Models, Calculation and Optimization of Gas Networks, Equipment and   Contracts for Design, Operation, Booking and Accounting
  There are proposed models of contracts, technological equipment and gas networks and methods of their optimization. The flow in network undergoes restrictions of contracts and equipment to be operated. The values of sources and sinks are provided by contracts. The contract models represent (sub-) networks. The simplest contracts represent either nodes or edges. Equipment is modeled by edges. More sophisticated equipment is represented by sub-networks. Examples of such equipment are multi-poles and compressor stations with many entries and exits. The edges can be of different types corresponding to equipment and contracts. On such edges, there are given systems of equation and inequalities simulating the contracts and equipment. On this base, the methods proposed that allow: calculation and control of contract values for booking on future days and for accounting of sales and purchases; simulation and optimization of design and of operation of gas networks. These models and methods are implemented in software systems ACCORD and Graphicord as well as in the distributed control system used by Wingas, Germany. As numerical example, the industrial computations are presented. 
Leonid A. Ostromuhov
cs.CE