Fast simulators of natural gas transmission networks are crucial for efficient system operation, management and design. In particular, the performance of conventional pipeline network simulation software makes it impractical to use mathematical programming methods for designing optimal control strategies based on this simulation. Therefore, parallel programming techniques must be used to improve the performance of simulation. The algorithm for parallel simulation of a natural gas transmission system and its implementation on the transputer network are discussed in this paper. Also presented are the results of the performance evaluation of the simulator implemented on a linear array transputer network.

1 Introduction

To increase the efficiency of planning or operation of gas pipeline networks it is necessary to improve performance of pipeline network simulation software. The performance is especially important when the pipeline network simulator is used for supporting system operation. Faster simulation means that more variants of an operating policy can be tested within a fixed time, and hence better operating decisionscan be made. The numerical algorithms for simulation of gas pipeline networks have reached such a level of advancement that major improvements in the performance of gas network simulators is not possible by simply refining the numerical algorithms. Utilization of more powerful conventional computers also offers limited promise for increasing performance of pipeline network simulators. Mainframe computers are too expensive to be used for pipeline network simulation and do not provide sufficient flexibility to be used in an engineering environment, especially for on-line, real-time operations. In this situation it is necessary to investigate other options which, with a reasonable investment can increase the efficiency of gas pipeline network simulators. The technology suggested for improving the performance of gas pipeline network simulators is parallel computing. Of special interest is parallel computing based on transputer technology. Only two attempts have been reported in the literature to apply parallel computing technology to gas pipeline network simulation. One attempt was made by Schmidt and Meier in Germany [17], the other by Osiadacz in Great Britain [Zl], [22]. The pipeline simulation problem was considered by Singh and others as an example for theoretical analysis of hierarchical simulation algorithms [18], [19] but these results had no impact on the practice of gas pipeline network simulation. Unfortunately, when these papers were written the cost of parallel computers was too high to justify the gains which would be obtained due to faster simulation, and therefore parallel computing technology has never been used in commercial gas pipeline networks simulators. But now, with the availability of transputer technology, the situation has changed. The transputer, developed by INMOS [6], [lo], [25] is a highly powerful, low cost processor with architecture supporting parallel computations. Each processor can communicate with 2 or 4 other processors. As a result, the transputer can be used to build parallel computing networks of various topologies and sizes. Several manufacturers [5] provide transputers as add-on boards to PCs.

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