CIM Issues #6342
Updated by Pat Brown 11 months ago
The population of attributes related to transformer windings, and of Currently, the related attributes of classes representing loads and distributed generation, posed ongoing challenges during GMDM test model creation. The power that ‘comes out of’ the low-side transformer end(s) – which is what load and/or distributed generation is connected CIM has 2 main (and largely redundant) approaches to - can have designating phasing that is not the same as what ‘goes into’ the high-side transformer end – which is what higher voltage ConductingEquipment (with xxxPhases) is connected to. There appear to be at least 2 requirements the description of low-side load/generation phasing needs to support: an accurate electrical representation for power flow (where characteristics of unbalanced models. One uses the feeding transformer are taken into account) and a ‘short hand’ that identifies the effect of high-side phase outages on low-side load/generation. A suggestion was made to add a .primaryPhase Terminal.phases attribute on the EnergyConsumerPhase and PowerElectronicsConnectionPhase classes. Further exploration is needed. Another area of difficulty related to the accurate description of phasing on load and distributed generation using the existing class attributes. The EnergyConsumer and EnergyConsumerPhase classes represent load and have the following phasing-related attributes: - EnergyConsumer.grounded (true/false) - EnergyConsumer.phaseConnection (with a datatype of PhaseShuntConnectionKind PhaseCode with 25+ possible values representing various combinations of D, Y, Yn, I phases and G) - EnergyConsumerPhase.phase neutral). The other approach relies on xxxPhase classes which are associated with many (but not all) of the ConductingEquipment child classes. xxxPhase classes typically have a .phase attribute (with a datatype of SinglePhaseKind with which has possible values of A, B, C, N, s1, s2) The PowerElectronicsConnection and PowerElectronicsConnectionPhase s2). Unbalanced impedance modeling relies on information in classes represent load and distributed generation and have the following phasing-related attributes: - PowerElectronicsConnection.ratedU - PowerElectronicsConnectionPhase.phase (datatype of SinglePhaseKind) Shortcomings/challenges identified during GMDM IOP modeling effort included: - For load modeling, the inability related to explicitly represent 240 load made up of s1 ConductingEquipment (the ACLineSegmentPhase class and s2. Expanding the list of enumerated values of the SinglePhaseKind datatype was suggested as possible solution, as was replacing the EnergyConsumerPhases.phase and PowerElectronicsConnectionPhase.phase attributes with .orderedPhases attributes (datatype OrderedPhaseCodeKind with 50+ possible values). (The TransformerTankEnd.orderedPhases attribute uses OrderedPhaseCodeKind.) - Difficulty in determining the appropriate values of EnergyConsumer.phaseConnection (datatype PhaseShuntConnectionKind with possible values of D, Y, Yn, I, G) and EnergyConsumer.grounded to accurately characterize the load while also aligning with TransformerEndInfo.connectionKind (datatype WindingConnection with possible values TransformerTank class), not on D, Y, Z,Yb, Zn, A and I) and TransformerEnd.grounded. Terminal.phase. The notes (description) of the .grounded attributes in UML require review as well. - The lack of PowerElectronicsConnection.phaseConnection GMDM profiles did not use Terminal.phases and PowerElectronicsConnection.grounded attributes which are present on the EnergyConsumer class. There seemed to be a consensus PNNL has indicated that they should be added. - Disagreement relative to the value that should be assigned to .ratedU have not found a need for Terminal.phases. Preliminary WG13 discussions on 2021-11-03 uncovered a single-phase inverter (0.12 vs 0.24) object (instance of PowerElectronicsConnection class). transmission use case or two where phase designations were useful in balanced modeling. Consider if Terminal.phases could be deprecated.