Friday, December 28, 2012

IEC 61400-25 is based on IEC 61850

During the year 2012 I have received more often the question about the relation between IEC 61400-25 and IEC 61850.

The most crucial issue in understanding IEC 61400-25 is this: The standard series IEC 61400-25 is based on the series IEC 61850 (mainly part 7-x, 8-1). A lot of definitions and basics defined in IEC 61850 are not repeated in IEC 61400-25. The part 6 (Configuration language) is not referenced in IEC 61400-25 at all and so on.

Could part IEC 61850-6 be used for IEC 61400-25? Yes, it could be used in almost all implementations of IEC 61400-25. Why? Because usually the implementation of the communication uses the mapping to MMS according to IEC 61850-8-1 which is referenced in IEC 61400-25-4.

To really understand IEC 61400-25, one needs to have a very good basic understanding of IEC 61850.

The standard IEC 61850 could be understood as extended IEC 61850 information models. There are a few special definitions in IEC 61400-25-2 which deviate partly from IEC 61850-7-3 and 7-4.

Example: LN WGEN – Generator

That model comprises among other data objects the objects for 3 phase currents and voltages for the stator and for the rotor:


The argument why the electrical measurements are contained in the LN WGEN is simple: The Generator generates voltages and currents … so these measurements are an integral part of the generator! Full stop. In IEC 68150 the modeling approach is to find the smallest parts of information to be exchanged by a function to be modeled.

The electrical measurements in IEC 61850-7-4 are contained in the LN MMXU. To indicate the use for the stator or rotor could be indicated by a prefix in the instance name: Sta_MMXU.A and Rtr_MMXU.A.


Note how the instance names are build (according to IEC 61850-7-2 Edition 2):

During the ongoing maintenance work on the first five parts of IEC 61400-25 it could be expected that the information models of IEC 61400-25-2 and IEC 61850-7-x will be harmonized as much as possible.

Note that the models may be different – there may be two model, but there is only one real world. The real world does not change depending on models! On the other side, models should be harmonized to a high degree … to prevent confusion. I have seen models implemented for a wind turbine that use MMXU instead of the models in WTUR.

The key issue is: different people and groups have different understanding of modeling!

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