected (unicast and multicast) while protection timing (if GOOSE used for inter-trips) is conducted. Similarly, responsiveness to controls should be tested with some background traffic. My philosophy is that I want to take the system to breaking point and figure out the safety margin from there. If you don’t break it you don’t know how close to that point you are.

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