Components

eDisGo represents a distribution grid as a set of typed components. This page lists the component types and points to where each is described in detail.

Grid components

The physical grid elements are stored as pandas.DataFrames in the Topology container — one frame per type (see The data model for how to access them):

Component	Data (in `edisgo.topology`)	Component object
Bus	`buses_df`	—
Line	`lines_df`	—
Transformer (MV/LV)	`transformers_df`	—
Transformer (HV/MV)	`transformers_hvmv_df`	—
Switch	`switches_df`	`Switch`
Generator	`generators_df`	`Generator`
Load (incl. heat pumps and charging points)	`loads_df`	`Load`
Storage unit	`storage_units_df`	`Storage`

To add, remove or integrate components, see Adding and modifying components.

Switches

What they are. A switch is a disconnecting point in the grid — above all the point where a ring is left open. Medium-voltage grids are built as rings (for redundancy / n-1) but operated radially, open at one point; the switch marks that open point. eDisGo so far only models switch disconnectors. They are held in switches_df, which is defined for the MV grid and its underlying LV grids; in the ding0 grids eDisGo uses they are the MV ring disconnectors, sitting at MV/LV stations.

How they are represented. A switch is a branch (a line in lines_df) with two candidate end buses and a state:

open (normal operation) — the branch is attached to a dedicated virtual bus bus_open, so the ring is broken and the grid is radial;
closed — the branch is attached to bus_closed instead, closing the ring.

switches_df therefore records, per switch, the branch it controls and the two candidate buses; opening or closing a switch just rewires that branch’s bus in lines_df.

What they are used for. Switches are not decorative — several parts of eDisGo depend on them:

The operating point of every power flow. Because the state is baked into lines_df, analyze() and the optimisation run on the current (normally radial) configuration. Closing a switch makes the grid meshed and changes the result.
Ring detection. rings finds the grid’s rings by temporarily closing all switches and looking for cycles — so it knows which buses form which ring.
Grid reinforcement. When reinforce() fixes MV voltage problems by splitting a feeder (Grid reinforcement), the feeder can only be split at an LV station, because that is where a switch disconnector can be operated to run the line as two half-rings. LV stations thus decide where MV line reinforcement can act, and the resulting half-ring structure feeds the voltage-level cost allocation (Grid-expansion costs).

Note

The feeder is split at the LV station and connected directly back to the MV station busbar; a switch disconnector is not yet inserted at the new split point (TODO in reinforce_lines_voltage_issues()), so the half-rings created by reinforcement are not switchable in the model.
Plotting. The MV topology plots mark the switch disconnectors.

Working with switches. Each switch is a Switch object:

# all switches, and the switch disconnectors of the MV grid
edisgo.topology.switches_df
list(edisgo.topology.mv_grid.switch_disconnectors)   # Switch objects

sw = next(edisgo.topology.mv_grid.switch_disconnectors)
sw.state          # "open" or "closed"
sw.branch         # the line in lines_df that represents the switch
sw.bus_open, sw.bus_closed
sw.close()        # close the ring (rewires sw.branch in lines_df)
sw.open()         # re-open it

Switches are imported from the ding0 switches.csv file, carried over through spatial_complexity_reduction() (buses and branches are remapped; switches that become unused or duplicated by the aggregation are dropped/merged), and — being expressed as ordinary branches — carried into the PyPSA network by to_pypsa() without any special switch element (see Relationship to the PyPSA format).

Flexibility components

Some loads and storage units can act as flexibilities. Their additional data lives in dedicated containers; the modelling is described in Flexibility & optimisation:

Flexibility	Container	Methodology
Electric vehicles (charging points)	`Electromobility`	Electromobility
Heat pumps (+ thermal storage)	`HeatPump`	Heat pumps
Demand side management	`DSM`	Demand side management
Battery / home storage	`topology.storage_units_df`	Battery storage
Overlying-grid requirements	`OverlyingGrid`	Overlying-grid requirements