cim:ActivePowerPerFrequency.unit is wrong

[VladimirAlexiev]

See qudt/qudt-public-repo#970
cim:ActivePowerPerFrequency is used with only one prop:
cim:ExternalNetworkInjection.governorSCD "Power Frequency Bias. This is the change in power injection divided by the change in frequency and negated. A positive value of the power frequency bias provides additional power injection upon a drop in frequency."

So I've corrected the unit as follows:

delete {cim:ActivePowerPerFrequency.unit cims:isFixed "WPers"}
insert {cim:ActivePowerPerFrequency.unit cims:isFixed "WPerHz"}
where  {cim:ActivePowerPerFrequency.unit cims:isFixed "WPers"};

[Sveino]

If we make this change we would also need to update the EAP model. I know that this was discussed in TF13. I found the following issues:

• Handling unit multiplier needs joint WG concensus on approach
• There should be one for governorSCD

However, I see for GeneratingUnit we are using PerCent:

Inst4CIM-KG/source/CGMES/v3.0/RDFS2020/61970-600-2_Equipment-AP-Voc-RDFS2020_v3-0-0.rdf

Lines 4181 to 4187 in 8a1846e

	<rdf:Description rdf:about="#GeneratingUnit.governorSCD">
	<cims:stereotype rdf:resource="http://iec.ch/TC57/NonStandard/UML#attribute"/>
	<rdfs:label xml:lang="en">governorSCD</rdfs:label>
	<rdfs:domain rdf:resource="#GeneratingUnit"/>
	<cims:dataType rdf:resource="#PerCent"/>
	<cims:multiplicity rdf:resource="http://iec.ch/TC57/1999/rdf-schema-extensions-19990926#M:0..1" />
	<rdfs:comment rdf:datatype="http://www.w3.org/2001/XMLSchema#string">Governor Speed Changer Droop. This is the change in generator power output divided by the change in frequency normalized by the nominal power of the generator and the nominal frequency and expressed in percent and negated. A positive value of speed change droop provides additional generator output upon a drop in frequency.</rdfs:comment>

I assume that this is an error and we should update it as PerCent.

[VladimirAlexiev]

• GeneratingUnit.governorSCD "This is the change in generator power output divided by the change in frequency normalized by the nominal power of the generator and the nominal frequency and expressed in percent and negated."
• The other one is not normalized, so it seems the two qk's are intentionally different
• I think you should examine some actual values or ask this question in a CIM committee
• I added cim:UnitSymbol.WPerHz, but will delete it if you confirm that PerCent should be used

[griddigit-ci]

We will need CIM issue here I guess