Gaslib¶
GasLib [Sch17] is a library for instances of gas networks. Each network from GasLib includes various XML files such as a network XML file and a nomination XML file. The former contains the edge data, and the latter specifies the flow that is supplied or consumed for each network node. The gas network is modeled as a directed graph \(G = (V, E)\) where \(E\) consists of the active and passive edges. Active edges are compressor groups, valves, and control valves. Passive edges are comprised of pipes and resistors. For the gas networks, all edges are undirected, i.e., flow can traverse a pipe in both ways. Thus, \(x_e > 0\) indicates to a gas flow in the direction of the edge and \(x_e < 0\) against the specified direction.
The gas flow for a pipe \(e\) can be modeled with the Weymouth equations [Wey12]:
where \(p_v\) denotes the gas pressure for a node \(v\) and \(\beta_e\) is factor that models the resistance of \(e\) [Pfe15] [War21]. We only consider a network consisting of pipes, i.e., network elements such as compressors and valves are collapsed. The coefficient \(\beta_e\) can then be calculated using physical specifications such as length and diameter. See [Pfe15] for further details on this conversion.
References
- Pfe15(1,2)
Pfetsch ME, et al. (2015) “Validation of nominations in gas network optimization: models, methods, and solutions.” Optimization Methods and Software 30.1: 15-53.
- Sch17
Schmidt M, Aßmann D, Burlacu R, Humpola J, Joormann I, Kanelakis N, … & Sirvent M (2017). “Gaslib—A library of gas network instances.” Data, 2(4), 40.
- War21
Warode P (2021). Parametric Computation of Equilibria and Flows. PhD thesis. TU Berlin, Berlin, Germany.
- Wey12
Weymouth RF (1912). “Problems in natural gas engineering.” In: Trans. Am. Soc. Mech. Eng. 34.1349, pp. 185–231.