This paper deals with the problem of transient optimization of gas transmission networks of arbitrary structure. We assume that the transient state of the network is described by the system of partial differential equations of hyperbolic type expressing mass, momentum and energy conservation in pipes and flow conservation in nodes. The optimization criterion is to minimize the fuel consumption of the compressor stations. Each compressor station can be equipped with gas turbine driven centrifugal compressors and/or motor-compressors, and has a local optimization algorithm for given suction pressure, discharge pressure and flow rate. The results of the solution of the transient flow model in each branch of the network are used to identify compressor station suction pressures and flow rates at each time step. Next the nonlinear programming problem is solved to evaluate the type and the number of simultaneously operating compressors so that the total fuel consumption in each time interval is minimized subject to the constraints imposed. If the difference between consecutive values of the input variables (in subsequent time steps) is less than the accepted value, the optimization algorithm is not altered. Where the difference between the suction and discharge pressure values is less than the minimum, the algorithm switches off the compressor station. The method presented has been verified experimentally on the telemetry data of a large-scale gas network. The practical verification has confirmed the correctness of the algorithm.
Proper functioning of the gas market requires safeguarding security of gas supplies in a competitive market framework. Therefore the operation of the gas network is managed with a view to ensure a secure supply to all customers while at the same time minimizing the operational costs and environmental impact of pipeline operation.