CIM Issues #6202
Modeling guide is missing instructions for data type names in attribute names
CIM Modeling Guide
Description
In a previous version of CIM, the UML was cleaned up to change all properties like "ratedkV" and "ratedVoltage" to be renamed to "ratedU" based on the policy that the data type abbreviations should be used instead of data type names or units of measurement.
However, this naming rule is missing in section "5.5 Attribute Rules" in the CIM Modeling Guide v1.1 (2021-02-13).
Decision
Reviewed on 12-Jun-2023 in Oslo:
Reviewed and universally agreed that this should be added to the CIM Modelling Guide document. It should be spelled out explicitly in the guide which values this should adhere to and what the required value should be. The below is what was decided should be added as a rule to the section:
Active Power (p)
Reactive Power (q)
Apparent Power (s)
Resistance (r)
Reactance (x)
Conductance (g)
Susceptance (b)
Power Factor (pf)
Participation Factor (participationFactor)
IMPORTANT: the rule should state that camel case is to be used. So an attribute would be just "x" and not "X" but ratedX if using camel case.
While there is agreement on the attributes with units listed above, the universal use of (U) for voltage needs further exploration.(e.g. voltage should voltage be using "U" e.g. not ratedkV or ratedVotage, but rather ratedU). It would be good to identify the voltage attributes to see if there are obvious attributes that should be cleaned up.
Additionally, the rule should include:
When expressing sequencing specifically for Reactance (x), Resistance (r), Susceptance (b) and Conductance (g) the following abbreviations are to be applied:
positive -> expressed as shown above as x, r, b, g
zero sequence -> express as x0, r0, b0, g0
negative sequence -> express as x2, r2, b2, g2
NOTE: As part of this task the UML should be updated so that wherever the existing model expresses or abbreviates "Participation Factor" today as PF it should be changed to fully spell the attribute out (i.e. participationFactor). This will remove any ambiguity that will exist. Also we have 2 instances in the UML today where we have negative sequencing expressed as RN and XN and should be changed to r2 and x2 (this would be a breaking change). Given that CIM18 has a lot of breaking changes it is recommended this goes in at the same time (before September 2023).
Question remains as to who to assign the modeling guide updates to.
Modeling should be done by respective modeling managers where applicable.
11-Oct-2023:
We have reviewed and updated the comments above today to clarify further.
26-Oct-2023 Joint WG Hybrid meetings in Minneapolis:
Final decisions were made today after discussion. We have committed to the following:
* The CIM Modelling Guidelines document must be updated with a new rule for this.
* We have decide NOT to change existing attributes so as to minimize breaking changes.
* Instead, starting as of the CIM18 release, any new attributes created that fit into the types specified in this Issue (and correspondingly outlined in the new modelling rule) will be required to conform to the new naming rules.
Release Notes
Section 5.5 in the online CIM Modeling Guide has been updated with new rule Rule059.
For details refer to:
https://cim-mg.ucaiug.io/section5-cim-uml-modeling-rules-and-recommendations/#55-attribute-rules
The corresponding GitHub issue for the change can be found here: