Application integration at electric utilities – System interfaces for distribution management – Part 13: CIM RDF Model exchange format for distribution
|Publication Date:||1 June 2008|
|ICS Code (Telecontrol. Telemetering):||33.200|
This part of IEC 61968 specifies the format and rules for exchanging modeling information based upon the CIM (Common Information Model) and related to distribution network data.
The intention of this part of IEC 61968 is to allow the exchange of instance data in bulk. Thus, the imported network model data should be sufficient to allow performing network connectivity analysis, including network tracing, outage analysis, load flow calculations, etc. This part could be used for synchronizing geographical information system databases with remote control system databases.
This part is closely linked to IEC 61970-452 Energy Management System Application Program Interface (EMS-API) CIM Network applications model exchange specification. Thus, this document has been written in order to reduce its maintenance. It describes only differences with IEC 61970-452. Nevertheless, as IEC 61970-452 is a future international standard, this part still has duplicate information with IEC 61970-452, in order to be more understandable.
It uses the CIM RDF1) Schema presented in IEC 61970-501 as the meta-model framework for constructing XML2) documents containing power system modeling information. The syntax of these documents is called CIM XML format. Model exchange by file transfer serves many useful purposes, specially when some applications need to have the complete network model defined. Though the format can be used for general CIM-based information exchange, in this part of IEC 61968, specific profiles (or subsets) of the CIM are identified in order to address particular exchange requirements.
Given the CIM RDF Schema described in IEC 61970-501, a DMS power system model can be converted for export as an XML document, see Figure 1. This document is referred to as a CIM XML document. All of the tags (resource descriptions) used in the CIM XML document are supplied by the CIM RDF schema. The resulting CIM XML model exchange document can be parsed and the information imported into a foreign system. This part of IEC 61968 is aligned to CIM Model version 11, CPSM 3.0 profile.
Similar to using any programming language, implementers have many choices when creating a CIM XML document. The RDF syntax itself can be used in several ways to achieve the same basic result. The way one approaches the CIM RDF Schema can yield various forms when producing a CIM XML document. The following clauses discuss the style guidelines for producing a CIM XML document. Such guideline rules are important to communicate and follow when producing these documents because they simplify and facilitate the software written to unambiguously interpret the model information.
Some comparisons have been made between CIM RDF and CIM XSD. Annexes A, B, C and D are extracted from articles and documents discussing CIM RDF and CIM XSD. A distribution management system can use only a CIM XSD message types architecture, but CIM RDF has three advantages:
• A UML model is a graph model and RDF helps to describe the graph model. XSD describes a hierarchical model which suits the message type approach.
• RDF is more readable and understandable by people working in the electrotechnical field.
• It is a basic requirement to build ontologies.
If required, tools would ensure the compatibility between CIM-RDF and, for instance, IEC 61968-4 and IEC 61968-3 message types concerning distribution network model representation.
1) RDF: Resource Description Framework.
2) XML: eXtensible Markup Language.