919 / 2019-04-30 16:45:13

Research on Auto-routing technology over Smart Substation Network

iec61850, SCD, auto-routing, GOOSE/SV path, IED-learning

Availability is still a tough job for IEC61850 based smart substation network, although the protocol has been put in use for nearly 10 years in China, the complicated network configuration and opaque data transmission are still the most obstacle. Auto-routing technology based on SCD file provided in this paper gives a flexible way to configure and manage the substation network, offering a plug-and-play capability for IEDs that need to access the substation network. The principle of combining the outcome of network topology discovery and IED-learning to build MAC/VLAN forwarding table to implement the auto-routing is described, and the characteristics compared with other existing substation network technologies and solutions. On the top of the auto-routing, there are useful and gettable data that could be collected to support visible supervision to facilitate the substation operation and management.
I. APPLICATION STATUS OF IEC61850
The survey results of IEC61850 application utilization situations were surprising. In Europe and US, IEC61850 is normally found solely in the lab research and rarely found in practical applications. It is mostly used as a fitness version applied in station bus and, most notably, barely involved with SV and GOOSE messages. Approximately 65% questions are focused on the integration of IEC61850, and yet, the EPC engineering mode masks more difficulties. The founders of IEC61850 protocol were astonished by the expanded IEC 61850 utilization scale in China. They had not anticipated the broader use of the applications. When the standards were revised to the second version, the scope was expanded to encompass power utility automation in addition to the substation only. Any Proposals which could promote additional solutions utilizing the IEC 61850 application, or expand its application field are greatly appreciated and very welcomed.
II. PROBLEM FACED IN SUBSTATION NETWORK
Using substation network technology to replace legacy cable wiring is a sharp turn for traditional power industry. While it's the right path that transiting toward network based information exchange on the substation network. But there are outstanding technical and practical issues exist:
1) Substation network configuration issues
In field practices, Goose/SV path setup has never been a one-time job. There are two variables whose changes could trigger network re-configuration process: SCD update and network topology change. An efficient network configuration method is so fundamental that it stays along with the life cycle of a substation.
2) Substation network testing & troubleshooting issues
For standalone IED functionality test, network can sometime been taken out of the scope. A simulator that generates Goose/SV packets can be directly connected to the IED under testing, nothing in the middle. However, any system level functionality test that involved multiple IEDs has to be conducted in a networked environment, no matter in the factory or in the field. In a networked environment, many things can goes wrong easily. Goose duplication, A/B accidently connected, loop, excessive packet lost due to poor bandwidth allocation, etc. It's obviously certain level supports provide by network infrastructure will help efficient system level testing.
III. AUTO-ROUTING BASED ON SCD FILE
Substation network auto-routing provides a way to dynamically build GOOSE/SV path according to GOOSE/SV associations extracted from SCD file, together with the substation physical network topology that auto-obtained from the outcome of network topology discovery and IED learning. VLAN/MAC table was generated automatically to forward the GOOSE/SV messages packets.
IV. AVAILABLE TECNICHAL COMPARISON
SV/GOOSE messages stay in L2 multicast domain, if without control strategies, the SV/GOOSE traffic will be forwarded to every available egress port in the whole substation network. So if all IEDs in network are on a single multicast domain, the traffic on each switch port may far beyond the port forwarding capability. Currently the main solution is VLAN, GMRP, and L2 multicast address filtering.
V. CONCLUSIOIN
Substation network auto-routing is aimed to demonstrate a user friendly, plug & play substation network that supports easy supervision and visualization to speed up the applications of IEC61850. How to use auto-routing network based on Substation Configuration Description file is also guided.