Functional Naming Basics

Functional naming is a concept that enables the creation of a structured data model within an IED based on the functional hierarchy within a substation. This hierarchy consists of four elements: Function, SubFunction, EqFunction, and EqSubFunction. SubFunction is a child of Function or another SubFunction, while EqSubFunction is a child of EqFunction or another EqSubFunction.

Function elements are used to define functional structure for non-equipment process elements such as Substation, VoltageLevel, Bay, Line, and Process. EqFunction elements can be allocated to equipment elements such as PowerTransformer, ConductingEquipment, and GeneralEquipment.

This structured approach allows users to organize logical node references within the Substation section. For instance, to specify a distance protection within Bay 1 along with a general trip, one could directly reference Bay 1 as part of this hierarchy.

<Bay name="bay1">
    <LNode iedName="None" lnClass="PTRC" lnInst="1" lnType="somePTRCtype"/>
    <LNode iedName="None" prefix="Zone1" lnClass="PDIS" lnInst="1" lnType="somePDIStype"/>
    <LNode iedName="None" prefix="Zone2" lnClass="PDIS" lnInst="2" lnType="somePDIStype"/>
    <LNode iedName="None" prefix="Zone3" lnClass="PDIS" lnInst="3" lnType="somePDIStype"/>
    <LNode iedName="None" prefix="Zone4" lnClass="PDIS" lnInst="4" lnType="somePDIStype"/>
</Bay>

While referencing logical nodes directly within a bay is acceptable, readability may become an issue as the number of logical node references grows. An alternative approach to improve readability is to implement the distance protection as follows:

<Bay name="bay1">
    <Function name="DistanceProtection">
        <LNode iedName="None" lnClass="PTRC" lnInst="1" lnType="somePTRCtype"/>
        <SubFunction name="Zone1">
            <LNode iedName="None" lnClass="PDIS" lnInst="1" lnType="somePDIStype"/>
        </SubFunction>
        <SubFunction name="Zone2">
            <LNode iedName="None" lnClass="PDIS" lnInst="1" lnType="somePDIStype"/>
        </SubFunction>
        <SubFunction name="Zone3">
            <LNode iedName="None" lnClass="PDIS" lnInst="1" lnType="somePDIStype"/>
        </SubFunction>
        <SubFunction name="Zone4">
            <LNode iedName="None" lnClass="PDIS" lnInst="1" lnType="somePDIStype"/>
        </SubFunction>
    </Function>
</Bay>

An example illustrating the use of EqFunction could be as follows:

<ConductingEquipment name="QB1" type="DIS">
    <Function name="BubBarDisconnector">
        <SubFunction name="Disconnector">
            <LNode iedName="None" lnClass="XSWI" lnInst="1" lnType="someXSWItype"/>
        </SubFunction>
        <SubFunction name="Control">
            <LNode iedName="None" lnClass="CSWI" lnInst="1" lnType="someCSWItype"/>
        </SubFunction>
        <SubFunction name="Interlocking">
            <LNode iedName="None" lnClass="CILO" lnInst="1" lnType="someCILOtype"/>
        </SubFunction>
    </Function>
</ConductingEquipment>

Can you infer its purpose? Would you be able to do so if these elements had been directly referenced in the bay along with the distance protection?

Note: The logical device element (LDevice) in the IED serves a similar purpose to the function structure in the substation section. It is intended to organize logical nodes into groups. Consequently, the function structure can be transformed into logical devices. OpenSCD facilitates this transformation using Create SPECIFICATION IED.

Create function structure in OpenSCD Manipulate function type elements with OpenSCD