Network

A "network" is a directed graph consisting of a set of elementary object types called nodes, branches, and externals that are connected to one another. A network may contain other types of auxiliary objects that are subsets of or represent relations between the elementary object types. A network contains a description of all geometric, topological, relational, and static properties of all the "Objects". These objects typically do not change during the execution of a scenario (e.g., diameter or length of a pipeline).

The information of a network is saved to a file with the file extension *.*net (e.g., *.enet for electric network, *.gnet for gas network, and *.tnet for thermal network).

A hub network is a special type of network that only contains hubs which link objects from different network types to each other (e.g., a gas-fired electricity generator which is represented as a generator in an electric network and a demand in a related gas network). It is saved to a file with the file extension *.hubs.

1. Network sub-division

A network object is a unique entity, element, or instance of a network model. A network object is the parent of all the objects of the corresponding energy carrier. Every network object has the following child objects: zones, subs, groups, nodes, branches and externals. The hierarchical structure is described in the "Objects" section.

Subs, zones, groups, and nodes are also referred to as container because they can contain or reference subsets of other elementary object types.

1.1. Sub

A "sub" (also referred to as sub-network, subnet, or subsystem) is a subset of nodes, branches, and externals of a network. A sub is branch-oriented, i.e., only branches can be assigned to a sub, and every branch can belong to only one sub. The FromNode and ToNode of a branch, and the externals connected to those two nodes, are implicitly added to the sub. Nodes connected to branches of different sub-networks, and the externals connected to these nodes, are included in multiple sub-networks.

1.2. Zone

A "zone" is a subset of nodes, branches, and externals of a network. A zone is node-oriented, i.e., only nodes can be assigned to a zone, and every node can belong to only one zone. Branches with a FromNode and ToNode belonging to the same zone are implicitly added to the corresponding zone. Branches with a FromNode and ToNode belonging to two different zones do not belong to any zone. Externals are also implicitly added to the zone of the node they are connected to.

1.3. Group

A "group" is a subset of any child object types (e.g., nodes, branches, externals, fuels, ancillary services, LNG terminals, etc.) of a network. In contrast to subs and zones, groups do not follow any specific assignment rules and are fully customizable by the user. Any child object can be assigned to any number of groups.

Subs, zones, and groups are useful for visualizing aggregated results.

2. Network files

The "network" is composed by a network file (*.enet, *.gnet, *.tnet) and some additional files for the visualization of the network in the Map window.

The *.*net file collects the technical details covering:

network’s properties like the compressibility equation factor or the friction factor equation;
objects' properties by object type, like different types of branches or externals;
other network-specific objects like gas qualities, fuel types or wind turbine power curves;
topological details of the connections between objects;
geometric and geographic details on coordinates, position and length.

The additional files are:

Polygon File: The polygon file (*.plg) contains coordinates of polygons, which may represent national, regional or user-specified boundaries, drawn in the network’s background of the map window.
Map File: The map file (*.*MAP) contains the graphical details of all the objects, like color or line stroke, and the project, network or objects labels. The map file depends on the type of network and the full extension is *.EMAP for electric systems, *.GMAP for gas systems, and *.TMAP for thermal systems.

Releases prior to 3.4 used to have a dedicated file for the vertices of polylines (the vertex file *.vtc) and a dedicated file for labels (the label file *.lbl).

Those files will be imported when migrating a model from previous releases but are not necessary with version 3.4 or newer.