Vision converter

The vision converter converts the excel exports of vision to PGM data. As mentioned in Converters, vision converter is an implementation of the tabular converter. The mapping of all attributes is stored in the vision_en.yaml and vision_nl.yaml files in config directory.

Load rate of elements

Certain elements in vision, ie. appliances like transformer loads and induction motor have a result parameter of load rate. In vision the load rate is calculated without considering the simultaneity factor of the connected node. So we may observe a variation in power inflow/outflow result (ie. P,Q and S) due to different simultaneity factors. But the load rate always corresponds to simultaneity of loads=1.

When we make conversion to PGM, the input data attributes of PGM for loads like p_specified and q_specified are modified as per simultaneity. The resulting loading then takes simultaneity into account. Hence, the loading of such elements may not correspond to the load rate obtained in vision

Transformer load modelling

power-grid-model-io converts the transformer load into a individual transformer and a load for usage in power-grid-model. In vision, the modelling of a transformer load seems to be different from an individual transformer and load. There is a minor difference in both in the reactive power consumed/generated. This can correspond to a minor voltage deviation too in the results.

Tip

It is recommended to split the transformer load into a individual components in vision beforehand to avoid this issue. This can be done by first selecting the transformer loads: (Start | Select | Object -> Element -> Check Transformer load, Ok) Then split it into individual components: (Start | Edit | Topological | Split)

Voltage angle of buses in symmetric power-flow

Note that vision does not include clock angles of transformer for symmetrical calculations in the result of voltage angles. power-grid-model however does consider them so a direct comparison of angle results needs to be done with this knowledge.

Modelling differences or unsupported attributes

Some components are yet to be modelled for conversions because they might not have a straightforward mapping in power-grid-model. Those are listed here.

  • power-grid-model currently does not support PV(Active Power-Voltage) bus and related corresponding features.

  • Currently, the efficiency type of PVs(Photovoltaics) element is also unsupported for all types except the 100% type.

  • The conversions for load behaviors of industry, residential, business are not yet modelled. The load behaviors usually do not create a significant difference in power-flow results for most grids when the voltage at bus is close to 1 p.u. Hence, the conversion of the mentioned load behaviors is approximated to be of Constant Power type for now.

  • The source bus in PGM is mapped with a source impedance. Sk"nom, R/X and Z0/Z1 are the attributes used in modelling source impedance. In vision, these attributes are used only for short circuit calculations

  • A minor difference in results is expected since Vision uses a power mismatch in p.u. as convergence criteria whereas power-grid-model uses voltage mismatch.