IEC TC 57 Reference Architecture For Power Systems Management And Associated Information Exchange

IEC TC 57 just published a new draft for IEC TR 62357-1 Ed. 2 “Power systems management and associated information exchange – Part 1: Reference architecture” (57/1621/DC)

“The new edition provides updates and defines layered Reference Architecture to help direct longer term goals and activities, specifically to ensure compatibility of all new standards developed in TC57 by benefitting from lessons learned during development of the current standards and their application on actual utility projects as well as through application of other internationally recognized architecture standards.

This edition reflects the progress recently achieved from the international Smart Grids (SG) initiatives and the CIGRE D2.24 large system architecture vision. It also leverage the work done by NIST-SGIP, CEN-CELELEC-ETSI SGCG M490, IEC TC8 Smart Grids Roadmap, and IEC TC8 WG5, WG6, The edition also reflects the most recent editions of the TC 57 standards including IEC 61850 Edition 2 and the IEC 61968, 61970, and 62325 Common Information Model (CIM) standards.”

One of the lessons learned is that the three information models (CIM, IEC 61850 and COSEM) need some additional harmonization – a reasonable level has already be reached.

IEC 61850 has a very broad application domain and has defined many useful information models that can (and will) be “tapped” by COSEM and CIM applications.

One example that shows that IEC 61850 can be used even for schedules (de: Fahrpläne):

These schedules can be mapped from COSEM directly to IEC 61840 logical node FSCH. COSEM may be used for flexible tariffs while IEC 61850 could be used for tariffs as well as for control of switchable equipment like circuit breakers or change settings for loads or generation. The schedule LN is applied in the VHPready 4.0 specification.

More to come soon.

IEC 61400-25 Part 2 and Part 3 CDV approved

The following two documents (CDV – Committee Drafts for Vote) have been accepted by 100 per cent of the Members of IEC TC 88 (in August resp. in September 2014):

Wind turbines – Part 25-2 (Edition 2): Communications for monitoring and control of wind power plants – Information models

Wind turbines - Part 25-3 (Edition 2): Communications for monitoring and control of wind power plants -Information exchange models

Both parts will be published as FDIS soon.

The Information Models are revised to make them consistent with the many other models defined in IEC 61850-7-x. For example in LN WTUR several names of DataObjects change:

SptDmdW to DmdWSpt
SptDmdVAr to DmdVArSpt
SptDmdPF to DmdPFSpt

The Edition 2 of the models is a major step towards harmonization of the information models. The wind power plant objects are now very stable – they are also incorporated into the UML master maintained by IEC TC 57 WG10, WG 17, WG 18, and JWG25 (TC57/TC88):

The changes proposed in conjunction of the CDV comments on part 25-2 have already been used for the UML model. Now we have a very stable and harmonized set of information models that can be used for the whole power delivery system – all over.

Additional models are under way, e.g., for condition monitoring (90-3).

Thanks to the UML team!

MultiSpeak – CIM Harmonization initiated at International Level

IEC TC 57 has published a new document (57/1437/CD - IEC 61968-14 TS Ed.1) trying to figure out the need for harmonization between the international standard series IEC 61968 (CIM) and MultiSpeak:

IEC 61968-14 TS:
Application integration at electric utilities
- System interfaces for distribution management - Part 14:
MultiSpeak - CIM harmonisation

Commenting period closes 2014-05-02

Please contact your national TC 57 mirror committee for a copy of the document.

I guess that more and more people all over realize the benefit of International Standards – good for utility customers. Here is an excerpt of the Introduction of the new document:

“Multiple standards that cover the same information domain present a problem for the vendor community when developing products, and for the customers that would use these products. The classic challenge becomes one of determining which standards to support or how best to support one or both standards. The problem for the customer is integrating products that follow different standards to work with each other.”

Fortunately the situation for IEC 61850 is quite different: Most of the definitions in the standard series are very unique … with little or no competition. That’s one of the reasons why the standard is liked all over.

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!