Power Grid

as Geographic Graph

Class for grid in planar graph format.

class mgrid.grid.geographic.GeoGrid(dg=None)

Bases: mgrid.graph.geographic.GeoGraph

Model multilayer graph in plane by contracting inter-edges.

Note

• There are two kinds of nodes, inter-nodes and planar nodes. If an inter-node is isolated in some layer, it cannot be recognised directly.

• It is assumed that every conversion element has a unique name.

inter_nodes

information on inter-nodes.

name	dtype	definition
name (index)	object	name in planar graph
upper	int64	connected upper layer
lower	int64	connected lower layer
element	object	transformer model

Type

DataFrame

layers

integer indices of all the layers.

Type

Set[int]

conversions

information on conversion elements.

name	dtype	definition
name (index)	object	name of conversion elements.
node	object	nodes to which elements are attached.
element	object	element models.
layer	int64	layers to which elements belong.

Type

DataFrame

df_layers

information on layers.

name	dtype	definition
idx (index)	int	integer indices of layers
name	object	layer names
voltage	float64	voltage levels

Type

DataFrame

nodelist

sorted nodelist containing layer information.

name	dtype	definition
node (index)	object	node name
idx	int64	layer to which node belongs
name	object	layer name
voltage	float64	voltage levels

Type

DataFrame

__init__(dg=None)

Init an empty directed graph or from existing directed graph.

Note

• All the edges are intra-edges, so they must be associated with some layer.

• It is essential to have the option for empty graph, or some built-in networkx function will not work. Don’t know why.

• Most inter-nodes can be detected. However, when one terminal of some inter-edge is isolated in that layer, the corresponding inter-node cannot be detected.

Parameters

dg (Optional[DiGraph]) – an existing directed graph. Default to be None.

add_conversion(name, node, element, layer=None)

Add a conversion element to the grid.

Note

Any conversion element is associated with a layer. If it is attached to a intra-node, then it inherent the node’s layer. If to a inter-node, layer should be specified.

Parameters

• name (str) – name of the conversion element.

• node (str) – name of the node to which the element is attached.

• element (Ejection) – model for the element.

• layer (Optional[str]) – layer to which the element belongs. If node is an intra-node, it is not necessary to specify it. When node is an inter-node and it is not specified, a warning will be echoed.

add_inter_node(name, element, upper=True)

Specify a planar node as an inter-node with an adjacent layer.

Sometimes, one terminal of an inter-edge is an isolated node in some layer, then it will not be recognised as an inter-node. It must be specified manually.

Warning

Upper layer has a smaller integer index.

Parameters

• name (str) – name of the inter-node.

• element (Union[Transformer, TransformerStd]) – the transformer model.

• upper (Optional[bool]) – whether the other terminal of the corresponding inter-edge is on upper layer.

as Supra Graph

Class for power grid as multilayer network in supra-graph format.

Any node in a supra graph is a bus, which is an imaginary concept to enforce Kirchhoff’s law. It can a conjunction of two cables or an entire nation. There is no power loss within any bus. When aggregating some area (like an entire country) as a bus, the loss within that area can be represented by a conversion element. However, it is impossible to derive the loss correctly.

Usually, in the literature, three types of buses, PQ, PV, and slack, are considered, but it is not necessary. Those features are resulted from attached conversion elements. There is only one type of node here.

class mgrid.grid.supra.SupraGrid(dg=None)

Bases: mgrid.graph.supra.SupraGraph

Power grid modelled as supra-graph.

Warning

Modification is impossible for now.

conversions

name	dtype	definition
name (index)	object	name of the element.
bus	object	buses to which the element is attached
element	object	model

Type

DataFrame

types

standard element types, keyed by type names.

Type

dict

buses

sorted list of buses.

name	dtype	definition
node (index)	object	node name
idx	int64	layer to which node belongs
layer_name	object	name of the layer
original	object	original node name

Type

DataFrame

__init__(dg=None)

Init an empty directed graph or existing directed graph.

Note

It is essential to have the option for empty graph, or some built-in networkx function will not work. Don’t know why.

Parameters

dg (Optional[DiGraph]) – an existing directed graph. Default to be None.