基于信息熵的燃气输配管网系统可靠性分析

ENTROPY-BASED RELIABILITY ANALYSIS OF PIPELINE SYSTEM FOR GAS TRANSMISSION AND DISTRIBUTION

环状燃气管网具有多条流通路径,路径流量分配的不确定性与可靠性密切相关,而信息熵作为量度不确定性的手段,可间接定量地反映系统的可靠性。为此,基于信息熵理论及最大熵原理提出了路径熵的概念,并以此来定量量度燃气管网中气体从气源至节点流动过程中对路径选择的不确定性。此外,通过定义路径流量比来构建路径熵的概率空间,从而建立了路径熵的计算模型,并提出利用序贯方法、采用分层排序的思想求解模型。最后求解了一个算例中燃气管网的各节点路径熵。结果表明,路径熵间接反映了管网系统的流动阻力特性;路径熵值越大的节点水力性能越好,其上游任一流通路径发生事故时该节点流量损失期望值越小,可靠性越大。

The pipeline system for gas transmission and distribution is the major urban infrastructure. It is very important to guarantee the operation reliability of the system. There are many flow paths in a ring gas pipeline. The uncertainty of flow distribution in the paths is closely correlative with the reliability. The information entropy as the tool to measure the uncertainty may reflect the reliability of the system indirectly and quantitatively. Based on the information entropy theory and maximum entropy principle, the concept of path entropy is proposed. The path entropy is used to quantitatively measure the uncertainty of flow distribution in the paths from the gas source to the nodes. By defining the path flow ratio to establish the probabilistic space of the path entropy, the calculating model of path entropy is developed. And the sequential method and the separate-layer ranking thought are used to solve the model. At last, with the model, the path entropies of the various nodes for a real pipeline system are calculated. The results show the path entropy reflects the features of the flow resistance for the pipeline system indirectly: the bigger the path entropy is, the better the hydraulic capability of the node is; the less the expectation of flow loss of the node is when an accident happens at its any upstream path, the more the reliability is.