Migration Strategies

One of the effects of the evolution in technology and utility philosophy is that migration will be a natural phenomena over the life time of substations. System wide replacement programs for protection and control equipment will become necessary and will require many different migration solutions based on local situations. The first step in such a process should be the definition of the possible use cases as well as application of a common base of references for functionality on all levels and one of the goals of migration should be to limit the impact of the migration of substation systems on the network level.

In some cases fast migration strategies are possible for smaller substations by accepting constraint operation conditions. However the issue that remains when replacing many systems per year is to preserve a high quality on the protection and automation systems. This requires that one has to optimize the engineering, the FAT, the SAT, uptime, maintenance, etc.

A major step forward would be if new systems would be "maintenance free" so that we can concentrate on replacement instead of on maintenance of newly installed systems.
The use of standardized communication protocols such as IEC 61850 will result in a decrease in the need for gateways and protocol converters and should make migration easier. However for applications that require gateways, standardized mappings will be needed to support interoperability and engineering efforts. Since IEC 61850 is currently limited to the substation environment existing protocols will continued to be applied via suitable gateways.

For the reduction of engineering costs, versatile tools are required which support continuous engineering of pure IEC 61850 communication systems as well as legacy systems. But it is clear that tools which base on an object oriented concept are superior to signal oriented tools.

When discussing migration an important aspect are the financial consequences of the migration path. Current cost/benefit results for IEC 61850 based substation automation systems show that savings are already realized by the elimination of gateways. Future savings are expected through:

• optimization of architectures and number of IEDs
• the use of GOOSE to replace hardwired connections
• the use and re-use of SCL based engineering for new substations and migration. This has to be supported however by the right set of tools.
• Process bus applications eliminating high voltage equipment and hardwired connections