Thursday, April 4, 2013

IEC 61850 as a kind of template for Modbus based SunSpec Standard

The standard IEC 61850 has influenced other groups defining domain specific standards like IETF EMAN (Energy Management) and SunSpec Alliance. I have reported on the IETF EMAN group in March 2012. The SunSpec Alliance is new to me. So I browsed a bit their website and figured out that they have “copied” parts of the IEC 61850 information models, remodeled them and mapped them to Modbus registers.

Example: The electrical measurements from logical node MMXU (right) have been used by SunSpec (smdx_00101.xml) to some extent:


Unfortunately the names are slightly different! “PPV.phsAB” in IEC 61850 and “PPVphAB” in sunspec … I would have expected that the names (that carry the semantic) are the same! This would make the mapping between the two worlds much simpler --> reducing the costs …


Path could map to the following Modbus address (as an element inside the value … using the SystemCorp IEC 61850 stack/API):


The mapping of the IEC 61850 model to Modbus could be easily specified in the corresponding SCL file as Private Elements!! This could even be done automatically if the models (the names and semantic) in both standards would be equivalent!! Then a gateway device could offer both protocols (IEC 61850 and Modbus) running at the same time using a SINGLE specification file!

IMHO this is putting some soft pressure on IEC 61850 community! Why? Because why are the vendors implementing SunSpec not using IEC 61850 (the mother of SunSpec … to some extend)? One reason seems to be that it is not easy (and not for free) to get the models for PV applications. Another issue is that the implementations of IEC 61850 stacks/APIs are in some cases too expensive for these vendors.

Fortunately there is a solution available that provides a full set of services and support of any model specified in SCL notation: The SystemCorp Stack/API. There is a free of charge IEC 61850 DLL (for server and clients) available that runs for six months … enough time to evaluate the solution.

With the approach shown above we have implemented a device that is configured by SCL and that runs an IEC 61850 server AND an IEC 60870-5-104 slave at the same time (running on Beck IPC com.tom)!

Please come by at the booth 45/1 in Hall 13 at the Hannover Messe next week.

No comments: