XML schemas and documentation
The Network File
The network file is an XML file (with suffix ".net"), which has to comply with the specification from the XML schema Gas.xsd (see below for a download). Here, the topology of the network as well as technical bounds on flows, pressures, etc., are specified. Every network element is given a unique ID. An exemplary network file for the GasLib-582 together with the corresponding XML schema definition can be found here.
The Compressor Station File
The files with the suffix ".cs" describe all compressor stations of the network. Within these files, every compressor station that is used in the corresponding .net file has to be specified. The .cs files have to comply with the XML schema CompressorStations.xsd (see below). The definition of a compressor station includes the technical description of the contained compressor units and drives as well as the list of all possible configuration of these machines. An exemplary .cs file for the GasLib-582 network can be found here.
The Nomination File
All XML files ending with suffix ".scn" are nomination specifications. They have to comply with the XML schema in Scenario.xsd. A nomination file has to specify the supply and demand as well as bounds for the supplied or withdrawn gas pressure for every entry and exit that is used in the corresponding network file (.net). The supplied or withdrawn flow can be given in power or flow. Fixed values can be realized by identical lower and upper bounds. A collection of exemplary nomination files for the GasLib-582 network can be found here.
The Combined Decisions File
A so called combined decisions file (.cdf) can be provided. These files have to comply with the XML schema CombinedDecisions.xsd. A .cdf file defines sets of controllable network elements (decision groups) and specifies a list of possible controls of these groups. In addition, every network element is only allowed to be part of at most one group. For a feasible network control, every decision group has to fulfill exactly one of the controls in the corresponding list. An exemplary file for the GasLib-582 network can be found here.
Other XML Schemas
Besides the four discussed XML schemas there exist three additional ones: PhysicalValues.xsd, Topology.xsd and Framework.xsd. None of these schemas define a complete data format. Instead, they define base types that support the definitions of the four main schemas. For instance, Topology.xsd demands that every edge of a gas network has a start and end node. This is then used to specify that every compressor station, pipe, etc., has a start and end node by inheriting from the base types in Topology.xsd. This hierarchical approach allows for a better structure of the data formats, reduced error-proneness, and a shorter specification.